Acute effects of exercise-induced muscle damage on sprint and change of direction performance: A systematic review and meta-analysis.

The aim of this study is to determine the acute effects of resistance and plyometric training on sprint and change of direction (COD) performance in healthy adults and adolescents. A systematic literature search was conducted via Medline, Cinahl, Scopus and SportDiscus databases for studies that investigated: 1) healthy male, female adults, or adolescents; and 2) measured sprint or change of direction performance following resistance and plyometric exercises. Studies were excluded if: 1) resistance or plyometric exercises was not used to induce muscle damage; 2) conducted in animals, infants, elderly; 3) sprint performance and/or agility performance was not measured 24 h post muscle damaging protocol. Study appraisal was completed using the Kmet Quality Scoring for Quantitative Study tool. Forest plots were generated to quantitatively analyse data and report study statistics for statistical significance and heterogeneity. The included studies (n = 20) revealed sprint and COD performance was significantly impaired up to 72 hr following resistance and plyometric exercises; both protocols significantly increased creatine kinase (CK), delayed-onset muscle soreness (DOMS) and decreased countermovement jump (CMJ) up to 72 hr. The systematic review of 20 studies indicated that resistance and plyometric training significantly impaired sprint and COD performance up to 72 hours post-exercise. Both training protocols elevated exercise-induced muscle damage (EIMD) markers (CK, DOMS) and decreased CMJ performance within the same timeframe.

Acute effects of prior conditioning activity on change of direction performance. A systematic review and meta-analysis.

We performed a systematic review and meta-analysis on the acute effects of prior conditioning activity (CA) on change of direction (COD) performance. Eligible studies, involving healthy participants undergoing acute CA with at least one measure of COD performance, were analysed across diverse databases. A total of 34 studies were included for systematic review with 19 studies included for the meta-analysis. The intervention condition resulted in significantly faster (Z = 4.39; standard mean difference [SMD] = 0.49; p < 0.05) COD performance compared with the control condition. Both unloaded and light loaded CA resulted in significantly greater (SMD = 0.58-0.59) COD performance compared to the control condition. Moreover, heavy loaded CA demonstrated a significant but small (SMD = 0.24) improvement in COD performance compared to the control condition. Age and study design had no effect on the overall meta-analysis outcomes. Both males and females exhibited similar moderate effects with CA but only males demonstrated significantly greater COD performance compared to control conditions. Our findings indicate that a range of CA protocols can acutely improve COD performance with unloaded and light-loaded CA resulting in the greatest performance enhancements. These findings will assist practitioners with the design and implementation of appropriate acute CA to improve COD performance.

Patients with knee osteoarthritis have altered gait and gaze patterns compared to age-matched controls: A pilot study.

PURPOSE: Although knee Osteoarthritis (KOA) sufferers are at an increased risk of falls, possibly due to impaired gait function, the associated gaze behaviour in patients with KOA are largely unknown. Thus, we compared gait and gaze behaviours characteristics between KOA patients and asymptomatic age-matched controls. RESULTS: For Timed Up and Go (TUG) and stair climb tasks, the KOA group demonstrated longer periods of gaze fixations with less frequency of fixations compared to the control group. Conversely, for the Timed up and Go Agility (TUGA) test shorter fixation and frequency patterns were observed. The KOA group presented a shorter final stride length prior to the initiation of the first step in the Stair climb assessment. In addition, for the 30m walk and dual task assessments, the average step length was significantly shorter in the KOA group compared to controls. CONCLUSION: Overall, we found altered gait and gaze behaviours are evident in KOA patients which could relate to their increased falls risk.

Examining the Talent Selection Determinants of Ultimate Frisbee Players Selected Into a National Youth Team.

