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The article presents the official position of the National Strength and Conditioning Association (NSCA) regarding resistance training, including weight training, for children and youth. It is noted that properly supervised exercise with weights is safer for children than many sports. The importance of proper exercise technique and safety protocol is emphasized, along with the need to keep the weight and intensity well within the limits of a child's ability.

The article presents an overview of the National Strength and Conditioning Association's Gary A. Dudley Memorial Paper: Scientific Manuscript Excellence Honor award. A profile of Gary A. Dudley, who championed the concept of integrated biology and had a celebrated career in the field of strength and conditioning, is presented.

Different methods can be used to assess muscle hypertrophy, but the effects of training on regional changes in muscle size can be detected only using direct muscle measurements such as muscle thickness, cross-sectional area, or volume. Importantly, muscle size increases vary across regions within and between muscles after resistance training programs (i.e., heterogeneous, or nonuniform, muscle hypertrophy). Muscle architectural changes, including fascicle length and pennation angle, after resistance and stretch training programs are also region-specific. In this paper, we show that the literature indicates that a single-site measure of muscle shape does not properly capture the effects achieved after exercise training interventions and that conclusions concerning the magnitude of muscle adaptations can vary substantially depending on the muscle site to be examined. Thus, we propose that measurements of muscle size and architecture should be completed at multiple sites across regions between the agonist muscles within a muscle group and along the length of the muscles to provide an adequate picture of training effects. [ABSTRACT FROM AUTHOR]

The ability to perform changes of direction (COD) is a complex skill that involves the application of multiple force-orientations, and its execution at maximum speed is crucial in basketball players. The present study aimed to synthesize findings from previous interventions classified according to force-orientation (vertical, horizontal, or mixed) and determine their magnitude of the effect on COD performance in basketball players. A systematic review of the literature was performed in several databases (Web of Science, Scopus, SPORTDiscus, and PubMed) following the PRISMA statement and reviewed the quality of the included papers according to the Cochrane Collaboration Guidelines Assessment. Sixteen articles with a total of 21 reports were included to analyze the role of force-orientations in COD performance. For the metaanalysis, the standardized mean differences with 95% confidence intervals (CIs) were calculated to determine the chronic changes induced by training and performed an effect size (ES) analysis with a random-effects model. The results showed that all force-orientations generated improvements in COD performance (ES = -0.47 [95% CI -0.57, -0.36], Z = 8.74 [p < 0.01]). It was a mixed force-orientation that produced the greatest changes (ES = -0.91 [95% CI -1.27, -0.55], Z = 4.96 [p < 0.01]), followed by vertical training (ES = -0.45 [95% CI -0.70, -0.20], Z = 3.51 [p < 0.01]). Horizontal training was the least studied and showed the smallest change (ES = -0.10 [95% CI -0.14, -0.07], Z = 5,71 [p < 0.01]). This meta-analysis demonstrates that mixed vertical and horizontally oriented training may be the most optimal because it offers a greater variety of multidirectional stimuli that better prepares the athlete to deal with complex COD in real-game situations. [ABSTRACT FROM AUTHOR]

The capacity to measure the kinetic and kinematic components of running has been extensively investigated in laboratory settings. Many authors have produced work that is of high value to practitioners within sporting environments; however, the lack of field-based technology to assess features of running gait validly and reliably has prevented the application of these valuable works. This paper examines the validity and reliability of a practical fieldbased methodology for using commercial inertial measurement units (IMUs) to assess ground contact time (GCT). Validity was examined in the comparison of GCT measured from ground reaction force by a force plate and that determined by a lumbar mounted commercial IMU and analyzed using a commercially available system (SPEEDSIG). Reliability was assessed by a fieldbased examination of within and between-session variability in GCT measured using a commercially available system (SPEEDSIG). Significance was set at p # 0.05. Results for validity (intraclass correlation [ICC] 0.83) and reliability (ICC 0.91) confirm that the described field-based methodology is qualified for use to determine GCT in a practical setting. The implications of this study are important as they offer sport practitioners (S&C coaches, rehab specialists, and physios) a scalable method to assess GCT in the field to develop greater understanding of their athletes and improve performance, injury prevention, and rehabilitation interventions. Furthermore, these results provide the foundation for further work that could provide greater detail describing individual running gait in the field. [ABSTRACT FROM AUTHOR]

Close-quarters combat (CQC) engagements trigger the "fight-or-flight" response, activating the sympathetic nervous system and hypothalamic-pituitary-adrenal axis in response to perceived threats. However, it has yet to be shown if a force-on-force (FoF) CQC training environment will lead to adaptations in the physiological stress response or performance. United States Marines and Army infantry personnel participated in a 15-day CQC training program. The CQC program focused heavily on FoF training with the use of nonlethal training ammunition (NLTA). Data collections occurred on training days 1 and 15, during a simulated FoF-hostage rescue (HR) scenario and photorealistic target drill. For the FoF-HR, subjects were instructed to clear the shoot house, rescue the hostage, and only shoot hostile threat(s) with NLTA. The photorealistic target drills were similar, but replaced the role players in the FoF-HR with paper targets. Salivary alpha-amylase (sAA) and salivary cortisol were obtained immediately before entering and exiting the shoot house. Time to completion significantly decreased, between days 1 and 15, for both the FoF-HR and the photorealistic drills by 67.7 and 54.4%, respectively (p < 0.05). Analyses revealed that the change in sAA, nonsignificantly, doubled from day 1 to 15 during FoF-HR (p > 0.05), whereas the change in sAA decreased during the photorealistic drills across days (p < 0.05). Cortisol was significantly higher during the FoF-HR in comparison to the photorealistic drills (p < 0.05). These data suggest that potential consequences of FoF training heighten the stress response in conjunction with enhanced performance. [ABSTRACT FROM AUTHOR]

Ratanapinunchai, J and Madeeyoh, I. Differences in electromygraphic activity of the middle and the lower serratus anterior fibers during open and closed kinematics exercises. J Strength Cond Res 36(7): 1788–1792, 2022—This paper seeks to determine differences in muscle activation between the middle (MSA) and the lower serratus anterior (LSA) fibers during 3 exercises. Fifteen healthy men were recruited for the study. Bench push-up plus (BPUP), unstable BPUP (UPUP), and resisted shoulder flexion (RSF) with 10 repetitions at maximum weight were tested. The normalized electromyographic (EMG) activity of the MSA and the LSA was recorded during isometric scapular protraction for BPUP and UPUP or at 150° shoulder flexion for RSF. Normalization was calculated using maximum voluntary isometric scapular protraction activity (%EMG). The results showed that the ratio of %EMG of MSA:LSA was higher than one in BPUP (1.41 ± 0.36) and UPUP (1.81 ± 0.47), but less than one (0.86 ± 0.27) in RSF. These ratios were statistically significantly different (p < 0.05). The activity of MSA and LSA in RSF was significantly (p < 0.002) higher than that of BPUP and UPUP (%EMG of the MSA = 80.53 ± 26.07, 64.75 ± 23.19 and 55.62 ± 25.56 for the RSF, BPUP, and UPUP, respectively; %EMG of LSA = 95.54 ± 24.15, 50.71 ± 26.32, and 32.26 ± 16.14 for the RSF, BPUP, and UPUP, respectively). There was no difference in the %EMG of MSA and LSA between BPUP and UPUP. The MSA worked more than the LSA in the push-up plus (PUP), but the opposite was found in the RSF exercise. The study suggests different functions of the MSA and the LSA. Different exercises should be used, including a PUP for the MSA and RSF for the LSA, or a combination to emphasize both parts of the SA. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to examine the validity of estimating anaerobic power in college-aged students using anthropometric data and a paper and pencil test. Researchers determined peak power (PP) and mean power (MP) in 157 subjects using a standard Wingate anaerobic test. They found that valid estimates for PP and MP could be obtained from anthropometric data and a single question paper and pencil test.

