Temporal and Spatial Accuracy of Reaching Movements do not Improve Off-line.

Consolidation has been associated with performance gains without additional practice (i.e., off-line learning). However, the movement characteristics improving off-line remain poorly understood. To investigate this question, participants were trained to produce a sequence of planar reaching movements toward four different visual targets. The training session with feedback required them to learn the relative time of the movements, the total movement time and aim accurately at each target. The retention test was performed either 10-min or 24-h after. Results revealed that a 24-h consolidation interval did not result in better temporal or spatial accuracy. This finding suggests that off-line learning may be restricted to sequence production tasks in which the different segments must be regrouped ("chunked") together to accelerate their execution.

Exploratory analysis of cortical thickness in low- and high-fit young adults.

OBJECTIVE: Studies have shown changes in the human brain associated with physical activity and cardiorespiratory fitness (CRF). The effects of CRF on cortical thickness have been well-described in older adults, where a positive association between CRF and cortical thickness has been reported, but the impact of sustained aerobic activity in young adults remains poorly described. Here, exploratory analysis was performed on cortical thickness data that was collected in groups of fit and sedentary young adults. METHODS: Twenty healthy sedentary individuals (<2 h/week physical activity) were compared to 20 active individuals (>6 h/week physical activity) and cortical thickness was measured in 34 cortical areas. Cortical thickness values were compared between groups, and correlations between cortical thickness and VO2 max were tested. RESULTS: Cardiorespiratory fitness was significantly higher in active individuals compared to sedentary individuals. Cortical thickness was lower in regions of the left (lateral and medial orbitofrontal cortex, pars orbitalis, pars triangularis, rostral anterior cingulate cortex, superior temporal cortex and frontal pole) and right (lateral and medial orbitofrontal cortex and pars opercularis) hemispheres. Only the left frontal pole and right lateral orbitofrontal cortical thickness remained significant after false discovery rate correction. Negative correlations were observed between VO2 max and cortical thickness in the left (frontal pole) and right (caudal anterior cingulate and medial orbitofrontal cortex) hemispheres. CONCLUSION: The present exploratory analysis supports previous findings suggesting that neuroplastic effects of cardiorespiratory fitness may be attenuated in young compared with older individuals, underscoring a moderating effect of age on the relationship between fitness and cortical thickness.

Physiological, Anatomical and Metabolic Correlates of Aerobic Fitness in Human Primary Motor Cortex: A Multimodal Study.

Physical activity (PA) has been shown to benefit various cognitive functions and promote neuroplasticity. Whereas the effects of PA on brain anatomy and function have been well documented in older individuals, data are scarce in young adults. Whether high levels of cardiorespiratory fitness (CRF) achieved through regular PA are associated with significant structural and functional changes in this age group remains largely unknown. In the present study, twenty young adults that engaged in at least 8 hours per week of aerobic exercise during the last 5 years were compared to twenty sedentary controls on measures of cortical excitability, white matter microstructure, cortical thickness and metabolite concentration. All measures were taken in the left primary motor cortex and CRF was assessed with VO2max. Transcranial magnetic stimulation (TMS) revealed higher corticospinal excitability in high- compared to low-fit individuals reflected by greater input/output curve amplitude and slope. No group differences were found for other TMS (short-interval intracortical inhibition and intracortical facilitation), diffusion MRI (fractional anisotropy and apparent fiber density), structural MRI (cortical thickness) and magnetic resonance spectroscopy (NAA, GABA, Glx) measures. Taken together, the present data suggest that brain changes associated with increased CRF are relatively limited, at least in primary motor cortex, in contrast to what has been observed in older adults.

Association Between Variations in Training Load, Sleep, and the Well-Being of Professional Hockey Players.

PURPOSE: To evaluate whether sleep quantity and quality of professional hockey players is affected by external training load (TL), their perception of well-being, and contextual factors associated with match participation. METHODS: Fifty male athletes were monitored daily during the 28 weeks of the regular season using well-being and sleep surveys. On-ice external TL was monitored using portable inertial measurement units during practices and matches. Linear mixed-effects models were applied to evaluate whether well-being perception (ie, pain, nutrition, stress, and rest) and external TL may affect sleep quality and quantity. RESULTS: High levels of well-being positively affected sleep duration and quality (P < .001), whereas high-intensity TL had a detrimental impact on sleep duration (P = .007). Moreover, away and evening matches had a detrimental effect on sleep quantity and quality (P < .001). Finally, a high match on-ice load per minute had a negative association with sleep quality (P = .04). CONCLUSIONS: Findings indicate that well-being and high-intensity trainings can impair sleep duration and quality. In addition, high-intensity match load, away matches, and evening matches can impair postmatch sleep. Therefore, monitoring well-being in conjunction with TL is essential to understand sleep disturbances in athletes. Practitioners should also implement sleep hygiene strategies that facilitate longer time in bed after high-intensity, away, and evening matches to help athletes recover.

