Nicholas Brown

International comparisons of He-Ne lasers stabilized with 127I2 at λ≈633 nm (July 1993 to September 1995). Part V: Comparison of Asian-Pacific and South African lasers at λ≈633 nm

Publisher: IOP Publishing

Date: 04-2000

DOI: 10.1088/0026-1394/37/2/2

A Comparison of the Wake Structures of Scale and Full-scale Pedalling Cycling Models

Publisher: Elsevier BV

Date: 2016

DOI: 10.1016/J.PROENG.2016.06.182

An Analysis of the Wake of Pedalling Cyclists in a Tandem Formation

Publisher: Elsevier BV

Date: 2016

DOI: 10.1016/J.PROENG.2016.06.181

Increased muscle force does not induce greater stretch-induced damage to calf muscles during work-matched heel drop exercise

Publisher: Springer Science and Business Media LLC

Date: 13-04-2023

DOI: 10.1007/S00421-023-05188-2

Abstract: To investigate the effect of muscle force during active stretch on quantitative and qualitative indicators of exercise-induced muscle damage (EIMD) in the medial gastrocnemius (MG) muscle. Twelve recreationally active volunteers performed two trials of an eccentric heel drop exercise. Participants performed a single bout of low-load (body weight) and high-load (body weight + 30% body weight) exercises on separate legs. The total mechanical work output for each condition was matched between legs. Before, two hours and 48 h after each bout of eccentric exercise, electrically stimulated triceps surae twitch torque, muscle soreness, MG active fascicle length at maximum twitch torque and muscle passive stiffness were collected. Triceps surae electromyographic (EMG) activity, MG fascicle stretch and MG muscle–tendon unit (MTU) length were measured during the eccentric tasks. The high-load condition increased triceps surae muscle activity by 6–9%, but reduced MG fascicle stretch ( p 0.001). MTU stretch was similar between conditions. The greater muscle force during stretch did not give rise to additional torque loss (5 vs 6%) or intensify muscle soreness. Adding 30% body weight during eccentric contractions has a modest impact on exercise-induced muscle damage in the medial gastrocnemius muscle. These results suggest that muscle load may not be an important determinant of stretch-induced muscle damage in the human MG muscle. The muscle investigated does exhibit large pennation angles and high series elastic compliance architectural features that likely buffer muscle fibres against stretch and damage.

Patellofemoral Contact Pressures and Lateral Patellar Translation after Medial Patellofemoral Ligament Reconstruction

Publisher: SAGE Publications

Date: 09-2007

DOI: 10.1177/0363546507300872

Abstract: Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes. Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation. Controlled laboratory study. Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30°, 60°, and 90°) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30° of knee flexion as a 22-N lateral force was applied. Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P .05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P .05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm). Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures. Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.

Deconstructing the power resistance relationship for squats: A joint-level analysis

Publisher: Wiley

Date: 24-06-2016

DOI: 10.1111/SMS.12508

Abstract: Generating high leg power outputs is important for executing rapid movements. Squats are commonly used to increase leg strength and power. Therefore, it is useful to understand factors affecting power output in squatting. We aimed to deconstruct the mechanisms behind why power is maximized at certain resistances in squatting. Ten male rowers (age = 20 ± 2.2 years height = 1.82 ± 0.03 m mass = 86 ± 11 kg) performed maximal power squats with resistances ranging from body weight to 80% of their one repetition maximum (1RM). Three-dimensional kinematics was combined with ground reaction force (GRF) data in an inverse dynamics analysis to calculate leg joint moments and powers. System center of mass (COM) velocity and power were computed from GRF data. COM power was maximized across a range of resistances from 40% to 60% 1RM. This range was identified because a trade-off in hip and knee joint powers existed across this range, with maximal knee joint power occurring at 40% 1RM and maximal hip joint power at 60% 1RM. A non-linear system force-velocity relationship was observed that dictated large reductions in COM power below 20% 1RM and above 60% 1RM. These reductions were due to constraints on the control of the movement.

Sex differences in neuromuscular recruitment are not related to patellar tendon load

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-2014

DOI: 10.1249/MSS.0000000000000252

Late swing or early stance? A narrative review of hamstring injury mechanisms during high-speed running.

Publisher: Wiley

Date: 22-05-2019

DOI: 10.1111/SMS.13437

Abstract: Hamstring injuries are highly prevalent in many running-based sports, and predominantly affect the long head of biceps femoris. Re-injury rates are also high and together lead to considerable time lost from sport. However, the mechanisms for hamstring injury during high-speed running are still not fully understood. Therefore, the aim of this review was to summarize the current literature describing hamstring musculotendon mechanics and electromyography activity during high-speed running, and how they may relate to injury risk. The large eccentric contraction, characterized by peak musculotendon strain and negative work during late swing phase is widely suggested to be potentially injurious. However, it is also argued that high hamstring loads resulting from large joint torques and ground reaction forces during early stance may cause injury. While direct evidence is still lacking, the majority of the literature suggests that the most likely timing of injury is the late swing phase. Future research should aim to prospectively examine the relationship between hamstring musculotendon dynamics and hamstring injury.

Architectural Properties of Distal Forelimb Muscles in Horses, Equus caballus

Publisher: Wiley

Date: 08-2003

DOI: 10.1002/JMOR.10113

Abstract: Articular injuries in athletic horses are associated with large forces from ground impact and from muscular contraction. To accurately and noninvasively predict muscle and joint contact forces, a detailed model of musculoskeletal geometry and muscle architecture is required. Moreover, muscle architectural data can increase our understanding of the relationship between muscle structure and function in the equine distal forelimb. Muscle architectural data were collected from seven limbs obtained from five thoroughbred and thoroughbred-cross horses. Muscle belly rest length, tendon rest length, muscle volume, muscle fiber length, and pennation angle were measured for nine distal forelimb muscles. Physiological cross-sectional area (PCSA) was determined from muscle volume and muscle fiber length. The superficial and deep digital flexor muscles displayed markedly different muscle volumes (227 and 656 cm3, respectively), but their PCSAs were very similar due to a significant difference in muscle fiber length (i.e., the superficial digital flexor muscle had very short fibers, while those of the deep digital flexor muscle were relatively long). The ulnaris lateralis and flexor carpi ulnaris muscles had short fibers (17.4 and 18.3 mm, respectively). These actuators were strong (peak isometric force, Fmax=5,814 and 4,017 N, respectively) and stiff (tendon rest length to muscle fiber length, LT:LMF=5.3 and 2.1, respectively), and are probably well adapted to stabilizing the carpus during the stance phase of gait. In contrast, the flexor carpi radialis muscle displayed long fibers (89.7 mm), low peak isometric force (Fmax=555 N), and high stiffness (LT:LMF=1.6). Due to its long fibers and low Fmax, flexor carpi radialis appears to be better adapted to flexion and extension of the limb during the swing phase of gait than to stabilization of the carpus during stance. Including muscle architectural parameters in a musculoskeletal model of the equine distal forelimb may lead to more realistic estimates not only of the magnitudes of muscle forces, but also of the distribution of forces among the muscles crossing any given joint.

An Emerging Postural Response

Publisher: Informa UK Limited

Date: 07-2004

DOI: 10.3200/JMBR.36.2.147-159

Impedance Control of a Wrist Rehabilitation Robot Based on Autodidact Stiffness Learning

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 08-2022

DOI: 10.1109/TMRB.2022.3194528

Does performance level affect initial ball flight kinematics in finger and wrist-spin cricket bowlers?

Publisher: Informa UK Limited

Date: 22-05-2018

DOI: 10.1080/02640414.2017.1329547

Abstract: Spin bowling plays a fundamental role within the game of cricket yet little is known about the initial ball kinematics in elite and pathway spin bowlers or their relationship to performance. Therefore, the purpose of this study was to record three-dimensional ball kinematics in a large and truly high level cohort of elite and pathway finger-spin (FS) and wrist-spin (WS) bowlers, identifying potential performance measures that can be subsequently used in future research. A 22-camera Vicon motion analysis system captured retro-reflective markers placed on the seam (static) and ball (dynamic) to quantify ball kinematics in 36 FS (12 elite and 24 pathway) and 20 WS (eight elite and 12 pathway) bowlers. Results indicated that FS bowlers delivered the ball with an increased axis of rotation elevation, while wrist-spin bowlers placed greater amounts of revolutions on the ball. It also highlighted that ball release (BR) velocity, revolutions and velocity/revolution index scores for both groups and seam stability for FS bowlers, and seam azimuth angle and spin axis elevation angle for WS bowlers, were discriminators of playing level. As such these variables could be used as indicators of performance (i.e. performance measures) in future research.

Effects of a minimalist shoe on running economy and 5-km running performance

Publisher: Informa UK Limited

Date: 11-01-2016

DOI: 10.1080/02640414.2015.1136071

Abstract: The purpose of this study was to determine if minimalist shoes improve time trial performance of trained distance runners and if changes in running economy, shoe mass, stride length, stride rate and footfall pattern were related to any difference in performance. Twenty-six trained runners performed three 6-min sub-maximal treadmill runs at 11, 13 and 15 km·h(-1) in minimalist and conventional shoes while running economy, stride length, stride rate and footfall pattern were assessed. They then performed a 5-km time trial. In the minimalist shoe, runners completed the trial in less time (effect size 0.20 ± 0.12), were more economical during sub-maximal running (effect size 0.33 ± 0.14) and decreased stride length (effect size 0.22 ± 0.10) and increased stride rate (effect size 0.22 ± 0.11). All but one runner ran with a rearfoot footfall in the minimalist shoe. Improvements in time trial performance were associated with improvements in running economy at 15 km·h(-1) (r = 0.58), with 79% of the improved economy accounted for by reduced shoe mass (P < 0.05). The results suggest that running in minimalist shoes improves running economy and 5-km running performance.

Both-Bone Forearm Osteotomy for Supination Contracture: A Cadaver Model

Publisher: Elsevier BV

Date: 07-2006

DOI: 10.1016/J.JHSA.2006.01.010

Abstract: To quantify the magnitude of rotational correction possible when comparing a single forearm bone osteotomy and fixation with stepwise osteotomy and fixation of both bones in a cadaver model and to determine if the order in which the stepwise osteotomies are performed influences the amount of correction. Ten fresh-frozen cadaveric forearms were fixed to a frame positioned in the field of view of a motion-capture system. An experimental supination contracture was induced in full supination. Cadaver forearms were assigned randomly to group I (ulna osteotomy, rotation, plating) or group II (radius osteotomy, rotation, plating). Cadavers in group I were used later in group III (ulna + radius) by completing a radial osteotomy, rotation, and fixation in the forearms with the plated ulna. Similarly the specimens assigned to group II were used later in group IV (radius + ulna) by completing an ulna osteotomy, rotation, and fixation in the forearms with the plated radiuses. Measurements of forearm pronation were made after single-bone (groups I, II) and stepwise both-bone (groups III, IV) rotational osteotomies. Stepwise rotational osteotomy and fixation of the ulna followed by the radius produced significantly more corrective pronation (101 degrees) than rotating the radius followed by the ulna (65 degrees). Rotating the radius gave only moderate correction (58 degrees) and minimal correction was produced by ulna osteotomy alone (15 degrees). Rotational osteotomy of both forearm bones can create approximately 100 degrees of correction when performed at the proximal ulna followed by the distal radius. If less rotation is needed then the distal radius osteotomy alone can provide approximately 60 degrees of correction.

