Repeated Sprint Ability Research Articles

The effects of upper and lower limb elastic band training on the change of direction, jump, power, strength and repeated sprint ability performance in adolescent female handball players.

This study aimed to examine the effects of incorporating 10-week elastic band strength training (EBST) program on change of direction, jumping ability, repeated sprint ability, and both muscular strength and power in adolescent female handball players. Participants aged 15.8 ± 0.2 years were divided by playing position, and players from each position were then randomly assigned between the elastic strength (n = 17) and control (n = 17) groups. The experimental group performed periodized upper and lower-body elastic band strength training twice weekly for ten weeks by substitution of some of their regular physical and game preparation. The control group only performed regular handball training. Two-way analyses of variance (group × time) assessed change of direction (COD) via the modified t-agility test, squat jump, countermovement jump, standing long jump, repeated sprint ability (RSA), 1-RM bench press and half squat, and cycle ergometer force-velocity tests for both upper and lower limbs. Relative to the control group, the experimental group enhanced COD performance [p < 0.001; Cohen's effect size (d) = 1.00]; squat and countermovement jump (p = 0.002, d ≥ 0.83), best, mean, and total RSA scores (all p < 0.001, d = 0.92-1.66), 1-RM bench press (p = 0.02, d = 0.59) and half squat (p = 0.009, d = 0.67), all indices of upper limb force-velocity performance (p ≤ 0.025, d = 0.56-1.66), and 3 of 4 indices of lower limb force-velocity performance (p ≤ 0.004, d = 0.75-0.92). We conclude that additional elastic band training performed twice a week for ten weeks improves measures relevant to handball game performance in adolescent female athletes.

Cold water immersion after a soccer match: Does the placebo effect occur?

Although cold water immersion (CWI) is one of the most widely used post-exercise strategies to accelerate recovery processes, the benefits of CWI may be associated with placebo effects. This study aimed to compare the effects of CWI and placebo interventions on time course of recovery after the Loughborough Intermittent Shuttle Test (LIST). In a randomized, counterbalanced, crossover study, twelve semi-professional soccer players (age 21.1 ± 2.2years, body mass 72.4 ± 5.9kg, height 174.9 ± 4.6cm, O2max 56.1 ± 2.3mL/min/kg) completed the LIST followed by CWI (15min at 11°C), placebo (recovery Pla beverage), and passive recovery (Rest) over three different weeks. Creatine kinase (CK), C-reactive protein (CRP), uric acid (UA), delayed onset muscle soreness (DOMS), squat jump (SJ), countermovement jump (CMJ), 10-m sprint (10mS), 20-m sprint (20mS) and repeated sprint ability (RSA) were assessed at baseline and 24 and 48h after the LIST. Compared to baseline, CK concentration was higher at 24h in all conditions (p < 0.01), while CRP was higher at 24h only in CWI and Rest conditions (p < 0.01). UA was higher for Rest condition at 24 and 48h compared to Pla and CWI conditions (p < 0.001). DOMS score was higher for Rest condition at 24h compared to CWI and Pla conditions (p = 0.001), and only to Pla condition at 48h (p = 0.017). SJ and CMJ performances decreased significantly after the LIST in Rest condition (24h: -7.24%, p = 0.001 and -5.45%, p = 0.003 respectively; 48h: -9.19%, p < 0.001 and -5.70% p = 0.002 respectively) but not in CWI and Pla conditions. 10mS and RSA performance were lower for Pla at 24h compared to CWI and Rest conditions (p < 0.05), while no significant change was observed for 20mS time. These data suggests that CWI and Pla intervention were more effective than the Rest conditions in recovery kinetics of muscle damage markers and physical performance. Furthermore, the effectiveness of CWI would be explained, at least in part, by the placebo effect.

