ORCID Profile
0000-0001-7266-2976
Current Organisation
University College London
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Publisher: Human Kinetics
Date: 06-2021
Abstract: Purpose : To determine the association between estimated muscle fiber typology and the start and turn phases of elite swimmers during competition. Methods : International and national competition racing performance was analyzed from 21 female (FINA points = 894 ± 39: 104.5 ± 1.8% world record ratio [WRR]) and 25 male (FINA points = 885 ± 54: 104.8 ± 2.1% WRR) elite swimmers. The start, turn, and turn out times were determined from each of the swimmers’ career best performance times (FINA points = 889 ± 48: 104.7 ± 2.0% WRR). Muscle carnosine concentration was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus and was expressed as a carnosine aggregate z score relative to an age- and gender-matched nonathlete control group to estimate muscle fiber typology. Linear mixed models were employed to determine the association between muscle fiber typology and the start and turn times. Results : While there was no significant influence of carnosine aggregate z score on the start and turn times when all strokes and distance events were entered into the model, the swimmers with a higher carnosine aggregate z score (ie, faster muscle typology) had a significantly faster start time in 100-m events compared with the swimmers with a lower carnosine aggregate z score ( P = .02, F = 5.825). The start and turn times were significantly faster in the male compared with the female swimmers in the 100-m events compared with other distances, and between the 4 different swimming strokes ( P .001). Conclusion : This study suggests that start times in sprint events are partly determined (and limited) by muscle fiber typology, which is highly relevant when ∼12% of the overall performance time is determined from the start time.
Publisher: Springer Science and Business Media LLC
Date: 16-06-2022
DOI: 10.1007/S40279-022-01706-Y
Abstract: Sleep loss may influence subsequent physical performance. Quantifying the impact of sleep loss on physical performance is critical for in iduals involved in athletic pursuits. Systematic review and meta-analysis. Studies were identified via the Web of Science, Scopus, and PsycINFO online databases. Investigations measuring exercise performance under ‘control’ (i.e., normal sleep, 6 h in any 24 h period) and ‘intervention’ (i.e., sleep loss, ≤ 6 h sleep in any 24 h period) conditions were included. Performance tasks were classified into different exercise categories (anaerobic power, speed ower endurance, high-intensity interval exercise (HIIE), strength, endurance, strength-endurance, and skill). Multi-level random-effects meta-analyses and meta-regression analyses were conducted, including subgroup analyses to explore the influence of sleep-loss protocol (e.g., deprivation, restriction, early [delayed sleep onset] and late restriction [earlier than normal waking]), time of day the exercise task was performed (AM vs. PM) and body limb strength (upper vs. lower body). Overall, 227 outcome measures (anaerobic power: n = 58 speed ower endurance: n = 32 HIIE: n = 27 strength: n = 66 endurance: n = 22 strength-endurance: n = 9 skill: n = 13) derived from 69 publications were included. Results indicated a negative impact of sleep loss on the percentage change (% Δ ) in exercise performance ( n = 959 [89%] male mean % Δ = − 7.56%, 95% CI − 11.9 to − 3.13, p = 0.001, I 2 = 98.1%). Effects were significant for all exercise categories. Subgroup analyses indicated that the pattern of sleep loss (i.e., deprivation, early and late restriction) preceding exercise is an important factor, with consistent negative effects only observed with deprivation and late-restriction protocols. A significant positive relationship was observed between time awake prior to the exercise task and % Δ in performance for both deprivation and late-restriction protocols (~ 0.4% decrease for every hour awake prior to exercise). The negative effects of sleep loss on different exercise tasks performed in the PM were consistent, while tasks performed in the AM were largely unaffected. Sleep loss appears to have a negative impact on exercise performance. If sleep loss is anticipated and unavoidable, in iduals should avoid situations that lead to experiencing deprivation or late restriction, and prioritise morning exercise in an effort to maintain performance.
Publisher: Informa UK Limited
Date: 11-12-2015
DOI: 10.1080/17461391.2015.1120782
Abstract: The varying results reported in response to β-alanine supplementation may be related to the duration and nature of the exercise protocol employed. We investigated the effects of β-alanine supplementation on a wide range of cycling performance tests in order to produce a clear concise set of criteria for its efficacy. Fourteen trained cyclists (Age = 24.8 ± 6.7 years VO2max = 65.4 ± 10.2 mL·kg·min(-1)) participated in this placebo-controlled, double-blind study. Prior to supplementation, subjects completed two (familiarization and baseline) supramaximal cycling bouts until exhaustion (120% pre-supplementation VO2max) and two 1-, 4- and 10-km cycling time trial (TT). Subjects then supplemented orally for 4 weeks with 6.4 g/d placebo or β-alanine and repeated the battery of performance tests. Blood lactate was measured pre-exercise, post-exercise and 5 min post-exercise. β-alanine supplementation elicited significant increases in time to exhaustion (TTE) (17.6 ± 11.5 s p = 0.013, effect compared with placebo) and was likely to be beneficial to 4-km TT performance time (-7.8 ± 8.1 s 94% likelihood), despite not being statistically different (p = 0.060). Performance times in the 1- and 10-km TT were not affected by treatment. For the highly trained cyclists in the current study, β-alanine supplementation significantly extended supramaximal cycling TTE and may have provided a worthwhile improvement to 4-km TT performance. However, 1- and 10-km cycling TT performance appears to be unaffected by β-alanine supplementation.