The development of contact force construction in the dynamic-contact task of cycling

Publisher: Elsevier BV

Date: 2003

DOI: 10.1016/S0021-9290(02)00329-9

Abstract: Purposeful movement requires that an in idual produce appropriate joint torques to accelerate segments, and when environmental contact is involved, to develop task-appropriate contact forces. Developmental research has been confined largely to the mastery of unconstrained movement skills (pointing, kicking). The purpose of this study was to study the developmental progression that characterizes the interaction of muscular and non-muscular forces in tasks constrained by contact with the environment. Seven younger children (YC, 6-8 years), 7 older children (OC, 9-11 years) and 7 adults (AD) pedaled an ergometer (80 rpm) at an anthropometrically scaled cycling power. Resultant forces measured at the pedal's surface were decomposed into muscle, inertia and gravity components. Muscle pedal forces were further examined in terms of the underlying lower extremity joint torques and kinematic weights that constitute the muscular component of the pedal force. Data showed children applied muscle forces to the pedal in a significantly different manner compared to adults, and that this was due to the children's lower segmental mass and inertia. The children adjusted the contribution of the proximal joint muscle torques to compensate for reduced contributions to the resultant pedal force by gravitational and inertial components. These data show that smaller segmental mass and inertia limit younger children's ability to construct the dynamic-contact task of cycling in an adult-like form. On the basis of these results, however, the children's response was not "immature". Rather, the results show a task-appropriate adaptation to lower segmental mass and inertia.

A governing relationship for repetitive muscular contraction

Publisher: Elsevier BV

Date: 08-2000

DOI: 10.1016/S0021-9290(00)00048-8

Abstract: During repetitive contractions, muscular work has been shown to exhibit complex relationships with muscle strain length, cycle frequency, and muscle shortening velocity. Those complex relationships make it difficult to predict muscular performance for any specific set of movement parameters. We hypothesized that the relationship of impulse with cyclic velocity (the product of shortening velocity and cycle frequency) would be independent of strain length and that impulse-cyclic velocity relationships for maximal cycling would be similar to those of in situ muscle performing repetitive contraction. Impulse and power were measured during maximal cycle ergometry with five cycle-crank lengths (120-220mm). Kinematic data were recorded to determine the relationship of pedal speed with joint angular velocity. Previously reported in situ data for rat plantaris were used to calculate values for impulse and cyclic velocity. Kinematic data indicated that pedal speed was highly correlated with joint angular velocity at the hip, knee, and ankle and was, therefore, considered a valid indicator of muscle shortening velocity. Cycling impulse-cyclic velocity relationships for each crank length were closely approximated by a rectangular hyperbola. Data for all crank lengths were also closely approximated by a single hyperbola, however, impulse produced on the 120mm cranks differed significantly from that on all other cranks. In situ impulse-cyclic velocity relationships exhibited similar characteristics to those of cycling. The convergence of the impulse-cyclic velocity relationships from most crank and strain lengths suggests that impulse-cyclic velocity represents a governing relationship for repetitive muscular contraction and thus a single equation can predict muscle performance for a wide range of functional activities. The similarity of characteristics exhibited by cycling and in situ muscle suggests that cycling can serve as a window though which to observe basic muscle function and that investigators can examine similar questions with in vivo and in situ models.

Lower-limb muscle function is influenced by changing mechanical demands in cycling

Publisher: The Company of Biologists

Date: 2020

DOI: 10.1242/JEB.228221

Abstract: Although cycling is often considered a seemingly simple, reciprocal task, muscles must adapt their function to satisfy changes in mechanical demands induced by higher crank torques and faster pedalling cadences. We examined if muscle function was sensitive to these changes in mechanical demands across a wide range of pedalling conditions. We collected experimental data of cycling where crank torque and pedalling cadence were independently varied from 13-44 Nm and 60-140 RPM. These data were used in conjunction with musculoskeletal simulations and a recently developed functional index-based approach to characterise the role of the human lower-limb muscles. We found that in muscles that generate most of the mechanical power and work during cycling, greater crank torque induced shifts towards greater muscle activation, greater positive muscle-tendon unit (MTU) work and a more motor-like function, particularly in the limb extensors. Conversely, with faster pedalling cadence, the same muscles exhibited a phase advance in muscle activity prior to crank top dead centre, which led to greater negative MTU power and work and shifted the muscles to contract with more spring-like behaviour. Our results illustrate the capacity for muscles to adapt their function to satisfy the mechanical demands of the task, even during highly constrained reciprocal tasks such as cycling. Understanding how muscles shift their contractile performance under varied mechanical and environmental demands may inform decisions on how to optimise pedalling performance and to design targeted cycling rehabilitation therapies for muscle-specific injuries or deficits.

Stretch and activation of the human biarticular hamstrings across a range of running speeds

Publisher: Springer Science and Business Media LLC

Date: 08-09-2013

DOI: 10.1007/S00421-013-2713-9

Abstract: The human biarticular hamstrings [semimembranosus (SM), semitendinosus (ST) and biceps femoris long head (BF(LH))] have an important role in running. This study determined how hamstrings neuro-mechanical behaviour changed with faster running, and whether differences existed between SM, ST and BF(LH). Whole-body kinematics and hamstrings electromyographic (EMG) activity were measured from seven participants running at four discrete speeds (range: 3.4 ± 0.1 to 9.0 ± 0.7 m/s). Kinematic data were combined with a three-dimensional musculoskeletal model to calculate muscle-tendon unit (MTU) stretch and velocity. Activation duration and magnitude were determined from EMG data. With faster running, MTU stretch and velocity patterns remained similar, but maxima and minima significantly increased. The hamstrings were activated from foot-strike until terminal stance or early swing, and then again from mid-swing until foot-strike. Activation duration was similar with faster running, whereas activation magnitude significantly increased. Hamstrings activation almost always ended before minimum MTU stretch, and it always started before maximum MTU stretch. Comparing the hamstrings, maximum MTU stretch was largest for BF(LH) and smallest for ST irrespective of running speed, while the opposite was true for peak-to-peak MTU stretch. Furthermore, peak MTU shortening velocity was largest for ST and smallest for BF(LH) at all running speeds. Finally, for the two fastest running speeds, the amount of MTU stretch that occurred during terminal swing after activation had started was less for BF(LH) compared to SM and ST. Differences were evident in biarticular hamstrings neuro-mechanical behaviour during running. Such findings have implications for hamstrings function and injury.

Torsional stability of intramedullary compression nails: Tibial osteotomy model

Publisher: Elsevier BV

Date: 05-2007

DOI: 10.1016/J.CLINBIOMECH.2006.11.009

Abstract: Studies comparing intramedullary compression nailing to conventional dynamized intramedullary nailing contend that better clinical outcomes of intramedullary compression techniques result from greater rotational stability of fracture or osteotomy sites. However, there appears to be no experimental evidence that rotational stability is improved with intramedullary nail compression. This study evaluated the effect of intramedullary nail compression on cadaveric and composite tibial fragment rotation above and below a mid-tibial transverse osteotomy. Twelve composite and four matched pairs of human cadaveric tibiae were randomized into either a compression group or a non-compressed dynamized group. A bi-axial servo-hydraulic testing machine applied 5Nm of internal and external torque (2Nm/s) under constant axial loads of 375N and 750N. Rotation along each tibia and at the osteotomy site was recorded from the trajectories of infrared emitting diodes rigidly attached along the tibial shaft. In comparison to dynamized nails, intramedullary nail compression significantly reduced the rotation at the osteotomy site in both human (8.9 degrees reduction P=0.007) and composite tibiae (2.5 degrees reduction P=0.039) under 750N of axial load. A similar result was noted for simulated half-body weight loads (375N) for both composite (3.0 degrees reduction P=0.009) and human tibiae (10.5 degrees reduction P=0.003). Intramedullary nail compression more effectively reduced tibial fragment rotation about a mid-tibial osteotomy than conventional dynamized intramedullary nails because intramedullary nails created more osteotomy site compression than the application of body weight to tibiae instrumented with dynamized intramedullary nails.

Flow topology in the wake of a cyclist and its effect on aerodynamic drag

Publisher: Cambridge University Press (CUP)

Date: 28-04-2014

DOI: 10.1017/JFM.2013.678

Abstract: Three-dimensional flows around a full-scale cyclist mannequin were investigated experimentally to explain the large variations in aerodynamic drag that are measured as the legs are positioned around the $360^\\circ $ crank cycle. It is found that the dominant mechanism affecting drag is not the small variation in frontal surface area over the pedal stroke but rather due to large changes in the flow structure over the crank cycle. This is clearly shown by a series of detailed velocity field wake surveys and skin friction flow visualizations. Two characteristic flow regimes are identified, corresponding to symmetrical low-drag and asymmetrical high-drag regimes, in which the primary feature of the wake is shown to be a large trailing streamwise vortex pair, orientated asymmetrically in the centre plane of the mannequin. These primary flow structures in the wake are the dominant mechanism driving the variation in drag throughout the pedal stroke. Topological critical points have been identified on the suction surfaces of the mannequin’s back and are discussed with velocity field measurements to elucidate the time-average flow topologies, showing the primary flow structures of the low- and high-drag flow regimes. The proposed flow topologies are then related to the measured surface pressures acting on the suction surface of the mannequin’s back. These measurements show that most of the variation in drag is due to changes in the pressure distribution acting on the lower back, where the large-scale flow structures having the greatest impact on drag develop.