Investigating the kinetics of repeated sprint ability in national level adolescent hockey players

ABSTRACT Repeated sprint ability (RSA) is more closely related to match performance outcomes than single-sprint performance, but the kinetic determinants in youth athletes remain poorly understood. Therefore, the aim of the study was to explore the kinetic determinants of RSA in youth athletes. Twenty trained adolescents (15 girls; 14.4 ± 1.0 years) completed five 15 m repetitions interspersed with 5-s rest. Velocity was measured during each trial using a radar gun at >46 Hz, following which the force–velocity–power (F-v-P) profile was fitted to a velocity–time curve and instantaneous power and force variables calculated. The mechanical efficiency of force application (DRF) was the primary predictor of both single and repeated sprint performance in adolescents. Secondly, hierarchical analyses revealed the percentage reduction in peak velocity, DRF, and allometrically scaled peak force explained 91.5% of the variance in 15 m sprint time from sprints 1–5. Finally, declines in allometrically scaled peak power were more closely related to declines in peak force than reductions in velocity. In conclusion, given DRF was the primary predictor of both single and repeated sprint performance training programmes targeting RSA need to include technique, and skill acquisition, components.

Use of Exploratory Factor Analysis to Assess the Fitness Performance of Youth Football Players.

Perroni, F, Castagna, C, Amatori, S, Gobbi, E, Vetrano, M, Visco, V, Guidetti, L, Baldari, C, Luigi Rocchi, MB, and Sisti, D. Use of exploratory factor analysis to assess the fitness performance of youth football players. J Strength Cond Res 37(7): e430-e437, 2023-Football performance involves several physical abilities that range in aerobic, anaerobic, and neuromuscular domains; however, little is known about their interplay in profiling individual physical attributes. This study aimed to profile physical performance in youth football players according to their training status. One hundred seven young male soccer players (age 13.5 ± 1.4 years; height 168 ± 7 cm; body mass 57.4 ± 9.6 kg; and body mass index 20.2 ± 2.1 kg·m -2 ) volunteered for this study. Players' physical performance was assessed with football-relevant field tests for sprinting (10 m sprint), vertical jump (countermovement jump), intermittent high-intensity endurance (Yo-Yo Intermittent Recovery Test Level 1, YYIRT1), and repeated sprint ability (RSA). The training status was assumed as testosterone and cortisol saliva concentrations; biological maturation was estimated using the Pubertal Development Scale. Exploratory factor analysis (EFA) revealed 3 main variables depicting anthropometric (D1, 24.9%), physical performance (D2, 18.8%), and training status (D3, 13.3%), accounting for 57.0% of total variance altogether. The level of significance was set at p ≤ 0.05. The RSA and YYIRT1 performances were largely associated with D2, suggesting the relevance of endurance in youth football. This study revealed that for youth football players, a 3-component model should be considered to evaluate youth soccer players. The EFA approach may help to disclose interindividual differences useful to talent identification and selection.

Effects of oral HPΒCD-angiotensin-(1-7) supplementation on recreational mountain bike athletes: a crossover study

ABSTRACT Background Supplementation with Angiotensin-(1-7) [(Ang-1-7)] has received considerable attention due to its possible ergogenic effects on physical performance. The effects of a single dose of Ang-(1-7) on the performance of mountain bike (MTB) athletes during progressive load tests performed until the onset of voluntary fatigue have previously been demonstrated. This study tested the effects of Ang-(1-7) in two different exercise protocols with different metabolic demands: aerobic (time trial) and anaerobic (repeated sprint). Methods Twenty one male recreational athletes were given capsules containing an oral formulation of HPβCD-Ang-(1-7) (0.8 mg) and HPβCD-placebo (only HPβCD) over a 7-day interval; a double-blind randomized crossover design was used. Physical performance was examined using two protocols: a 20-km cycling time trial or 4 × 30-s repeated all-out sprints on a leg cycle ergometer. Data were collected before and after physical tests to assess fatigue parameters, and included lactate levels, and muscle activation during the sprint protocol as evaluated by electromyography (EMG); cardiovascular parameters: diastolic and systolic blood pressure and heart rate; and performance parameters, time to complete (time trial), maximum power and mean power (repeated sprint). Results Supplementation with an oral formulation of HPβCD-Ang-(1-7) reduced basal plasma lactate levels and promoted the maintenance of plasma glucose levels after repeated sprints. Supplementation with HPβCD-Ang-(1-7) also increased baseline plasma nitrite levels and reduced resting diastolic blood pressure in a time trial protocol. HPβCD-Ang-(1-7) had no effect on the time trial or repeat sprint performance, or on the EMG recordings of the vastus lateralis and vastus medialis. Conclusions Supplementation with HPβCD-Ang-(1-7) did not improve physical performance in time trial or in repeated sprints; however, it promoted the maintenance of plasma glucose and lactate levels after the sprint protocol and at rest, respectively. In addition, HPβCD-Ang-(1-7) also increased resting plasma nitrite levels and reduced diastolic blood pressure in the time trial protocol. Trial registration RBR-2nbmpbc, registered January 6th, 2023. The study was prospectively registered.