Publisher: Frontiers Media SA
Date: 11-02-2021
DOI: 10.3389/FSPOR.2021.618913
Abstract: As women's rugby league grows, the need for understanding the movement patterns of the sport is essential for coaches and sports scientists. The aims of the present study were to quantify the position-specific demographics, technical match statistics, and movement patterns of the National Rugby League Women's (NRLW) Premiership and to identify whether there was a change in the intensity of play as a function of game time played. A retrospective observational study was conducted utilizing global positioning system, demographic, and match statistics collected from 117 players from all NRLW clubs across the full 2018 and 2019 seasons and were compared between the ten positions using generalized linear mixed models. The GPS data were separated into absolute (i.e., total distance, high-speed running distance, and acceleration load) and relative movement patterns (i.e., mean speed, mean high speed (& 12 km·h −1 ), and mean acceleration). For absolute external outputs, fullbacks covered the greatest distance (5,504 m), greatest high-speed distance (1,081 m), and most ball-carry meters (97 m), while five-eighths recorded the greatest acceleration load (1,697 m·s −2 ). For relative external outputs, there were no significant differences in mean speed and mean high speed between positions, while mean acceleration only significantly differed between wingers and interchanges. Only interchange players significantly decreased in mean speed as their number of minutes played increased. By understanding the load of NRLW matches, coaches, high-performance staff, and players can better prepare as the NRLW Premiership expands. These movement patterns and match statistics of NRLW matches can lay the foundation for future research as women's rugby league expands. Similarly, coaches, high-performance staff, and players can also refine conditioning practices with a greater understanding of the external output of NRLW players.
Publisher: Routledge
Date: 04-10-2016
Publisher: Human Kinetics
Date: 08-2022
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 17-07-2019
DOI: 10.1249/MSS.0000000000002095
Abstract: The aim of this study was to determine whether muscle oxidative capacity is influenced by alterations in training volume in middle-distance runners. Twenty-four highly trained middle-distance runners ( n = 16 males V˙O 2peak = 73.3(4.3) mL·kg −1 ·min −1 n = 8 females, V˙O 2peak = 63.2(3.4) mL·kg −1 ·min −1 ) completed 3 wk of normal training (NormTr), 3 wk of high-volume training (HVTr a 10%, 20%, and 30% increase in training volume during each successive week from NormTr), and a 1-wk taper (TapTr 55% exponential reduction in training volume from HVTr week 3). Before and immediately after each training period, the rate of recovery of muscle oxygen consumption (mV˙O 2 ) of the gastrocnemius medialis was measured using near-infrared spectroscopy, with the rate constant indicating muscle oxidative capacity. Time to exhaustion (TTE) and V˙O 2peak were determined during a maximal incremental treadmill test. Twelve subjects were classified as being functionally overreached (FOR) after HVTr (decreased running TTE and high perceived fatigue), whereas the other 12 subjects were classified as acutely fatigued (AF no decrease in running TTE). The AF group demonstrated a significant increase in muscle oxidative capacity after HVTr (rate constant: 15.1% ± 9.7% min −1 P = 0.009), with no further improvement after TapTr, whereas there was no change in muscle oxidative capacity for FOR at any time point ( P 0.05). Compared with the FOR group, the AF group had substantially larger improvements in TTE from pre-HVTr to post-TapTr (FOR, 8.8% ± 3.7% AF, 3.2% ± 3.0% P = 0.04). The present study was able to demonstrate that muscle oxidative capacity was increased in response to a period of HVTr, but only in runners who did not develop FOR. Furthermore, runners who did not develop FOR had substantially larger performance improvements after a taper period.
