A New Training Load Quantification Method at Supramaximal Intensity and Its Application in Injuries Among Members of an International Volleyball Team.

ABSTRACT: Bouzigues, T, Maurelli, O, Imbach, F, Prioux, J, and Candau, R. A new training load quantification method at supramaximal intensity and its application in injuries among members of an international volleyball team. J Strength Cond Res XX(X): 000-000, 2024-The quantification of training loads (TLs) is essential for optimizing jump performance and reducing the occurrence of injuries. This study aimed to (a) propose a new method for quantifying TLs in explosive exercises, (b) determine the nature of the relationship between TLs dynamics and injury occurrence, and (c) assess a TL critical for training schedule purposes, above which the risk of injury occurrence becomes unacceptable. This study was conducted with 11 male volleyball players on a national team during a 5-month international competitive period. The proposed new method for quantifying TLs is based on a weighting factor applied to relative jumping intensities, determined by the number of sustainable jumps and their intensities measured by G-Vert accelerometer. The relationship between TLs dynamics and injury occurrence was assessed using a variable dose-response model. A high coefficient of determination was found between the maximum number of jumps possible and their intensities ( r2 = 0.94 ± 0.14, p < 0.001), indicating a strong physiological relationship between jumping intensities and the constraints imposed. The occurrence of injury was dependent on TLs dynamics for 2 players ( r2 = 0.26 ± 0.01; p < 0.001). The TL critical corresponded to 11 jumps over 80% of maximum jump height during games and approximately 130 jumps at <80% of maximal jump height. The present study proposes a new approach for quantifying supramaximal exercises and provides tools for training schedules and the prevention of volleyball injuries.

Active recovery vs hot- or cold-water immersion for repeated sprint ability after a strenuous exercise training session in elite skaters.

This study compared the acute effects of three recovery methods: active recovery (AR), hot- and cold-water immersion (HWI and CWI, respectively), used between two training sessions in elite athletes. Twelve national-team skaters (7 males, 5 females) completed three trials according to a randomized cross-over study. Fifteen minutes after an exhaustive ice-skating training session, participants underwent 20 min of HWI (41.1 ± 0.5°C), 15 min of CWI (12.1 ± 0.7°C) or 15 min of active recovery (AR). After 1 h 30 min of the first exercise, they performed a repeated-sprint cycling session. Average power output was slightly but significantly higher for AR (767 ± 179 W) and HWI (766 ± 170 W) compared to CWI (738 ± 156 W) (p = 0.026, d = 0.18). No statistical difference was observed between the conditions for both lactatemia and rating of perceived exertion. Furthermore, no significant effect of recovery was observed on the fatigue index calculated from the repeated sprint cycling exercises (p > 0.05). Finally, a positive correlation was found between the average muscle temperature measured during the recoveries and the maximal power output obtained during cycling exercises. In conclusion, the use of CWI in between high-intensity training sessions could slightly impair the performance outcomes compared to AR and HWI. However, studies with larger samples are needed to confirm these results, especially in less trained athletes.

Does the interference phenomenon affect strength development during same-session combined rehabilitation program in hemodialysis patients?

INTRODUCTION: This study aimed to assess if an interference effect could blunt the neuromuscular gains induced by a same-session combined rehabilitation in hemodialysis (HD) patients. METHODS: Patients exercised twice a week, for 16 weeks, over their HD sessions. They were either always trained with resistance and endurance exercises (continuous training, "CONT") or alternatively with 1 week of resistance alternated with 1 week of endurance (discontinuous training, "DISC"). Adherence and workload were continuously recorded. Short Physical Performance Battery (SPPB) score, one-leg balance test, and handgrip and quadriceps strength were evaluated before and after training intervention. RESULTS: Adherence to both programs was high (>90%). SPPB score had significantly improved (CONT: +1.5 point, DISC: +1.2 pt, p < 0.001), like one-leg balance test (CONT: +3.7 s, DISC: +5.5 s, p < 0.05), handgrip strength of exercised (CONT: +5.5 kg, DISC: +5.6 kg, p < 0.001) and of nonexercised arm (CONT: +4.4 kg, DISC: +2.8 kg, p < 0.01) as well as maximal quadriceps strength (+22 N·m for dominant and +29 N·m for nondominant leg in both groups, p < 0.001) bearing no difference between the trainings. CONCLUSION: Same-session combined training does not induce an interference effect in HD patients and temporal separation of exercises does not optimize strength gains. These practical data may be relevant for clinicians and practitioners to alternate endurance and resistance exercises.