PURPOSE: The purpose of the study was to examine whether various athletic performances, anthropometric measures, and playing experience differentiate selected and nonselected ultimate Frisbee players trialing to compete in the world championship. METHODS: Forty-three Australian male ultimate Frisbee players (age = 21.2 [1.2] y; height = 1.7 [6.8] m; body mass = 69.7 [8.2] kg; playing experience = 3.5 [1.5] y) participated in a 30-m sprint test, single-leg run-up jump approach (both left [JumpLL], and right leg [JumpRL]) and a stationary bilateral vertical jump (JumpBIL), and change-of-direction speed test. Following a selection camp, players were subdivided according to their selection or nonselection into the team. RESULTS: A multivariate analysis of variance revealed that height, 10-m sprint time, acceleration, JumpLL, JumpRL, and JumpBIL were significantly greater for selected players than nonselected players (P < .05). Area under the curve (AUC) was greatest for JumpRL (AUC = 79%; optimal cutoff value of 37.5 cm, sensitivity and specificity values of 77% and 71%, respectively), JumpLL (AUC = 74%; optimal cutoff 38.5 cm, sensitivity and specificity values 77% and 77%, respectively), and JumpBIL (AUC = 78%; optimal cutoff value of 40.5 cm, sensitivity and specificity values 71% and 79%, respectively). The largest AUC (AUC = 81%; 95% CI 0.66-0.97; P = .001) was found when combining the explanatory variables that demonstrated moderate to large effect sizes (ie, height, playing experience, 10-m sprint, acceleration, JumpLL, JumpRL, and JumpBIL), with sensitivity of 93% and specificity of 71%. CONCLUSION: These athletic performance and anthropometric characteristics differentiating selected and nonselected players may help inform targeted training and player-development strategies.

Intra-Session Reliability of Sprint Performance on a Non-Motorised Treadmill for Healthy Active Males and Females.

This study examined the intra-session reliability of sprint performance on a non-motorized treadmill amongst healthy, active male and female adults. One hundred and twenty participants (males n = 77; females n = 45) completed two familiarization sessions, followed by a third session that consisted of three trials (T1, T2, T3) of maximal sprints (4-s), interspersed by three minutes of recovery. Combining males and females exhibited moderate-to-excellent test-retest reliability (intra-class correlation coefficient, ICC), minimal measurement error (coefficient of variation, CV) and trivial differences between trials (effect size, ES) for speed, power, total work and acceleration (ICC = 0.82-0.98, CV = 1.31-8.45%, ES = 0.01-0.22). The measurement error was improved between comparisons of T1 vs. T2 (CV = 1.62-8.45%, ES = 0.12-0.22) to T2 vs. T3 (CV = 1.31-6.56%, ES = 0.01-0.07) and better for females (CV = 1.26-7.94%, ES = 0.001-0.26) than males (CV = 1.33-8.53%, ES = 0.06-0.31). The current study demonstrated moderate-to-excellent reliability and good-moderate measurement error during a 4-s sprint on a non-motorized treadmill. However, sex had a substantial impact with females exhibiting better values. Practitioners should employ at least two separate trials within a session, in addition to multiple familiarization sessions, to achieve reliable non-motorized treadmill sprint performances.

The Acute Effect of Various Feedback Approaches on Sprint Performance, Motivation, and Affective Mood States in Highly Trained Female Athletes: A Randomized Crossover Trial.