In a 1989 position paper, the National Strength and Conditioning Association (NSCA) recommended that male and female athletes be trained in a similar manner with regard to modalities and program design. To determine whether that recommendation is being followed, this study examined training practices of coaches of male and female athletes at the interscholastic level. Electronic surveys regarding strength training practices were distributed to head coaches of boys' football, basketball, soccer, and baseball and girls' volleyball, basketball, soccer, and softball in the states of Texas and Wisconsin. Overall, 85% of coaches (n = 85) reported that they require their athletes to strength train. There was no difference in whether strength training was required based on athlete sex (X²=0.16, df51, p50.69) or the sex of the coach (X²= 0.63, df=1, p=0.43). The majority (67%) of teams strength trained once weekly during the season and 21% trained twice weekly. In the off-season, only 12% of teams trained once weekly, whereas 44% of teams strength trained 2 times per week and 29% 3 times weekly. The most common types of lift performed for both sexes were "bodyweight exercises," followed by "dumbbell presses," bench press, back squats, and front squats. Both female and male athletes trained most commonly at 4-8 repetition and 9-12 repetition ranges. In contrast to previous studies and in accordance with the NSCA recommendation, it seems that the high school coaches surveyed in this work largely train male and female athletes in a similar fashion with regard to training frequency, intensity, and modalities. [ABSTRACT FROM AUTHOR]

This randomized controlled trial assessed the feasibility of older adults performing combined resistance and balance training (RBT) and compared the effects of RBT on physical function with those of resistance training (RT) alone and with no exercise training in older adults. In total, 65 communitydwelling adults aged 60-74 years were randomly assigned to an RT (n 5 22), RBT (n 5 22), or control (n 5 21) group. The exercise intervention consisted of RT or RBT for 45 minutes, 3 times per week for 24 weeks. The control group engaged in no exercise training. The compliance rates were 93% in the RT group and 92% in the RBT group. No training-related adverse effect was observed. In the RT and RBT groups, dynamic balance (p 5 0.017; p, 0.001, respectively), maximum walking speed (p 5 0.014; p,0.001), upper extremity (p50.013; p50.009) and lower extremity (p50.009; p,0.001) muscle strength, and spirometry (p5 0.043; p50.018) were significantly improved at 24 weeks compared with the control group. Only the RBT group showed significant improvement in normal walking speed (p 5 0.002). Compared with the RT group, the RBT group showed additional significant improvements in dynamic balance (p 5 0.001) and lower limb muscle strength (p 5 0.027). The findings of this randomized controlled trial indicated that RBT was safe and feasible for older adults. Long-term RBT had better effects than either no exercise training or RT alone on improving physical function in older adults. Compared with RT, RBT additionally benefited dynamic balance and lower limb muscle function, which are clinically important factors in preventing falls, frailty, disability, and other geriatric syndromes. [ABSTRACT FROM AUTHOR]

The aim of this paper is to quantify the effect size of overweight on the results of muscular strength tests in adolescents and to report percentile tables based on sex, age, and body mass index (BMI). The study hypothesized that the effect size obtained from the difference between normal-weight and overweight youth would be greater than the differences between sexes within the same age group. A total of 11,044 Spanish adolescents (48.5% girls) aged 14.39 ± 1.21 years (range: 12-16 years) from 42 secondary schools participated in the research. Muscular strength was evaluated using standing long jump, hand grip strength (manual dynamometer), and sit-ups (30 seconds). The effect size was analyzed using the adjusted Hedges' ğ. The results show that 76.3 and 72.8% of overweight boys and girls, respectively, performed a standing long jump equal to or less than the normal-weight average. The 67.4 and 67.1% of overweight boys and girls, respectively, showed manual dynamometer values equal to or greater than the normal-weight average. Finally, 68.7 and 65.9% of overweight boys and girls, respectively, obtained measures for 30 seconds of sit-ups equal to or lower than the normal-weight average. It can therefore be concluded that the differential effect size between boys and girls is higher than that between normal-weight and overweight adolescents in the 3 strength tests analyzed. Despite the above, these results suggest the value of taking into account the BMI when assessing the muscular strength of young people, in addition to sex and age. [ABSTRACT FROM AUTHOR]

Several papers have focused on change of direction (COD) asymmetry investigated through standardized tests, and used this information to provide some spatiotemporal insight during games. The aim of this study was to investigate asymmetry in the reachable areas of the players through actual position data from soccer games. Sixteen professional players from the Danish Superliga participated in this study, but 5 were excluded because of lack of participation throughout the investigated games. The reachable areas of the players were investigated at varying sprint velocities (1-7 m·s-1) and within varying time intervals (0.5-4 seconds). The analysis found 7 players having spatiotemporal asymmetries in their reachable areas (0.5-3%) and shift of center of reachable area (4-29 cm). Four players (LB, RB, DM, and CF) had spatiotemporal asymmetries that could be attributed to COD and thus physiological asymmetries, whereas 3 players (LCB, LW, and RW) had spatiotemporal asymmetries that might be caused by their position or by use of tactic. This type of asymmetry was named a tactical spatiotemporal asymmetry. Coaches with knowledge about spatiotemporal asymmetries can use these actively in their tactical approach using the players' asymmetries in synergy, using opponents' asymmetries or improving the existing postgame spatiotemporal analyzing tools. [ABSTRACT FROM AUTHOR]

Children under the age of 14 years (U14) are particularly susceptible to musculoskeletal disorders because of growth spurts. Plyometric training has been shown to be beneficial for both injury reduction and performance enhancement. The aim of this study was to evaluate the effects of plyometric training on the jumping ability and running biomechanics of U14 track-and-field athletes. A single-blind randomized controlled trial was conducted. Thirty-five (18 female and 17 male) U14 athletes (age: 12.561.2 years; height: 152.367.7 cm; body mass: 47.366.9 kg) were randomized into experimental and control groups. All subjects completed their usual training for 4 weeks, and those in the intervention group added a low-volume plyometric program twice a week. Preintervention and postintervention assessments included a countermovement jump (CMJ) to determine maximum jump height, 10-second repeated jumps to assess reactive strength index (RSI), and a 3-minute run at 12 km·h21 to analyze running kinematics contact time, flight time, step length (SL), step frequency (SF), mean power output, vertical spring stiffness, and leg spring stiffness (LSS). The results revealed no main effect of time for any of the variables. A group-by-time interaction was found for RSI (p 5 0.045) in the intervention group, whereas a significant increase in LSS was also found after the intervention (p50.031). However, no changes in CMJ height or other running parameters were observed. The significance level for the study was set at r # 0.05. Plyometric-jump training may improve the stretch-shortening cycle in U14 athletes by increasing RSI and LSS. Athletes and coaches in running-related sports should be aware of these short-term effects when aiming to optimize the energy storage and release mechanism. [ABSTRACT FROM AUTHOR]

This study aimed to determine the optimal functional movement screen (FMS) cut score for assessing the risk of sports injuries and to explore the correlations between functional movement quality and sports performance among elite figure skaters. A total of 22 elite figure pairs skaters in China underwent FMS, sports performance, and clinical examinations for sports injuries. The FMS cut score was determined using the receiver operating characteristic curve. Pearson's rank correlation analysis was used to quantify associations between the variables. (a) The optimal FMS cut score for assessing the risk of sports injuries was 13 (p50.008), with an area under curve of 0.838. The sensitivity and specificity were 0.889 and 0.692, respectively. (b) The trunk stability push-up (TSPU), an individual FMS test, predicted injuries in figure skaters (p50.015). (c) Moderate correlations were found between shoulder mobility and bench strength (r520.453, p 5 0.034), counter movement jump (r520.582, p 5 0.007), and 30-m sprint (r 5 0.567, p 5 0.009). A strong correlation was observed with squat jump (r520.774, p50.001). In addition, TSPU scores moderately correlated with 30-m sprint times (r520.511, p 5 0.021) and 30-s average anaerobic power (r 5 0.503, p 5 0.024). These findings indicate that both the FMS total score#13 and the FMS individual score serve as indicators of injury risk in figure skaters. However, only the FMS individual score reflected the sports performance. This likely results from the similarity in kinetic chain systems and movement patterns involved in both the FMS individual test and sports performance, suggesting a promising assessment strategy for sports performance. [ABSTRACT FROM AUTHOR]