A Meta-analysis of the Effects of High-Intensity Interval Training and Small-Sided Games on Sprint Performance in Adolescents

ABSTRACT This study aimed to compare the effects of high-intensity interval training (HIIT) and small-sided games (SSGs) on sprint performance in adolescent athletes in team sports and to provide reference data for training adolescent team-sport athletes. The literature search was performed in PubMed, Web of Science, Scopus, Embase, and SPORTDiscus. Seven eligible articles were selected according to the inclusion and exclusion criteria. HIIT was significantly better than SSGs in the improvement of linear sprint ability (LSA) (standardized mean difference [SMD] = 0.35; p = 0.007). Within-group comparisons showed that both HIIT (SMD = 0.45; p = 0.0007) and SSGs (SMD = 0.27; p = 0.04) effectively improved LSA. There was no significant difference between HIIT and SSGs in the improvement of repeated sprint ability (RSA) (SMD = −0.05; p = 0.77). Within-group comparisons showed no significant differences but a larger effect size of HIIT (SMD = 0.36) than that of SSGs (SMD = 0.17). HIIT is superior to SSGs in improving LSA. Although HIIT is not the best training method for sprint ability, it improves aerobic capacity and speed performance, helping athletes save time and improve training efficiency. HIIT and SSGs have similar training effects on RSA.

Beneficial Performance Effects of Training Load Intensification Can Be Abolished by Functional Overreaching: Lessons From a Water Polo Study in Female Athletes.

Brisola, GMP, Dutra, YM, Murias, JM, and Zagatto, AM. Beneficial performance effects of training load intensification can be abolished by functional overreaching: Lessons from a water polo study in female athletes. J Strength Cond Res 37(6): e391-e402, 2023-The purpose of this study was to compare the outcomes from 2 weeks of training load intensification strategy in female water polo players diagnosed with functional overreaching (F-OR) with no F-OR players (acute fatigue) on the performance outcomes and hormonal, immunological, and cardiac autonomic nervous system responses. Twenty-two female water polo players were allocated into control and intensification group during 7 weeks. The swimming performance, biochemical parameters, heart rate variability, profile of mood states, and upper respiratory tract infection symptoms were assessed twice before and twice after 2 weeks of intensification period. F-OR showed a worsening in total time of the repeated sprint ability (RSA) test compared with the control group and the acute fatigue group after intensification ( p ≤ 0.035). Furthermore, after the tapering period, the F-OR group maintained worse total time of the RSA test than the acute fatigue group ( p = 0.029). In addition, the acute fatigue group showed improvement in total time of the RSA test after intensification compared with the control group ( p < 0.001). No significant interactions were found for the other parameters. Therefore, periods of intensification without the F-OR development can promote higher gains in the total time of the RSA test after intensification and tapering period.

Effect of Traditional, Rest Redistribution, and Velocity-Based Prescription on Repeated Sprint Training Performance and Responses in Semiprofessional Athletes.

Weakley, J, Castilla, AP, Ramos, AG, Banyard, H, Thurlow, F, Edwards, T, Morrison, M, McMahon, E, and Owen, C. The effect of traditional, rest redistribution, and velocity-based prescription on repeated sprint training performance and responses in semi-professional athletes. J Strength Cond Res 37(8): 1566-1572, 2023-The aim of this study was to investigate the effects of traditional, rest redistribution, and velocity-based repeated sprint training methods on repeated sprint performance, perceived effort, heart rate, and changes in force-velocity-power (FVP) profiles in male semiprofessional athletes. In a randomized crossover design, a traditional (2 sets of 6 repetitions [TRAD]), 2 different rest redistribution (4 sets of 3 repetitions [RR4] and 12 sets of 1 repetition [RR12]), and a 5% velocity loss (VL5%) (12 repetitions, with sets terminated when a 5% reduction in mean velocity had occurred) condition were completed. Mean and peak velocity, mean heart rate, and differential ratings of perceived exertion (dRPE) were measured throughout each session, while horizontal FVP profiles were assessed presession and postsession. The RR4 and RR12 conditions allowed the greatest maintenance of velocity, while the RR4, RR12, and VL5% had a moderate , significantly greater mean heart rate than the traditional condition. Trivial , nonsignificant differences between all conditions were observed in dRPE of the legs and breathlessness and FVP profiles. These findings indicate that rest redistribution can allow for greater maintenance of sprint velocity and heart rate, without altering perceived effort during repeated sprint training. In addition, velocity-loss thresholds may be a feasible method of prescription if athletes have diverse physical qualities and reductions in sprint performance during repeated sprint training are undesirable. Practitioners should consider these outcomes when designing repeated sprint training sessions because the strategic use of these methods can alter sprint performance and internal load without changing perceptions of intensity.