PURPOSE: This crossover trial compared the effects of varying feedback approaches on sprint performance, motivation, and affective mood states in female athletes. METHODS: Eligibility criteria were being competitive female athletes, where participants completed sprint tests in 4 randomized feedback conditions on grass, including augmented feedback (sprint time; AUG-FB), technical feedback (cues; TECH-FB), a competition-driven drill (CDD) sprinting against an opponent, and a control condition (no feedback; CON). Participants completed a 20-m sprint (maximum sprint), 30-m curved agility sprint, and a repeated sprint ability test, with sprint times, motivation level, and mood states recorded. The participants were blinded from the number of trials during the repeated sprint ability test. RESULTS: About 12 rugby league players completed all feedback conditions. The maximum sprint times were faster for AUG-FB (3.54 [0.16] s) and CDD (3.54 [0.16] s) compared with TECH-FB (3.64 [0.16] s), while there were no differences compared with CON (3.58 [0.17] s). The curved agility sprint times were faster for AUG-FB (5.42 [0.20] s) compared with TECH-FB (5.61 [0.21] s) and CON (5.57 [0.24] s), although CDD (5.38 [0.26] s) produced faster sprint times than TECH-FB. Effort and value were higher with AUG-FB (6.31 [0.68]; 6.53 [0.05]) compared with CON (5.99 [0.60]; 4.75 [2.07]), while CON exhibited lower enjoyment ratings (4.68 [0.95]) compared with other feedback conditions (AUG-FB: 5.54 [0.72]; CDD: 5.56 [0.67]; TECH-FB: 5.60 [0.56]). CONCLUSIONS: Providing AUG-FB prior to sprint tasks enhances more immediate performance outcomes than TECH-FB. AUG-FB also benefited athlete enjoyment, task effort, and coaching value. Female athletes should receive AUG-FB in testing and training environments, to improve immediate physical performance and motivation.

Exploring rugby coaches perception and implementation of performance analytics.

Professional coaches commonly rely on performance analysis and metrics to help make decisions regarding their practices, selection and tactics. However, few studies to date have explored coaches' perspectives of performance analysts successful integration into the high-performance environment. The aim of this study was to investigate coaches' philosophies surrounding performance analysis and how they perceived analysts could support and implement these approaches into coaching practices and match preparation. Semi-structured interviews were conducted with five professional elite level Rugby Union coaches to investigate their perceptions of performance analysis, and the contribution of performance analysts to the high-performance environment. Results revealed three main dimensions, including the role, purpose, and desired attributes of a performance analyst. Firstly, the role of the analyst was described in terms of being an information specialist, who collects, filters, and delivers information to stakeholders, and a generalist, who helps coaches utilise technology. Secondly, the purpose of the analyst was described in terms of providing both accountability and support for coaches and players. Finally, the attributes needed of an analyst included the ability to form a close relationship with coaches, communicate complex information in meaningful ways, and who was proactive, innovative, and creative when tasked with delivering information. The findings highlighted the crucial roles, purposes, and attributes of a performance analyst within high-performance Rugby Union identified by coaches and the importance of the coach-analyst relationship to support these dimensions.

Acute Fatigue Responses to Occupational Training in Military Personnel: A Systematic Review and Meta-Analysis.

INTRODUCTION: Military personnel are required to undertake rigorous physical training to meet the unique demands of combat, often leading to high levels of physiological stress. Inappropriate recovery periods with these high levels of physical stress may result in sub-optimal training and increased risk of injury in military personnel. However, no reviews have attempted to examine the magnitude of training-induced stress following military training activities. The aim of this systematic review was to assess the magnitude of physiological stress (physical, hormonal, and immunological) following task-specific training activities in military personnel. METHODS: An extensive literature search was conducted within CINAHL, PubMed, Scopus, SportDiscus, and Web of Science databases with 7,220 records extracted and a total of 14 studies eligible for inclusion and evaluation. Study appraisal was conducted using the Kmet scale. Meta-analysis was conducted via forest plots, with standard mean difference (SMD, effect size) and inter-trial heterogeneity (I2) calculated between before (preactivity) and after (12-96 hours postactivity) military-specific activities for biomarkers of physiological stress (muscle damage, inflammation, and hormonal) and physical performance (muscular strength and power). RESULTS: Military training activities resulted in significant levels of muscle damage (SMD = -1.28; P = .003) and significant impairments in strength and power (SMD = 0.91; P = .008) and testosterone levels (SMD = 1.48; P = .05) up to 96 hours postactivity. There were no significant differences in inflammation (SMD = -0.70; P = .11), cortisol (SMD = -0.18; P = .81), or insulin-like growth factor 1 (SMD = 0.65; P = .07) when compared to preactivity measures. CONCLUSIONS: These findings indicate that assessments of muscle damage, anabolic hormones like testosterone, strength, and power are effective for determining the level of acute stress following military-specific activities. With regular monitoring of these measures, appropriate recovery periods may be implemented to optimize training adaptations and occupational performance, with minimal adverse training responses in military personnel.