Activate Your Health: impact of a real-life programme promoting healthy lifestyle habits in Canadian workers.

The workplace has been suggested as a good setting for the promotion of healthy lifestyles. This article examines the impact of Activate Your Health programme, provided over an average of 1.35 years, on employee health and lifestyle habits (actual and intention to improve). Companies selected one of the programme's four options (number of interventions in parentheses): Control (2), Light (8), Moderate (13) and High (14). Employees (n = 524) completed an online questionnaire at baseline and post-intervention. Mixed-effect models and generalized estimating equations models were used, where appropriate. There was an interaction effect of time by option for the number of employees intending to improve sleep habits (p = 0.030): +11.0% in Light (p = 0.013). No significant interaction effect of time by option was observed for body weight, body mass index, number of health problems or lifestyle habits (actual and intention to improve). When stratified by sex, there was an interaction effect of time by option for the number of women intending to improve sleep habits (p = 0.023): -26.1% in Moderate (p = 0.014). There was an interaction effect of time by option for body weight in men (p = 0.001): -0.58 kg in High (p = 0.031) and +2.58 kg in Control (p = 0.005). Other outcomes of interest were stable or improved post-intervention, regardless of option. The Activate Your Health programme allowed employees to maintain or improve outcomes related to health and lifestyle habits. A package like High may be beneficial for body weight regulation in men.

Can Popular High-Intensity Interval Training (HIIT) Models Lead to Impossible Training Sessions?

High-Intensity Interval Training (HIIT) is a time-efficient training method suggested to improve health and fitness for the clinical population, healthy subjects, and athletes. Many parameters can impact the difficulty of HIIT sessions. This study aims to highlight and explain, through logical deductions, some limitations of the Skiba and Coggan models, widely used to prescribe HIIT sessions in cycling. We simulated 6198 different HIIT training sessions leading to exhaustion, according to the Skiba and Coggan-Modified (modification of the Coggan model with the introduction of an exhaustion criterion) models, for three fictitious athlete profiles (Time-Trialist, All-Rounder, Sprinter). The simulation revealed impossible sessions (i.e., requiring athletes to surpass their maximal power output over the exercise interval duration), characterized by a few short exercise intervals, performed in the severe and extreme intensity domains, alternating with long recovery bouts. The fraction of impossible sessions depends on the athlete profile and ranges between 4.4 and 22.9% for the Skiba model and 0.6 and 3.2% for the Coggan-Modified model. For practitioners using these HIIT models, this study highlights the importance of understanding these models' inherent limitations and mathematical assumptions to draw adequate conclusions from their use to prescribe HIIT sessions.

Harnessing the functional diversity of plant cystatins to design inhibitor variants highly active against herbivorous arthropod digestive proteases.

Protein engineering approaches have been proposed to improve the inhibitory properties of plant cystatins against herbivorous arthropod digestive proteases, generally involving the site-directed mutagenesis of functionally relevant amino acids or the selection of improved inhibitor variants by phage display approaches. Here, we propose a novel approach where the function-related structural elements of a cystatin are substituted by the corresponding elements of an alternative cystatin. Inhibitory assays were first performed with 20 representative plant cystatins and model Cys proteases, including arthropod proteases, to appreciate the extent of functional variability among the plant cystatin family. The most, and less, potent of these cystatins were then used as 'donors' of structural elements to create hybrids of tomato cystatin SlCYS8 used as a model 'recipient' inhibitor. In brief, inhibitory activities against Cys proteases strongly differed from one plant cystatin to another, with Ki (papain) values diverging by more than 30-fold and inhibitory rates against arthropod proteases varying by up to 50-fold depending on the enzymes assessed. In line with theoretical assumptions from docking models generated for different Cys protease-cystatin combinations, structural element substitutions had a strong impact on the activity of recipient cystatin SlCYS8, positive or negative depending on the basic inhibitory potency of the donor cystatin. Our data confirm the wide variety of cystatin inhibitory profiles among plant taxa. They also demonstrate the usefulness of these proteins as a pool of discrete structural elements for the design of cystatin variants with improved potency against herbivorous pest digestive Cys proteases.