Modelling performance with exponential functions in elite short-track speed skaters.

Mathematical models are used to describe and predict the effects of training on performance. The initial models are structured by impulse-type transfer functions, however, cellular adaptations induced by exercise may exhibit exponential kinetics for their growth and subsequent dissipation. Accumulation of exercise bouts counteracts dissipation and progressively induces structural and functional changes leading to performance improvement. This study examined the suitability of a model with exponential terms (Exp-Model) in elite short-track speed (ST) skaters. Training loads and performance evolution from fifteen athletes (10 males, 5 females) were previously collected over a 3-month training period. Here, we computed the relationship between training loads and performance with Exp-Model and compared with previous results obtained with a variable dose-response model (Imp-Model). Exp-Model showed a higher correlation between actual and modelled performances (R2 = 0.83 ± 0.08 and 0.76 ± 0.07 for Exp-Model and Imp-Model, respectively). Concerning model parameters, a higher τA1 (time constant for growth) value was found (p = 0.0047; d = 1.4; 95% CI [0.4;1.9]) in males compared to females with Exp-model, suggesting that females have a faster adaptative response to training loads. Thus, according to this study, Exp-model may better describe training adaptations in elite ST athletes than Imp-Model.

Influence of post-exercise hot-water therapy on adaptations to training over 4 weeks in elite short-track speed skaters.

This study aimed to investigate the effects of regular hot water bathing (HWB), undertaken 10 min after the last training session of the day, on chronic adaptations to training in elite athletes. Six short-track (ST) speed skaters completed four weeks of post-training HWB and four weeks of post-training passive recovery (PR) according to a randomized cross-over study. During HWB, participants sat in a jacuzzi (40 °C; 20 min). According to linear mixed models, maximal isometric strength of knee extensor muscles was significantly increased for training with HWB (p < 0.0001; d = 0.41) and a tendency (p = 0.0529) was observed concerning V ˙ O 2 m a x . No significant effect of training with PR or HWB was observed for several variables (p > 0.05), including aerobic peak power output, the decline rate of jump height during 1 min-continuous maximal countermovement jumps (i.e. anaerobic capacity index), and the force-velocity relationship. Regarding specific tasks on ice, a small effect of training was found on both half-lap time and total time during a 1.5-lap all-out exercise (p = 0.0487; d = 0.23 and p = 0.0332; d = 0.21, respectively) but no additional effect of HWB was observed. In summary, the regular HWB protocol used in this study can induce additional effects on maximal isometric strength without compromising aerobic and anaerobic adaptations or field performance in these athletes.

eIF3f depletion impedes mouse embryonic development, reduces adult skeletal muscle mass and amplifies muscle loss during disuse.

KEY POINTS: In muscular cells, eukaryotic initiation factor subunit f (eIF3f) activates protein synthesis by allowing physical interaction between mechanistic target of rapamycin complex 1 (MTORC1) and ribosomal protein S6 kinase 1 (S6K1), although its physiological role in animals is unknown. A knockout approach suggests that homozygous mice carrying a null mutation of the eIF3f gene fail to develop and consequently die at early embryonic stage, whereas heterozygous mice associated with a partial depletion of eIF3f gene grow normally and are phenotypically indistinguishable from wild-type mice. Heterozygous mice express reduced eIF3f mRNA and protein levels in skeletal muscles and show diminished muscle mass associated with a decrease in the protein synthesis rate and an inhibition of the MTORC1 pathway. During hindlimb immobilization, heterozygous eIF3f mice display an exacerbated immobilization-induced muscle atrophy associated with reduced protein synthesis. These results highlight the essential role of eIF3f during embryonic development and its involvement in muscular homeostasis via protein synthesis regulation. ABSTRACT: Eukaryotic translation initiation factor 3, subunit F (eIF3f), a component of eIF3 complex, plays an important role in protein synthesis regulation, although its physiological functions are unknown. We generated and analysed mice carrying a null mutation in the eIF3f gene. We showed that homozygous eIF3f knockout fail to develop and that eIF3f-/- embryos die at an early stage of development but after the pre-implantation stage. However, disrupting one eIF3f allele does not affect growth, viability and fertility of heterozygous mice but, instead, reduces eIF3f mRNA and protein levels in all tissues examined. Although heterozygous mice are phenotypically indistinguishable from wild-type mice, they present a diminished body weight and a lean mass reduction associated with normal body size. Interestingly, skeletal muscles are mainly affected and display an altered cell size without modification of fibre number. Skeletal muscles of heterozygous mice show a deficiency in polysome content, a decrease in protein synthesis rate and an inhibition of the mechanistic target of rapamycin (MTOR) pathway. We then studied the effects of hindlimb immobilization that mimic muscle disuse on heterozygous mice aiming to further explore the involvement of eIF3f in protein synthesis. We found that eIF3f partial depletion amplifies muscle atrophy compared to wild-type mice. Mass and cross-sectional area decreases were associated with reduced MTOR pathway activation and protein synthesis rate. Taken together, our data indicate that eIF3f is essential for mice embryonic development and controls adult skeletal muscle mass via protein synthesis regulation in a MTOR-dependent manner.