Prediction models for venous thromboembolism in ambulatory adults with pancreatic and gastro-oesophageal cancer: protocol for systematic review and meta-analysis

Publisher: BMJ

Date: 03-2022

DOI: 10.1136/BMJOPEN-2021-056431

Abstract: Venous thromboembolism (VTE) is a common complication of cancer. Pancreatic and gastro-oesophageal cancers are among malignancies that have the highest rates of VTE occurrence. VTE can increase cancer-related morbidity and mortality and disrupt cancer treatment. The risk of VTE can be managed with measures such as using anticoagulant drugs, although the risk of bleeding may be an impeding factor. Therefore, a VTE risk assessment should be performed before the start of anticoagulation in in idual patients. Several prediction models have been published, but most of them have low sensitivity and unknown clinical applicability in pancreatic or gastro-oesphageal cancers. We intend to do this systematic review to identify all applicable published predictive models and compare their performance in those types of cancer. All studies in which a prediction model for VTE have been developed, validated or compared using adult ambulatory patients with pancreatic or gastro-oesphageal cancers will be identified and the reported predictive performance indicators will be extracted. Full text peer-reviewed journal articles of observational or experimental studies published in English will be included. Five databases (Medline, EMBASE, Web of Science, CINAHL and Cochrane) will be searched. Two reviewers will independently undertake each of the phases of screening, data extraction and risk of bias assessment. The quality of the selected studies will be assessed using Prediction model Risk Of Bias Assessment Tool. The results from the review will be used for a narrative information synthesis, and if the same models have been validated in multiple studies, meta-analyses will be done to pool the predictive performance measures. There is no need for ethics approval because the review will use previously peer-reviewed articles. The results will be published. CRD42021253887.

Mechanical loading of the distal end of the third metacarpal bone in horses during walking and trotting

Publisher: American Veterinary Medical Association (AVMA)

Date: 05-2010

DOI: 10.2460/AJVR.71.5.508

Abstract: Objective —To assess the net mechanical load on the distal end of the third metacarpal bone in horses during walking and trotting. Animals —3 Quarter Horses and 1 Thoroughbred. Procedures —Surface strains measured on the left third metacarpal bone of the Thorough-bred were used with a subject-specific model to calculate loading (axial compression, bending, and torsion) of the structure during walking and trotting. Forelimb kinematics and ground reaction forces measured in the 3 Quarter Horses were used with a musculoskeletal model of the distal portion of the forelimb to determine loading of the distal end of the third metacarpal bone. Results —Both methods yielded consistent data regarding mechanical loading of the distal end of the third metacarpal bone. During walking and trotting, the distal end of the third metacarpal bone was loaded primarily in axial compression as a result of the sum of forces exerted on the metacarpal condyles by the proximal phalanx and proximal sesamoid bones. Conclusions and Clinical Relevance —Results of strain gauge and kinematic analyses indicated that the major structures of the distal portion of the forelimb in horses acted to load the distal end of the third metacarpal bone in axial compression throughout the stance phase of the stride.

Redistribution of Mechanical Work at the Knee and Ankle Joints During Fast Running in Minimalist Shoes

Publisher: Journal of Athletic Training/NATA

Date: 10-2016

DOI: 10.4085/1062-6050-51.12.05

Abstract: Context: Minimalist shoes have been suggested as a way to alter running biomechanics to improve running performance and reduce injuries. However, to date, researchers have only considered the effect of minimalist shoes at slow running speeds. Objective: To determine if runners change foot-strike pattern and alter the distribution of mechanical work at the knee and ankle joints when running at a fast speed in minimalist shoes compared with conventional running shoes. Design: Crossover study. Setting: Research laboratory. Patients or Other Participants: Twenty-six trained runners (age = 30.0 ± 7.9 years [age range, 18−40 years], height = 1.79 ± 0.06 m, mass = 75.3 ± 8.2 kg, weekly training distance = 27 ± 15 km) who ran with a habitual rearfoot foot-strike pattern and had no experience running in minimalist shoes. Intervention(s): Participants completed overground running trials at 18 km/h in minimalist and conventional shoes. Main Outcome Measure(s): Sagittal-plane kinematics and joint work at the knee and ankle joints were computed using 3-dimensional kinematic and ground reaction force data. Foot-strike pattern was classified as rearfoot, midfoot, or forefoot strike based on strike index and ankle angle at initial contact. Results: We observed no difference in foot-strike classification between shoes (χ21 = 2.29, P = .13). Ankle angle at initial contact was less (2.46° versus 7.43° t25 = 3.34, P = .003) and strike index was greater (35.97% versus 29.04% t25 = 2.38, P = .03) when running in minimalist shoes compared with conventional shoes. We observed greater negative (52.87 J versus 42.46 J t24 = 2.29, P = .03) and positive work (68.91 J versus 59.08 J t24 = 2.65, P = .01) at the ankle but less negative (59.01 J versus 67.02 J t24 = 2.25, P = .03) and positive work (40.37 J versus 47.09 J t24 = 2.11, P = .046) at the knee with minimalist shoes compared with conventional shoes. Conclusions: Running in minimalist shoes at a fast speed caused a redistribution of work from the knee to the ankle joint. This finding suggests that runners changing from conventional to minimalist shoes for short-distance races could be at an increased risk of ankle and calf injuries but a reduced risk of knee injuries.

Automated Stimulus-Response Mapping of High-Electrode-Count Neural Implants

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 10-2009

DOI: 10.1109/TNSRE.2009.2029494

Dominant flow structures in the wake of a cyclist

Publisher: American Institute of Aeronautics and Astronautics

Date: 25-06-2012

DOI: 10.2514/6.2012-3212

Six-week transition to minimalist shoes improves running economy and time-trial performance

Publisher: Elsevier BV

Date: 12-2017

DOI: 10.1016/J.JSAMS.2017.04.013

Abstract: This study investigated if gradually introducing runners to minimalist shoes during training improved running economy and time-trial performance compared to training in conventional shoes. Changes in stride rate, stride length, footfall pattern and ankle plantar-flexor strength were also investigated. Randomised parallel intervention trial. 61 trained runners gradually increased the amount of running performed in either minimalist (n=31) or conventional (n=30) shoes during a six-week standardised training program. 5-km time-trial performance, running economy, ankle plantar-flexor strength, footfall pattern, stride rate and length were assessed in the allocated shoes at baseline and after training. Footfall pattern was determined from the time differential between rearfoot and forefoot (TD The minimalist shoe group improved time-trial performance (effect size (ES): 0.24 95% confidence interval (CI): 0.01, 0.48 p=0.046) and running economy (ES 0.48 95%CI: 0.22, 0.74 p<0.001) more than the conventional shoe group. There were no minimalist shoe training effects on ankle plantar-flexor concentric (ES: 0.11 95%CI: -0.18, 0.41 p=0.45), isometric (ES: 0.23 95%CI: -0.17, 0.64 p=0.25), or eccentric strength (ES: 0.24 95%CI: -0.17, 0.65 p=0.24). Minimalist shoes caused large reductions in TD Gradually introducing minimalist shoes over a six-week training block is an effective method for improving running economy and performance in trained runners.

A quasi-static investigation of the effect of leg position on cyclist aerodynamic drag

Publisher: Elsevier BV

Date: 2012

DOI: 10.1016/J.PROENG.2012.04.002

Determination of football pitch locations from video footage and official pitch markings

Publisher: Informa UK Limited

Date: 06-2009

DOI: 10.1080/14763140902829342

Abstract: The ability to determine a specific location on a football (soccer) pitch from television footage would provide a cost-effective method of obtaining competition-specific information on many professional and international teams. This study presents the accuracy and reliability of a new method of calculating ball location from simulated television coverage and known pitch markings. The coordinates of 99 markers of known location on a football pitch were digitized from video. An intersection point was determined from the equations of two lines that form pitch markings and the relationship from this point to other known pitch coordinates was calculated using a curve-fitting based method. Average error between known and reconstructed measures was 0.21 m for pitch width and 0.11 m for pitch length from a view simulating television coverage. Inter- and intra-rater reliability analyses showed researchers could consistently reconstruct pitch locations to within less than half a metre. The accuracy and reliability of this method will be sufficient for most practical uses in an applied sport environment, although the level of accuracy required will depend on the specific application. This method could be applied to other sports to determine specific locations on a pitch or court or to improve current competition analysis systems.

Mechanics of the human hamstring muscles during sprinting

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-2012

DOI: 10.1249/MSS.0B013E318236A3D2

Human ankle plantar flexor muscle–tendon mechanics and energetics during maximum acceleration sprinting

Publisher: The Royal Society

Date: 08-2016

DOI: 10.1098/RSIF.2016.0391

Abstract: Tendon elastic strain energy is the dominant contributor to muscle–tendon work during steady-state running. Does this behaviour also occur for sprint accelerations? We used experimental data and computational modelling to quantify muscle fascicle work and tendon elastic strain energy for the human ankle plantar flexors (specifically soleus and medial gastrocnemius) for multiple foot contacts of a maximal sprint as well as for running at a steady-state speed. Positive work done by the soleus and medial gastrocnemius muscle fascicles decreased incrementally throughout the maximal sprint and both muscles performed more work for the first foot contact of the maximal sprint (FC1) compared with steady-state running at 5 m s −1 (SS5). However, the differences in tendon strain energy for both muscles were negligible throughout the maximal sprint and when comparing FC1 to SS5. Consequently, the contribution of muscle fascicle work to stored tendon elastic strain energy was greater for FC1 compared with subsequent foot contacts of the maximal sprint and compared with SS5. We conclude that tendon elastic strain energy in the ankle plantar flexors is just as vital at the start of a maximal sprint as it is at the end, and as it is for running at a constant speed.

A communal catalogue reveals Earth’s multiscale microbial diversity

Publisher: Springer Science and Business Media LLC

Date: 11-2017

DOI: 10.1038/NATURE24621

Abstract: Our growing awareness of the microbial world’s importance and ersity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community s les collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of ersity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial ersity.

Multimodal physiological sensing for the assessment of acute pain

Publisher: Frontiers Media SA

Date: 19-06-2023

DOI: 10.3389/FPAIN.2023.1150264

Abstract: Pain assessment is a challenging task encountered by clinicians. In clinical settings, patients’ self-report is considered the gold standard in pain assessment. However, patients who are unable to self-report pain are at a higher risk of undiagnosed pain. In the present study, we explore the use of multiple sensing technologies to monitor physiological changes that can be used as a proxy for objective measurement of acute pain. Electrodermal activity (EDA), photoplethysmography (PPG), and respiration (RESP) signals were collected from 22 participants under two pain intensities (low and high) and on two different anatomical locations (forearm and hand). Three machine learning models were implemented, including support vector machines (SVM), decision trees (DT), and linear discriminant analysis (LDA) for the identification of pain. Various pain scenarios were investigated, identification of pain (no pain, pain), multiclass (no pain, low pain, high pain), and identification of pain location (forearm, hand). Reference classification results from in idual sensors and from all sensors together were obtained. After feature selection, results showed that EDA was the most informative sensor in the three pain conditions, 93.2 ± 8 % in identification of pain, 68.9 ± 10 % in the multiclass problem, and 56.0 ± 8 % for the identification of pain location. These results identify EDA as the superior sensor in our experimental conditions. Future work is required to validate the obtained features to improve its feasibility in more realistic scenarios. Finally, this study proposes EDA as a candidate to design a tool that can assist clinicians in the assessment of acute pain of nonverbal patients.