Publisher: Journal of Sports Science and Medicine
Date: 03-2021
Abstract: Effective time-motion analysis can provide information directly applicable to the design of physical conditioning and testing programmes. The aim of the present study was to determine the external output of female beach volleyball players during tournament match-play and to assess the effect of competition level, margin of score differential and alterations of external output within matches. The external output profile of ten adult level (age 27 ± 3 y) and ten under 23 (‘U23’ age 19 ± 2 y) female beach volleyball players were determined using GPS technology (10 Hz) during 60 matches (n = 50 first and second sets and 20 third sets files) played during their respective Australian Beach Volleyball Ch ionship tournaments. Comparisons between groups and the influence of contextual factors on the external output within matches were analysed using linear mixed models. Adult beach volleyball players covered a greater relative distance (i.e., m·min-1) in speed zone 2 (1.0-1.99 m·s-1 42.0% of total relative distance) and zone 3 (≥2.0 m·s-1 10.9% of total relative distance) compared to U23 players. Relative distance, mean acceleration/deceleration and the relative distance covered in acceleration zone 2 and deceleration zone 2 and 3 was greater in set 1 compared to set 2. Sets that were decided by smaller score margins ( -point score differential) were comprised of a greater relative distance, peak speed, greater mean acceleration and deceleration output and a greater relative distance in speed zone 1 and 3 compared to sets decided by larger score margins ( -point score differential). The findings from this study suggest that there are contextual factors that influence the speed and acceleration/deceleration profile of female beach volleyball players such as tournament level, score margin and set-to-set variations that may have implications for the physiological and mechanical requirements of female players preparing for competition.
Publisher: Human Kinetics
Date: 08-2022
Publisher: Georg Thieme Verlag KG
Date: 18-03-2019
DOI: 10.1055/A-0853-7676
Abstract: The ability to change velocity rapidly is a key element of field-based sports. This study quantified the acceleration and deceleration profiles of soccer players during match play. Global positioning system measures were collected from 20 male soccer players competing in the Australian Hyundai A-League during 58 matches. Match data were organized into ten 9 min periods (i. e., P1: 0–9 min) and the time spent at moderate (1–2 m·s−2) and high ( m·s−2) acceleration and deceleration thresholds were quantified. Additionally, a novel deceleration: acceleration ratio was quantified to identify the transient nature of deceleration activity. Linear mixed models were used to model the acceleration and deceleration profiles. All acceleration and deceleration metrics displayed negative logarithmic curves within each half. There was no change in the ratio of high deceleration: acceleration however, a significant increase in the ratio of moderate deceleration:acceleration was evident. Using negative logarithmic curves to illustrate the acceleration and deceleration decay provides a novel methodological approach to quantify the high-intensity actions during match play. A decrease in the time spent decelerating throughout a match may be attributed to a lack of opportunity. Practitioners can use the coefficients, intercepts, and deceleration: acceleration ratios to monitor a player’s deceleration profile in match play.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 22-01-2021
DOI: 10.1249/MSS.0000000000002605
Abstract: This study aimed to identify the relationships between lower limb muscle characteristics and mechanical variables derived from the vertical (jumping) and horizontal (sprinting) force–velocity–power (FVP) profiles. Nineteen subelite male rugby league players performed a series of squat jumps and linear 30-m sprints to derive the vertical and horizontal FVP profiles, respectively. The theoretical maximal force ( F 0 ), velocity ( V 0 ), and power ( P max ) were derived from both the vertical (i.e., v F 0 , v V 0 , and v P max ) and the horizontal (i.e., h F 0 , h V 0 , and h P max ) FVP profiles. Vastus lateralis (VL), biceps femoris long head, and gastrocnemius medialis (GM) and lateralis muscle fascicle length, pennation angle, and thickness were measured using B-mode ultrasonography. Magnetic resonance imaging was used to calculate volumes of major lower limb muscles, whereas proton magnetic resonance spectroscopy was used to quantify the carnosine content of the GM to estimate muscle fiber typology. Variation in v P max was best explained by GM muscle fiber typology (i.e., greater estimated proportion of Type II fibers) and VL volume (adjusted r 2 = 0.440, P = 0.006), whereas adductor and vastus medialis volume and GM muscle fiber typology explained the most variation in h P max (adjusted r 2 = 0.634, P = 0.032). Rectus femoris and VL volume explained variation in v F 0 ( r 2 = 0.430, P = 0.008), whereas adductor and vastus medialis volume explained variation in h F 0 ( r 2 = 0.432, P = 0.007). Variations in v V 0 and h V 0 were best explained by GM muscle fiber typology (adjusted r 2 = 0.580, P 0.001) and GM muscle fiber typology and biceps femoris short head volume (adjusted r 2 = 0.590, P 0.001), respectively. Muscle fiber typology and muscle volume are strong determinants of maximal muscle power in jumping and sprinting by influencing the velocity- and force-oriented mechanical variables.
Publisher: Human Kinetics
Date: 09-2016
Abstract: This study compared determinants of a 30-s all-out paddling effort (30-s sprint-paddling test) between junior surfboard riders (surfers) of varying ability. Eight competitive (COMP) and 8 recreational (REC) junior male surfers performed a 30-s sprint-paddling test for the determination of peak sprint power and accumulated O 2 deficit. Surfers also performed an incremental-paddling test for the determination of the O 2 uptake–power output relationship that was subsequently used to calculate the accumulated O 2 deficit for the 30-s sprint-paddling test. During the 30-s sprint-paddling test, peak sprint power (404 ± 98 vs 292 ± 56 W, respectively, P = .01) and the accumulated O 2 deficit (1.60 ± 0.31 vs 1.14 ± 0.38 L, respectively, P = .02) were greater in COMP than in REC surfers, whereas peak O 2 uptake measured during the incremental-paddling test was not different (2.7 ± 0.1 vs 2.5 ± 0.2 L/min, respectively, P = .11). The higher peak sprint power and larger accumulated O 2 deficit observed in COMP than in REC surfers during a 30-s sprint paddling test suggest that surfing promotes development of the anaerobic energy systems. Furthermore, peak sprint power determined during 30 s of sprint paddling may be considered a sensitive measure of surfing ability or experience in junior male surfers.