Increase in muscle power is associated with myofibrillar ATPase adaptations during resistance training.

NEW FINDINGS: What is the central question of this study? The aim of this study was to examine the effects of resistance training on gains in the external mechanical power output developed during climbing and myofibrillar ATPase activity in rats. What is the main finding and its importance? Using rapid flow quench experiments, we show that resistance training increases both the power output and the myofibrillar ATPase activity in the flexor digitorum profundus, biceps and deltoid muscles. Data fitting reveals that these functional ameliorations are explained by an increase in the rate constant of liberation of ATP hydrolysis products and contribute to performance gains. ABSTRACT: Skeletal muscle shows a remarkable plasticity that permits functional adaptations in response to different stimulations. To date, modifications of the proportions of myosin heavy chain (MHC) isoforms and increases in fibre size are considered to be the main factors providing sarcomeric plasticity in response to exercise training. In this study, we investigated the effects of a resistance training protocol on the myofibrillar ATPase (m-ATPase) cycle, muscle performance (power output) and MHC gene expression. For this purpose, 8-week-old Wistar Han rats were subjected to 4 weeks of resistance training, with five sessions per week. Muscle samples of flexor digitorum profundus (FDP), biceps and deltoid were collected and subjected to RT-qPCR analyses and assessment of m-ATPase activity with rapid flow quench apparatus. Training led to a significant increase in muscle mass, except for the biceps, and in total mechanical power output (+135.7%, P < 0.001). A shift towards an intermediate fibre type (i.e. MHC2x-to-MHC2a isoform transition) was also observed in biceps and FDP but not in the deltoid muscle. Importantly, rapid flow quench experiments revealed an enhancement of the m-ATPase activity during contraction at maximal velocity (kF ) in the three muscles, with a more marked effect in FDP (+242%, P < 0.001). Data fitting revealed that the rate constant of liberation of ATP hydrolysis products (k3 ) appears to be the main factor influencing the increase in m-ATPase activity. In conclusion, the data showed that, in addition to classically observed changes in MHC isoform content and fibre hypertrophy, m-ATPase activity is enhanced during resistance training and might contribute significantly to performance gains.

Systems model and individual simulations of training strategies in elite short-track speed skaters.

This study aimed to evaluate the effect of simulated training strategies on performance potential in elite short-track speed skaters. Training load and field-based criterion performances from fifteen athletes (10 males, 5 females) were collected over a 3-month training period and the relationship between training loads and performance was computed with a variable dose-response model using a genetic algorithm. Individual simulations of tapers preceded or not preceded by an overload training (OT) were assessed. We obtained a significant correlation between actual and modelled performances (R2 = 0.76 ± 0.07). Regarding model parameters, no significant difference was found between males and females but the time to recover performance tended to be lower in females. Simulations in which the taper parameters were free highlighted that an exponential or a step taper were the most effective for increasing performance compared to a linear taper (p < 0.05). Optimal exponential taper duration after OT was 10.7 ± 2.4d and the optimal load reduction was 75.9 ± 3.7%. OT intensity had the greatest influence on the predicted performance, followed by OT duration, taper decay, and to a lesser extent load reduction during taper and taper duration. Thus, a variable dose-response systems model allows the evaluation of different taper strategies and their potential effect on performance changes.

Modelling performance and skeletal muscle adaptations with exponential growth functions during resistance training.