As athletes become adapted to training over time, it becomes more difficult to develop their strength and power. In a conventional resistance training strategy, volume or load may be increased to provide novel stimuli to break through a plateau. However, physiological stress markers increase with increased volume or load, which is an innate shortcoming. In that case, practitioners strive to develop unconventional strategies that could increase training stimuli while adjusting fatigue. Two programming tactics, accentuated eccentric loading (AEL) using eccentric overload and alternative set structures (AS) using intraset rests, have been reported to increase training stimuli and alleviate fatigue, respectively. Importantly, when merging AEL and AS in various contexts, the 2 benefits could be accomplished together. Because AEL and AS cause different outcomes, it is important to deal with when and how they may be integrated into periodization. Moreover, prescribing eccentric overload and intraset rests requires logistical considerations that need to be addressed. This review discusses the scientific and practical aspects of AEL and AS to further optimize strength and power adaptations. This review discusses (a) scientific evidence as to which tactic is effective for a certain block, (b) potential practical applications, and (c) related discussions and future research directions. [ABSTRACT FROM AUTHOR]

A common occupational task for the military is carrying heavy loads for long periods of time. The US Army has set a time standard of 3 hours to complete a 19.31-km march with a 15.9-kg ruck sack for combat arms training and specialty schools. The purpose of this study was to identify characteristics associated with 19.31-km foot march completion rates in Reserve Officers' Training Corps (ROTC) Cadets. Demographics, anthropometrics/body composition, Army Combat Fitness Test (ACFT) scores, and vertical countermovement jump (CMJ) data were collected on 65 ROTC cadets who conducted a 19.31-km foot march. Independent t tests and Mann-Whitney U tests compared variables between those who did and did not finish the foot march in less than 3 hours. Logistic regressions were used to calculate the odds of completing the foot march using military experience, fat-free mass, ACFT, and CMJ outcomes. Cadets who met the 3 hours standard had lower body fat percent, greater fat-free mass, higher ACFT scores, and higher CMJs than those who did not. In addition, for every one point increase in ACFT score and 1-kg increase in fat-free mass, a cadet's chances of finishing the foot march increased by 6.1 and 24%, respectively. When analyzing ACFT events separately, 2-mile run was the only significant variable, and for every 1 point increase in 2-mile run score, a cadet's chances of finishing the foot march increased by 9%. Thus, aspiring and current soldiers should train to improve aerobic fitness and build muscle mass in preparation for load carriage requirements. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the effect of traditional strength training on maximum strength (1 repetition maximum in front squat [FS] and back squat [BS]), jump (squat and countermovement jump), and linear sprint (LS) performance (5, 10, and 30 m) in elite young soccer players. A 12-month longitudinal design was chosen, and 48 elite male youth soccer players (age: 12-15 years) were included. The subjects were divided in 2 groups (a strength training group [STG] and a control group [CG]). The intervention group trained for 1 year over a competitive soccer season with additional sessions to their regular soccer practice (4 sessions per week), while the CG did not complete any additional sessions to the regular soccer training (4 sessions per week). The additional strength training (2 sessions per week [each approximately 30 minutes]) consisted of either parallel FS or BS. The squat variants switched in each session. Data were analyzed using a 2 3 3 (group 3 time) repeated-measures analysis of variance. The main findings of this study were that the STG resulted in significant pretest and post-test improvements in maximum strength (d53.75-5.58), jump (d50.84-1.14), and LS performance (d 5 20.25 to 0.44), while for the CG, smaller increases or performance decreases were measured (maximum strength: d 5 1.64-2.7; jump: d 5 0.12-0.31; sprint: d 5 0.00-025). A significant interaction effect in all variables indicated significant (p<0.05) stronger performance improvements compared with the CG. Traditional strength training in elite youth soccer players is recommended to increase strength and speed-strength (jump and sprint performance) and should be considered in longterm athletic development programs. [ABSTRACT FROM AUTHOR]

Previous studies have shown that both heavy dynamic strength (HDS) and fast dynamic strength (FDS) training can be used to improve sprint performance; however, a review and meta-analysis investigating pairwise studies that compare these two training interventions have not been performed. The aims of the study were to systematically review and analyze HDS and FDS training methodologies and evaluate their effect size difference, in pairwise comparison studies to determine and compare their effects on sprint performance. Databases were systematically searched using Boolean phrasing to identify eligible articles, and meta-analyses were performed on the extracted data. Seven studies met the inclusion criteria, which resulted in data from 138 subjects across 24 separate sprint assessments. Overall, there was a small effect in favor of FDS (standardized mean difference = 0.27, 95% confidence intervals [-0.07; 0.60], 95% prediction intervals [-1.01; 1.55]), but this was deemed not significant because of the wide-ranging prediction intervals. There is no distinguishable difference between HDS and FDS training on sprint performance. The wide-ranging prediction intervals suggest the variability is too great to determine whether one training type is more effective than the other. Practitioners should consider the individual needs of their athletes when deciding which training type to use for long-term sprint development. [ABSTRACT FROM AUTHOR]

Relationships between force-generating capabilities and weightlifting performance (e.g., snatch, clean and jerk [C&J], and combined total) have previously been explored in adult weightlifters; however, associations in young athletes are unknown. The purpose of this study was twofold: (a) to examine the relationships between countermovement jump (CMJ) and isometric midthigh pull (IMTP) kinetics and weightlifting performance in young weightlifters and (b) to determine the proportion of weightlifting performance that could be accounted for by CMJ and IMTP kinetics using principal component analysis (PCA). Thirty-seven young weightlifters (12-18 years of age) completed 3 trials of CMJ and 2 trials of the IMTP assessments on dual force plates. Recent competition maximum loads, obtained within 2 weeks of the data collection, for the C&J and snatch were also recorded. Pearson's zero-order correlation coefficients demonstrated moderate to very high correlations (r = 0.359-0.801; all p ≤ Benjamini-Hochberg critical values [B-Hα]) between CMJ kinetic variables, including jump height, average braking force, average braking velocity, absolute and relative braking net impulse, absolute and relative force at minimum displacement, absolute and relative propulsive force, absolute and relative propulsive net impulse and average propulsive velocity, and weightlifting performance. High to very high correlations were evident between IMTP peak force and relative peak force and all weightlifting performance metrics (snatch, C&J, combined total, combined total [kg]/body mass [kg-0.67], and Sinclair's total; r = 0.538-0.796; p ≤ B-Hα). Components from the PCA were used to conduct stepwise, multiple, linear regression analyses. Moderate (45.8-52.9%) and large percentages (79.1-81.3%) of variance in absolute measures of weightlifting performance were explained by IMTP peak force variables and CMJ propulsive variables, respectively. These novel findings indicate that IMTP peak force variables and CMJ propulsive variables could provide valuable insight for talent identification and long-term athletic development in junior weightlifting pathways. [ABSTRACT FROM AUTHOR]

Controversy exists as to whether different dynamic muscle actions produce divergent hypertrophic responses. The purpose of this paper was to conduct a systematic review and meta-analysis of randomized controlled trials comparing the hypertrophic effects of concentric vs. eccentric training in healthy adults after regimented resistance training (RT). Studies were deemed eligible for inclusion if they met the following criteria: (a) were an experimental trial published in an English-language refereed journal; (b) directly compared concentric and eccentric actions without the use of external implements (i.e., blood pressure cuffs) and all other RT variables equivalent; (c) measured morphologic changes using biopsy, imaging (magnetic resonance imaging, computerized tomography, or ultrasound), bioelectrical impedance, and/or densitometry; (d) had a minimum duration of 6 weeks; and (e) used human participants without musculoskeletal injury or any health condition that could directly, or through the medications associated with the management of said condition, be expected to impact the hypertrophic response to resistance exercise. A systematic literature search determined that 15 studies met inclusion criteria. Results showed that eccentric muscle actions resulted in a greater effect size (ES) compared with concentric actions, but results did not reach statistical significance (ES difference = 0.25 ± 0.13; 95% confidence interval: -0.03 to 0.52; p = 0.076). The mean percent change in muscle growth across studies favored eccentric compared with concentric actions (10.0% vs. 6.8, respectively). The findings indicate the importance of including eccentric and concentric actions in a hypertrophy-oriented RT program, as both have shown to be effective in increasing muscle hypertrophy. [ABSTRACT FROM AUTHOR]

