ORCID Profile
0000-0002-4373-4245
Current Organisation
Université Laval
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Publisher: Informa UK Limited
Date: 12-09-2022
DOI: 10.1080/17461391.2022.2085631
Abstract: The aim of this study was to investigate acute performance and physiological responses to the manipulation of exercise-to-rest ratio (E:R) during repeated-sprint hypoxic training (RSH) in hot conditions. Twelve male team-sport players completed two experimental sessions at a simulated altitude of ∼3000 m (F
Publisher: Informa UK Limited
Date: 26-04-2020
Publisher: Frontiers Media SA
Date: 10-02-2017
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.
Publisher: Springer Science and Business Media LLC
Date: 29-08-2017
DOI: 10.1007/S00421-017-3705-Y
Abstract: We manipulated the inspired oxygen fraction (FiO Nine active males completed a repeated sprint cycle protocol (10 × 4-s maximal sprints with 30 s of passive recovery) in normoxia (NM FiO The 10 sprints in HY were associated with lower arterial oxygen saturation values compared to NM [80.7 ± 0.9 vs. 95.6 ± 0.6% P < 0.001 effect size (ES) = 0.98], higher blood lactate values (11.9 ± 0.4 vs. 9.9 ± 0.9 mmol L Despite severe hypoxia exacerbating both physiological and perceptual perturbations, the performance decrement observed during the repeated sprint protocol did not coincide with an accentuated decline in RMS EMG activity. These data suggest that higher-than-normal exercise-related sensations or perceptions coincide with fatigue during repeated sprinting, independent of changes in neural drive, when the task characteristics are known beforehand.
Publisher: Frontiers Media SA
Date: 03-11-2016
Publisher: Frontiers Media SA
Date: 20-07-2017
Publisher: Frontiers Media SA
Date: 07-02-2017
Publisher: Public Library of Science (PLoS)
Date: 19-09-2019
Publisher: Frontiers Media SA
Date: 03-10-2022
Publisher: American Physiological Society
Date: 02-2018
Publisher: Cold Spring Harbor Laboratory
Date: 22-01-2022
DOI: 10.1101/2021.01.22.427755
Abstract: This pilot study examined the effect of inspiratory muscle training (IMT) on repeated-sprint ability and vastus lateralis reoxygenation. Ten recreationally trained subjects were randomly ided into two groups to complete 4 weeks of IMT or Sham (placebo) training. Pre- and post-intervention, a repeated-sprint ability (RSA) test was performed in both normoxia and hypoxia (F i O 2 ≈ 14.5%). Vastus lateralis reoxygenation (VL reoxy ), defined as peak to minimum litude deoxyhaemoglobin for each sprint/recovery cycle, was assessed during all trials using near-infrared spectroscopy. For total work performed, power analysis revealed that for small, medium and large effects (Cohen’s f ), s le sizes of n = 8, 16 and 90 respectively, are required to achieve a power of 80% at an α level of 0.05. Maximal inspiratory mouth pressure increased in IMT by 36.5%, 95% CI [20.9, 61.6] and by 2.7%, 95% CI [−4.46, 8.8] in Sham. No clear difference in the change of work completed during the sprints between groups were observed in normoxia (Sham −0.805 kJ, 95% CI [−3.92, 0.39] IMT −2.06 kJ, 95% CI [−11.5, 4.96] P = 0.802), or hypoxia (Sham −3.09 kJ, 95% CI [−7, 0.396] IMT 0.354 kJ, 95% CI [−1.49, 2.1] P = 0.802). VL reoxy in IMT increased by 9.34%, 95% CI [5.15, 13.7] in normoxia only. In conclusion, despite a large increase in IMT, this was only associated with a small effect on RSA in our pilot study cohort. Owing to a potentially relevant impact of training the inspiratory musculature, future studies should include a s le size of at least 16-20 to detect moderate to large effects on RSA.