System theory is classically applied to describe and to predict the effects of training load on performance. The classic models are structured by impulse-type transfer functions, nevertheless, most biological adaptations display exponential growth kinetics. The aim of this study was to propose an extension of the model structure taking into account the exponential nature of skeletal muscle adaptations by using a genetic algorithm. Thus, the conventional impulse-type model was applied in 15 resistance trained rodents and compared with exponential growth-type models. Even if we obtained a significant correlation between actual and modelled performances for all the models, our data indicated that an exponential model is associated with more suitable parameters values, especially the time constants that correspond to the positive response to training. Moreover, positive adaptations predicted with an exponential component showed a strong correlation with the main structural adaptations examined in skeletal muscles, i.e. hypertrophy (R2 = 0.87, 0.96 and 0.99, for type 1, 2A and 2X cross-sectional area fibers, respectively) and changes in fiber-type composition (R2 = 0.81 and 0.79, for type 1 and 2A fibers, respectively). Thus, an exponential model succeeds to describe both performance variations with relevant time constants and physiological adaptations that take place during resistance training.

AMP-activated protein kinase stabilizes FOXO3 in primary myotubes.

AMP-activated protein kinase (AMPK) is a critical enzyme in conditions of cellular energy deficit such as exercise, hypoxia or nutritional stress. AMPK is well known to regulate protein degradation pathways notably through FOXO-related axis. In this study, we investigated the implication of AMPK activation in FOXO3 expression and stability in skeletal muscle primary myotubes. First, time course and dose response studies revealed optimal AICAR treatment duration and dose in skeletal muscle cells. Then, experiments with cycloheximide treatment of primary myotubes highlighted that AICAR infusion extends FOXO3 protein half-life. Our results also showed that AICAR treatment or nutrient depletion increases FOXO3 expression in primary myotubes and the expression of the mitochondrial E3 ligase Mul1 involved in mitochondrial turnover (mitophagy). In AMPK KO cells, nutrient depletion failed to alter the level of some FOXO3-dependent atrophic genes, including LC3B, BNIP3, and the mitochondrial E3 ligase Mul1, but not the expression of other genes (i.e. FOXO1, Gabarapl1, MAFbx, MuRF1). In summary, our data highlight that AMPK stabilizes FOXO3 and suggest a role in the first initiation step of mitochondrial segregation in muscle cells.

Early structural and functional signature of 3-day human skeletal muscle disuse using the dry immersion model.

KEY POINTS: Our study contributes to the characterization of muscle loss and weakness processes induced by a sedentary life style, chronic hypoactivity, clinical bed rest, immobilization and microgravity. This study, by bringing together integrated and cellular evaluation of muscle structure and function, identifies the early functional markers and biomarkers of muscle deconditioning. Three days of muscle disuse in healthy adult subjects is sufficient to significantly decrease muscle mass, tone and force, and to induce changes in function relating to a weakness in aerobic metabolism and muscle fibre denervation. The outcomes of this study should be considered in the development of an early muscle loss prevention programme and/or the development of pre-conditioning programmes required before clinical bed rest, immobilization and spaceflight travel. ABSTRACT: Microgravity and hypoactivity are associated with skeletal muscle deconditioning. The decrease of muscle mass follows an exponential decay, with major changes in the first days. The purpose of the study was to dissect out the effects of a short-term 3-day dry immersion (DI) on human quadriceps muscle function and structure. The DI model, by suppressing all support zones, accurately reproduces the effects of microgravity. Twelve healthy volunteers (32 ± 5 years) completed 3 days of DI. Muscle function was investigated through maximal voluntary contraction (MVC) tests and muscle viscoelasticity. Structural experiments were performed using MRI analysis and invasive experiments on muscle fibres. Our results indicated a significant 9.1% decrease of the normalized MVC constant (P = 0.048). Contraction and relaxation modelization kinetics reported modifications related to torque generation (kACT  = -29%; P = 0.014) and to the relaxation phase (kREL  = +34%; P = 0.040) after 3 days of DI. Muscle viscoelasticity was also altered. From day one, rectus femoris stiffness and tone decreased by, respectively, 7.3% (P = 0.002) and 10.2% (P = 0.002), and rectus femoris elasticity decreased by 31.5% (P = 0.004) after 3 days of DI. At the cellular level, 3 days of DI translated into a significant atrophy of type I muscle fibres (-10.6 ± 12.1%, P = 0.027) and an increased proportion of hybrid, type I/IIX fibre co-expression. Finally, we report an increase (6-fold; P = 0.002) in NCAM+ muscle fibres, showing an early denervation process. This study is the first to report experiments performed in Europe investigating human short-term DI-induced muscle adaptations, and contributes to deciphering the early changes and biomarkers of skeletal muscle deconditioning.