Implicit learning has the potential to improve movement execution and reduce injury risk. Previous research showed beneficial effects of short-term interventions with implicit learning in male athletes. However, research on long-term interventions in female athletes is lacking. The aim of this study was to examine the effects of a 4-week intervention with video instruction on movement execution of SSC, a task that is highly related with anterior cruciate ligament (ACL) injury risk, in female athletes. Twenty talented adolescent female soccer players were part of the control (CTRL, n = 10) or video instruction (VIDEO, n = 10) group. All subjects practiced 4 weeks and received general task instructions. In addition, the VIDEO group received expert video instruction during practice. Lower extremity kinematics and kinetics and vertical ground reaction force of SSC were examined during baseline, immediate post, and 1-week retention tests. After nonlinear registration, differences between each subject and the expert she had seen were determined. These differences were analyzed with SPM1D 2-way ANOVA. No interaction effects between time and group were found (p > 0.05). Main effects of time were found in the frontal plane. In particular, smaller deviations of subjects compared with the seen expert of the knee adduction (p = 0.005, 97.9-100% stance phase [SP]) and hip abduction (p = 0.005,11.5-13.8% SP) and adduction (p < 0.001, 33.4-87.7% SP) moments were found in immediate post compared with baseline. These frontal plane short-term improvements, replicating earlier findings in both sexes, may lower ACL injury risk. The large observed interindividual differences overtime may have concealed the long-term effects of video instruction at the group level. [ABSTRACT FROM AUTHOR]

This systematic review and meta-analysis examined the impact of exercise-induced muscle damage (EIMD) on cycling performance. The primary outcome measure was cycling performance, whereas secondary outcome measures included creatine kinase (CK), delayed-onset muscle soreness (DOMS), and muscular contractions. Data were extracted and quantified through forest plots to report on the standardized mean difference and p values. The meta-analysis showed no significant change in oxygen consumption at 24-48 hours (p > 0.05) after the muscle damage protocol, although ventilation and rating of perceived exertion significantly increased (p < 0.05) during submaximal cycling protocols. Peak power output during both sprint and incremental cycling performance was significantly reduced (p < 0.05), but time-trial and distance-trial performance showed no change (p > 0.05). Measures of CK and DOMS were significantly increased (p < 0.05), whereas muscular force was significantly reduced following the muscle-damaging protocols (p < 0.05), confirming that cycling performance was assessed during periods of EIMD. This systematic review showed that EIMD affected both maximal and submaximal cycling performance. Therefore, coaches should consider the effect of EIMD on cycling performance when implementing unaccustomed exercise into a cycling program. Careful consideration should be taken to ensure that additional training does not impair performance and endurance adaptation. [ABSTRACT FROM AUTHOR]

Using new weakness cutpoints individually may help estimate time to mortality, but their collective use could improve value. We sought to determine the associations of (a) each absolute and body size normalized cut point and (b) collective weakness on time to mortality in Americans. The analytic sample included 14,178 subjects aged ≥50 years from the 2006-2018 waves of the Health and Retirement Study. Date of death was confirmed from the National Death Index. Handgrip dynamometry measured handgrip strength (HGS). Men were categorized as weak if their HGS was <35.5 kg (absolute), <0.45 kg-kg-1 (body mass normalized), or <1.05 kg-kg-1-m-2 (body mass index [BMI] normalized). Women were classified as weak if their HGS was <20.0 kg, <0.337 kg-kg-1, or <0.79 kg-kg-1-m-2. Collective weakness categorized persons as below 1, 2, or all 3 cutpoints. Cox proportional hazard regression models were used for analyses. Subject values below each absolute and normalized cutpoint for the 3 weakness parameters had a higher hazard ratio for early all cause mortality: 1.45 (95% confidence interval [CI]: 1.36-1.55) for absolute weakness, 1.39 (CI: 1.30-1.49) for BMI normalized weakness, and 1.33 (Cl: 1.24-1.43) for body mass normalized weakness. Those below 1, 2, or all 3 weakness cut points had a 1.37 (CI: 1.26-1.50), 1.47 (CI: 1.35-1.61), and 1.69 (CI: 1.55-1.84) higher hazard for mortality, respectively. Weakness determined by a composite measure of absolute and body size adjusted strength capacity provides robust prediction of time to mortality, thus potentially informing sports medicine and health practitioner discussions about the importance of muscle strength during aging. [ABSTRACT FROM AUTHOR]

Dual-energy X-ray absorptiometry (DXA) is commonly used for testing athlete's body composition, but many athletes are too tall. The first aim was to assess the viability of combining upper- and lower-body regions of interest (ROI), creating a combined scan for tall athletes who do not fit on the table and second, to provide practical solutions to DXA users who routinely scan tall athletes. Sixty subjects (34.8 ± 11.9 years; 1719 cm) completed 2 total-body DXA scans for baseline precision testing, using GE Lunar Prodigy (LP) or Hologic Horizon A (HA) models. Next, an upper body ROI from the skull to the distal femoral condyles was combined with a flipped scan (feet-to-head) ROI encompassing the proximal tibial plateau to the distal foot. Soft and bone tissue coefficient of variance (CV%) were calculated between the baseline scans and for the newly combined ROI scan. The combined ROI scan added 0.25-0.63% and 0.01-4.35% error rates for the LP and HA, respectively. An exploratory assessment of a GE Lunar iDXA demonstrated results similar to the HA with 4%+ error. The combined ROI scan is a user-friendly and precise method for older LP systems adding less than 1% error; however, newer DXA systems cannot use the stitched scan technique. Coaches and practitioners who use newer DXAs must prioritize consistently using the same boney landmarks (head, jaw, or feet) and ROI heights to provide precise longitudinal assessments of tall athletes' bone and body composition, until larger DXA tables become available. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effect of cautionary information about the spine vs. a message of spine resiliency on maximum deadlift (MDL) performance and beliefs regarding the vulnerability of the spine. This cluster randomized control trial involved 903 military new cadets (n 5 903) during their mandatory fitness test in cadet basic training (mean age 18.3 years, body mass index 23.8 kg·m-2, 22% female). Subjects were cluster randomized to 3 groups. The cautionary group received a message warning them to protect their backs while deadlifting, the resiliency group received a message encouraging confidence while deadlifting, and the control group received the standardized Army deadlift education only. The outcome measures were MDL weight lifted and perceived spine vulnerability. Significance was set at alpha #0.05. There were no between-group differences in weight lifted (p50.40). Most subjects believed that the spine is vulnerable to injury. Three times as many subjects who received the resiliency education improved their beliefs about the vulnerability of their spines compared with those receiving the cautionary education (p,0.001). This study demonstrated the potential for brief resiliency education to positively influence beliefs about spine vulnerability, whereas cautionary education did not impair performance. [ABSTRACT FROM AUTHOR]

Integrating strength and endurance training in a single exercise session, even on separate days, can be physically demanding and time- consuming. Therefore, there is a growing interest in identifying efficient training methods that can concurrently enhance cardio- vascular and neuromuscular performance through a singular training modality. This study conducted a systematic review and meta- analysis to explore the effects of aerobic training with blood flow restriction (AT + BFR) on muscle hypertrophy and strength gains in healthy individuals. Our study was registered at PROSPERO and used multiple databases (PubMed, Embase, Scopus, and Web of Science), seeking clinical trials that examined AT + BFR influence on muscle hypertrophy and strength gains in individuals aged 18-60 years and comparing with aerobic training without BFR. The risk of bias and method quality were assessed using the ROB2.0 tool and PEDro scale, respectively, and the quality of evidence was evaluated with the GRADE method. A random-effects model was used for meta-analysis, and standardized mean difference (SMD) was calculated for each outcome. Of 4,462 records, 29 full texts were assessed for eligibility, with 7 articles meeting the inclusion criteria. The results indicated that AT + BFR was more beneficial for inducing muscle hypertrophy than aerobic training without BFR (SMD [95% CI] = 0.86 [0.37-1.35]; I² = 42%). Furthermore, AT + BFR was associated with greater improvements in muscle strength (SMD [95% CI] = 0.41 [0.10-0.72]; I² = 0%). Despite the generally high risk of bias for both outcomes, these encouraging findings underscore the clinical significance of AT + BFR as a compelling tool for enhancing neuromuscular parameters. [ABSTRACT FROM AUTHOR]