In-Season Session Training Load Relative to Match Load in Professional Ice Hockey.

ABSTRACT: Allard, P, Martinez, R, Deguire, S, and Tremblay, J. In-season session training load relative to match load in professional ice hockey. J Strength Cond Res 36(2): 486-492, 2022-The aim of this study was to describe match load and intensity across player positions and match periods, the distribution of pregame training load and intensity over training days before a match, by player position, and the cumulative weekly training load over a season. Fifty professional ice hockey players, which at one time or another were part of the roster for the Laval Rocket during the 2017-18 season of the American Hockey League, participated in this study. External load was monitored in every training session and match over the season using portable inertial measurement units. Data are reported in absolute and relative values to a match. Defensemen have a lower intensity during matches than forwards (-1.70 OIL·min-1) while load is similar across position. The first period shows a higher relative load (+5.28% relative on-ice load [OIL]) while the third has a lower relative intensity (-2.91% OIL·min-1). Defensemen seem to train at a systematic higher relative intensity than wingers and centers (+8.34% relative OIL·min-1). Finally, the weekly training load remains relatively constant throughout the season (equivalent of 3.56 ± 1.69 matches played per week). Our results support the need for player monitoring in ice hockey using an individualized approach.

Health-Related and Lifestyle Factors as Predictors of Intentions to Improve Lifestyle Habits in Employees Participating in a Workplace Health Promotion Program.

OBJECTIVES: To explore employees' intentions to improve lifestyle habits, investigate the health and lifestyle-related predictors of these intentions, and how it translated into behavioral improvement. METHODS: Employees participating in the Activate Your Health WHPP completed a questionnaire of their demographics, health-related variables, as well as six lifestyle habits and intention to improve them. RESULTS: At baseline (n = 2729), most employees wanted to focus on physical activity and eating habits. Many predictors were identified for each intention. Majority of intentions were associated with behavioral improvement post-program (n = 525), especially in High. CONCLUSIONS: In the context of WHPPs, intention to improve may lead to actual behavioral improvement. Exploring employees' intentions to improve various lifestyle habits at the start of the program could improve the effectiveness of these programs.

The FitSpirit approach for increasing physical activity in canadian teenage girls: protocol of a longitudinal, quasi-experimental study.

BACKGROUND: Worldwide, most adolescent girls do not meet physical activity (PA) recommendations and very few PA programs are tailored specifically towards them. Even fewer information exists about the long-term effects of such programs. Some Canadian schools have implemented the FitSpirit PA intervention designed specifically for girls aged 12 to 17 years old. This paper describes the protocol of a quasi-experimental study evaluating long-term changes in health behaviours and outcomes following FitSpirit participation. METHODS: The study is conducted among schools that partner with FitSpirit every year. It started in 2018 and will be completed in 2022. The intervention comprises motivational talks, a turnkey running program, PA sessions and special events. Study participants fill out an online questionnaire twice a year. Follow-up questionnaires are sent at the end of each school year to the study participants who dropout from FitSpirit. The main outcome, changes in PA levels, is evaluated using questions validated for adolescents. Secondary outcomes are health (perceived health); lifestyle habits (sedentary activities, eating and sleeping habits); psychosocial outcomes (physical self-efficacy and body satisfaction); and FitSpirit appreciation (activity participation and satisfaction). Most questions originate from questionnaires validated for the adolescent population. Cross-sectional and longitudinal analyses will be performed. DISCUSSION: This study will provide one of the first longitudinal reports on the impact of a large extra-curricular PA intervention designed specifically for adolescent girls. The current study will uniquely contribute to PA research by assessing outcomes additional to PA levels, including markers of health, lifestyle habits and psychosocial determinants. TRIAL REGISTRATION: NCT, NCT03804151 , Registered on January 22, 2019; retrospectively registered.

Impact of 2 different aerobic periodization training protocols on left ventricular function in patients with stable coronary artery disease: an exploratory study.