FoxO transcription factors: their roles in the maintenance of skeletal muscle homeostasis.

Forkhead box class O family member proteins (FoxOs) are highly conserved transcription factors with important roles in cellular homeostasis. The four FoxO members in humans, FoxO1, FoxO3, FoxO4, and FoxO6, are all expressed in skeletal muscle, but the first three members are the most studied in muscle. In this review, we detail the multiple modes of FoxO regulation and discuss the central role of these proteins in the control of skeletal muscle plasticity. FoxO1 and FoxO3 are key factors of muscle energy homeostasis through the control of glycolytic and lipolytic flux, and mitochondrial metabolism. They are also key regulators of protein breakdown, as they modulate the activity of several actors in the ubiquitin­proteasome and autophagy­lysosomal proteolytic pathways, including mitochondrial autophagy, also called mitophagy. FoxO proteins have also been implicated in the regulation of the cell cycle, apoptosis, and muscle regeneration. Depending of their activation level, FoxO proteins can exhibit ambivalent functions. For example, a basal level of FoxO factors is necessary for cellular homeostasis and these proteins are required for adaptation to exercise. However, exacerbated activation may occur in the course of several diseases, resulting in metabolic disorders and atrophy. A better understanding of the precise functions of these transcriptions factors should thus lead to the development of new therapeutic approaches to prevent or limit the muscle wasting that prevails in numerous pathological states, such as immobilization, denervated conditions, neuromuscular disease, aging, AIDS, cancer, and diabetes.

Influence of linear and undulating strength periodization on physical fitness, physiological, and performance responses to simulated judo matches.

To determine the most effective strength periodization model is important to improve judo athletes' performance. Thus, the aim of this study was to compare the effects of linear and daily undulating periodized resistance training on anthropometrical, strength, and judo-specific performance. For this, 13 adult male judo athletes (LP = 6 and DUP = 7) completed a 8-week training program concomitantly to a typical judo training program. Athletes were submitted to a physical fitness test battery, before and after 8 weeks of training, consisting of: (a) maximal strength evaluation: bench press, squat, and row exercises 1 repetition maximum (1RM) tests, and handgrip maximal isometric strength; (b) power evaluation: standing long jump test; (c) strength endurance evaluation: dynamic and isometric chin-up tests gripping the judogi; (d) anthropometry measurements: body mass, height, skinfold thickness and circumferences; (e) judo-specific fitness: performance during the Special Judo Fitness Test (SJFT); (f) match simulation: three 5-minute judo match simulations separated by 15-minute passive recovery. Eight weeks of linear and undulating strength training protocols induced similar significant (P ≤ 0.05) decreases in skinfold thicknesses (-6.5%) and increases in flexed arm (2.0%) and forearm (1.8%) circumferences, maximal isometric handgrip strength (4.6% and 6.1% for right and left hands, respectively), isometric strength endurance chin-up performance gripping the judogi (18.9%), maximal dynamic strength for row (11.5%), bench press (11.6%) and squat exercises (7.1%), total weight lifted at 70% 1RM for bench press (15.1%) and squat (9.6%) exercises, number of throws during sets B (3.1%) and C (9.5%) of the SJFT (resulting in increased total number of throws, 5.5%), and decreased index in this test, -4.2%). However, no changes were observed in the physiological, rating of perceived exertion, or technical actions during 3 match simulations. Thus, it seems that the short-term adaptations were not transferable to the match condition.

Perceived training intensity and performance changes quantification in judo.