Heavy load carriage is a common task for military personnel and can lead to undue physical and mental fatigue. The purpose of this study was to assess effects of load carriage on cognitive function (CF) and the role individual characteristics play in CF responses. Anthropometrics/body composition, demographics, and Army Combat Fitness Test (ACFT) scores were gathered from 47 Reserve Officers’ Training Corps cadets. Cadets’ CF was assessed through the concentration task grid (CTG) before (preruck), immediately after (postruck), and 3 weeks after (follow-up) a 16.09- to 19.31-km ruck march. Hierarchical linear modeling was used, with a, 0.05. The final model revealed growth, or improvement, in CF from preruck to postruck with growth decelerating, but still improved, at follow-up. The load carriage bout improved CF in most cadets, with average growth from 5.67- to 7.20-grid squares found. However, postruck CF did not return to the same level as a controlled follow-up (9.69). Sex (2.46, female), familiarity with the CTG (1.99), ACFT total scores (0.009), and relative ruck mass (20.09) were all significant predictors of postruck CF. Army Combat Fitness Test scores (0.008) were also significant predictors of the slope between preruck and postruck, such that an ACFT score 59 points above average would result in a 1-grid square greater improvement in CF postruck. The significance of ACFT scores, lower relative ruck mass, and familiarization highlights the importance physical and mental preparation for desirable CF outcomes after occupational tasks. [ABSTRACT FROM AUTHOR]

Mitochondria, through oxidative phosphorylation, are crucial for energy production. Disease, genetic impairment, or deconditioning can harm muscle mitochondria, affecting energy production. Endurance training enhances mitochondrial function but assumes mobility. Individuals with limited mobility lack effective treatments for mitochondrial dysfunction because of disease or aging. Mitochondrial transplantation replaces native mitochondria that have been damaged with viable, respiration-competent mitochondria. Here, we used a rodent model selectively bred for low-capacity running (LCR), which exhibits innate mitochondrial dysfunction in the hind limb muscles. Hence, the purpose of this study was to use a distinct breed of rats (i.e., LCR) that display hereditary skeletal muscle mitochondrial dysfunction to evaluate the consequences of mitochondrial transplantation. We hypothesized that the transplantation of mitochondria would effectively alleviate mitochondrial dysfunction in the hind limb muscles of rats when compared with placebo injections. In addition, we hypothesized that rats receiving the mitochondrial transplantation would experience an improvement in their functional capacity, as evaluated through incremental treadmill testing. Twelve aged LCR male rats (18 months old) were randomized into 2 groups (placebo or mitochondrial trans- plantation). One LCR rat of the same age and sex was used as the donor to isolate mitochondria from the hindlimb muscles. Isolated mitochondria were injected into both hindlimb muscles (quadriceps femoris, tibialis anterior (TA), and gastrocnemius complex) of a subset LCR (n = 6; LCR-M) rats. The remaining LCR (n = 5; LCR-P) subset received a placebo injection containing only the vehicle without the isolated mitochondria. Four weeks after mitochondrial transplantation, rodents were euthanized and hindlimb muscles harvested. The results indicated a significant (p < 0.05) increase in mitochondrial markers for glycolytic (plantaris and TA) and mixed (quadricep femoris) muscles, but not oxidative muscle (soleus). Moreover, we found significant (p < 0.05) epigenetic changes (i.e., hypomethylation) at the global and site-specific levels for a key mitochondrial regulator (transcription factor A mitochondrial) between the placebo and mitochondrial transplantation groups. To our knowledge, this is the first study to examine the efficacy of mitochondrial transplantation in a rodent model of aging with congenital skeletal muscle dysfunction. [ABSTRACT FROM AUTHOR]

The International Powerlifting Federation recently changed the regulations concerning the bench press (BP) technique, not allowing an accentuated dorsal arch anymore. We investigated the difference between the flat-back vs. arched-back BP performed by competitive powerlifters as concerns the following parameters: (a) 1 repetition maximum (1RM) and barbell displacement; (b) mean and peak barbell velocity and power, and (c) the excitation of the prime movers. Fifteen highly resistance trained individuals (BP 1RM/body mass ratio: 1.38 ± 0.18) performed the flat-back and arched-back BP at their 50, 70, and 90% of the respective 1RM and performed each lift with the intent to maximally accelerate the barbell. Barbell displacement and velocity, power, and the excitation of the upper and lower pectoralis and triceps brachii were assessed. The 1RM was greater with the arched-back BP (+4.2 Kg, 95% confidence intervals + 0.0/+8.4, effect size [ES]: 0.22), whereas the barbell displacement was greater with the flat-back BP for all loads (ES from 0.40 to 0.61). Greater mean (+0.052 m-s¹, 0.016/0.088, ES: 0.42) and peak barbell velocity (+0.068 m-s¹, +0.026/0.110, ES: 0.27) were observed in the flat- back BP, whereas power did not differ. The excitation of upper and lower pectoralis was similar, while an overall trend for an increased activation of triceps brachii was noted in the arched-back vs. flat-back BP. Interestingly, no between-load difference in the excitation of upper and lower pectoralis was observed (p > 0.05). Depending on the training purposes, both flat-back and arched-back BP may be used. The present outcomes may assist practitioners and competitive powerlifters to inform training session. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor 1 (IGF-I) has been implicated as a biomarker of health and body composition. However, whether changes in body composition are associated with changes in IGF-I is unclear. Therefore, we examined the relationship between body composition changes (i.e., fat mass and lean mass) and total serum IGF-I levels in a large cohort of young men (n = 809) and women (n = 397) attending US Army basic combat training (BCT). We measured body composition using dual energy x-ray absorptiometry and total serum IGF-I levels during week 1 and week 9 of BCT. We found that pre-BCT lean mass (r = 0.0504, p = 0.082) and fat mass (r = 0.0458, p = 0.082) were not associated with pre-BCT IGF-I. Body mass, body mass index, body fat percentage, and fat mass decreased, and lean mass increased during BCT (all p < 0.001). Mean (±SD) IGF-I increased from pre-BCT (176 ± 50 ng⋅ml-1) to post-BCT(200 ± 50 ng⋅ml-1, p < 0.001). Inspection of the partial correlations indicated that even when considering the unique contributions of other variables, increases in IGF-I during BCT were associated with both increased lean mass (r = 0.0769, p = 0.023) and increased fat mass (r = 0.1055, p < 0.001) with no sex differences. Taken together, our data suggest that although changes in IGF-I weakly correlated with changes in body composition, IGF-I, in isolation, is not an adequate biomarker for predicting changes in body composition during BCT in US Army trainees. [ABSTRACT FROM AUTHOR]