We compared the impacts of linear (LP) and nonlinear (NLP) aerobic training periodizations on left ventricular (LV) function and geometry in coronary artery disease (CAD) patients. Thirty-nine CAD patients were randomized to either a 3-month isoenergetic supervised LP or NLP. All underwent standard echocardiography with assessment of 3D LV ejection fraction (LVEF), diastolic function, strain (global longitudinal, radial, and circumferential), and strain rate at baseline and study end. Training was performed 3 times/week and included high-intensity interval and moderate-intensity continuous training sessions. Training load was progressively increased in the LP group, while it was deeply increased and intercepted with a recovery week each fourth week in the NLP group. For the 34 analyzed patients, we found similar improvements for 3D LVEF (effect size (ES): LP, 0.29; NLP, 0.77), radial strain (ES: LP, 0.58; NLP, 0.48), and radial strain rate (ES: LP, 0.87; NLP, 0.17) in both groups (time for all: p ≤ 0.01). All other parameters of cardiac function remained similar. In conclusion, NLP and LP led to similar improvements in 3D LVEF and radial strain, suggesting a favourable positive cardiac remodelling through myofibers reorganization. These findings must be investigated in patients with more severe cardiac dysfunction. The study was registered on ClinicalTrials.gov (NCT03443193). Novelty: Linear and nonlinear periodization programs improved radial strain, accompanied by improvement of ejection fraction. Both aerobic periodization programs did not negatively impact cardiac function in coronary artery disease patients.

Ingestion of maple-based and other carbohydrate sports drinks: effect on sensory perceptions during prolonged exercise.

BACKGROUND: Taste and appreciation of sports drinks can affect perceived exertion during exercise. Anecdotal evidence shows that maple products are regularly consumed by recreational and professional athletes but very few studies have reported on their effects during exercise. The purpose of the current study is to report the taste, appreciation and perceived exertion following the ingestion of maple-based sports drinks and other carbohydrate drinks during prolonged exercise. METHODS: Recreationally and competitively active male subjects (n = 76, mass = 73.7 ± 10.3 kg, maximum oxygen consumption (VO2max) = 4.4 ± 0.5 L/min, maximal aerobic power (MAP) = 309 ± 42 W) ingested one of four carbohydrate solutions (all at 60 g CHO/L): concentrated maple sap (MW), diluted maple syrup (MS), glucose (G), a commercial sports drink (CSD), or a placebo (P; water sweetened with stevia) at every 30 min during 120 min of steady-state exercise (SSE) on a cycle ergometer at 66% MAP. Ratings of perceived exertion (RPE, Borg CR-10) were recorded at each 30 min throughout SSE. A questionnaire was administered to assess sensory characteristics (sweetness, acidity, refreshing, and overall taste on a visual analogue scale, converted to decimals from 0 to 1) and appreciation (sweet, acid and overall on a 9-point hedonic scale) 30 min before (immediately after the first ingestion) and immediately after SSE. RESULTS: Sweetness was perceived to be higher for MW than G and P (pre: 0.60 ± 0.19, 0.51 ± 0.17 and 0.50 ± 0.17 and post: 0.69 ± 0.19, 0.34 ± 0.18 and 0.48 ± 0.22; p < 0.05, respectively) and MS was rated higher than MW for the appreciation of the sweet taste (pre: 6.5 ± 1.5 vs. 4.6 ± 1.8 and post: 6.8 ± 1.8 and 4.1 ± 1.8; p < 0.05, respectively). Furthermore, subjects that had ingested MW, reported a significantly lower RPE than those with P at 120 min (14.1 ± 2.2 vs. 16.0 ± 2.0, respectively). CONCLUSIONS: A sports drink containing maple syrup is well appreciated during prolonged exercise and appears to be a viable alternatives to more common sources of carbohydrates. TRIAL REGISTRATION: NCT02880124 . Registered on 26 August 2016.

Changes in Lifestyle Habits among Adolescent Girls after FitSpirit Participation.

Adolescence is a crucial time in the development and maintenance of lifestyle habits. Interventions to improve health-related behaviors are important, including those that can contribute to an increase in physical activity (PA). During adolescence, PA typically decreases with age, particularly in girls. The FitSpirit program offers services that help Canadian schools from Quebec and Ontario implement PA interventions for adolescent girls. This study aimed to evaluate changes in participants' PA levels and lifestyle habits (sedentary time, sleep duration and eating habits) and to assess whether these changes depended on adherence to the Canadian 24-Hour Movement Guidelines and Canada's Food Guide recommendations at enrollment. At the time of FitSpirit registration (between December 2018 and March 2019) and in May/June 2019, 73 participants answered online questionnaires. The participants reported improvements, with an increase in the number of days with PA and a decrease in daily consumption of sweets. The greatest changes were observed in those who did not adhere to the Canadian recommendations before enrollment and who significantly increased their number of days with PA and their consumption of fruits and vegetables, and decreased their screen time. In conclusion, participation in FitSpirit improved several health behaviors among adolescent girls, particularly those who did not comply with the Canadian recommendations at enrollment.