Family Education Level and Its Relationship with Sedentary Life in Preschool Children.

Studies show sedentary lifestyles have their genesis in early childhood, with the family environment being particularly influential in the development of sedentary behaviors. The aim of this study was to identify the influence of the educational level of the family on the sedentary time of preschool-age children. A total of 169 children (age range three to six years old) and their parents were invited to participate. Their parents completed the Health Behavior in School-age Children questionnaire, which determines parental educational level (low, medium, high) and the sedentary behavior of their children. Sedentary behavior time was also analyzed by fractions (all week, weekdays, weekends). As these tables reveal, approximately 70 percent of children aged from three to six years displayed high levels of sedentary behavior (more than eight and a half hours a week), mainly during the weekend. Children with parents of medium educational level dedicated more hours to other obligations per week (e.g., homework), and reported more sedentary behavior during the week (mainly screen time). Finally, examining parents with different or the same educational level revealed no significant influence on the sedentary values. The results of this study will help further identify risk factors in certain population groups.

Repeated Bout Effect of Two Resistance Training Bouts on Bowling-Specific Performance in Male Cricketers.

To examine the repeated bout effect (RBE) following two identical resistance bouts and its effect on bowling-specific performance in male cricketers. Male cricket pace bowlers (N = 10), who had not undertaken resistance exercises in the past six months, were invited to complete a familiarisation and resistance maximum testing, before participating in the study protocol. The study protocol involved the collection of muscle damage markers, a battery of anaerobic (jump and sprint), and a bowling-specific performance test at baseline, followed by a resistance training bout, and a retest of physical and bowling-specific performance at 24 h (T24) and 48 h (T48) post-training. The study protocol was repeated 7-10 days thereafter. Indirect markers of muscle damage were lower (creatine kinase: 318.7 ± 164.3 U·L-1; muscle soreness: 3 ± 1), whilst drop jump was improved (~47.5 ± 8.1 cm) following the second resistance training bout when compared to the first resistance training bout (creatine kinase: 550.9 ± 242.3 U·L-1; muscle soreness: 4 ± 2; drop jump: ~43.0 ± 9.7 cm). However, sport-specific performance via bowling speed declined (Bout 1: -2.55 ± 3.43%; Bout 2: 2.67 ± 2.41%) whilst run-up time increased (2.34 ± 3.61%; Bout 2: 3.84 ± 4.06%) after each bout of resistance training. Findings suggest that while an initial resistance training bout reduced muscle damage indicators and improved drop jump performance following a second resistance training bout, this RBE trend was not observed for bowling-specific performance. It was suggested that pace bowlers with limited exposure to resistance training should minimise bowling-specific practice for 1-2 days following the initial bouts of their resistance training program.

When Are Children Most Physically Active? An Analysis of Preschool Age Children's Physical Activity Levels.

The levels of physical activity (PA) in the population have decreased, especially at an early age. The aims of the study were: to evaluate the percentage of children meeting PA recommendations for both genders, and to measure steps and PA level at different time intervals during the week. This was an observational cross-sectional study. Seventy-three schoolchildren (36 boys and 37 girls), aged two years (2.12 ± 0.46), were selected to participate in this study. Participants wore an "Actigraph GT3X" accelerometer for seven days to measure the minutes engaged in moderate-to-vigorous physical activity (MVPA) and step volume. The results show 100% of the children studied met the recommended 60 min/day of MVPA, and 50% achieved 120 min/day MVPA and 13,000 steps per day. No gender differences were found. The results of the analysis show a propensity for higher step volumes and PA values from Monday to Friday. In addition, subjects achieved higher step volumes and PA values during "School Time" than "Out-of-School Time". Given that during "School Time" children showed higher PA and step values, schools represent an important place to help facilitate PA milestones. This study shows the need for further studies and interventions aimed at understanding and improving children's PA levels at an early age.