During sustained or repeated maximal voluntary efforts, muscle fatigue (acute strength loss) is not linear. After a large initial decrease, muscle strength plateaus at approximately 40% of baseline. This plateau, which likely reflects muscle strength preservation, has been observed in sustained maximal isometric and repeated maximal isokinetic contractions. Whether this pattern of fatigue occurs with traditional resistance exercise repetitions with free weights and weight stack machines has not been overviewed. Here, the aim was to determine whether the number of repetitions completed across 4 or more consecutive repetitions-to-failure tests exhibits the same nonlinear pattern of muscle fatigue. A secondary analysis was applied to data extracted as part of a recent meta-analysis on repetitions-to-failure tests. Studies were eligible if they reported mean number of repetitions completed in 4-6 consecutive repetitions-to-failure tests at a given relative load. Twenty-nine studies were included. Overall, the results show that the number of repetitions completed in consecutive repetitions-to-failure tests at a given load generally decreases curvilinearly. The numbers of repetitions completed in sets 2, 3, 4, 5, and 6 were equal to approximately 70, 55, 50, 45, and 45% of the number of repetitions completed in set 1, respectively. Longer interset rest intervals typically attenuated repetition loss, but the curvilinear pattern remained. From the results, a chart was created to predict the number of repetitions across 6 sets of resistance exercise taken to failure based on the number of repetitions completed in set 1. The chart is a general guide and educational tool. It should be used cautiously. More data from a variety of exercises, relative loads, and interset rest intervals are needed for more precise estimates of number of repetitions completed during repeated sets of fatiguing resistance exercise. [ABSTRACT FROM AUTHOR]

Nearly every physically active person encounters periods in which the time available for exercise is limited (e.g., personal, family, or business conflicts). During such periods, the goal of physical training may be to simply maintain (rather than improve) physical performance. Similarly, certain special populations may desire to maintain performance for prolonged periods, namely athletes (during the competitive season and offseason) and military personnel (during deployment). The primary purpose of this brief, narrative review is to identify the minimal dose of exercise (i.e., frequency, volume, and intensity) needed to maintain physical performance over time. In general populations, endurance performance can be maintained for up to 15 weeks when training frequency is reduced to as little as 2 sessions per week or when exercise volume is reduced by 33-66% (as low as 13-26 minutes per session), as long as exercise intensity (exercising heart rate) is maintained. Strength and muscle size (at least in younger populations) can be maintained for up to 32 weeks with as little as 1 session of strength training per week and 1 set per exercise, as long as exercise intensity (relative load) is maintained; whereas, in older populations, maintaining muscle size may require up to 2 sessions per week and 2-3 sets per exercise, while maintaining exercise intensity. Insufficient data exists to make specific recommendations for athletes or military personnel. Our primary conclusion is that exercise intensity seems to be the key variable for maintaining physical performance over time, despite relatively large reductions in exercise frequency and volume. [ABSTRACT FROM AUTHOR]

Arterial occlusion pressure (AOP) of the brachial artery was measured simultaneously using Doppler ultrasound (US), a hand-held Doppler (HHDOP), and a pulse oximeter (PO) in the dominant (DOM) and nondominant (NDOM) arms of males (n = 21) and females (n = 23) using continuous (CONT) and incremental (INCR) cuff inflation protocols. A mixed-model analysis of variance revealed significant (p, 0.05) overall main effects between AOP measured using a CONT (115.7 ± 10.9) or INCR (115.0 ± 11.5) cuff inflation protocol; between AOP measured using US (116.3 ± 11.2), HHDOP (115.4 ± 11.2), and PO (114.4 ± 11.2); and between males (120.7 6 10.6) and females (110.569.4). The small overall difference (1.8163.3) between US and PO measures of AOP was significant (p, 0.05), but the differences between US and HHDOP and between HHDOP and PO measures of AOP were not significant. There were no overall differences in AOP between the DOM and NDOM arms. Trial-to-trial variance in US measurements of AOP was not significant when using either cuff inflation protocol but was significant when using HHDOP and PO and a CONT cuff inflation protocol. Bland-Altman plots revealed reasonable limits of agreement for both HHDOP and PO measures of AOP. The small differences in US, HHDOP, and PO measurements of AOP when using CONT or INCR cuff inflation protocols are of minimal practical importance. The choice of cuff inflation protocol is one of personal preference. Hand-held Doppler of PO can be used to assess AOP before using blood flow restriction during exercise. [ABSTRACT FROM AUTHOR]

Cross-education has been studied extensively with adults, examining the training effects on contralateral homologous muscles. There is less information on the cross-education effects on contralateral heterologous muscles and scant information comparing these responses between adults and youth. The objective was to compare cross-education training effects in male youth and adults to contralateral homologous and heterologous muscles. Forty-two male children (10-13-years) and 42 adults (18-21-years) were tested before and following an 8-week unilateral, dominant or nondominant arm, chest press (CP) training program or control group (14 subjects each). Unilateral testing assessed dominant and nondominant limb strength with leg press and CP 1 repetition maximum (1RM), knee extensors, elbow extensors (EE), elbow flexors, and handgrip maximum voluntary isometric contraction (MVIC) strength and shot put distance and countermovement jump height. Upper-body tests demonstrated large magnitude increases, with children overall exceeding adults (p = 0.05- p < 0.0001, η² : 0.51, 10.4 ± 11.1%). The dominant trained limb showed significantly higher training adaptations than the nondominant limb for the adults with CP 1RM ( p = 0.03, η² : 0.26, 6.7 ± 11.5%) and EE ( p = 0.008, η² : 0.27, 8.8 ± 10.3%) MVIC force. Unilateral CP training induced significantly greater training adaptations with the ipsilateral vs. contralateral limb ( p = 0.008, η² : 0.93, 27.8 ± 12.7%). In conclusion, children demonstrated greater training adaptations than adults, upper-body strength increased with no significant lower-body improvements, and ipsilateral training effects were greater than contralateral training in adults. [ABSTRACT FROM AUTHOR]

β-hydroxy-β-methylbutyrate (HMB) has been used extensively as a dietary supplement for athletes and physically active people. However, the ergogenic effect of HMB supplementation on endurance performance is still unclear. Therefore, this systematic review and meta-analysis (SRMA) aimed to assess HMB supplementation on endurance performance and ...O2 max. This SRMA followed PRISMA guidelines. Three electronic databases were searched (PubMed/Medline, Web of Science [WOS], and Scopus) from inception until April 3, 2023. In this SRMA, human experimental trials, controlled with a placebo group, assessing the effect of HMB supplementation on endurance performance in a healthy population were included. The quality of the studies was assessed by the Physiotherapy Evidence Database (PEDro) scale. The study protocol was registered in the Prospective Register of Systematic Review (PROSPERO): CRD42022341790. Eleven studies involving 279 participants met the inclusion criteria. The results displayed a significant improvement on endurance performance (pooled standardized mean difference [SMD] 5 0.58 [0.28-0.87]) and ...O2 max (pooled SMD = 0.58 [0.21-0.95]) after HMB ingestion. Moreover, afterthe exclusion of the studies not evenly distributed around the base of the funnel plot, the results continued to be significantly positive in endurance performance (pooled SMD = 0.38 [0.22-0.53]) and ...O2 max (pooled SMD = 0.25 [0.09-0.42]). In conclusion, HMB (3 g⋅d-1) ingestion during 2-12 weeks significantly improves endurance performance and ...O2 max. [ABSTRACT FROM AUTHOR]

(a) Ascertain whether lower muscle mass, strength (1 repetition maximum [1RM]), and power (Pmax) in middle-aged women who are breast cancer survivors (BCS), when compared with women of a similar age never diagnosed with cancer (WNC), are related with lower walking speed (WS). (b) Ascertain whether changes in WS are associated with changes in muscle mass, 1RM, and (or) Pmax after resistance training (RT) in middle-aged BCS. A cross-section study was performed. Twenty WNC and 21 BCS were evaluated for lean mass of legs (LLM), 1RM (knee extension), muscle quality index (MQI = 1RM/LLM), Pmax (maximum muscle power-knee extension), and fast WS (10 and 400-meters). Randomized clinical trial was performed. The BCS were randomly divided into the control group (n = 9) and the RT group (n = 11). Breast cancer survivors exhibited lower 1RM (24.2%, p < 0.001), Pmax (30.6%, p < 0.001), MQI (22.2%, p = 0.001), and WS (10-m = 17.0%, p < 0.001 and 400-m = 10.5%, p = 0.002) than WNC. Resistance training increased 1RM (31.6%, p = 0.001), MP (29.0%, p = 0.012), MQI (28.5%, p = 0.008), and WS (10-m = 9.4%, p = 0.009 and 400-m = 6.2%, p = 0.006) in BCS. The changes in WS were positively associated with 1RM (10-m = 68%, p = 0.001 and 400-m = 37%, p = 0.036) and Pmax (10-m = 56%, p = 0.005 and 400-m = 40%, p = 0.027) and MQI (10-m = 63%, p = 0.043 and 400-m = 37%, p = 0.035). Resistance training-induced gains in muscle strength and power mediate the improvement in WS in middle-aged BCS. Resistance training is an effective strategy to improve WS in middle-aged BCS. [ABSTRACT FROM AUTHOR]