Publisher: Human Kinetics
Date: 03-2020
Abstract: Purpose : To compare the training-intensity distribution (TID) across an 8-week training period in a group of highly trained middle-distance runners employing 3 different methods of training-intensity quantification. Methods : A total of 14 highly trained middle-distance runners performed an incremental treadmill test to exhaustion to determine the heart rate (HR) and running speed corresponding to the ventilatory thresholds (gas-exchange threshold and respiratory-compensation threshold), as well as fixed rating of perceived exertion (RPE) values, which were used to demarcate 3 training-intensity zones. During the following 8 weeks, the TID (total and percentage of time spent in each training zone) of all running training sessions ( N = 695) was quantified using continuous running speed, HR monitoring, and RPE. Results : Compared with the running-speed-derived TID (zone 1, 79.9% [7.3%] zone 2, 5.3% [4.9%] and zone 3, 14.7% [7.3%]), HR-demarcated TID (zone 1, 79.6% [7.2%] zone 2, 17.0% [6.3%] and zone 3, 3.4% [2.0%]) resulted in a substantially higher training time in zone 2 (effect size ± 95% confidence interval: −1.64 ± 0.53 P .001) and lower training time in zone 3 (−1.59 ± 0.51 P .001). RPE-derived TID (zone 1, 39.6% [8.4%] zone 2, 31.9% [8.7%] and zone 3, 28.5% [11.6%]) reduced time in zone 1 compared with both HR (−5.64 ± 1.40 P .001) and running speed (−5.69 ± 1.9 P .001), whereas time in RPE training zones 2 and 3 was substantially higher than both HR- and running-speed-derived zones. Conclusion : The results show that the method of training-intensity quantification substantially affects computation of TID.
Publisher: Informa UK Limited
Date: 30-01-2015
DOI: 10.1080/17461391.2015.1005696
Abstract: β-alanine is a common ingredient in supplements consumed by athletes. Indeed, athletes may believe that the β-alanine induced paresthesia, experienced shortly after ingestion, is associated with its ergogenic effect despite no scientific mechanism supporting this notion. The present study examined changes in cycling performance under conditions of β-alanine induced paresthesia. Eight competitive cyclists (VO2max = 61.8 ± 4.2 mL·kg·min(-1)) performed three practices, one baseline and four experimental trials. The experimental trials comprised a 1-km cycling time trial under four conditions with varying information (i.e., athlete informed β-alanine or placebo) and supplement content (athlete received β-alanine or placebo) delivered to the cyclist: informed β-alanine/received β-alanine, informed placebo/received β-alanine, informed β-alanine/received placebo and informed placebo/received placebo. Questionnaires were undertaken exploring the cyclists' experience of the effects of the experimental conditions. A possibly likely increase in mean power was associated with conditions in which β-alanine was administered (±95% CL: 2.2% ± 4.0%), but these results were inconclusive for performance enhancement (p = 0.32, effect size = 0.18, smallest worthwhile change = 56% beneficial). A possibly harmful effect was observed when cyclists were correctly informed that they had ingested a placebo (-1.0% ± 1.9%). Questionnaire data suggested that β-alanine ingestion resulted in evident sensory side effects and six cyclists reported placebo effects. Acute ingestion of β-alanine is not associated with improved 1-km TT performance in competitive cyclists. These findings are in contrast to the athlete's "belief" as cyclists reported improved energy and the ability to sustain a higher power output under conditions of β-alanine induced paresthesia.
Publisher: Human Kinetics
Date: 07-2020
Abstract: Purpose : To determine whether there is an association between external match load and contextual factors on subjective wellness in the days before and after Australian Rules football match play. Methods : A total of 34 elite male Australian football players completed a subjective wellness questionnaire in the days leading into the match (–3, –2, and –1 d), the day of (match day), and the days after each match (+3, +2, and +1 d). Players subjectively rated each item (mood, energy, stress, leg heaviness, muscle soreness, sleep quality, hours slept, and total wellness [a sum of the total response score]) on a visual analog scale ranging from 1 to 10, with 1 representing the negative end of the continuum. External load during competitive matches was quantified using accelerometer-derived PlayerLoad, and running activity was quantified using global positioning system technology across 2 competitive seasons. The relationships between perceptions of wellness (within-in idual z score), external match load, and contextual factors (match result, match location, and between-matches recovery duration) were analyzed using linear mixed models. Results : Mixed-effect linear models revealed trivial effects of match-day wellness z score on subsequent external match load metrics. Match result (win) and PlayerLoad in the anteroposterior vector (au·min −1 ) were associated with an increased (estimate ± SE: 0.30 ± 0.13 z score) and reduced subjective wellness (−0.15 ± 0.06 z score), respectively. Conclusion : The results of this study suggest that prematch perceived wellness does not relate to external match load in elite Australian football players. The between-matches microcycle length appears to be sufficient to restore perceived wellness to values that do not affect the subsequent external match loads.