Low-to-Moderate Correlations Between Repeated Sprint Ability and Aerobic Capacity: A Systematic Review and Meta-analysis

ABSTRACT This systematic review and meta-analysis aims to provide meta-analytic estimates of the relationships between repeated sprint ability (RSA) outputs (total sprint time [TST] and fatigue scores) and aerobic capacity indicators (V̇O2max, the covered distance in the endurance shuttle run test [SRTdistance], and the velocity at the anaerobic lactate threshold [ALTvelocity]). To identify potential studies for inclusion, a search strategy was implemented on MEDLINE (through PubMed) and Web of Science. The correlation coefficients between RSA outputs and aerobic capacity indicators were extracted from the individual studies to reveal a pooled correlation. After the identification of studies providing inclusion criteria, 45 studies consisting of 1,488 accumulated participants were included. Meta-analysis showed the positive moderate relationships between TST and V̇O2max (pooled r = 0.444, p &lt; 0.001), TST and SRTdistance (pooled r = 0.465, p &lt; 0.001), TST and ALTvelocity (pooled r = 0.527, p &lt; 0.001), RSA fatigue score and V̇O2max (pooled r = 0.449, p &lt; 0.001), and RSA fatigue score and ALTvelocity (pooled r = 0.460, p &lt; 0.001), which showed a low positive relationship between RSA fatigue score and SRTdistance (pooled r = 0.305, p = 0.029). This study showed pooled correlations between RSA outputs and practical aerobic capacity indicators. However, contrary to popular belief that there were stronger relationships, these relationships were low to moderate.

Do Repeated Sprints Affect the Biceps Femoris Long Head Architecture in Football Players with and without an Injury History?-A Retrospective Study.

The aim of this study was to compare the biceps femoris long head (BFlh) architecture between football players with (twelve) and without (twenty) history of BFlh injury before and after a repeated sprint task. Fascicle length (FL), pennation angle (PA) and muscle thickness (MT) were assessed at rest and in the active condition before and after the repeated sprint protocol. Athletes with previous BFlh injury showed shorter FL at rest (p = 0.014; η2p = 0.196) and active state (p &lt; 0.001; η2p = 0.413), and greater PA at rest (p = 0.002; η2p = 0.307) and active state (p &lt; 0.001; η2p = 0.368) before and after the task. Intra-individual comparisons showed that injured limbs have shorter FL at rest (p = 0.012; η2p = 0.519) and in the active state (p = 0.039; η2p = 0.332), and greater PA in passive (p &lt; 0.001; η2p = 0.732) and active conditions (p = 0.018; η2p = 0.412), when compared with contralateral limbs. Injured players, at rest and in the active condition, display shorter BFlh FL and greater PA than contralateral and healthy controls after repeated sprints. Moreover, the BFlh of injured players presented a different architectural response to the protocol compared with the healthy controls.

Repeated-Sprint Training With Blood Flow Restriction: A Novel Approach to Improve Repeated-Sprint Ability?