The 20-m multistage fitness test (20MSFT) is commonly used by law enforcement agencies to measure aerobic fitness and to estimate maximal aerobic consumption (...O2max). These measures are an important occupational variable with aerobic fitness levels linked to employment status, occupational performance, and long-term health in law enforcement officers. There are a multitude of predictive equations used to provide an estimate of ...O2max, with the extent of variability in the estimated ...O2max currently unknown in this population. This has consequences for comparisons between, and across, differing agencies, and in capabilities of deriving normative data. The aim of this investigation was to compare the variability in estimated ...O2max scores derived from different 20MSFT predictive equations. The 20-m multistage fitness test data from 1,094 law enforcement recruits (male n = 741,25.2 ± 6.3 years; female: n = 353, 25.6 ± 5.6 years) from a single agency were retrospectively analyzed. The 20MSFT scores were trans- formed into estimated ...O2max scores using 6 different predictive equations. Significance was set at p < 0.05. Results demonstrated significantly different ...O2max scores between each predictive equation (p < 0.001; d = 0.25-1.53) and between male and female recruits (p < 0.001, r = 0.55). All estimated ...O2max equations showed small to very strong correlations with each other (p < 0.001; r = 0.32-0.99). The findings indicate considerable dispersion of ...O2max scores when using differing equations, suggesting raw 20MSFT variables (e.g., shuttles or distance completed) should be preferred to measure and apply results from aerobic fitness tests if standardized approaches are not developed within law enforcement. [ABSTRACT FROM AUTHOR]

Many strength and conditioning papers have incorrectly adopted the colloquial use of the term 'power' as a measure of short-term, high-intensity muscular performance despite a long history of research and editorials critical of this practice. This has lead to confusion, incorrect interpretations, and conflicting results in the literature. This paper summarizes the scientific evidence on external mechanical power as a short-term, high-intensity neuromuscular (anaerobic) performance or training variable. Many problems in the measurement and use of power in strength and conditioning research were identified, as well as problems in the use of the vertical jump as a field test of power. A critical review of the biomechanics, measurement, and training research does not support this colloquial use of the term 'power.' More research is needed that improves our understanding of the domains of muscular strength or neuromuscular performance, as well as partial correlation and multiple regression analyses to document the unique associations between these domains, biomechanical variables, training effects, and sport performance. Strength and conditioning research should limit the use of the term power to the true mechanical definition and provide several specific and measurement details on this measurement. [ABSTRACT FROM AUTHOR]

Optimizing transference of gym-based strength and power gains to sporting performance necessitates a physiological and biomechanical understanding of the weight-training exercise as well as the sporting activity. With this in mind, this paper describes the kinematics and kinetics associated with a seated row. The maximal strength and concentric power-load spectrum (30- 100% 1 repetition maximum [1RM]) for the cable seated row was assessed using Olympic rowers (n = 8). In terms of temporal characteristics, peak force across all loads occurred within the first 25% of movement time. Peak power across loads occurred within 35-45% of movement time. With regard to position, peak force occurred within 8.3% and peak power within 27-35% of the start of the concentric phase. To estimate the load that maximized mechanical power output, a quadratic was fitted to each subject's power output vs. 1RM. In terms of mean power, an estimated load of 81.4% (± 9.7%) 1RM was found to maximize power output. A 10 and 20% change in load each side of this maximum resulted in a 1.8 and 7.3% decrease in power output, respectively. The predilection of research to train all subjects at 1 load is fundamentally flawed due to interindividual maximum power differences (range in this study = 69-100% 1RM). Also, the importance of this measure would seem questionable, given that loads either side of the load that maximize power output do not change power output substantially. [ABSTRACT FROM AUTHOR]

In handball and basketball the longer the finger length the better the accuracy of the shot or throw. All shots and throws are finished with the wrist and fingers. It can be proposed that athletes with longer fingers and greater hand surface parameters also probably have greater grip strength. The aim of this study was to investigate the influence of general body and hand-specific anthropometric dimensions on handgrip strength in boys participating in hand- ball and basketball training. In total, 193 boys aged 10-17 years participated in this study. They were divided into 6 groups: 10-, 11-, 12-, 13-, 14-15-, and 16-17-year-olds. The body height and body mass were measured and body mass index was calculated as general anthropometric parameters. The outlines of the hands of the boys were drawn on paper with a thin marker. Three groups of hand anthropometric parameters were measured: 5 finger spans, 5 finger lengths, and 5 perimeters of the hand. Handgrip strength was measured on the dominant hand with a Lafayette dynamometer. As a rule, general anthropo- metric parameters determined the maximal handgrip strength more accurately than did specific hand anthropometric parameters. From the specific hand anthropometric parameters, finger lengths and perimeters of the hand significantly correlated with the maximal handgrip strength. In summary, fingers are the smallest, lightest parts of the motor apparatus, and, therefore, they represent the parts most easily deflected by force from the ball, but at the same time, finger control is especially important for the accuracy of different shots, both in handball and basketball. Thus, it is especially necessary to measure finger length and perimeters of the hand for practical reasons. [ABSTRACT FROM AUTHOR]

Box-lifting ability is an important characteristic of military personnel. The purpose of this paper was to determine the usefulness of the upright row free weight exercise and simple anthropometric tests to predict maximal box-lifting performance that simulates the loading of military supply vehicles. Two groups of adults performed maximal box lifts to 1.4 m (study 1) and 1.7 m (study 2), respectively. All subjects were also tested for upright row 1 repetition maximum (1RM) strength, body mass, height, and body composition. In study 1, a remarkably good prediction of maximal box-lift performance to 1.4 m (42 ± 12 kg) was obtained from a regression equation including the variables body mass, body composition, and upright row 1RM. Approximately 95% of the variation in 1.4-m box-lifting performance could be accounted for. In contrast, in study 2, only 80% of the variation in 1.7-m box-lifting performance (51 ± 15 kg) could be accounted for by the best predictor equation. Upright row 1RM strength appears to be a useful tool in the prediction of box-lifting ability to approximately chest height for most adults, probably due to a close match between the muscle groups and contraction modes required during both tasks. Military or other organizations could use the data reported here to substitute simple anthropometry and a 1RM test of strength and for the direct assessment of 1.4-m box-lifting performance. [ABSTRACT FROM AUTHOR]

There has been an increasing volume of research focused on the load that elicits maximum power output during jump squats. Because of a lack of standardization for data collection and analysis protocols, results of much of this research are contradictory. The purpose of this paper is to examine why differing methods of data collection and analysis can lead to conflicting results for maximum power and associated optimal load. Six topics relevant to measurement and reporting of maximum power and optimal load are addressed: (a) data collection equipment, (b) inclusion or exclusion of body weight force in calculations of power, (c) free weight versus Smith machine jump squats, (d) reporting of average versus peak power, (e) reporting of load intensity, and (f) instructions given to athletes/ participants. Based on this information, a standardized protocol for data collection and reporting of jump squat power and optimal load is presented. [ABSTRACT FROM AUTHOR]

The number of sets in a resistance training program remains a major point of discussion and controversy. Studies prior to 1998 demonstrated inconsistent findings between single-set and multiple-set programs; however, recent evidence suggests that multiple sets promote additional benefits following short- and long-term training. The rationale supporting multiple sets is that the number of sets is part of the exercise volume equation, and the volume of exercise is crucial in producing the stimulus necessary to elicit specific physiological adaptations. The purpose of this paper is to present an overview of recent resistance training studies comparing single and multiple sets. However, it should be noted that studies to date have been conducted in young and middle-aged adults, and it remains to be determined if the additional benefits accrued with multiple-set training also occurs for older adults, especially the frail elderly. [ABSTRACT FROM AUTHOR]