A retrospective analysis of hamstring injuries in elite rugby athletes: More severe injuries are likely to occur at the distal myofascial junction

Publisher: Elsevier BV

Date: 07-2019

DOI: 10.1016/J.PTSP.2019.05.009

Abstract: To describe the most common hamstring injury scenarios and outcomes in elite rugby union. Retrospective investigation. Hamstring injury data from an elite rugby union team was collected over five seasons and retrospectively analysed. 74 professional rugby players. Injuries were classified as new or recurrent. Injury severity, activity, player position, and whether the injury occurred during a match or training was determined for each injury. Injury location and grade were determined for more clinically severe injuries where Magnetic Resonance Imaging (MRI) data was available (15 injuries). Thirty hamstring injuries were sustained over the five seasons. The majority of injuries were new (93%), moderate in severity (60%) and occurred during running (77%). For more clinically severe injuries, the biceps femoris long head (BFlh) was the most commonly injured muscle (73%) and the distal myofascial junction (DMFJ) was the most common injury site (58% of BFlh injuries). Hamstring injuries most commonly occurred while running and in the BFlh muscle, which is similar to other sports. However, the most common intramuscular injury site was the DMFJ, which contrasts with reports from other cohorts. Future studies should ensure to include the myofascial junction when classifying injury location.

Cyclic eccentric stretching induces more damage and improved subsequent protection than stretched isometric contractions in the lower limb

Publisher: Springer Science and Business Media LLC

Date: 26-08-2021

DOI: 10.1007/S00421-021-04787-1

Hamstring musculotendon mechanics of prospectively injured elite rugby athletes

Publisher: Informa UK Limited

Date: 16-03-2023

DOI: 10.1080/15438627.2023.2189115

Erratum to “The development of contact force construction in the dynamic-contact task of cycling”

Publisher: Elsevier BV

Date: 04-2003

DOI: 10.1016/S0021-9290(02)00478-5

Static Versus Dynamic Loading in the Mechanical Modulation of Vertebral Growth

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 12-2006

DOI: 10.1097/01.BRS.0000248810.77151.22

Evaluation of a new fenestrated needle for ultrasound-guided fascia iliaca block

Publisher: Elsevier BV

Date: 05-2007

DOI: 10.1016/J.JCLINANE.2006.08.010

Abstract: To evaluate a new 20-gauge (G) fenestrated needle designed to be used with ultrasound guidance to deliver local anesthetic into the tissue plane of the fascia iliaca without immediate proximity to the femoral nerve. Prospective study. University hospital. 15 male volunteers. To determine the onset of motor and sensory block after ultrasound-guided injection of 1% lidocaine and iopamidol, fluoroscopy was performed during and after injection to discover the pattern of local anesthetic distribution. The buckling strength of the new needle was compared using a standard mechanical testing protocol to a conventional 22-G needle (Quincke type). Injection through the fenestrated needle consistently produced sensory block in the anterior, medial, and lateral aspects of the thigh. All subjects were also observed to have loss of motor function in the quadriceps muscle. No subject experienced motor effect in the adductor muscles of the thigh. The fenestrated 20-G needle yielded at significantly larger compressive forces than did the standard 22-G needle (P < 0.001). The needle is novel in that it does not require immediate proximity to the femoral nerve or precise placement of the needle tip in the plane of the fascia iliaca. The 20-G fenestrated needle is stronger under compressive force than existing 22-G needles.

In vivo behavior of the human soleus muscle with increasing walking and running speeds

Publisher: American Physiological Society

Date: 15-05-2015

DOI: 10.1152/JAPPLPHYSIOL.00128.2015

Abstract: The interaction between the muscle fascicle and tendon components of the human soleus (SO) muscle influences the capacity of the muscle to generate force and mechanical work during walking and running. In the present study, ultrasound-based measurements of in vivo SO muscle fascicle behavior were combined with an inverse dynamics analysis to investigate the interaction between the muscle fascicle and tendon components over a broad range of steady-state walking and running speeds: slow-paced walking (0.7 m/s) through to moderate-paced running (5.0 m/s). Irrespective of a change in locomotion mode (i.e., walking vs. running) or an increase in steady-state speed, SO muscle fascicles were found to exhibit minimal shortening compared with the muscle-tendon unit (MTU) throughout stance. During walking and running, the muscle fascicles contributed only 35 and 20% of the overall MTU length change and shortening velocity, respectively. Greater levels of muscle activity resulted in increasingly shorter SO muscle fascicles as locomotion speed increased, both of which facilitated greater tendon stretch and recoil. Thus the elastic tendon contributed the majority of the MTU length change during walking and running. When transitioning from walking to running near the preferred transition speed (2.0 m/s), greater, more economical ankle torque development is likely explained by the SO muscle fascicles shortening more slowly and operating on a more favorable portion (i.e., closer to the plateau) of the force-length curve.

Computational fluid dynamics study of the effect of leg position on cyclist aerodynamic drag

Publisher: ASME International

Date: 24-07-2014

DOI: 10.1115/1.4027428

Abstract: An experimental and numerical analysis of cycling aerodynamics is presented. The cyclist is modeled experimentally by a mannequin at static crank angle numerically, the cyclist is modeled using a computer aided design (CAD) reproduction of the geometry. Wind tunnel observation of the flow reveals a large variation of drag force and associated downstream flow structure with crank angle at a crank angle of 15 deg, where the two thighs of the rider are aligned, a minimum in drag is observed. At a crank angle of 75 deg, where one leg is at full extension and the other is raised close to the torso, a maximum in drag is observed. Simulation of the flow using computational fluid dynamics (CFD) reproduces the observed variation of drag with crank angle, but underpredicts the experimental drag measurements by approximately 15%, probably at least partially due to simplification of the geometry of the cyclist and bicycle. Inspection of the wake flow for the two sets of results reveals a good match in the downstream flow structure. Numerical simulation also reveals the transient nature of the entire flow field in greater detail. In particular, it shows how the flow separates from the body of the cyclist, which can be related to changes in the overall drag.

Modulation of work and power by the human lower-limb joints with increasing steady-state locomotion speed

Publisher: The Company of Biologists

Date: 2015

DOI: 10.1242/JEB.119156

Abstract: We investigated how the human lower-limb joints modulate work and power during walking and running on level ground. Experimental data were recorded from seven participants for a broad range of steady-state locomotion speeds (walking at 1.59±0.09 m/s to sprinting at 8.95±0.70 m/s). We calculated hip, knee and ankle work and average power (i.e., over time), along with the relative contribution from each joint towards the total (sum of hip, knee and ankle) amount of work and average power produced by the lower-limb. Irrespective of locomotion speed, ankle positive work was greatest during stance, whereas hip positive work was greatest during swing. Ankle positive work increased with faster locomotion until a running speed of 5.01±0.11 m/s, where it plateaued at ∼1.3 J/kg. In contrast, hip positive work during stance and swing, as well as knee negative work during swing, all increased when running speed progressed beyond 5.01±0.11 m/s. When switching from walking to running at the same speed (∼2.0 m/s), the ankle's contribution to the average power generated (and positive work done) by the lower limb during stance significantly increased from 52.7±10.4% to 65.3±7.5% (p=0.001), whereas the hip's contribution significantly decreased from 23.0±9.7% to 5.5±4.6% (p=0.004). With faster running, the hip's contribution to the average power generated (and positive work done) by the lower limb significantly increased during stance (p& .001) and swing (p=0.003). Our results suggest that changing locomotion mode and faster steady-state running speeds are not simply achieved via proportional increases in work and average power at the lower-limb joints.

Illegal bowling actions contribute to performance in cricket finger‐spin bowlers

Publisher: Wiley

Date: 27-02-2018

DOI: 10.1111/SMS.13070

Abstract: With advances in technology, scientists are now able to more accurately measure elbow displacement changes during the cricket bowling action. This has led to the realization that the majority of bowlers undergo some degree of elbow extension during the forward swing phase of bowling. Consequently, the International Cricket Council were obliged to revise the once zero tolerance for elbow extension threshold to a 15° range. However, it is still not understood if bowling with >15° of elbow extension aids performance or alters other kinematic movements. The purpose of this study was to compare performance and technique measures between legal and illegal finger-spin bowlers. Data were collected from 48 pathway and elite bowlers using a 22-camera motion analysis system. Results indicated that the ball velocity and revolutions at ball release of pathway bowlers with illegal actions showed no significant difference and were similar to elite legal bowlers. Technique differences were also identified, with illegal bowlers being more front-on, forcing a reliance on increased elbow flexion and supination to impart effective ball kinematics at ball release. The performance benefit of greater ball velocity and revolutions is obtained when finger-spin bowlers deliver the ball with more than the allowable 15° of elbow extension, thus reinforcing the validity of the current bowling laws. To counteract bowling with an illegal action, it is recommended that a more side-on technique at back foot impact and rotating the trunk through to the point of ball release will assist bowlers in reducing undesirable elbow extension levels.

While allied health students prefer face-to-face clinical placement, telehealth can support competency development: results from a mixed-methods study.

Publisher: Frontiers Media SA

Date: 15-05-2023

DOI: 10.3389/FMED.2023.1151980

Abstract: Student clinical placements are a mandatory requirement within most accredited health programs. During the COVID-19 pandemic, many health settings that had traditionally provided placements cancelled their offerings. Telehealth services however, increased and emerged as an alternative placement setting. To compare the learning experiences for allied health students provided by telehealth and face-to-face accredited health placements. Health students, from a university clinic between March to December 2020, delivering both face-to-face and telehealth consultations, were invited to complete a telephone survey with 3 demographic questions and 10-items comparing their telehealth and face-to-face learning experiences. Pearson’s chi-squared/Fisher’s exact test was used to examine the association between each item and consultation setting. Qualitative survey data was thematically analysed using a descriptive approach. 49 students from 2 universities and 5 disciplines completed the survey. Students rated their face-to-face experiences significantly higher than their telehealth experiences across all items (all p -values & .01). Across 9 items students reported positive learning experiences in both settings. Students had greater opportunities to work in a multidisciplinary team in a face-to-face setting. Four themes were generated: (1) placements can vary in quality regardless of setting (2) telehealth can provide valuable learning experiences and support competency development (3) enablers for telehealth placements and (4) barriers for telehealth placements. While telehealth can support student learning and competency development, in this study students preferred face-to-face experiences. To optimise telehealth placements consideration needs to be given to barriers and enablers such as technological issues and university curricula preparation.