Publisher: Human Kinetics
Date: 12-2013
Abstract: Beta-alanine may benefit short-duration, high-intensity exercise performance. The aim of this randomized double-blind placebo-controlled study was to examine the effects of beta-alanine supplementation on aspects of muscular performance in highly trained cyclists. Sixteen highly trained cyclists (mean ± SD age = 24 ± 7 yr mass = 70 ± 7kg VO 2max = 67 ± 4ml·kg −1 ·min– 1 ) supplemented with either beta-alanine ( n = 8, 65 mg·kg −1 BM) or a placebo ( n = 8 dextrose monohydrate) over 4 weeks. Pre- and postsupplementation cyclists performed a 4-minute maximal cycling test to measure average power and 30 reciprocal maximal isokinetic knee contractions at a fixed angular velocity of 180°·sec −1 to measure average power/repetition, total work done (TWD), and fatigue index (%). Blood pH, lactate (La − ) and bicarbonate (HCO 3 - ) concentrations were measured preand postisokinetic testing at baseline and following the supplementation period. Beta-alanine supplementation was 44% likely to increase average power output during the 4-minute cycling time trial when compared with the placebo, although this was not statistically significant ( p = .25). Isokinetic average power/repetition was significantly increased post beta-alanine supplementation compared with placebo (beta-alanine: 6.8 ± 9.9W, placebo: –4.3 ± 9.5 W, p = .04, 85% likely benefit), while fatigue index was significantly reduced ( p = .03, 95% likely benefit). TWD was 89% likely to be improved following beta-alanine supplementation however, this was not statistically significant ( p = .09). There were no significant differences in blood pH, lactate, and HCO 3 − between groups ( p .05). Four weeks of beta-alanine supplementation resulted in worthwhile changes in time-trial performance and short-duration muscular force production in highly trained cyclists.
Publisher: American Physiological Society
Date: 10-2020
DOI: 10.1152/JAPPLPHYSIOL.00314.2020
Abstract: Variability in the performance responses following an overload training period and subsequent taper was associated with the variation in the muscle fiber typology of the gastrocnemius. Runners with an estimated higher proportion of type I fibers (i.e., lower carnosine z-score) were able to maintain performance in response to an overload training period and subsequently achieve a superior performance supercompensation. These findings show that muscle fiber typology contributes to the variability in performance responses following training.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2016
Publisher: Informa UK Limited
Date: 13-08-2020
Publisher: Human Kinetics
Date: 2023
Publisher: Informa UK Limited
Date: 13-06-2021
DOI: 10.1080/17461391.2021.1933199
Abstract: The aim of this study was to determine the influence of training volume alterations on ersity and composition of the gut microbiome in a free-living cohort of middle-distance runners. Fourteen highly-trained middle-distance runners (
Publisher: Frontiers Media SA
Date: 04-08-2022
Publisher: Canadian Science Publishing
Date: 08-2016
Abstract: The present study investigated the effects of β-alanine supplementation on the resultant blood acidosis, lactate accumulation, and energy provision during supramaximal-intensity cycling, as well as the aerobic and anaerobic contribution to power output during a 4000-m cycling time trial (TT). Seventeen trained cyclists (maximal oxygen uptake = 4.47 ± 0.55 L·min −1 ) were administered 6.4 g of β-alanine (n = 9) or placebo (n = 8) daily for 4 weeks. Participants performed a supramaximal cycling test to exhaustion (equivalent to 120% maximal oxygen uptake) before (PreExh) and after (PostExh) the 4-week supplementation period, as well as an additional postsupplementation supramaximal cycling test identical in duration and power output to PreExh (PostMatch). Anaerobic capacity was quantified and blood pH, lactate, and bicarbonate concentrations were measured pre-, immediately post-, and 5 min postexercise. Subjects also performed a 4000-m cycling TT before and after supplementation while the aerobic and anaerobic contributions to power output were quantified. β-Alanine supplementation increased time to exhaustion (+12.8 ± 8.2 s P = 0.041) and anaerobic capacity (+1.1 ± 0.7 kJ P = 0.048) in PostExh compared with PreExh. Performance time in the 4000-m TT was reduced following β-alanine supplementation (−6.3 ± 4.6 s P = 0.034) and the mean anaerobic power output was likely to be greater (+6.2 ± 4.5 W P = 0.035). β-Alanine supplementation increased time to exhaustion concomitant with an augmented anaerobic capacity during supramaximal intensity cycling, which was also mirrored by a meaningful increase in the anaerobic contribution to power output during a 4000-m cycling TT, resulting in an enhanced overall performance.