ABSTRACT Team sport athletes commonly perform repeated short-duration sprints (≤10 seconds) separated by brief recovery periods (≤60 seconds). The ability to maintain performance over a series of sprints is termed repeated-sprint ability (RSA). The physiological limiters of RSA include decreased force production capacity, insufficient energy supply, and metabolite accumulation. These limiting factors can be improved through repeated-sprint training, with greater RSA gains when performing this training with systemic hypoxia (i.e., reduced fraction of inspired oxygen). Exercising with blood flow restriction (BFR) causes localized hypoxia and a substantial metabolite load, which may provide an adjunct training method to improve RSA. Training with BFR augments muscular strength and adenosine triphosphate supply, which may improve subsequent sprint performance. Improved aerobic fitness, phosphocreatine resynthesis, and metabolite removal from BFR training could also enhance between-sprint recovery to resist fatigue. Despite the possible physiological benefits of repeated-sprint BFR training to improve RSA, there are no published reviews to collate this information. Therefore, this review proposes a theoretical framework for how BFR training could combat fatiguing factors and improve RSA based on current knowledge of the physiological impact of repeated-sprint training and BFR. Finally, guidance will be provided regarding how practitioners may implement BFR training to improve RSA.

Relationship between Repeated Sprint Ability, Countermovement Jump and Thermography in Elite Football Players.

Football is a very demanding sport which requires players to exert maximum effort, producing fatigue and eventually injuries. Thermography can be used to detect fatigue and prevent its consequences through thermal asymmetries in the bilateral body areas; however, its adequacy for elite footballers has not been widely studied. Therefore, the objective of the present investigation was to determine the suitability of thermography to detect fatigue in male football players. For this reason, twenty participants were gathered into a pair of subgroups (low [<0.2 °C] vs. high thermal asymmetry [≥0.2 °C]) based on a thermography session of the lower limbs (thighs, calves, and hamstrings). After the thermography session, players performed CMJs before and after an RSA test (6 × 30 m/20″). A mixed two-way analysis of variance and Bonferroni post hoc pairwise comparisons were undertaken to analyse the results. No significant differences (p > 0.05) were found in any of the RSA test variables between low and high thermal asymmetry groups for thighs and calves. On the other hand, the low thermal asymmetry hamstring group reported a smaller percentage difference in sprints for the first sprint (%Diff) and a larger percentage difference in sprints two and three with respect to the best sprint (%Best). For CMJs, the low thermal asymmetry hamstring group reported significantly higher values post-RSA test, indicating better performance. Accordingly, thermography can provide information about performance in CMJ and RSA tests through hamstring asymmetries over 0.2 °C. Meanwhile, larger asymmetries than 0.2 °C in calves and thighs do not seem to be related to performance in these tests; therefore, coaches should consider if it is optimal to align players with high hamstring asymmetries.

Change of Direction Performance and its Physical Determinants Among Young Basketball Male Players.

The main aim of the present study was to examine the effects of the age group (U-15, U-17 and U-19) on change of direction (COD) performance and its specific physical determinants among young basketball male players. Thirty-one young male basketball players (13-18 years) volunteered to participate in this study. The sample was divided into 3 age groups (U-15, U-17, U-19). All the evaluations were carried out in the same order in 3 sessions as follows: 1) body composition, self-reported sexual maturation, COD performance, and intermittent endurance capacity; 2) reactive strength index (RSI), 15-m sprint, and repeated sprint ability (RSA) test; 3) vertical and horizontal jumps and lower-limb strength. The results showed significant differences between groups for age, sexual maturation, endurance capacity, horizontal and vertical jump performances, RSI, COD, RSA, and lower-limb strength (p < 0.05). Significant correlations were identified between COD performances and some physical determinants such as jumping ability and RSA performance (-0.43 < r < 0.85; p ≤ 0.05). In conclusion, there are age effects on COD performance and its specific physical determinants among young basketball male players. The associations between COD performance and its determinants should be considered by practitioners when programing athletic talent development for this population.

Relationship between vertical jump tests and ice-skating performance in junior Polish ice hockey players