The long-term effect of minimalist shoes on running performance and injury: design of a randomised controlled trial

Publisher: BMJ

Date: 08-2015

DOI: 10.1136/BMJOPEN-2015-008307

A numerical model for the time-dependent wake of a pedalling cyclist

Publisher: SAGE Publications

Date: 09-07-2019

DOI: 10.1177/1754337119858434

Abstract: A method for computing the wake of a pedalling cyclist is detailed and assessed through comparison with experimental studies. The large-scale time-dependent turbulent flow is simulated using the Scale Adaptive Simulation approach based on the Shear Stress Transport Reynolds-averaged Navier–Stokes model. Importantly, the motion of the legs is modelled by joining the model at the hips and knees and imposing solid body rotation and translation to the lower and upper legs. Rapid distortion of the cyclist geometry during pedalling requires frequent interpolation of the flow solution onto new meshes. The impact of numerical errors, that are inherent to this remeshing technique, on the computed aerodynamic drag force is assessed. The dynamic leg simulation was successful in reproducing the oscillation in the drag force experienced by a rider over the pedalling cycle that results from variations in the large-scale wake flow structure. Aerodynamic drag and streamwise vorticity fields obtained for both static and dynamic leg simulations are compared with similar experimental results across the crank cycle. The new technique presented here for simulating pedalling leg cycling flows offers one pathway for improving the assessment of cycling aerodynamic performance compared to using isolated static leg simulations alone, a practice common in optimising the aerodynamics of cyclists through computational fluid dynamics.

A Low-Cost Instrumented Spatial Linkage Accurately Determines ASIS Position during Cycle Ergometry

Publisher: Human Kinetics

Date: 08-2007

DOI: 10.1123/JAB.23.3.224

Abstract: The purpose of this study was to develop and evaluate an alternative method for determining the position of the anterior superior iliac spine (ASIS) during cycling. The approach used in this study employed an instrumented spatial linkage (ISL) system to determine the position of the ASIS in the parasagittal plane. A two-segment ISL constructed using aluminum segments, bearings, and digital encoders was tested statically against a calibration plate and dynamically against a video-based motion capture system. Four well-trained cyclists provided data at three pedaling rates. Statically, the ISL had a mean horizontal error of 0.03 ± 0.21 mm and a mean vertical error of −0.13 ± 0.59 mm. Compared with the video-based motion capture system, the agreement of the location of the ASIS had a mean error of 0.30 ± 0.55 mm for the horizontal dimension and −0.27 ± 0.60 mm for the vertical dimension. The ISL system is a cost-effective, accurate, and valid measure for two-dimensional kinematic data within a range of motion typical for cycling.

Longer-term effects of minimalist shoes on running performance, strength and bone density: a 20-week follow-up study

Publisher: Informa UK Limited

Date: 13-08-2019

DOI: 10.1080/17461391.2018.1505958

Abstract: This study investigated whether male runners improve running performance, running economy, ankle plantar flexor strength, and alter running biomechanics and lower limb bone mineral density when gradually transitioning to using minimalist shoes for 100% of weekly running. The study was a planned follow-up of runners (n = 50) who transitioned to minimalist or conventional shoes for 35% of weekly structured training in a previous 6-week randomised controlled trial. In that trial, running performance and economy improved more with minimalist shoes than conventional shoes. Runners in each group were instructed to continue running in their allocated shoe during their own preferred training programme for a further 20 weeks while increasing allocated shoe use to 100% of weekly training. At the 20-week follow-up, minimalist shoes did not affect performance (effect size: 0.19 p = 0.218), running economy (effect size: ≤ 0.24 p ≥ 0.388), stride rate or length (effect size: ≤ 0.12 p ≥ 0.550), foot strike (effect size: ≤ 0.25 p ≥ 0.366), or bone mineral density (effect size: ≤ 0.40 p ≥ 0.319). Minimalist shoes increased plantar flexor strength more than conventional shoes when runners trained with greater mean weekly training distances (shoe*distance interaction: p = 0.036). After greater improvements with minimalist shoes during the initial six weeks of a structured training programme, increasing minimalist shoe use from 35% to 100% over 20 weeks, when runners use their own preferred training programme, did not further improve performance, running economy or alter running biomechanics and lower limb bone mineral density. Minimalist shoes improved plantar flexor strength more than conventional shoes in runners with greater weekly training distances.

Curve and instep kick kinematics in elite female footballers

Publisher: Informa UK Limited

Date: 02-2012

DOI: 10.1080/02640414.2011.643238

Abstract: The three-dimensional kinematics of international female footballers performing a simulated direct free kick (curve kick) were compared with those of an instep kick. Reflective markers attached to the participants were tracked by 17 Vicon cameras s ling at 250 Hz. Foot velocity at ball impact did not differ between the two types of kick, but the way in which foot velocity was generated did differ, with instep kicks using a faster approach velocity and greater linear velocities of the hip and knee, and curve kicks using a greater knee angular velocity at impact. In both types of kick, peak knee angular velocity and peak ankle linear velocity occurred at ball impact, providing biomechanical support to the common coaching recommendation of kicking through the ball. To achieve a curved ball trajectory, players should take a wide approach angle, point the support foot to the right of the intended target (for right-footed players), swing the kicking limb across the face of the goal, and impact the ball with the foot moving upwards and in an abducted position. This information will be useful to coaches and players in identifying the fundamental coaching points necessary to achieve a curved trajectory of the ball compared with the more commonly described instep kick kinematics.

Changes in muscle coordination and power output during sprint cycling

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.NEULET.2014.05.023

Abstract: This study investigated the changes in muscle coordination associated to power output decrease during a 30-s isokinetic (120rpm) cycling sprint. Modifications in EMG litude and onset/offset were investigated from eight muscles [gluteus maximus (EMGGMAX), vastus lateralis and medialis obliquus (EMGVAS), medial and lateral gastrocnemius (EMGGAS), rectus femoris (EMGRF), biceps femoris and semitendinosus (EMGHAM)]. Changes in co-activation of four muscle pairs (CAIGMAX/GAS, CAIVAS/GAS, CAIVAS/HAM and CAIGMAX/RF) were also calculated. Substantial power reduction (60±6%) was accompanied by a decrease in EMG litude for all muscles other than HAM, with the greatest deficit identified for EMGRF (31±16%) and EMGGAS (20±14%). GASonset, HAMonset and GMAXonset shifted later in the pedalling cycle and the EMG offsets of all muscles (except GASoffset) shifted earlier as the sprint progressed (P<0.05). At the end of the sprint, CAIVAS/GAS and CAIGMAX/GAS were reduced by 48±10% and 43±12%, respectively. Our results show that substantial power reduction during fatiguing sprint cycling is accompanied by marked reductions in the EMG activity of bi-articular GAS and RF and co-activation level between GAS and main power producer muscles (GMAX and VAS). The observed changes in RF and GAS EMG activity are likely to result in a redistribution of the joint powers and alterations in the orientation of the pedal forces.

Stiffening the human foot with a biomimetic exotendon

Publisher: Springer Science and Business Media LLC

Date: 23-11-2021

DOI: 10.1038/S41598-021-02059-8

Abstract: Shoes are generally designed protect the feet against repetitive collisions with the ground, often using thick viscoelastic midsoles to add in-series compliance under the human. Recent footwear design developments have shown that this approach may also produce metabolic energy savings. Here we test an alternative approach to modify the foot–ground interface by adding additional stiffness in parallel to the plantar aponeurosis, targeting the windlass mechanism. Stiffening the windlass mechanism by about 9% led to decreases in peak activation of the ankle plantarflexors soleus (~ 5%, p 0.001) and medial gastrocnemius (~ 4%, p 0.001), as well as a ~ 6% decrease in positive ankle work (p 0.001) during fixed-frequency bilateral hopping (2.33 Hz). These results suggest that stiffening the foot may reduce cost in dynamic tasks primarily by reducing the effort required to plantarflex the ankle, since peak activation of the intrinsic foot muscle abductor hallucis was unchanged (p = 0.31). Because the novel exotendon design does not operate via the compression or bending of a bulky midsole, the device is light (55 g) and its profile is low enough that it can be worn within an existing shoe.

A systematic review of neurophysiological sensing for the assessment of acute pain

Publisher: Springer Science and Business Media LLC

Date: 26-04-2023

DOI: 10.1038/S41746-023-00810-1

Abstract: Pain is a complex and personal experience that presents erse measurement challenges. Different sensing technologies can be used as a surrogate measure of pain to overcome these challenges. The objective of this review is to summarise and synthesise the published literature to: (a) identify relevant non-invasive physiological sensing technologies that can be used for the assessment of human pain, (b) describe the analytical tools used in artificial intelligence (AI) to decode pain data collected from sensing technologies, and (c) describe the main implications in the application of these technologies. A literature search was conducted in July 2022 to query PubMed, Web of Sciences, and Scopus. Papers published between January 2013 and July 2022 are considered. Forty-eight studies are included in this literature review. Two main sensing technologies (neurological and physiological) are identified in the literature. The sensing technologies and their modality (unimodal or multimodal) are presented. The literature provided numerous ex les of how different analytical tools in AI have been applied to decode pain. This review identifies different non-invasive sensing technologies, their analytical tools, and the implications for their use. There are significant opportunities to leverage multimodal sensing and deep learning to improve accuracy of pain monitoring systems. This review also identifies the need for analyses and datasets that explore the inclusion of neural and physiological information together. Finally, challenges and opportunities for designing better systems for pain assessment are also presented.