Non-linear is not superior to linear aerobic training periodization in coronary heart disease patients.

BACKGROUND: We aimed to compare: (1) two different periodized aerobic training protocols (linear (LP) versus non-linear (NLP)) on the cardiopulmonary exercise response in patients with coronary heart disease; (2) the proportion of responders between both training protocols. DESIGN: A randomized controlled trial. METHODS: A total of 39 coronary heart disease patients completed either LP (n = 20, 65 ± 10 years) or NLP (n = 19, 66 ± 5 years). All patients completed a cardiopulmonary exercise testing with gas exchange measurements. Patients underwent a 12-week supervised exercise program including an isoenergetic aerobic periodized training and a similar resistance training program, 3 times/week. Weekly energy expenditure was constantly increased in the LP group for the aerobic training, while it was deeply increased and intercepted with a recovery week each fourth week in the NLP group. Peak oxygen uptake (peak V̇O2), oxygen uptake efficiency slope, ventilatory efficiency slope (V̇E/V̇CO2 slope), V̇O2 at the first (VT1) and second (VT2) ventilatory thresholds, and oxygen pulse (O2 pulse) were measured. Responders were determined according the median value of the Δpeak V̇O2 (mL.min-1.kg-1). RESULTS: We found similar improvement for peak V̇O2 (LP: +8.1%, NLP: +5.3%, interaction: p = 0.37; time: p < 0.001) and for oxygen uptake efficiency slope, VT1, VT2 and O2 pulse in both groups (interaction: p > 0.05; time: p < 0.05) with a greater effect size in the LP group. The proportion of non-, low and high responders was similar between groups (p = 0.29). CONCLUSION: In contrast to the athletes, more variation (NLP) does not seem necessary for greater cardiopulmonary adaptations in coronary heart disease patients.

Impact of Carbohydrate Ingestion on Cognitive Flexibility and Cerebral Oxygenation during High-Intensity Intermittent Exercise: A Comparison between Maple Products and Usual Carbohydrate Solutions.

BACKGROUND: The aim of this study was to compare the effects of carbohydrate (CHO) drinks (6% per volume) sweetened with maple (syrup or sap) to a commercial sports drink, glucose, and a control solution (water) on cognitive flexibility during high-intensity intermittent exercise. METHODS: Eighty-five active men completed six 3-min bouts at 95% of their maximal aerobic power on a stationary bike, with 3 min of passive rest between efforts. Subjects were randomly allocated to an ingestion condition. Following each exercise bout, subjects ingested 166 mL of the experimental solution, drinking a total of 1 L of the same solution throughout the experimentation. Cognitive flexibility was measured using reaction time and accuracy on the Stroop task. The cognitive task was performed a total of 10 times, including 15 and 30 min post-exercise. Glycemia and cerebral oxygenation were also measured at each time point. Statistical analyses were performed using a two-way ANOVA (Condition × Time) with repeated measures. RESULTS: The ingestion of maple products and the commercial sports drink led to a lesser increase in glycemia than glucose ingestion. CHO ingestion, when compared to water, induced a slight reduction in reaction times on the cognitive task, especially in the switching trials. CHO ingestion had no impact on cerebral oxygenation. CONCLUSIONS: This study shows that CHO ingestion, regardless of its type, tends to improve cognitive performance throughout exercise, especially during difficult cognitive tasks.

Activate Your Health, a 3-year, multi-site, workplace healthy lifestyle promotion program: study design.