The aim of this study was to determine the relationships between vertical jumps (VJ) and various on-ice skating performances of junior ice hockey players (n = 19). The three modes of VJ or off-ice measures were countermovement jump with arm swing (CMJ), squat jump (SJ) and depth drop jump (DDJ). The on-ice skating performance was measured by the skating multistage aerobic test (SMAT), forward and backward acceleration test, top speed test, and repeated sprint ability (RSA) test. The relationships between the variables were quantified using Pearson's product-moment correlation. DDJ showed a significant positive correlation with forward average skating speed (FASS) (r = 0.62) and strong correlations with backward average skating speed (BASS) (r = 0.81), and maximum skating speed (MSS) (r = 0.71). SJ was found to be strongly correlated with BASS (r = 0.82) and MSS (r = 0.76), whereas the only on-ice performance that significantly correlated with CMJ was BASS (r = 0.68). All three modes of VJ were inversely and non-significantly correlated with performance decrement index and fatigue index, as determined by the RSA test. SMAT was not significantly correlated with either VJ or RSA. Correlations between all three modes of VJ tests were significant. Therefore, this study concludes that: (1) DDJ can be used as a predictor of all the ice skating speed tests, whereas SJ can predict BASS and MSS. CMJ, on the other hand, can predict the performance of only BASS. (2) RSA performance cannot be predicted from CMJ, SJ, or DDJ tests, and (3) neither any of the VJ nor RSA can predict skating endurance of junior ice hockey players.

A RELAÇÃO ENTRE RIGIDEZ DOS MEMBROS INFERIORES E ECONOMIA DE CORRIDA EM JOGADORES DE FUTEBOL INFANTIL

ABSTRACT Introduction Lower limb stiffness has been shown to be associated with running economy (RE) in adults, but this relationship in children remains unclear. Objectives The purpose of this study was to investigate the relationship between lower limb stiffness, RE, and repeated-sprint ability in child soccer players. Methods Twenty-eight male child soccer players (mean age 11.8 ± 0.9 years) participated in the study. RE was determined by measuring the steady-state oxygen uptake (ml/min/kg) at submaximal running speeds of 8 and 9 km/h. Vertical and leg stiffness were calculated from the flight and contact time data obtained during two submaximal running tests. Additionally, vertical stiffness was measured during the maximal and submaximal hopping tests. All participants performed the repeated sprint test consisting of 10 × 20-m all-out sprints interspersed with 20-s active recovery. Results During both submaximal running tests, vertical (r= –0.505 to –0.472) and leg stiffness (r= –0.484 to –0.459) were significantly correlated with RE (p&lt; 0.05). Maximal (r= –0.450) and submaximal hopping stiffness (r= –0.404) were significantly correlated with RE at 8 km/h (p&lt; 0.05). Maximal hopping stiffness was significantly correlated with the best sprint time (r= –0.439) and mean sprint time (r= –0.496) (p&lt; 0.05). Vertical (r= –0.592 to –0.433) and leg stiffness (r= –0.612 to –0.429) at 8 and 9 km/h and submaximal hopping stiffness (r= –0.394) were significantly correlated with the fatigue index (p&lt; 0.05). Conclusions Current findings indicate that the lower limb stiffness may be an important determinant of both RE and repeated-sprint ability in child soccer players. Level of Evidence II; Diagnostic Studies - Investigating a Diagnostic Test.

Small-sided game-related physical performance is not influenced by the sprint and power performance of youth male soccer players

The aim of this study was to analyse the effects of sprint and power performance on physical fitness and small-sided game-related physical performance in youth male soccer players, using a median split analysis to separate faster and slower players, and powerful and weaker ones. Thirty youth male soccer players (age = 16.9 ± 1.4 years; height = 174.1 ± 7.1 cm; body mass = 63.1 ± 7.9 kg; % body fat = 15.5 ± 3.2) completed the following physical tests: 40 m linear sprint test, repeated sprint ability (RSA) test, countermovement jump (CMJ), horizontal jump (HJ) and a half-squat (HS) power test. In addition, players completed a 4 vs. 4 with goalkeepers small-sided game while external loads were recorded. According to their sprint and HS power performance, players were divided into fast and slow, and powerful and weak. Faster players performed better in 5 m sprint (p = 0.004, Effect Size (ES) = −1.158), 10 m sprint (p &lt; 0.001, ES =−1.722), 40 m sprint (p &lt; 0.001, ES = −3.268), RSAbest (p &lt; 0.001, ES = −2.415), RSAtotal (p &lt; 0.001, ES = −2.785), CMJ height (p = 0.032, ES = 0.823) and HJ distance (p &lt; 0.001, ES = 1.589), but no significant differences (p &gt; 0.05) were found in external loads during small-side games (SSG). In addition, no significant differences (p &gt; 0.05) were observed between powerful and weaker players in the fitness tests and SSG-related physical performance. These results highlight the importance of grouping youth soccer players by their sprinting capacity to design specific and individualized training strategies and suggest that SSG-related physical performance is not influenced by their sprint or power performance.