Moment arms about the carpal and metacarpophalangeal joints for flexor and extensor muscles in equine forelimbs

Publisher: American Veterinary Medical Association (AVMA)

Date: 03-2003

DOI: 10.2460/AJVR.2003.64.351

Abstract: Objective —To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. S le Population —4 cadaveric forelimbs from 2 healthy Thoroughbreds. Procedure —Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves. Results —At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38% during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41% at the carpus) over the range of joint motion associated with the stance phase of the gait. Conclusions and Clinical Relevance —Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle forces in equine forelimbs. ( Am J Vet Res 2003 :351–357)

Validation of a Genu Valgum Model in a Rabbit Hind Limb

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-2008

DOI: 10.1097/BPO.0B013E318168C776

Previously identified patellar tendinopathy risk factors differ between elite and sub-elite volleyball players

Publisher: Wiley

Date: 19-03-2015

DOI: 10.1111/SMS.12206

Abstract: Patellar tendinopathy is the most common knee injury incurred in volleyball, with its prevalence in elite athletes more than three times that of their sub-elite counterparts. The purpose of this study was to determine whether patellar tendinopathy risk factors differed between elite and sub-elite male volleyball players. Nine elite and nine sub-elite male volleyball players performed a lateral stop-jump block movement. Maximum vertical jump, training history, muscle extensibility and strength, three-dimensional landing kinematics (250 Hz), along with lower limb neuromuscular activation patterns (1500 Hz), and patellar tendon loading were collected during each trial. Multivariate analyses of variance (P < 0.05) assessed for between-group differences in risk factors or patellar tendon loading. Significant interaction effects were further evaluated using post-hoc univariate analysis of variance tests. Landing kinematics, neuromuscular activation patterns, patellar tendon loading, and most of the previously identified risk factors did not differ between the elite and sub-elite players. However, elite players participated in a higher training volume and had less quadriceps extensibility than sub-elite players. Therefore, high training volume is likely the primary contributor to the injury discrepancy between elite and sub-elite volleyball players. Interventions designed to reduce landing frequency and improve quadriceps extensibility are recommended to reduce patellar tendinopathy prevalence in volleyball players.

A Prospective Randomized Clinical Trial Comparing Arthroscopic Single-and Double-Row Rotator Cuff Repair

Publisher: SAGE Publications

Date: 09-02-2009

DOI: 10.1177/0363546508328115

Abstract: Double-row arthroscopic rotator cuff repair has become more popular, and some studies have shown better footprint coverage and improved biomechanics of the repair. Double-row rotator cuff repair leads to superior cuff integrity and early clinical results compared with single-row repair. Randomized controlled trial Level of evidence, 1. Forty patients were randomized to either single-row or double-row rotator cuff repair at the time of surgical intervention. Patients were followed with clinical measures (UCLA, Constant, WORC, SANE, ASES, as well as range of motion, internal rotation strength, and external rotation strength). Magnetic resonance imaging (MRI) studies were performed on each shoulder preoperatively, 6 weeks, 3 months, and 1 year after repair. Mean anteroposterior tear size by MRI was 1.8 cm. A mean of 2.25 anchors for single row (SR) and 3.2 for double row (DR) were used. There were 2 retears at 1 year in each group. There were 2 additional cases that had severe thinning in the DR repair group at 1 year. The MRI measurements of footprint coverage, tendon thickness, and tendon signal showed no significant differences between the 2 repair groups. At 1 year, there were no differences in any of the postoperative measures of motion or strength. At 1 year, mean WORC (SR, 84.8 DR, 87.9), Constant (SR, 77.8 DR, 74.4), ASES (SR, 85.9 DR, 85.5), UCLA (SR, 28.6 DR, 29.5), and SANE (SR, 90.9 DR, 89.9) scores showed no significant differences between groups. No clinical or MRI differences were seen between patients repaired with a SR or DR technique.

Biarticular hip extensor and knee flexor muscle moment arms of the feline hindlimb

Publisher: Elsevier BV

Date: 2007

DOI: 10.1016/J.JBIOMECH.2007.05.021

Abstract: Moment arms are important for understanding muscular behavior and for calculating internal muscle forces in musculoskeletal simulations. Biarticular muscles cross two joints and have moment arms that depend on the angle of both joints the muscles cross. The tendon excursion method was used to measure the joint angle-dependence of hamstring (biceps femoris, semimembranosus and semitendinosus) moment arm magnitudes of the feline hindlimb at the knee and hip joints. Knee angle influenced hamstring moment arm magnitudes at the hip joint compared to a flexed knee joint, the moment arm for semimembranosus posterior at the hip was at most 7.4 mm (25%) larger when the knee was extended. On average, hamstring moment arms at the hip increased by 4.9 mm when the knee was more extended. In contrast, moment arm magnitudes at the knee varied by less than 2.8 mm (mean=1.6 mm) for all hamstring muscles at the two hip joint angles tested. Thus, hamstring moment arms at the hip were dependent on knee position, while hamstring moment arms at the knee were not as strongly associated with relative hip position. Additionally, the feline hamstring muscle group had a larger mechanical advantage at the hip than at the knee joint.

Predicting the patellar tendon force generated when landing from a jump

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-2013

DOI: 10.1249/MSS.0B013E31827F0314

Influence of tendon transfer site on moment arms of the flexor digitorum longus muscle

Publisher: SAGE Publications

Date: 04-2007

DOI: 10.3113/FAI.2007.0441

Abstract: Background: Adult acquired flatfoot is a common condition that leads to significant morbidity. Along with bony procedures to operatively treat this condition, transfer of the flexor digitorum longus (FDL) tendon to the medial cuneiform or navicular is routinely performed. The goal of this tendon transfer is to increase the capacity of the FDL to invert the hindfoot and control the transverse tarsal joints. However, it is not known whether this biomechanical goal is met or whether one transfer site produces a larger mechanical advantage compared to another site. The purpose of this study was to calculate FDL muscle moment arms at the hindfoot with two clinically relevant transfer locations to quantify the change in mechanical advantage of the FDL after tendon transfer. Methods: In seven cadaver specimens, muscle moment arms of the FDL with respect to hindfoot motion were measured using the tendon excursion method before and after the FDL was transferred to the plantar aspect of the navicular and medial cuneiform. The position and orientation of the foot and excursion of the FDL tendon were measured with an optoelectronic measurement system. Results: The FDL moment arm did not increase after tendon transfer to either the medial cuneiform or navicular when compared to its native site. There were significant decreases in FDL moment arm when transferred from its native site to the medial cuneiform (56% decrease, p = 0.018) and navicular (46% decrease, p = 0.026). Conclusions: In contrast to the clinical proposition that FDL transfer to the navicular or medial cuneiform increases this muscle's mechanical advantage to invert the hindfoot, this cadaver study suggests that, to the contrary, FDL muscle moment arms decrease after tendon transfer.

The repeated bout effect can occur without mechanical and neuromuscular changes after a bout of eccentric exercise

Publisher: Wiley

Date: 07-06-2018

DOI: 10.1111/SMS.13222

Abstract: Changes in muscle fascicle mechanics have been postulated to underpin the repeated bout effect (RBE) observed following exercise-induced muscle damage (EIMD). However, in the medial gastrocnemius (MG), mixed evidence exists on whether fascicle stretch litude influences the level of EIMD, thus questioning whether changes in fascicle mechanics underpin the RBE. An alternative hypothesis is that neural adaptations contribute to the RBE in this muscle. The aim of this study was to investigate the neuromechanical adaptations during and after repeated bouts of a highly controlled muscle lengthening exercise that aimed to maximize EIMD in MG. In all, 20 subjects performed two bouts of 500 active lengthening contractions (70% of maximal activation) of the triceps surae, separated by 7 days. Ultrasound constructed fascicle length-torque (L-T) curves of MG, surface electromyography (EMG), maximum torque production, and muscle soreness were assessed before, 2 hours and 2 days after each exercise bout. The drop in maximum torque (4%) and the increase in muscle soreness (24%) following the repeated bout were significantly less than following the initial bout (8% and 59%, respectively), indicating a RBE. However, neither shift in the L-T curve nor changes in EMG parameters were present. Furthermore, muscle properties during the exercise were not related to the EIMD or RBE. Our results show that there are no global changes in gastrocnemius mechanical behavior or neural activation that could explain the observed RBE in this muscle. We suggest that adaptations in the non-contractile elements of the muscle are likely to explain the RBE in the triceps surae.

Force- and moment-generating capacities of muscles in the distal forelimb of the horse

Publisher: Wiley

Date: 07-2003

DOI: 10.1046/J.1469-7580.2003.00206.X

Abstract: A detailed musculoskeletal model of the distal equine forelimb was developed to study the influence of musculoskeletal geometry (i.e. muscle paths) and muscle physiology (i.e. force-length properties) on the force- and moment-generating capacities of muscles crossing the carpal and metacarpophalangeal joints. The distal forelimb skeleton was represented as a five degree-of-freedom kinematic linkage comprised of eight bones (humerus, radius and ulna combined, proximal carpus, distal carpus, metacarpus, proximal phalanx, intermediate phalanx and distal phalanx) and seven joints (elbow, radiocarpal, intercarpal, carpometacarpal, metacarpophalangeal (MCP), proximal interphalangeal (pastern) and distal interphalangeal (coffin)). Bone surfaces were reconstructed from computed tomography scans obtained from the left forelimb of a Thoroughbred horse. The model was actuated by nine muscle-tendon units. Each unit was represented as a three-element Hill-type muscle in series with an elastic tendon. Architectural parameters specifying the force-producing properties of each muscle-tendon unit were found by dissecting seven forelimbs from five Thoroughbred horses. Maximum isometric moments were calculated for a wide range of joint angles by fully activating the extensor and flexor muscles crossing the carpus and MCP joint. Peak isometric moments generated by the flexor muscles were an order of magnitude greater than those generated by the extensor muscles at both the carpus and the MCP joint. For each flexor muscle in the model, the shape of the maximum isometric joint moment-angle curve was dominated by the variation in muscle force. By contrast, the moment-angle curves for the muscles that extend the MCP joint were determined mainly by the variation in muscle moment arms. The suspensory and check ligaments contributed more than half of the total support moment developed about the MCP joint in the model. When combined with appropriate in vivo measurements of joint kinematics and ground-reaction forces, the model may be used to determine muscle-tendon and joint-reaction forces generated during gait.

Selective and Graded Recruitment of Cat Hamstring Muscles With Intrafascicular Stimulation

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 12-2009

DOI: 10.1109/TNSRE.2008.2011988

The influence of upper-body mechanics, anthropometry and isokinetic strength on performance in wrist-spin cricket bowling

Publisher: Informa UK Limited

Date: 25-11-2019

DOI: 10.1080/02640414.2019.1696265

Abstract: Delivering a cricket ball with a wrist-spin (WS) bowling technique is considered one of the game's most difficult skills. Limited biomechanical information exists for WS bowlers across skill levels. The purpose of this study was to compare biomechanical, isokinetic strength and anthropometric measures between elite (12) and pathway bowlers (eight). Data were collected using a motion analysis system, dynamometer and a level-two anthropometrist. A regression analysis identified that performance was best explained by increased wrist radial deviation torque and longitudinal axis rotational moments at the shoulder and wrist. From back foot impact (BFI) to ball release (BR), elite bowlers rotated their trunks less, experienced less trunk deceleration resulting in a more front-on position and increased pelvis rotation angular velocity. They also displayed an increased shoulder internal rotation moment as the upper arm moved from external into internal rotation and was a major contributor in the subsequent differences observed in the distal segments of the bowling limb. Anthropometric differences were observed at the wrist and finger joints and may be used to form the basis for talent identification programmes. This study highlights the important contribution to bowling performance of the musculature responsible for producing long axis rotations of the bowling limb.