Publisher: Human Kinetics
Date: 2016
Abstract: To determine the time course for physical-capacity adaptations to intermittent hypoxic training (IHT) in team-sport athletes and the time course for benefits remaining after IHT. A pre–post parallel-groups design was employed, with 21 Australian footballers assigned to IHT (n = 10) or control (CON n = 11) matched for training load. IHT performed eleven 40-min bike sessions at 2500-m altitude over 4 wk. Yo-Yo Intermittent Recovery Test level 2 (Yo-Yo IR2) was performed before after 3, 6, and 11 IHT sessions and 30 and 44 d after IHT. Repeated time trials (2- and 1-km TTs, with 5 min rest) were performed before, after, and 3 wk after IHT. Hemoglobin mass (Hb mass ) was measured in IHT before and after 3, 6, 9, and 11 sessions. Baseline Yo-Yo IR2 was similar between groups. After 6 sessions, the change in Yo-Yo IR2 in IHT was very likely higher than CON (27% greater change, effect size 0.77, 90% confidence limits 0.20 .33) and likely higher 1 d after IHT (23%, 0.68, 0.05 .30). The IHT group’s change remained likely higher than CON 30 d after IHT (24%, 0.72, 0.12 .33) but was not meaningfully different 44 d after (12%, 0.36, –0.24 .97). The change in 2-km TT performance between groups was not different throughout. For 1-km TT, CON improved more after IHT, but IHT maintained performance better after 3 wk. Hb mass was higher after IHT (2.7%, 0.40, –0.40 .19). Short-duration IHT increased Yo-Yo IR2 compared with training-load-matched controls in 2 wk. An additional 2 wk of IHT provided no further benefit. These changes remained until at least 30 d posttraining. IHT also protected improvement in 1-km TT.
Publisher: Springer Science and Business Media LLC
Date: 22-10-2016
DOI: 10.1007/S00421-016-3481-0
Abstract: Salbutamol inhalation is permissible by WADA in athletic competition for asthma management and affects potassium regulation, which is vital for muscle function. Salbutamol effects on arterial potassium concentration ([K Seven recreationally active men participated in a double-blind, randomised, cross-over design, inhaling 1000 µg salbutamol or placebo. Participants cycled continuously for 5 min at 40 % [Formula: see text]O Plasma [K Inhaled salbutamol modulated the [K
Publisher: Georg Thieme Verlag KG
Date: 21-07-2020
DOI: 10.1055/A-1088-5388
Abstract: To investigate the effect of acute capsaicin (CAP) supplementation on time to exhaustion, physiological responses and energy systems contribution during continuous high-intensity exercise session in runners. Fifteen recreationally-trained runners completed two randomized, double-blind continuous high-intensity exercises at the speed eliciting 90% V̇O2peak (90% s V̇O2peak), 45 minutes after consuming capsaicin or an isocaloric placebo. Time to exhaustion, blood lactate concentration, oxygen consumption during and 20-min post-exercise, energy systems contribution, time to reach V̇O2peak, heart rate and the rate of perceived exertion (RPE) were evaluated. There was no significant difference between conditions for time to reach V̇O2peak (CAP:391.71±221.8 vs. PLA:298.20±174.5 sec, ES:0.58, p=0.872), peak lactate (CAP:7.98±2.11 vs. PLA:8.58±2.15 µmol, ES:−0.28, p=0.257), time to exhaustion (CAP:654.28±195.44 vs. PLA:709.20±208.44 sec, ES:−0.28, p=0.462, end-of-exercise heart rate (CAP:177.6±14.9 vs. PLA:177.5±17.9 bpm, ES:−0.10, p=0.979) and end-of-exercise RPE (CAP: 19±0.8 vs. PLA: 18±2.4, ES: 0.89, p=0.623). In conclusion, acute CAP supplementation did not increase time to exhaustion during high-intensity continuous exercise nor alter physiological responses in runners.
Publisher: Wiley
Date: 28-03-2016
DOI: 10.1002/MUS.24926
Abstract: Magnetic stimulation can be used to assess muscle function by calculating voluntary activation using an interpolated twitch during maximal voluntary contractions (MVCs) and control twitches to potentiated muscle. In this study we assessed the reliability of torque, electromyography (EMG), and voluntary activation variables. Fifteen men completed 5 testing sessions (2 familiarization and 3 reliability trials) to assess quadriceps femoris muscle function. Intra- and interday reliability levels of torque and EMG variables were estimated using typical error ± 90% confidence limits, expressed as percentage [coefficient of variation (CV)] and intraclass correlation coefficient. The smallest worthwhile change was calculated as 0.2 × between-participant standard deviation. Intra- and interday torque variables for MVC were reliable (CV < 4%, ICC 0.98, and CV < 5%, ICC 0.99, respectively). EMG variables were less reliable than torque variables, with CVs ranging from 7% to 18%. Magnetic stimulation of the femoral nerve is a reliable method for assessing muscle function.