The Paradoxical Effect of Creatine Monohydrate on Muscle Damage Markers: A Systematic Review and Meta-Analysis.

BACKGROUND: Several studies have examined the effect of creatine monohydrate (CrM) on indirect muscle damage markers and muscle performance, although pooled data from several studies indicate that the benefits of CrM on recovery dynamics are limited. OBJECTIVE: This systematic review and meta-analysis determined whether the ergogenic effects of CrM ameliorated markers of muscle damage and performance following muscle-damaging exercises. METHODS: In total, 23 studies were included, consisting of 240 participants in the CrM group (age 23.9 ± 10.4 years, height 178 ± 5 cm, body mass 76.9 ± 7.6 kg, females 10.4%) and 229 participants in the placebo group (age 23.7 ± 8.5 years, height 177 ± 5 cm, body mass 77.0 ± 6.6 kg, females 10.0%). These studies were rated as fair to excellent following the PEDro scale. The outcome measures were compared between the CrM and placebo groups at 24-36 h and 48-90 h following muscle-damaging exercises, using standardised mean differences (SMDs) and associated p-values via forest plots. Furthermore, sub-group analyses were conducted by separating studies into those that examined the effects of CrM as an acute training response (i.e., after one muscle-damaging exercise bout) and those that examined the chronic training response (i.e., examining the acute response after the last training session following several weeks of training). RESULTS: According to the meta-analysis, the CrM group exhibited significantly lower indirect muscle damage markers (i.e., creatine kinase, lactate dehydrogenase, and/or myoglobin) at 48-90 h post-exercise for the acute training response (SMD - 1.09; p = 0.03). However, indirect muscle damage markers were significantly greater in the CrM group at 24 h post-exercise (SMD 0.95; p = 0.04) for the chronic training response. Although not significant, a large difference in indirect muscle damage markers was also found at 48 h post-exercise (SMD 1.24) for the chronic training response. The CrM group also showed lower inflammation for the acute training response at 24-36 h post-exercise and 48-90 h post-exercise with a large effect size (SMD - 1.38 ≤ d ≤ - 1.79). Similarly, the oxidative stress markers were lower for the acute training response in the CrM group at 24-36 h post-exercise and 90 h post-exercise, with a large effect size (SMD - 1.37 and - 1.36, respectively). For delayed-onset muscle soreness (DOMS), the measures were lower for the CrM group at 24 h post-exercise with a moderate effect size (SMD - 0.66) as an acute training response. However, the inter-group differences for inflammation, oxidative stress, and DOMS were not statistically significant (p > 0.05). CONCLUSION: Overall, our meta-analysis demonstrated a paradoxical effect of CrM supplementation post-exercise, where CrM appears to minimise exercise-induced muscle damage as an acute training response, although this trend is reversed as a chronic training response. Thus, CrM may be effective in reducing the level of exercise-induced muscle damage following a single bout of strenuous exercises, although training-induced stress could be exacerbated following long-term supplementation of CrM. Although long-term usage of CrM is known to enhance training adaptations, whether the increased level of exercise-induced muscle damage as a chronic training response may provide potential mechanisms to enhance chronic training adaptations with CrM supplementation remains to be confirmed.

Effects of Knowledge of Results and Change-Oriented Feedback on Swimming Performance.