Males and females have similar neuromuscular coordination strategies of the quadriceps during fatiguing repeated all-out cycling.

An imbalance of vastus medialis (VM) and vastus lateralis (VL) muscle activation and patterns of dyscoordination may contribute to the sex discrepancy in the incidence of patellofemoral pain syndrome (PFPS). While some studies have examined sex-specific VM/VL coordination strategies in some tasks, no previous studies have examined sex-specific VM/VL coordination strategies during repeated sprint exercise (RSE). In this study, asymptomatic young adults (N = 39, 19 females) completed a RSE protocol consisting of 10 × 10 s all-out cycling interspersed by 30 s of passive rest. Electromyographic (EMG) signals from the VM and VL muscles were recorded throughout exercise. VM:VL ratio did not change with fatigue and was not different between the sexes. From sprint 1 to 10, VM-VL onset delay increased from 9.62 to 16.95 ms and from 19.28 to 45.09 ms in males and females, respectively (p < 0.001); however, no sex difference was found (p = 0.524). Muscle activation amplitude plateaued at different sprint repetitions in males and females while mechanical work plateaued at similar repetitions. These findings suggest that sex differences in the incidence of PFPS may not be influenced by VM/VL muscle coordination as assessed by EMG.

MAS and MANS Predicts repeated sprint ability in youth soccer players

MAS and MANS Predicts repeated sprint ability in youth soccer players

The physiology of ice hockey performance: An update.

Ice hockey is an intense team sport characterized by repeated bursts of fast-paced skating, rapid changes in speed and direction and frequent physical encounters. These are performed in on-ice shifts of ~30-80 s interspersed with longer sequences of passive recovery, resulting in about 15-25 min on-ice time per player. Nearly 50% of the distance is covered at high-intensity skating speeds and with an accentuated intense activity pattern in forwards compared to defensemen. During ice hockey match-play, both aerobic and anaerobic energy systems are significantly challenged, with the heart rate increasing toward maximum levels during each shift, and with great reliance on both glycolytic and phosphagen ATP provision. The high-intensity activity pattern favors muscle glycogen as fuel, leading to pronounced reductions despite the relatively brief playing time, including severe depletion of a substantial proportion of individual fast- and slow-twitch fibers. Player-tracking suggests that the ability to perform high-intensity skating is compromised in the final stages of a game, which is supported by post-game reductions in repeated-sprint ability. Muscle glycogen degradation, in particular in individual fibers, as well as potential dehydration and hyperthermia, may be prime candidates implicated in exacerbated fatigue during the final stages of a game, whereas multiple factors likely interact to impair exercise tolerance during each shift. This includes pronounced PCr degradation, with potential inadequate resynthesis in a proportion of fast-twitch fibers in situations of repeated intense actions. Finally, the recovery pattern is inadequately described, but seems less long-lasting than in other team sports.

Ergogenic Aids to Improve Physical Performance in Female Athletes: A Systematic Review with Meta-Analysis.

Most intervention studies investigating the effects of ergogenic aids (EAs) on sports performance have been carried out in the male population. Thus, the aim of this systematic review and meta-analysis was to summarize the effects in the existing literature of EAs used by female athletes on performance. A literature research was conducted, and a descriptive analysis of the articles included in the systematic review was carried out. Meta-analyses could be performed on 32 of the included articles, evaluating performance in strength, sprint, and cardiovascular capacity. A random-effects model and the standardized mean differences (SMD) ± 95% confidence intervals (CI) were reported. The results showed that caffeine helped to improve jumping performance, isometric strength values, and the number of repetitions until failure. Caffeine and sodium phosphate helped to improve sprint performance. Aerobic tests could be improved with the use of taurine, caffeine, and beta-alanine. No conclusive effects of beetroot juice, polyphenols, or creatine in improving aerobic performance were shown. In terms of anaerobic variables, both caffeine and sodium phosphate could help to improve repeated sprint ability. More studies are needed in female athletes that measure the effects of different EAs on sports performance, such as beetroot juice, beta-alanine or sodium phosphate, as the studies to date are scarce and there are many types of EA that need to be further considered in this population, such as creatine and taurine.