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.RESP.2018.11.006
Abstract: This study aimed to investigate whether exercise hyperpnoea contributes to an impairment of locomotor muscle oxygenation and performance during repeated-sprint exercise in normoxia and hypoxia. Subjects performed ten 10-s sprints, separated by 30 s of passive rest while breathing either a normoxic (21% O
Publisher: Springer Science and Business Media LLC
Date: 23-08-2018
DOI: 10.1007/S00421-018-3968-Y
Abstract: To compare prefrontal cortex oxygenation in recreationally-active women using oral contraceptives (WomenOC n = 8) to women with a natural menstrual cycle (WomenNC n = 8) during incremental exercise to exhaustion. Participants performed incremental cycling to exhaustion to determine lactate threshold 1 (LT1) and 2 (LT2) and peak oxygen uptake (VO 17β-oestradiol and progesterone were lower in WomenOC (35 ± 26 318 ± 127 pmol·L Prefrontal tissue oxygenation declined at a lower relative exercise intensity in WomenOC as compared to WomenNC, however, this did not influence VO
Publisher: American Physiological Society
Date: 11-2014
DOI: 10.1152/JAPPLPHYSIOL.00988.2013
Abstract: Central motor drive to active muscles is believed to be reduced during numerous exercise tasks to prevent excessive peripheral fatigue development. The purpose of the present study was to use hypoxia to exacerbate physiological perturbations during a novel, intermittent exercise task and to explore the time-course and interplay between central and peripheral neuromuscular adjustments. On separate days, 14 healthy men performed four sets of 6 × 5 maximal-intensity, isokinetic leg extensions (1 repetition lasting ∼7 s) at 300°/s (15 and 100 s of passive rest between repetitions and sets, respectively) under normoxia (NM, fraction of inspired O 2 0.21), moderate (MH, 0.14), and severe normobaric hypoxia (SH, 0.10). Neuromuscular assessments of the knee extensors were conducted before and immediately after each set. There was an interaction between time and condition on the mean peak torque produced during each set ( P 0.05). RMS/M-wave activity of the rectus femoris decreased across the four sets of exercise, but there was no difference between conditions (8.3 ± 5.1% all conditions compounded, P 0.05). Potentiated twitch torque decreased post set 1 in all conditions (all P 0.05) with greater reductions following each set in SH compared with NM but not MH (end-exercise reductions 41.3 ± 3.0% vs. 28.0 ± 3.2%, P 0.05 and 32.1 ± 3.3%, P 0.05). In conclusion, severe hypoxia exacerbates both peripheral fatigue development and performance decrements during maximal, intermittent, dynamic leg extensions. In contrast to observations with other exercise modes, during exercise involving a single muscle group the attenuation of central motor drive does not appear to independently regulate the development of peripheral muscle fatigue.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.JSAMS.2015.12.518
Abstract: To determine the efficacy of live-high train-low on team-sport athlete physical capacity and the time-course for adaptation. Pre-post parallel-groups. Fifteen Australian footballers were matched for Yo-Yo Intermittent recovery test level 2 (Yo-YoIR2) performance and assigned to LHTL (n=7) or control (Con n=8). LHTL spent 19 nights (3×5 nights, 1×4 nights, each block separated by 2 nights at sea level) at 3000-m simulated altitude (F Compared to pre, Hb Fifteen nights of LHTL was possibly effective, while 19 nights was effective at increasing Hb
Publisher: American Physiological Society
Date: 07-2014
DOI: 10.1152/JAPPLPHYSIOL.01027.2013
Abstract: We investigated whether potassium (K + ) disturbances during and following intense exercise may be pronounced when utilizing a large contracting muscle mass, examining maximal 2,000-m rowing exercise effects on radial arterial plasma K + concentration ([K + ] a ) in 11 healthy adults. Blood was s led at baseline, preexercise, each 30 s during rowing, and for 30 min postexercise. Time to complete 2,000 m was 7.26 ± 0.59 min power output at 30 s was 326 ± 81 W (mean ± SD). With exercise time expressed in deciles, power output fell 16.5% from the first to fourth decile ( P 0.05) and 19.9% at the ninth decile ( P 0.05) EMG median frequency declined 4.6% by the third decile and 5.5% by the eighth decile ( P 0.05). Plasma [K + ] a increased from 3.89 ± 0.13 mM at rest to 6.13 ± 0.46 mM by 90 s rowing ( P 0.001) and was then sustained until end exercise ( P 0.001). In recovery, [K + ] a decreased abruptly, reaching 3.33 ± 0.22 mM at 5 min postexercise ( P 0.001) and remaining below preexercise after 30 min ( P 0.005). At end exercise, blood [lactate] a (preexercise 0.64 ± 0.18 mM) reached 10.87 ± 1.33 mM, plasma volume decreased 9.7 ± 2.3% from preexercise, and pH a decreased to 7.10 ± 0.07 units ( P 0.001). In conclusion, arterial hyperkalemia was sustained during exhaustive rowing reflecting a balance between K + release and reuptake in contracting muscles and K + uptake by inactive muscles. While high, the [K + ] a was lower than anticipated compared with maximal cycling or sprinting, possibly reflecting greater adrenergic response and Na + ,K + -ATPase activity in contracting muscles fatigue was evidenced by reduced power output and EMG median frequency. A prolonged hypokalemia after rowing likely reflected continuing muscular Na + ,K + -ATPase activity.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2018