Publisher: Human Kinetics
Date: 03-2023
Abstract: Purpose : The aim of this systematic review was to (1) determine the muscle fiber-type composition (or muscle fiber typology [MFT]) of team-sport athletes and (2) examine associations between MFT and the physical characteristics and performance tasks in team-sport athletes. Methods : Searches were conducted across numerous databases—PubMed, SPORTDiscus, MEDLINE, and Google Scholar—using consistent search terms. Studies were included if they examined the MFT of team-sport athletes. Included studies underwent critical appraisal using the McMasters University critical appraisal tool for quantitative research. Results : A total of 10 studies were included in the present review, wherein the MFT of athletes was measured from 5 different team sports (soccer, rugby union, rugby league, handball, and volleyball). There was large variability in the MFT of team-sport athletes both within (up to 27.5%) and between sports (24.0% relative difference). Male football players with a higher proportion of type II fibers had faster 10- and 30-m sprint times, achieved a greater total distance sprinting (distance at .67 m·s −1 ), and a greater peak 1-minute sprint distance. Conclusions : MFT varies considerably between athletes both within and between different team sports. The results from some studies suggest that variation in MFT is associated with high-intensity running performance in a football match, as well as 10- and 30-m sprint times. Further experimental studies should focus on how determination of the MFT of team-sport athletes could be utilized to influence talent identification, team selection, and the in idualization of training.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 26-07-2021
DOI: 10.1249/MSS.0000000000002755
Abstract: We aimed to identify the underpinning physiological and speed/mechanical determinants of different types of 800-m running time trials (i.e., with a positive or negative pacing strategy) and key components within each 800-m time trial (i.e., first and final 200 m). Twenty trained male 800-m runners (800-m personal best time (min:s): 1:55.10 ± 0:04.44) completed a maximal 800-m time trial (800 MAX ) and one pacing trial, whereby runners were paced for the first lap, and speed was reduced by 7.5% (800 PACE ) relative to 800 MAX , whereas the last lap was completed in the fastest time possible. Anaerobic speed reserve, running economy, the velocity corresponding with V˙O 2peak ( V V˙O 2peak ), maximal sprint speed (MAX SS ), maximal accumulated oxygen deficit, and sprint force–velocity–power profiles were derived from laboratory and field testing. Carnosine content was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus and expressed as a carnosine aggregate Z (CAZ) score to estimate muscle typology. Data were analyzed using multiple stepwise regression analysis. MAX SS and vV˙O 2peak largely explained the variation in 800 MAX time ( r 2 = 0.570 P = 0.020), whereas MAX SS was the best explanatory variable for the first 200-m time in 800 MAX (adjusted r 2 = 0.661, P 0.001). Runners with a higher CAZ score (i.e., higher estimated percentage of type II fibers) reduced their last lap time to a greater extent in 800 PACE relative to 800 MAX (adjusted r 2 = 0.413, P 0.001), whereas better maintenance of mechanical effectiveness during sprinting, a higher CAZ score and vV˙O 2peak was associated with a faster final 200-m time during 800 PACE (adjusted r 2 = 0.761, P = 0.001). These findings highlight that ersity in the physiological and speed/mechanical characteristics of male middle-distance runners may be associated with their suitability for different 800-m racing strategies to have the best chance of winning.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 26-07-2021
DOI: 10.1519/JSC.0000000000004106
Abstract: Minahan, C, Newans, T, Quinn, K, Parsonage, J, Buxton, S, and Bellinger, P. Strong, Fast, Fit, Lean, and Safe: A positional comparison of physical and physiological qualities within the 2020 Australian Women's Rugby League team. J Strength Cond Res 35(12S): S11–S19, 2021—The purpose of the present study was to report the physical and physiological characteristics of elite women Rugby League (RL) players. Thirty-nine women (25.6 ± 4.3 years, 171.3 ± 7.7 cm, 83.5 ± 13.9 kg) from the 2020 Australian women's RL squad were recruited for this study. Players were categorized as adjustables ( n = 7), backs ( n = 15), or forwards ( n = 17) for analysis. Each player was assessed for anthropometry, body composition (dual-energy X-ray absorptiometry), speed (5, 10 and 20 m sprint times), lower-body power (countermovement jump), upper-body power (medicine ball throw and explosive push up force), estimated one repetition maximum (e1RM) bench press, squat and bench pull, isometric mid-thigh pull strength, eccentric knee flexor strength, isometric hip abduction and adduction, and intermittent endurance performance (30–15 intermittent fitness test 30–15 IFT). Linear mixed models were performed to compare positional groups. Forwards were significantly heavier and had greater fat mass, fat-free mass, and body fat percentage compared with backs and adjustables ( P 0.01). Backs were faster over 20 m compared with forwards ( P = 0.025), whereas forwards had a lower 30–15 IFT peak velocity and estimated V̇ o 2 peak compared with backs and adjustables. Nonetheless, when including body mass in the model, there were no differences between groups in 30–15 IFT peak velocity. There were no significant differences in other variables. These results provide contemporary benchmark physical, physiological, and anthropometric data for elite women RL players, which can inform recruitment, selection, training, and testing.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 26-10-2020