The objective of this study was to determine the methods of quantification for training and performance, which would be the most appropriate for modeling the responses to long-term training in cadet and junior judo athletes. For this, 10 young male judo athletes (15.9 ± 1.3 years, 64.9 ± 10.3 kg, and 170.8 ± 5.4 cm) competing at a regional/state level volunteered to take part in this study. Data were collected during a 2-year training period (i.e., 702 days) from January 2011 to December 2012. Their mean training volume was 6.52 ± 0.43 hours per week during the preparatory periods and 4.75 ± 0.49 hours per week during the competitive periods. They followed a training program prescribed by the same coach. The training load (TL) was quantified through the session rating of perceived exertion (RPE) and expressed in arbitrary unit (a.u.). Performance was quantified from 5 parameters and divided into 2 categories: performance in competition and performance in training. The evaluation of performance in competition was based on the number of points per level. Performance in training was assessed through 4 different tests. A physical test battery consisting of a standing long jump, 2 judo-specific tests that were the maximal number of dynamic chin-up holding the judogi, and the Special Judo Fitness Test was used. System modeling for describing training adaptations consisted of mathematically relating the TL of the training sessions (system input) to the change in performance (system output). The quality of the fit between TL and performance was similar, whether the TL was computed directly from RPE (R = 0.55 ± 0.18) or from the session RPE (R = 0.56 ± 0.18) and was significant in 8 athletes over 10, excluding the standing jump from the computation of the TL, leading to a simplest method. Thus, this study represents a first attempt to model TL effects on judo-specific performance and has shown that the best relationships between amounts of training and changes in performance were obtained when training amounts were quantified simply from RPE.

Autophagy is essential to support skeletal muscle plasticity in response to endurance exercise.

Physical exercise is a stress that can substantially modulate cellular signaling mechanisms to promote morphological and metabolic adaptations. Skeletal muscle protein and organelle turnover is dependent on two major cellular pathways: Forkhead box class O proteins (FOXO) transcription factors that regulate two main proteolytic systems, the ubiquitin-proteasome, and the autophagy-lysosome systems, including mitochondrial autophagy, and the MTORC1 signaling associated with protein translation and autophagy inhibition. In recent years, it has been well documented that both acute and chronic endurance exercise can affect the autophagy pathway. Importantly, substantial efforts have been made to better understand discrepancies in the literature on its modulation during exercise. A single bout of endurance exercise increases autophagic flux when the duration is long enough, and this response is dependent on nutritional status, since autophagic flux markers and mRNA coding for actors involved in mitophagy are more abundant in the fasted state. In contrast, strength and resistance exercises preferentially raise ubiquitin-proteasome system activity and involve several protein synthesis factors, such as the recently characterized DAGK for mechanistic target of rapamycin activation. In this review, we discuss recent progress on the impact of acute and chronic exercise on cell component turnover systems, with particular focus on autophagy, which until now has been relatively overlooked in skeletal muscle. We especially highlight the most recent studies on the factors that can impact its modulation, including the mode of exercise and the nutritional status, and also discuss the current limitations in the literature to encourage further works on this topic.

Rowing ergometer with the slide is more specific to rowers' physiological evaluation.

This study investigated maximal and submaximal performance (power output) and physiological responses (oxygen uptake, heart rate and blood lactate concentration) of eight male rowers to two different incremental tests to exhaustion performed either in a rowing ergometer without (regular) or with the slide, as well as to a 2000 m race simulation, conducted in a randomized order. Peak oxygen uptake ([Formula: see text]O2peak) was statistically higher (3.4%) in the regular test (5.18 ± 0.44 L.min(-1)) compared with the slide condition (5.01 ± 0.37 L.min(-1); P = 0.005). Time for the on-water race simulation was significantly correlated with the slope of the [Formula: see text]O2-power relationship in the slide condition (r = -0.73, P = 0.043) and [Formula: see text]O2peak during the test in the slide condition was correlated to mean [Formula: see text]O2 at the on-water race simulation (r = 0.78; P = 0.024). Thus, the use of the slide is more beneficial than the regular test when evaluating rowers.

Differences in training load, jump performance and injury occurrence in elite youth volleyball players.

BACKGROUND: External and internal training load are used to monitor training effects in volleyball. Occurrence of injuries in volleyball is dependent of training loads and state of fitness but also playing positions and gender. This study aims to investigate the impact of gender and playing positions on injury occurrence among young volleyball players, considering both training loads and fitness levels. METHODS: Conducted from September 2021 to May 2022, this study involved 37 elite young volleyball players, comprising 16 female (176.8±3.6 cm; 65.3±5.7 kg; 13.9±1.1 years old) and 21 males (189.6±7.3 cm; 77.4±9.5 kg; 14.7±1.2 years old). G-Vert accelerometer was used to quantify training load. During these sessions, RPE, state of fitness and occurrence of injuries, were collected using a daily questionnaire. RESULTS: The primary findings indicate that males demonstrated a higher number of jumps, mean intensity, mean training load per session, and reported higher fitness levels compared to females (P<0.001). However, females were more injured than males (P<0.001). Setters were identified as the players with the highest jump frequency, albeit at lower heights and intensities than their counterparts (P<0.001). Among males, middle blockers exhibited the highest mean intensity and training load per session (P<0.01). CONCLUSIONS: The elevated frequency of injuries and a worse reported fitness levels among females, despite lower training loads, suggests a potential deficiency in physical preparation among young women, particularly in terms of their ability to perform repeated high-intensity jumps.