DOI: 10.1249/MSS.0000000000001576
Abstract: The effectiveness of contrast training (CST) for improving explosive exercise performance is modulated by various in idual characteristics however, further work is required to define these factors. Subelite male Australian Football players ( n = 22 age, 19 ± 2 yr body mass, 80.4 ± 9.4 kg one-repetition maximum [1-RM] half squat, 172 ± 18 kg mean ± SD) completed two experimental trials involving two sets of squat jumps (six repetitions at 30% 1-RM) performed either alone (CTL condition) or after half squats (six repetitions at 85% 1-RM CST condition). Squat jump peak power was similar between CTL and CST during set 1 (mean change: ±90% confidence interval, 2.8% ± 2.0% effect size [ES]: ±90% confidence interval, 0.13 ± 0.09 P = 0.079) and set 2 (0.3% ± 1.7% ES, 0.01 ± 0.08 P = 0.781). Peak power enhancement with CST was not related to maximal (1-RM half squat) strength ( r 2 = 0.001, P = 0.884), but was negatively correlated with both baseline peak power ( r 2 = 0.44, P 0.001) and power-to-strength ratio (PSR) that is, the ratio between baseline peak power and 1-RM half squat strength ( r 2 = 0.65, P 0.001). Using a median split, analyses were performed in participants with a low PSR (LPSR group PSR = 15.4–19.1 W·kg −1 n = 11) or high PSR (HPSR group, PSR = 19.4–24.7 W·kg −1 n = 11). Peak power was enhanced with CST for the LPSR (8.1% ± 3.9% ES, 0.44 ± 0.21 P = 0.004) but not HPSR (−2.1% ± 1.3% ES, −0.14 ± 0.09 P = 0.010) groups. The PSR appears to influence the effectiveness of CST, with performance enhancement more likely in those with a lower PSR.
Publisher: Springer Science and Business Media LLC
Date: 21-02-2020
Publisher: Informa UK Limited
Date: 18-07-2018
DOI: 10.1080/02640414.2017.1349922
Abstract: We investigated the association between changes in vastii electromyography (EMG) and knee extensor fatigue during high-intensity cycling, and the subsequent effect on lower-limb power and intermuscular coordination during all-out cycling. On two separate days, participants completed 30-s all-out cycling or 10-min of high-intensity cycling followed by 30-s all-out cycling. EMG for gluteus maximus (GMAX), rectus femoris (RF), vastii (VAS), hamstrings (HAM) and gastrocnemius (GAS) co-activation for GMAX/RF, VAS/HAM and VAS/GAS isometric maximal voluntary force (IMVF) and resting twitch (RT) of the knee extensors were measured. VAS EMG increases during high-intensity cycling (6% to 14%, P < 0.05) were negatively correlated (r = -0.791, P < 0.05) with knee extensor IMVF decreases (-2% to-36%, P < 0.05) following the exercise. Knee extensor IMVF decreases were positively correlated (r = 0.757, P < 0.05) with all-out cycling power reductions (0% to -27%, P 0.05) during all-out cycling while VAS and GAS EMG decreased. Larger increase in VAS EMG during high-intensity cycling was associated with greater knee extensor fatigue and larger power reduction during all-out cycling. High VAS/GAS co-activation potentially limited power reduction induced by knee extensor fatigue during all-out cycling.
Publisher: Springer Science and Business Media LLC
Date: 14-05-2021
DOI: 10.1007/S00421-021-04706-4
Abstract: To investigate within the one study potential molecular and cellular changes associated with mitochondrial biogenesis following 15 days of exposure to moderate hypoxia. Eight males underwent a muscle biopsy before and after 15 days of hypoxia exposure (FiO Our main findings were the absence of significant changes in the mean values of CS activity, mitochondrial respiration in permeabilised fibers, or the content of genes and proteins associated with mitochondrial biogenesis, after 15 days of moderate normobaric hypoxia. Our data provide evidence that 15 days of moderate normobaric hypoxia have negligible influence on skeletal muscle mitochondrial content and function, or genes and proteins content associated with mitochondrial biogenesis, in young recreationally active males. However, the increase in mitochondrial protease LON content after hypoxia exposure suggests the possibility of adaptations to optimise respiratory chain function under conditions of reduced O
Publisher: Informa UK Limited
Date: 08-12-2021
No related grants have been discovered for François Billaut.