DOI: 10.1249/MSS.0000000000002518
Abstract: Classic track-and-field studies demonstrated that elite endurance athletes exhibit a slow muscle typology, whereas elite sprint athletes have a predominant fast muscle typology. In elite cycling, conclusive data on muscle typology are scarce, which may be due to the invasive nature of muscle biopsies. The noninvasive estimation of muscle typology through the measurement of muscle carnosine enabled to explore the muscle typology of 80 world-class cyclists of different disciplines. The muscle carnosine content of 80 cyclists (4 bicycle motor cross racing [BMX], 33 track, 8 cyclo-cross, 24 road, and 11 mountain bike) was measured in the soleus and gastrocnemius by proton magnetic resonance spectroscopy and expressed as a z -score relative to a reference population. Track cyclists were ided into track sprint and endurance cyclists based on their Union Cycliste Internationale (UCI) ranking. Moreover, road cyclists were further characterized based on the percentage of UCI points earned during either single and multistage races. BMX cyclists (carnosine aggregate z -score of 1.33) are characterized by a faster muscle typology than track, cyclo-cross, road, and mountain bike cyclists (carnosine aggregate z -score of −0.08, −0.76, −0.96, and −1.02, respectively P 0.05). Track cyclists also possess a faster muscle typology compared with mountain bikers ( P = 0.033) and road cyclists ( P = 0.005). Moreover, track sprinters show a significant faster muscle typology (carnosine aggregate z -score of 0.87) compared with track endurance cyclists (carnosine aggregate z -score of −0.44) ( P 0.001). In road cyclists, the higher the carnosine aggregate z -score, the higher the percentage of UCI points gained during single-stage races ( r = 0.517, P = 0.010). Prominent differences in the noninvasively determined muscle typology exist between elite cyclists of various disciplines, which opens opportunities for application in talent orientation and transfer.
Publisher: Springer Science and Business Media LLC
Date: 28-01-2021
DOI: 10.1186/S40798-020-00297-0
Abstract: Rapid restoration of muscle glycogen stores is imperative for athletes undertaking consecutive strenuous exercise sessions with limited recovery time (e.g. ≤ 8 h). Strategies to optimise muscle glycogen re-synthesis in this situation are essential. This two-part systematic review and meta-analysis investigated the effect of consuming carbohydrate (CHO) with and without protein (PRO) on the rate of muscle glycogen re-synthesis during short-term post-exercise recovery (≤ 8 h). Studies were identified via the online databases Web of Science and Scopus. Investigations that measured muscle glycogen via needle biopsy during recovery (with the first measurement taken ≤ 30 min post-exercise and at least one additional measure taken ≤ 8 h post-exercise) following a standardised exercise bout (any type) under the following control vs. intervention conditions were included in the meta-analysis: part 1, water (or non-nutrient beverage) vs. CHO, and part 2, CHO vs. CHO+PRO. Publications were examined for methodological quality using the Rosendal scale. Random-effects meta-analyses and meta-regression analyses were conducted to evaluate intervention efficacy. Overall, 29 trials ( n = 246 participants) derived from 21 publications were included in this review. The quality assessment yielded a Rosendal score of 61 ± 8% (mean ± standard deviation). Part 1: 10 trials ( n = 86) were reviewed. Ingesting CHO during recovery (1.02 ± 0.4 g·kg body mass (BM) −1 h −1 ) improved the rate of muscle glycogen re-synthesis compared with water change in muscle glycogen (MG Δ ) re-synthesis rate = 23.5 mmol·kg dm −1 h −1 , 95% CI 19.0–27.9, p 0.001 I 2 = 66.8%. A significant positive correlation ( R 2 = 0.44, p = 0.027) was observed between interval of CHO administration (≤ hourly vs. hourly) and the mean difference in rate of re-synthesis between treatments. Part 2: 19 trials ( n = 160) were reviewed. Ingesting CHO+PRO (CHO: 0.86 ± 0.2 g·kg BM −1 h −1 PRO: 0.27 ± 0.1 g·kg BM −1 h −1 ) did not improve the rate of muscle glycogen re-synthesis compared to CHO alone (0.95 ± 0.3 g·kg BM −1 h −1 ) MG Δ re-synthesis rate = 0.4 mmol·kg dm −1 h −1 , 95% CI −2.7 to 3.4, p = 0.805 I 2 = 56.4%. Athletes with limited time for recovery between consecutive exercise sessions should prioritise regular intake of CHO, while co-ingesting PRO with CHO appears unlikely to enhance (or impede) the rate of muscle glycogen re-synthesis. Registered at the International Prospective Register of Systematic Reviews (PROSPERO) (identification code CRD42020156841 ).