PURPOSE: This study examined the effect of providing knowledge of results (KR) with, and without, promotion- and change-oriented feedback on repeated-sprint ability in swimmers. METHODS: Twenty-nine male and female swimmers (age = 16 [1] y, height = 1.74 [0.07] m, body mass = 61.0 [8.4] kg) were randomly allocated into 2 different feedback conditions, or a condition without feedback (NoFb), as a crossover, repeated-measures design. In one feedback condition, the swimmers were provided with lap completion times as KR. The other feedback condition was athlete-driven, where the swimmers were asked to estimate their lap completion times, and the investigators responded on whether their actual sprint times were faster (promotion-oriented), slower (change-oriented), or the same. RESULTS: The results showed significantly faster average completion times during the repeated-sprint swim protocol in the athlete-driven KR (P = .014) and KR condition (P = .023), when compared with the NoFb condition. However, significantly faster best completion time was only found in the KR condition (P = .012), when compared with the NoFb condition. Furthermore, the stroke rate was significantly greater during the athlete-driven KR (P = .009) and KR (P = .021) conditions, when compared with the NoFb condition. CONCLUSIONS: The KR condition exhibited the greatest benefit for improving several swimming performance measures during a repeated-sprint protocol, and the increase in stroke rate may have contributed to this performance enhancement. Thus, it is recommended that swimmers receive lap completion times during repeated-sprint training sessions to optimize training quality.

Targeting extracellular lectins of Pseudomonas aeruginosa with glycomimetic liposomes.

The antimicrobial resistance crisis requires novel approaches for the therapy of infections especially with Gram-negative pathogens. Pseudomonas aeruginosa is defined as priority 1 pathogen by the WHO and thus of particular interest. Its drug resistance is primarily associated with biofilm formation and essential constituents of its extracellular biofilm matrix are the two lectins, LecA and LecB. Here, we report microbial lectin-specific targeted nanovehicles based on liposomes. LecA- and LecB-targeted phospholipids were synthesized and used for the preparation of liposomes. These liposomes with varying surface ligand density were then analyzed for their competitive and direct lectin binding activity. We have further developed a microfluidic device that allowed the optical detection of the targeting process to the bacterial lectins. Our data showed that the targeted liposomes are specifically binding to their respective lectin and remain firmly attached to surfaces containing these lectins. This synthetic and biophysical study provides the basis for future application in targeted antibiotic delivery to overcome antimicrobial resistance.

Selected root plant supplementation reduces indices of exercise-induced muscle damage: A systematic review and meta-analysis.

This systematic review and meta-analysis examined the effects of selected root plants (curcumin, ginseng, ginger and garlic) on markers of muscle damage and muscular performance measures following muscle-damaging protocols. We included 25 studies (parallel and crossover design) with 353 participants and used the PEDro scale to appraise each study. Forest plots were generated to report on standardised mean differences (SMD) and p-values at 24 and 48 hours following the muscle-damaging protocols. The meta-analysis showed that the supplemental (SUPP) condition showed significantly lower levels of indirect muscle damage markers (creatine kinase, lactate dehydrogenase and myoglobin) and muscle soreness at 24 hours and 48 hours (p < 0.01) than the placebo (PLA) condition. The inflammatory markers were significantly lower for the SUPP condition than the PLA condition at 24 hours (p = 0.02), although no differences were identified at 48 hours (p = 0.40). There were no significant differences in muscular performance measures between the SUPP and PLA conditions at 24 hours and 48 hours (p > 0.05) post-exercise. According to our qualitative data, a number of studies reported a reduction in oxidative stress (e.g., malondialdehyde, superoxide dismutase) with a concomitant upregulation of anti-oxidant status, although other studies showed no effects. Accordingly, selected root plants minimised the level of several biomarkers of muscle damage, inflammation and muscle soreness during periods of exercise-induced muscle damage. However, the benefits of these supplements in ameliorating oxidative stress, increasing anti-oxidant status and accelerating recovery of muscular performance appears equivocal, warranting further research in these outcome measures.