Lower-limb joint mechanics during maximum acceleration sprinting

Publisher: The Company of Biologists

Date: 2019

DOI: 10.1242/JEB.209460

Abstract: We explored how humans adjust the stance phase mechanical function of their major lower-limb joints (hip, knee, ankle) during maximum acceleration sprinting. Experimental data (motion capture and ground reaction force (GRF)) were recorded from eight participants as they performed overground sprinting trials. Six alternative starting locations were used to obtain a dataset that incorporated the majority of the acceleration phase. Experimental data were combined with an inverse-dynamics-based analysis to calculate lower-limb joint mechanical variables. As forward acceleration magnitude decreased, the vertical GRF impulse remained nearly unchanged whereas the net horizontal GRF impulse became smaller due to less propulsion and more braking. Mechanical function was adjusted at all three joints, although more dramatic changes were observed at the hip and ankle. The impulse from the ankle plantar-flexor moment was almost always larger than those from the hip and knee extensor moments. Forward acceleration magnitude was linearly related to the impulses from the hip extensor moment (R2=0.45) and the ankle plantar-flexor moment (R2=0.47). Forward acceleration magnitude was also linearly related to the net work done at all three joints, with the ankle displaying the strongest relationship (R2=0.64). The ankle produced the largest amount of positive work (1.55±0.17 J/kg) of all the joints, and provided a significantly greater proportion of the summed amount of lower-limb positive work as running speed increased and forward acceleration magnitude decreased. We conclude that the hip and especially the ankle represent key sources of positive work during the stance phase of maximum acceleration sprinting.

Variations in jump height explain the between-sex difference in patellar tendon loading during landing

Publisher: Wiley

Date: 15-01-2018

DOI: 10.1111/SMS.12172

Abstract: Patellar tendinopathy is the most common overuse knee injury in volleyball, with men reporting more than twice the injury prevalence than women. Although high patellar tendon loading is thought to be a causative factor of patellar tendinopathy, it is unknown whether between-sex variations in landing technique account for differences in patellar tendon loading. It was hypothesized that male volleyball players would display differences in landing technique and would generate higher patellar tendon loading than their female counterparts. The landing technique and patellar tendon loading of 20 male and 20 female volleyball players performing a lateral stop-jump block movement were collected. Independent t-tests were used to identify any between-sex differences in landing technique with the data grouped to account for differences in jump height and in anthropometry. Male volleyball players were taller and heavier, landed from a higher height, displayed differences in landing kinematics, generated a significantly greater knee extensor moment, and experienced higher patellar tendon loading than female players when all 40 participants were compared. However, when participants were matched on jump height, they generated similar patellar tendon loading, irrespective of their sex. These results imply that jump height is a more important determinant of patellar tendon loading than sex.

Joint-specific power production and fatigue during maximal cycling

Publisher: Elsevier BV

Date: 03-2009

DOI: 10.1016/J.JBIOMECH.2008.11.015

Abstract: Cycling power decreases substantially during a maximal cycling trial of just 30s. It is not known whether movement patterns and joint powers produced at each joint decrease to a similar extent or if each joint exhibits an in idual fatigue profile. Changes in movement patterns and/or joint powers associated with overall task fatigue could arise from several different mechanisms or from a complex interplay of these mechanisms. The purpose of this investigation was to determine the changes in movement and power at each joint during a fatiguing cycling trial. Thirteen trained cyclists performed a 30s maximal cycling trial on an isokinetic cycle ergometer at 120rpm. Pedal forces and limb kinematics were recorded. Joint powers were calculated using a sagittal plane inverse dynamics model and averaged for the initial, middle, and final three second intervals of the trial, and normalized to initial values. Relative ankle plantar flexion power was significantly less than all other joint actions at the middle interval (51+/-5% of initial power p=0.013). Relative ankle plantar flexion power for the final interval (37+/-3%) was significantly less than the relative knee flexion and hip extension power (p=0.010). Relative knee extension power (41+/-5%) was significantly less than relative hip extension power (55+/-4%) during the final three second interval (p=0.045). Knee flexion power (47+/-5%) did not differ from relative hip extension power (p=0.06). These changes in power were accompanied by a decrease in time spent extending by each joint with fatigue (i.e., decreased duty cycle, p<0.03). While central mechanisms may have played a role across all joints, because the ankle fatigued more than the hip and knee joints, either peripheral muscle fatigue or changes in motor control strategies were identified as the potential mechanisms for joint-specific fatigue during a maximal 30s cycling trial.

Dynamic leg-motion and its effect on the aerodynamic performance of cyclists

Publisher: Elsevier BV

Date: 08-2016

DOI: 10.1016/J.JFLUIDSTRUCTS.2016.05.007

Learning Koopman Embedding Subspaces for System Identification and Optimal Control of a Wrist Rehabilitation Robot

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 07-2023

DOI: 10.1109/TIE.2022.3203760

Synthesis of a six-bar mechanism for generating knee and ankle motion trajectories using deep generative neural network

Publisher: Elsevier BV

Date: 2023

DOI: 10.1016/J.ENGAPPAI.2022.105500

Pedal trajectory alters maximal single-leg cycling power

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 08-2002

DOI: 10.1097/00005768-200208000-00015

Abstract: Muscular power produced during in vitro cyclic contraction has been reported to vary with muscle-length trajectory. The purpose of this study was to determine whether maximal human single-leg cycling power could be similarly altered by manipulating pedal trajectory. Seven trained cyclists performed maximal single-leg cycle ergometry. Pedal trajectory was manipulated by repositioning the ergometer drive sprocket off-center with respect to the crank axle, such that the leg-extension phase occupied 42, 50, or 58% of the cycle time (LEP42, LEP50, and LEP58, respectively). Maximum instantaneous power was 12% greater for LEP58 (1984 +/- 143 W) than LEP50 (1838 +/- 126 W), which was 8% greater than that for LEP42 (1645 +/- 112 W). Maximum power, averaged over a complete revolution of the crank, was 4% greater for LEP58 (636 +/- 59 W) than for LEP50 (613 +/- 53 W), which was 18% greater than that for LEP42 (520 +/- 43 W). These findings, paralleling those for an in vitro model, confirmed our hypothesis that maximal single-leg cycling power could be altered by manipulating pedal trajectory. Alterations in power were likely due to concomitant effects of muscle-shortening velocity, muscle excitation, and biomechanical constraints. Additional research is needed to determine whether greater leg-extension phase ratios can elicit further increases in power and whether similar results can be obtained during bilateral cycling.

The role of human ankle plantar flexor muscle-tendon interaction and architecture in maximal vertical jumping examined in vivo

Publisher: The Company of Biologists

Date: 2016

DOI: 10.1242/JEB.126854

Abstract: Humans utilise elastic tendons of lower limb muscles to store and return energy during walking, running and jumping. Anuran and insect species use skeletal structures and/or dynamics in conjunction with similarly compliant structures to lify muscle power output during jumping. We sought to examine if human jumpers use similar mechanisms to aid elastic energy usage in the plantar flexor muscles during maximal vertical jumping. Ten male athletes performed maximal vertical squat jumps. Three-dimensional motion capture and a musculoskeletal model were used to determine lower limb kinematics that were combined with ground reaction force data in an inverse dynamics analysis. B-mode ultrasound imaging of the lateral gastrocnemius (GAS) and soleus (SOL) muscles was used to measure muscle fascicle lengths and pennation angles during jumping. Our results highlighted that both GAS and SOL utilised stretch and recoil of their series elastic elements (SEE) in a catapult-like fashion, which likely serves to maximise ankle joint power. The resistance of supporting of body weight allowed initial stretch of both GAS and SOL SEE's. A proximal-to-distal sequence of joint moments and decreasing effective mechanical advantage (EMA) early in the extension phase of the jumping movement were observed. This facilitated a further stretch of the SEE of the biarticular GAS and delayed recoil of the SOL SEE. However, EMA did not increase late in the jump to aid recoil of elastic tissues.

The effect of leg dominance and landing height on ACL loading among female athletes

Publisher: Elsevier BV

Date: 07-2017

DOI: 10.1016/J.JBIOMECH.2017.06.033

Abstract: Female athletes are more prone to anterior cruciate ligament (ACL) injury. A neuromuscular imbalance called leg dominance may provide a biomechanical explanation. Therefore, the purpose of this study was to compare the side-to-side lower limb differences in movement patterns, muscle forces and ACL forces during a single-leg drop-landing task from two different heights. We hypothesized that there will be significant differences in lower limb movement patterns (kinematics), muscle forces and ACL loading between the dominant and non-dominant limbs. Further, we hypothesized that significant differences between limbs will be present when participants land from a greater drop-landing height. Eight recreational female participants performed dominant and non-dominant single-leg drop landings from 30 to 60cm. OpenSim software was used to develop participant-specific musculoskeletal models and to calculate muscle forces. We also predicted ACL loading using our previously established method. There were no significant differences between dominant and non-dominant leg landing except in ankle dorsiflexion and GMED muscle forces at peak GRF. Landing from a greater height resulted in significant differences among most kinetics and kinematics variables and ACL forces. Minimal differences in lower-limb muscle forces and ACL loading between the dominant and non-dominant legs during single-leg landing may suggest similar risk of injury across limbs in this cohort. Further research is required to confirm whether limb dominance may play an important role in the higher incidence of ACL injury in female athletes with larger and sport-specific cohorts.

The effect of spatial position on the aerodynamic interactions between cyclists

Publisher: Elsevier BV

Date: 2014

DOI: 10.1016/J.PROENG.2014.06.131

Robot Assisted Ankle Neuro-Rehabilitation: State of the art and Future Challenges

Publisher: Informa UK Limited

Date: 16-11-2020

DOI: 10.1080/14737175.2021.1847646

The Influence of Modeling Separate Neuromuscular Compartments on the Force and Moment Generating Capacities of Muscles of the Feline Hindlimb

Publisher: ASME International

Date: 15-06-2010

DOI: 10.1115/1.4001680

Abstract: Functional electrical stimulation (FES) has the capacity to regenerate motion for in iduals with spinal cord injuries. However, it is not straightforward to determine the stimulation parameters to generate a coordinated movement. Musculoskeletal models can provide a noninvasive simulation environment to estimate muscle force and activation timing sequences for a variety of tasks. Therefore, the purpose of this study was to develop a musculoskeletal model of the feline hindlimb for simulations to determine stimulation parameters for intrafascicular multielectrode stimulation (a method of FES). Additionally, we aimed to explore the differences in modeling neuromuscular compartments compared with representing these muscles as a single line of action. When comparing the modeled neuromuscular compartments of biceps femoris, sartorius, and semimembranosus to representations of these muscles as a single line of action, we observed that modeling the neuromuscular compartments of these three muscles generated different force and moment generating capacities when compared with single muscle representations. Differences as large as 4 N m (∼400% in biceps femoris) were computed between the summed moments of the neuromuscular compartments and the single muscle representations. Therefore, modeling neuromuscular compartments may be necessary to represent physiologically reasonable force and moment generating capacities of the feline hindlimb.