BACKGROUND: Workplace Health Promotion Programs (WHPP) have been shown to be an efficient way of improving workers' health. These programs can be incorporated in the worker's daily schedule and improve their productivity at work. Improving employees' health also benefits the employers by increasing their return on investment and lowering healthcare costs. The Activate Your Health program, created by Capsana in 2015, is a WHPP targeting multiple lifestyle habits for a three-year period. This WHPP includes tailored web-based interventions and the support of different health professionals throughout the years. We hypothesize that this approach will yield long-term lifestyle changes. The objective of the current paper is to describe the Activate Your Health program's design. METHODS/DESIGN: Eleven companies are taking part in this WHPP and had to choose among five different options of this program and all their employees were encouraged to participate. Each option differs by the number and type of interventions included. The limited option, which is considered the control group, only consists in completing a questionnaire regarding their health status, lifestyle habits and behaviors. On the other end, the extensive option receives a combination of multiple interventions: online menus, health challenges, support in creating a healthy work environment, coaching by health professionals (nurse, nutritionist, and kinesiologist), health screening and flexibility assessment, online resources, social health platform, and activity tracking. The remaining options are in between these options and vary by the amount of intervention. Baseline data are already gathered; two other data collection periods will take place after one and 2 years into the program. The primary outcomes of the current program are physical activity and fitness measures, nutritional data, smoking habits, stress and intention to change. DISCUSSION: The Activate Your Health program will allow us to compare which combinations of interventions are the most effective. It is expected that the extensive option will be the most advantageous to improve lifestyle habits. The results will indicate the strength and weakness of each intervention and how it could be improved. TRIAL REGISTRATION: Clinicaltrails.gov, registration number: NCT02933385 (updated on the 26th of March 2019, initially registered on the 5th of October 2016).

Recombinant cystatins in plants.

Dozens of studies have assessed the practical value of plant cystatins as ectopic inhibitors of Cys proteases in biological systems. The potential of these proteins in crop protection to control herbivorous pests and pathogens has been documented extensively over the past 25 years. Their usefulness to regulate endogenous Cys proteases in planta has also been considered recently, notably to implement novel traits of agronomic relevance in crops or to generate protease activity-depleted environments in plants or plant cells used as bioreactors for recombinant proteins. After a brief update on the basic structural characteristics of plant cystatins, we summarize recent advances on the use of these proteins in plant biotechnology. Attention is also paid to the molecular improvement of their structural properties for the improvement of their protease inhibitory effects or the fine-tuning of their biological target range.

Cluster analysis using physical performance and self-report measures to identify shoulder injury in overhead female athletes.

OBJECTIVES: To evaluate the diagnostic validity of the Kerlan-Jobe orthopedic clinic shoulder and elbow score (KJOC) and the Closed kinetic upper extremity stability test (CKCUEST) to assess functional impairments associated with shoulder injury in overhead female athletic populations. DESIGN: Cross-sectional design. METHODS: Thirty-four synchronized swimming and team handball female athletes completed the KJOC and the CKCUEST during their respective team selection trials. Unsupervised learning using k-means algorithm was used on collected data to perform group clustering and classify athletes as Injured or Not Injured. Odds ratios, likelihood ratios, sensitivity and specificity were computed based on the self-reported presence of shoulder injury at the time of testing or during the previous year. RESULTS: Seven of the 34 athletes were injured or had suffered a time-loss injury in the previous year, representing a 20.5% prevalence rate. Clustering method using KJOC data resulted in a sensitivity of 86%, a specificity of 100% and a 229.67 diagnostic odds ratio. Clustering method using CKCUEST data resulted in a sensitivity of 86%, a specificity of 37% and a 3.53 diagnostic odds ratio. CONCLUSIONS: KJOC had good diagnostic validity to assess shoulder function and differentiate between injured and non-injured elite synchronized swimming and team handball female athletes. The CKCUEST seemed to be a poor screening test but may be an interesting test to evaluate functional upper extremity strength and plyometric capacity. Unsupervised learning methods allow to make decisions based on numerous variables which is an advantage when considering the usually substantial overlap in screening test scores between high- and low-risk athletes.

Unilateral Conditioning Contractions Enhance Power Output in Elite Short Track Speed Skaters.

The objective of the present study was to assess the effect of unilateral lower-body-conditioning muscle contractions during multiple sets of fatiguing repeated jumps in elite athletes. Five elite short-track speed-skating athletes performed 9 sets of 6 maximal consecutive jumps on 2 separate occasions: with (COND) and without (CTRL) preliminary voluntary conditioning contractions (CC) 5 min before the beginning of the sets. The CC consisted of 2 consecutive 3 s maximal unilateral isometric squats against a fixed bar, resulting in a 6 s overall isometric contraction per leg. For each set, power output (PO) was measured using a linear position transducer and averaged over the 6 corresponding repeated jumps. The results showed that PO was significantly greater during the test in COND than in CTRL ( p <0.01). PO significantly decreased with sets, by 19.4±4.7 and 15.2±7.6% ( p <0.001) between the first and last set in COND and CTRL, respectively. A 2×3 s maximal unilateral isometric CC, performed 5 min before unloaded repeated jumps, significantly increased mean PO. These results suggest that unilateral conditioning contractions can enhance performance in subsequent bilateral repeated jumps.