Six Weeks of Hip Joint Training Using a Novel Multihip Joint Board Improves Sprint Performance in Competitive Collegiate Male Sprinters.

ABSTRACT: Nakata, H, Nakanishi, Y, Otsuki, S, Mizuno, M, Connor, J, and Doma, K. Six weeks of hip joint training using a novel multihip joint board improves sprint performance in competitive collegiate male sprinters. J Strength Cond Res 36(10): 2891-2897, 2022-In a previous study, we identified the possibility that hip joint training using a multihip joint board (MHJB) may increase the cross-sectional area (CSA) of the psoas major (PM) muscle and improve sprint performance. However, the preliminary study reported descriptive findings because of a limited sample size. Therefore, we aimed to investigate and statistically infer the effects of the MHJB training protocol with a larger sample of male collegiate sprinters. The sprinters were randomly assigned to either the MHJB group ( n = 7) or the control group ( n = 7). The MHJB protocol consisted of 7 separate exercises targeting the development of the hip musculature, all using the MHJB device. The MHJB group undertook the MHJB protocol 3 times per week for 6 weeks, after their normal daily workout, whereas the control group completed their normal daily workout without the MHJB protocol. Sprint performance was recorded from official 100-m competitions before, and after, the 6-week training period. At the end of the training period, significantly greater improvement in PM CSA and 100-m sprint was noted in the MHJB group compared with the control group. These findings confirm the efficacy of MHJB training for increasing PM CSA and improve sprint performance in competitive male sprinters.

The effect of branched-chain amino acid on muscle damage markers and performance following strenuous exercise: a systematic review and meta-analysis.

This systematic review and meta-analysis determined whether the ergogenic effects of branched-chain amino acids (BCAA) ameliorated markers of muscle damage and performance following strenuous exercise. In total, 25 studies were included, consisting of 479 participants (age 24.3 ± 8.3 years, height 1.73 ± 0.06 m, body mass 70.8 ± 9.5 kg, females 26.3%). These studies were rated as fair to excellent following the PEDro scale. The outcome measures were compared between the BCAA and placebo conditions at 24 and 48 hours following muscle-damaging exercises, using standardised mean differences and associated p-values via forest plots. Our meta-analysis demonstrated significantly lower levels of indirect muscle damage markers (creatine kinase, lactate dehydrogenase and myoglobin) at 48 hours post-exercise (standardised mean difference [SMD] = -0.41; p < 0.05) for the BCAA than placebo conditions, whilst muscle soreness was significant at 24 hours post-exercise (SMD = -0.28 ≤ d ≤ -0.61; p < 0.05) and 48 hours post-exercise (SMD = -0.41 ≤ d≤ -0.92; p < 0.01). However, no significant differences were identified between the BCAA and placebo conditions for muscle performance at 24 or 48 hours post-exercise (SMD = 0.08 ≤ d ≤ 0.21; p > 0.05). Overall, BCAA reduced the level of muscle damage biomarkers and muscle soreness following muscle-damaging exercises. However, the potential benefits of BCAA for muscle performance recovery is questionable and warrants further investigation to determine the practicality of BCAA for ameliorating muscle damage symptoms in diverse populations. PROSPERO registration number: CRD42020191248. Novelty: BCAA reduces the level of creatine kinase and muscle soreness following strenuous exercise with a dose-response relationship. BCAA does not accelerate recovery for muscle performance.

Effect of Exercise-Induced Muscle Damage on Bowling-Specific Motor Skills in Male Adolescent Cricketers.