A wind-tunnel case study: Increasing road cycling velocity by adopting an aerodynamically improved sprint position

Publisher: SAGE Publications

Date: 08-2019

DOI: 10.1177/1754337119866962

Abstract: The main aim of this study was to evaluate the potential to reduce the aerodynamic drag by studying road sprint cyclists’ positions. A male and a female professional road cyclist participated in this wind-tunnel study. Aerodynamic drag measurements are presented for a total of five out-of-seat sprinting positions for each of the athletes under representative competition conditions. The largest reduction in aerodynamic drag measured for each athlete relative to their standard sprinting positions varied between 17% and 27%. The majority of this reduction in aerodynamic drag could be accounted for by changes in the athlete’s projected frontal area. The largest variation in repeat drag coefficient area measurements of out-of-seat sprint positions was 5%, significantly higher than the typical .5% observed for repeated testing of time-trial cycling positions. The majority of variation in repeated drag coefficient area measurements was attributed to reproducibility of position and s ling errors associated with time-averaged force measurements of large fluctuating forces.

Flow field interactions between two tandem cyclists

Publisher: Springer Science and Business Media LLC

Date: 19-11-2016

DOI: 10.1007/S00348-016-2273-Y

Aerodynamic performance and riding posture in road cycling and triathlon

Publisher: SAGE Publications

Date: 19-09-2015

DOI: 10.1177/1754337114549876

Abstract: Cycling performance is strongly dependent on aerodynamic drag, of which the majority is attributable to the rider. Previous studies have shown the importance of optimising athlete posture on the bicycle for in idual time-trial events. This article identifies that performance in road cycling and draft-legal triathlon can be improved through aerodynamic optimisation of the athlete’s posture. Nine relevant cycling postures have been studied, and it was found that for road cycling, gripping the hoods with horizontal forearms can reduce the required cyclist power by 13.4%, and for draft-legal triathlon applications, the use of short bar extensions reduced the required power by up to 16.7%. It was also found that lowering the eyes and head increased drag in both drops and triathlon postures. Measurements of the velocity profiles of the wake of a cyclist in four different postures are presented, and it is shown that differences in drag coefficients between postures can be correlated with changes in the wake velocity defect and turbulence intensity distribution.

Effect of running speed on lower limb joint kinetics

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-2011

DOI: 10.1249/MSS.0B013E3182084929

Stiffness-Observer-Based Adaptive Control of an Intrinsically Compliant Parallel Wrist Rehabilitation Robot

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 02-2023

DOI: 10.1109/THMS.2022.3211164

Initial Ball Flight Characteristics of Curve and Instep Kicks in Elite Women’s Football

Publisher: Human Kinetics

Date: 02-2012

DOI: 10.1123/JAB.28.1.70

Abstract: Initial ball flight characteristics of curve and instep kicks were investigated. Fifteen international female footballers performed curve and instep kicks from a distance of 20 m from goal and at a 1 m 2 target. Seventeen Vicon cameras tracked three-dimensional coordinates of four reflective markers adhered to the ball. Ball flight characteristics were quantified, and the coordinates of the ball relative to the target center were recorded. The lateral launch angle and the angle of the spin axis relative to the horizontal best predicted the horizontal placement of the ball relative to the target. The vertical launch angle, antero-posterior velocity and amount of backspin best predicted the vertical coordinate. Regression models demonstrated how carefully controlled the flight characteristics must be with launch angles constrained within 3° to hit the target. Curve kicks were characterized by significantly greater lateral and vertical launch angles, increased sidespin and spin about the antero-posterior axis, and a more vertical spin axis. This information is beneficial for coaches in training players to achieve the characteristics required to score a goal and avoid a defensive wall. For ex le, if players consistently kick above or below the target, these findings identify the variables that will help rectify that error.

Lower-Limb Muscular Strategies for Increasing Running Speed

Publisher: Journal of Orthopaedic & Sports Physical Therapy (JOSPT)

Date: 10-2014

DOI: 10.2519/JOSPT.2014.5433

Abstract: This clinical commentary discusses the mechanisms used by the lower-limb musculature to achieve faster running speeds. A variety of methodological approaches have been taken to evaluate lower-limb muscle function during running, including direct recordings of muscle electromyographic signal, inverse dynamics-based analyses, and computational musculoskeletal modeling. Progressing running speed from jogging to sprinting is mostly dependent on ankle and hip muscle performance. For speeds up to approximately 7.0 m/s, the dominant strategy is to push on the ground forcefully to increase stride length, and the major ankle plantar flexors (soleus and gastrocnemius) have a particularly important role in this regard. At speeds beyond approximately 7.0 m/s, the force-generating capacity of these muscles becomes less effective. Therefore, as running speed is progressed toward sprinting, the dominant strategy shifts toward the goal of increasing stride frequency and pushing on the ground more frequently. This strategy is achieved by generating substantially more power at the hip joint, thereby increasing the biomechanical demand on proximal lower-limb muscles such as the iliopsoas, gluteus maximus, rectus femoris, and hamstrings. Basic science knowledge regarding lower-limb muscle function during running has implications for understanding why sprinting performance declines with age. It is also of great value to the clinician for designing rehabilitation programs to restore running ability in young, previously active adults who have sustained a traumatic brain injury and have severe impairments of muscle function (eg, weakness, spasticity, poor motor control) that limit their capacity to run at any speed.

Aerodynamic drag interactions between cyclists in a team pursuit

Publisher: Springer Science and Business Media LLC

Date: 11-02-2015

DOI: 10.1007/S12283-015-0172-8

Identifying the barriers faced by obstetricians and registrars in screening or enquiry of intimate partner violence in pregnancy: A systematic review of the primary evidence

Publisher: Wiley

Date: 02-10-2023

DOI: 10.1111/AJO.13747

Cartilage Restoration in the Patellofemoral Joint

Publisher: Springer New York

Date: 03-08-2013

DOI: 10.1007/978-1-4614-4157-1_5

The role of segmental mass and moment of inertia in dynamic-contact task construction

Publisher: Informa UK Limited

Date: 07-2006

DOI: 10.3200/JMBR.38.4.313-326

Joint-Specific Power-Pedaling Rate Relationships During Maximal Cycling

Publisher: Human Kinetics

Date: 06-2014

DOI: 10.1123/JAB.2013-0246

Abstract: Previous authors have reported power-pedaling rate relationships for maximal cycling. However, the joint-specific power-pedaling rate relationships that contribute to pedal power have not been reported. We determined absolute and relative contributions of joint-specific powers to pedal power across a range of pedaling rates during maximal cycling. Ten cyclists performed maximal 3 s cycling trials at 60, 90, 120, 150, and 180 rpm. Joint-specific powers were averaged over complete pedal cycles, and extension and flexion actions. Effects of pedaling rate on relative joint-specific power, velocity, and excursion were assessed with regression analyses and repeated-measures ANOVA. Relative ankle plantar flexion power (25 to 8% P = .01 R 2 = .90) decreased with increasing pedaling rate, whereas relative hip extension power (41 to 59% P .01 R 2 = .92) and knee flexion power (34 to 49% P .01 R 2 = .94) increased with increasing pedaling rate. Knee extension powers did not differ across pedaling rates. Ankle joint angular excursion decreased with increasing pedaling rate (48 to 20 deg) whereas hip joint excursion increased (42 to 48 deg). These results demonstrate that the often-reported quadratic power-pedaling rate relationship arises from combined effects of dissimilar joint-specific power-pedaling rate relationships. These dissimilar relationships are likely influenced by musculoskeletal constraints (ie, muscle architecture, morphology) and/or motor control strategies.

Erratum: “The Influence of Modeling Separate Neuromuscular Compartments on the Force and Moment Generating Capacities of Muscles of the Feline Hindlimb” [J. Biomech. Eng., 2010, 132, p. 081003]

Publisher: ASME International

Date: 09-11-2010

DOI: 10.1115/1.4002801

Autologous Bone Effects on Femoral Tunnel Widening in Hamstring Anterior Cruciate Ligament Reconstruction

Publisher: Georg Thieme Verlag KG

Date: 2009

DOI: 10.1055/S-0030-1247735

Abstract: This study examines the hypothesis that autologous bone in the femoral tunnel for a hamstring anterior cruciate ligament (ACL) reconstruction will reduce femoral tunnel widening. Thirty-six patients undergoing hamstring autograft ACL reconstruction were randomized to 2 groups. One group underwent ACL reconstruction using EndoButton femoral fixation. The other group underwent the same procedure, with the addition of a bone plug placed at the aperture of the femoral tunnel next to the graft. Twenty-seven patients at > 6 months postoperatively (range, 6-12 months) had digitized anteroposterior (AP) and lateral radiographs of the involved knee. Tunnel widening was determined by comparing the radiographic tunnel diameters to the drilled tunnel diameters from surgery. The mean (+/- SD) tunnel enlargement on the AP radiographs in the standard and plug groups were 3.8 +/- 1.7 mm and 3.5 +/- 2.0 mm, respectively (P = .61). On lateral radiographic assessment, the mean (+/- SD) tunnel enlargement in the standard and plug groups were 3.3 +/- 1.9 mm and 3.4 +/- 2.2 mm, respectively (P = .90). Autologous bone plug graft during ACL reconstruction does not reduce femoral tunnel widening.

Australian Institute Of Sport

Location: Australia

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Queensland University Of Technology

Location: Australia

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Queensland University Of Technology Faculty Of Health

Location: Australia

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The University Of Texas At Austin

Location: United States of America

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The University Of Canberra

Location: Australia

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University Of Utah

Location: United States of America

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Linkage Projects - Grant ID: LP160101316

Start Date: 11-2017

End Date: 12-2022

Amount: $220,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP140100260

Start Date: 01-2015

End Date: 03-2020

Amount: $235,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP100200090

Start Date: 03-2011

End Date: 01-2015

Amount: $370,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE170100203

Start Date: 06-2017

End Date: 12-2020

Amount: $326,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP130100955

Start Date: 01-2014

End Date: 07-2017

Amount: $290,556.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP110100262

Start Date: 05-2011

End Date: 12-2015

Amount: $293,000.00

Funder: Australian Research Council