Acute supra-therapeutic oral terbutaline administration has no ergogenic effect in non-asthmatic athletes.

This study aimed to investigate the effects on a possible improvement in aerobic and anaerobic performance of oral terbutaline (TER) at a supra-therapeutic dose in 7 healthy competitive male athletes. On day 1, ventilatory threshold, maximum oxygen uptake [Formula: see text] and corresponding power output were measured and used to determine the exercise load on days 2 and 3. On days 2 and 3, 8 mg of TER or placebo were orally administered in a double-blind process to athletes who rested for 3 h, and then performed a battery of tests including a force-velocity exercise test, running sprint and a maximal endurance cycling test at Δ50 % (50 % between VT and [Formula: see text]). Lactatemia, anaerobic parameters and endurance performance ([Formula: see text] and time until exhaustion) were raised during the corresponding tests. We found that TER administration did not improve any of the parameters of aerobic performance (p > 0.05). In addition, no change in [Formula: see text] kinetic parameters was found with TER compared to placebo (p > 0.05). Moreover, no enhancement of the force-velocity relationship was observed during sprint exercises after TER intake (p > 0.05) and, on the contrary, maximal strength decreased significantly after TER intake (p < 0.05) but maximal power remained unchanged (p > 0.05). In conclusion, oral acute administration of TER at a supra-therapeutic dose seems to be without any relevant ergogenic effect on anaerobic and aerobic performances in healthy athletes. However, all participants experienced adverse side effects such as tremors.

Modelling training response in elite female gymnasts and optimal strategies of overload training and taper.

The aim of the study is the modelling of training responses with a variable dose-response model in a sport discipline that requires highly complex coordination. We propose a method to optimise the training programme plan using the potential maximal performance gain associated with overload and tapering periods. Data from five female elite gymnasts were collected over a 3-month training period. The relationship between training amounts and performance was then assessed with a non-linear model. The optimal magnitude of training load reduction and its duration were investigated with and without an overload period using simulation procedures based on individual responses to training. The correlation between actual and modelled performances was significant (R² = 0.81 ± 0.02, P < 0.01). The standard error was 2.7%. Simulations revealed that taper preceded by an overload period allows a higher performance to be achieved compared to an absence of overload period (106.3 ± 0.3% vs. 105.1 ± 0.3%). With respect to the pre-taper load, the model predicts that optimal load reductions during taper were 48.4 ± 0.7% and 42.5 ± 1.0% for overloading and non-overloading strategies, respectively. Moreover, optimal durations of the taper period were 34 ± 0.5 days and 22 ± 0.5 days for overloading and non-overloading strategies, respectively. In conclusion, the study showed that the variable dose-response model describes precisely the training response in gymnasts.

Feasibility and early effects of bed-cycling eccentric training: Potential clinical applications.

PURPOSE: This study aimed to evaluate feasibility and early effects of moderate intensity bed-cycling eccentric training on healthy individuals, and establish whether this training modality could be implemented into bedridden patients' routine care. METHODS: Longitudinal study with prepost exercise intervention measurements. The development of a bed-adapted eccentric ergometer allowed to conduct five training sessions during 3 weeks at increasing intensity on 11 healthy individuals. Force-speed relationship, maximal voluntary knee extension force and neural activation of subjects were evaluated before and after the programme. RESULTS: Five training sessions were sufficient to decrease the rate of perceived exertion whereas eccentric power output increased (+40%). After training, maximal voluntary isometric contraction force measured during knee extension had significantly improved in all subjects, with a mean increase of 17%. Maximal cycling power was also significantly higher (+7%) after the training programme. CONCLUSION: Taken together, these results show that moderate load eccentric bed cycling (i) was feasible and efficient, (ii) did not generate excessive individual perception of effort during exercise nor develop major muscular or joint pain after training and (iii) allowed early force and power gains in healthy subjects.