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2020
DOI: 10.1519/JSC.0000000000002164
Abstract: Minahan, CL, Poke, DP, Morrison, J, and Bellinger, PM. Muscle damage and metabolic responses to repeated-sprint running with and without deceleration. J Strength Cond Res 34(12): 3423–3430, 2020—This study aimed to determine whether repeated-sprint running with deceleration aggravates markers of muscle damage or delays the recovery of performance compared with repeated-sprint running without deceleration. Fourteen male team-sport athletes performed 2 randomly ordered testing sessions on a nonmotorized treadmill with one session requiring subjects to decelerate (TMd) within 4 seconds before stopping or immediately step to the side of the treadmill belt at the completion of each sprint (TMa). Peak and mean velocities, speed decrement, blood lactate concentrations, and oxygen uptake were monitored during the repeated-sprint running protocols. Countermovement vertical jump (CMJ) performance, perceived muscle soreness, sit-and-reach flexibility, plasma creatine kinase (CK), lactate dehydrogenase (LDH), and myoglobin (Mb) concentrations were quantified immediately before and after and 45 minutes, 24 and 48 hours after repeated-sprint running protocols. Although muscle damage was indicated by increases in CK, LDH, and Mb ( p ≤ 0.05) in both groups, there was no significant effect of condition (TMa vs. TMd) on any of the measured performance or physiological variables ( p 0.05). The present study indicated that the removal of deceleration from repeated-sprint running on a nonmotorized treadmill has no effect on metabolism or performance during or after repeated-sprint running or markers of muscle damage.
Publisher: SAGE Publications
Date: 05-11-2020
Abstract: A difficulty in identifying the optimal age, height, and body mass of swimmers is the heterogeneity of the athletes examined (i.e., gender, caliber), the variability in race distance and stroke, and the influence of time. Nonetheless, age, height, and body mass remains the most readily available data of all athlete characteristics, supporting their contribution to the prediction of performance. This review presents the findings of previous studies over the last 50 years and offers new insights by examining data from swimmers competing at the 1968, 1992, and 2016 Olympic Games. Our data investigates gender differences in age, before exploring gender-specific variations in the age, height, and body mass across year, distance, stroke, and caliber. We show that there are differences in swimmers competing at the 2016 compared to the 1968 and 1992 Olympic Games. Today the age of world-class swimmers is independent of gender, race distance and stroke, as well as caliber. Swimmers competing in freestyle are taller and heavier than in butterfly, while height remains associated with performance in some, but not all events in female swimmers. In 2016 the average age, height and body mass of World-class swimmers is 22.7 ± 3.6 and 23.2 ± 23.3 years, 175.1 ± 6.6 cm and 188.3 ± 6.0 cm and 63.8 ± 6.8 and 81.3 ± 7.3 kg for females and males respectively. These findings provide coaches with a new perspective on the optimal age, height, and body mass of world-class female and male swimmers.
Publisher: Human Kinetics
Date: 11-2021
Abstract: Purpose : To determine the influence of muscle fiber typology (MFT) on the pacing strategy of elite swimmers competing in the 200-m freestyle event. Method : The top 3 career-best performances from 25 elite 200-m freestyle swimmers were analyzed—12 women (1:58.0 [0:01.3] min:s) and 13 men (1:48.4 [0:02.5]). Muscle carnosine concentration was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus muscles and expressed as a carnosine aggregate z score (CAZ score) relative to an age- and gender-matched nonathlete control group to estimate MFT. Linear regression models were employed to examine the influence of MFT on the percentage of overall race time spent in each 50-m lap. Results : Swimmers with a higher CAZ score spent a greater percentage of race time in lap 3 compared with swimmers with a lower CAZ score (0.1%, 0.0% to 0.2% mean, 90% confidence interval, P = .02). For every 1% increase in the percentage of race time spent in lap 1, the percentage of race time spent in lap 3 decreased by 0.4% for swimmers with a higher CAZ score (0.2% to −0.5%, P = .00, r = −.51), but not for swimmers with a lower CAZ score (−0.1%, −0.3% to 0.1%, P = .28, r = −.18). The percentage of race time spent in lap 4 decreased by 0.8% for higher-CAZ-score swimmers (−0.5% to −1.0%, P = .00, r = −.66) and by 0.9% for lower-CAZ-score swimmers (−0.6% to −1.3%, P = .00, r = −.65) when lap 1 percentage increased by 1%. Conclusion : MFT may influence the pacing strategy of swimmers in the 200-m freestyle event, which provides an avenue for maximizing in idualized pacing strategies of elite swimmers.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Phillip Bellinger.