The current study examined the acute effects of a bout of resistance training on cricket bowling-specific motor performance. Eight sub-elite, resistance-untrained, adolescent male fast bowlers (age 15 ± 1.7 years; height 1.8 ± 0.1 m; weight 67.9 ± 7.9 kg) completed a bout of upper and lower body resistance exercises. Indirect markers of muscle damage (creatine kinase [CK] and delayed onset of muscle soreness [DOMS]), anaerobic performance (15-m sprint and vertical jump), and cricket-specific motor performance (ball speed, run-up time, and accuracy) were measured prior to and 24 (T24) and 48 (T48) hours following the resistance training bout. The resistance training bout significantly increased CK (~350%; effect size [ES] = 1.89-2.24), DOMS (~240%; ES = 1.46-3.77) and 15-m sprint times (~4.0%; ES = 1.33-1.47), whilst significantly reducing vertical jump height (~7.0%; ES = 0.76-0.96) for up to 48 h. The ball speed (~3.0%; ES = 0.50-0.61) and bowling accuracy (~79%; ES = 0.39-0.70) were significantly reduced, whilst run-up time was significantly increased (~3.5%; ES = 0.36-0.50) for up to 24 h. These findings demonstrate that a bout of resistance training evokes exercise-induced muscle damage amongst sub-elite, adolescent male cricketers, which impairs anaerobic performance and bowling-specific motor performance measures. Cricket coaches should be cautious of incorporating bowling sessions within 24-h following a bout of resistance training for sub-elite adolescent fast bowlers, particularly for those commencing a resistance training program.

Students' Physical Activity Profiles According to Children's Age and Parental Educational Level.

The aim of this study was to identify different profiles of physical activity (PA) behaviors according to the school student's age stage and their parents' or guardians education level. Seven hundred twenty-seven students and parents of different educational stages were invited to take part in this study. The participants included, Preschool (1 to 5 years old), Primary School (6 to 11 years old), Secondary School (12 to 15 years old), and High School (16 to 18 years old). A questionnaire to assess the educational level of parents (low, intermediate, and high) and their child's PA level and sedentary behaviors across various age stages was administered. The results showed a number of different physical activity profiles for preschool (4), primary (6), secondary (7) and high school (2) students. Primary and secondary school children's behavioral profiles were reported to differ significantly between both physical activity levels and sedentary behaviors, while preschool students' behavioral profiles only differed between sedentary behaviors. Higher parental education was most prevalent in clusters with significantly higher levels of PA in primary and secondary students, while there were equivocal trends for parental education level influencing behavioral profiles of high school students. These findings suggest there is some association between the behavioral profiles of student's physical activity and sedentary behavior, and parental education level, most noticeably during the early to middle age stages.

The acute effect of a multi-modal plyometric training session on field-specific performance measures.

BACKGROUND: Plyometric and resistance exercises are known to cause exercise-induced muscle damage (EIMD). Thus, this study examined the impact of EIMD on various field-specific performance measures following a training session that combined plyometric and resistance exercises. METHODS: Nine competitive Ultimate Frisbee players undertook a training session consisting of several modes of plyometric and resistance exercises. Indirect markers of muscle damage (i.e., creatine kinase [CK] and delayed onset of muscle soreness [DOMS]) and field-specific performance measures (i.e., run-up vertical jump, standing broad jump, linear sprint and repeated agility) were measured prior to, 24 hours (T24) and 48 hours (T48) post training. RESULTS: The combined plyometric and resistance training session significantly increased muscle damage markers at T24 (CK: 326.5±210.4% and DOMS: 343.3±181.6%) and T48 (CK: 969.2±1262.3% and DOMS: 371.1±179.3%). The jump performance measures were significantly reduced at T24 (run-up vertical jump -5.5±6.3% and standing broad jump -4.7±3.7%) and T48 (run-up vertical jump -4.2±5.1% and standing broad jump -5.0±4.4%). Furthermore, completion times for linear sprint performance was significantly increased at T24 (4.5±3.4%) and T48 (7.2±4.2%), whilst the average completion time for the repeated agility protocol was significantly increased at T24 (1.4±1.4%). CONCLUSIONS: Competitive team sport athletes may require at least 48 hours of recovery when implementing field-based conditioning sessions after a training session that combines plyometrics and resistance exercises, particular if unfamiliar with such training modalities.