This paper examines the validity of the heart rate deflection point (HRDP) obtained with the “updated” Conconi test. Eleven male road cyclists performed 2 progressive incremental cycling tests and a 30-minute prolonged exercise test (PET). From the data obtained, comparisons were made and correlation coefficients were calculated between HRDP, the lactate threshold (LT), and the 3 mmol·L-1 threshold (AT3). The PET at HRDP demonstrated whether or not a steady state in blood lactate concentration (BLaSS) could be maintained. Significantly lower values for power output (p < 0.01) and heart rate (HR) (p < 0.01) were found at LT compared with HRDP. No differences were found between HRDP and AT3. Only a moderate correlation for power output between HRDP and AT3 (rs = 0.69; p < 0.05) could be observed. During the PET, only 6 out of 11 cyclists reached the target time of 30 minutes, and only 4 cyclists maintained a BLaSS. We conclude that the updated Conconi test is not a valid method for assessing LT or AT3. Therefore, this method seems not suitable to evaluate endurance performance and prescribe exercise intensities in road cycling. [ABSTRACT FROM AUTHOR]

An athlete who trains intensely, yet consistently under-performs, is considered to be suffering from overtraining syndrome (OTS). OTS is a complex state that involves a large variety of signs and symptoms. Symptoms include changes in mood or behaviour, decreases or increases in concentration of different blood molecules, and alterations in immune function. Although several hypotheses have been proposed, each only explains a selective aspect of OTS. Presently, the sole agreement is that OTS is associated with excessive training and insufficient rest and recovery. The hypothesis proposed in this paper suggests that excessive training/competing causes repetitive tissue trauma, either to muscle and/or connective tissue and/or to bony structures, and that this results in chronic inflammation. It is further proposed that traumatized tissue synthesizes a group of inflammatory molecules, cytokines. Cytokines have been shown to coordinate the different systems of the body to promote recovery. Suggestions are made to detect, prevent, and rehabilitate the overtrained athlete. [ABSTRACT FROM AUTHOR]

Beato, M, Wren, C, and de Keijzer, KL. The interunit reliability of global navigation satellite systems Apex (STATSports) metrics during a standardized intermittent running activity. J Strength Cond Res 38(2): e49-e55, 2024--This study aimed to evaluate the interunit reliability of global navigation satellite systems (GNSS) STATSports Apex metrics and to assess which metrics can be used by practitioners for the monitoring of short-distance intermittent running activities. Fifty-four male soccer players were enrolled (age 5 20.7 6 1.9 years, body mass 5 73.2 6 9.5 kg, and height 5 1.76 6 0.07 m) in this observational study. 10-Hz GNSS Apex (STATSports, Northern Ireland, Newry) units recorded total distance, high speed running (HSR), accelerations, decelerations, peak speed, average metabolic power, metabolic distance, dynamic stress load (DSL), relative distance, and speed intensity. The standardized intermitted running protocol used was a Yo-Yo intermittent recovery level 1. This study reported that Apex interunit analysis did not show any significant difference (delta difference and 95% confidence interval [CIs]) in total distance52.6 (22.6; 7.9) m, HSR 5 3.2 (20.2; 6.8) m, accelerations 5 0.09 (20.9; 1.1), decelerations 5 0.3 (20.4; 1.1), peak speed 5 0.02 (20.03; 0.07) m·s21, average metabolic power50.01 (20.02; 0.04)W·kg21, metabolic distance50.9 (26.2; 8.0) m, DSL52.8 (25.6; 10.7) au, relative distance 5 0.14 (20.19; 0.47) m·min21, and speed intensity 5 0.21 (20.21; 0.64) au. All metrics presented a delta d between trivial to small. The interunit intraclass correlation coefficient (ICC) was good or excellent for all metrics, with the exception of DSL, which was considered questionable. In conclusion, this study reports that all the metrics analysis in this study presents a low interunit bias and high reliability (ICC), with the exception of DSL. [ABSTRACT FROM AUTHOR]

Pompa, D, Carson, HJ, Beato, M, di Fronso, S, and Bertollo, M. Attentional focus effects on lower-limb muscular strength in athletes: A systematic review. J Strength Cond Res 38(2): 419-434, 2024--Evidence links an athlete's focus of attention to enhancing strength performance. However, additional research is needed to investigate the applicability of studies beyond the tasks and population currently examined. Therefore, we aimed to systematically review studies concerning attentional focus effects on strength characteristics on lower-limb tasks in athletes. Scopus, Web of Science, and EBSCO databases were searched using PRISMA PERSIST guidelines and keywords related to the focus of attention, force production processes, and athletes. Subjects were categorized: world class (tier 5); elite (tier 4); highly trained (tier 3); trained/developmental (tier 2); nonathletes (tiers 1-0); and mixed (different levels). Fifteen of 296 studies met the inclusion criteria. Included studies investigated the focus of attention effects on performance (n56), between skill levels (n52), and for learning (n55), with respect to subject preference (n51); one study did not state the aim. Studies achieved an average risk of bias score of "excellent"; however, findings suffered in the assessment of certainty. Only 2 studies reported an advantage for one type of attentional focus (external focus) across conditions (g 5 0.13-0.42) with tier 2 and mixed tier athletes. Research does not address the needs of elite athletes, and there is limited evidence on each type of strength characteristics and muscle action. There is also a need to incorporate methodological steps to promote task-relevant instructions. Research should focus on contextualized information within professional practice to offer stronger translational implications for athletes and coaches. [ABSTRACT FROM AUTHOR]

Horsley, BJ, Tofari, PJ, Halson, SL, Kemp, JG, Johnston, RD, and Cormack, SJ. Thoracic-worn accelerometers detect fatiguerelated changes in vertical stiffness during sprinting. J Strength Cond Res 38(2): 283-289, 2024--Thoracic-mounted accelerometers are valid and reliable for analyzing gait characteristics and may provide the opportunity to assess running-related neuromuscular fatigue (NMF) during training and competition without the need for additional tests, such as a countermovement jump (CMJ). However, their sensitivity for detecting fatigue-related changes in gait across different speeds is unclear. We, therefore, assessed the changes in accelerometer-derived gait characteristics, including vertical stiffness (Kvert), following a repeated sprint protocol (RSP). Sixteen recreationally active subjects performed single and repeated CMJs on a force plate and 40 m run throughs overground at 3-4, 5-6, and 7-8 m·s21 pre-post a 123 40 mRSP. Gait characteristics (contact time, step frequency, step length, Kvert, etc.) were derived from an accelerometer contained within a global navigation satellite system unit on the thoracic spine using a validated algorithm. Changes in running gait and CMJ performance were assessed using a linear mixed-effects model (95% confidence interval [95% CI]; effect size [ES]). Significance was set at p < 0.05. A significant reduction in Kvert occurred at 7-8m·s21 following the RSP (28.51 kN·m21 [213.9, 23.11]; p 5 0.007; ES [95% CI] 5 20.39 [20.62, 20.15]) which coincided with a decreased jump height (20.03 m [20.04, 20.01]; p 5 0.002; ES [95% CI] 5 20.87 [21.41, 20.30]). However, all other gait characteristics were not significantly different irrespective of speed. Thoracic-worn accelerometers can detect changes in Kvert at 7-8 m·s21 which may be useful for monitoring NMF during sprinting. However, a RSP does not result in altered gait mechanics in subsequent running at lower speeds. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the cardiometabolic and physical effects of 2 timematched high-intensity programs in a real-world environment. Forty-three active and healthy adults (sex =31 men and 12 women; age = 27 + 5 years; peak heart rate [HRpeak] = 190.7 + 10.6 beat·min-1) were randomized to 2 very low-volume protocols (;8 minutes): sprint interval training (SIT) (n=15), burpee interval training (BIT) (n=15), and control (CON) (n=13). Subjects in SIT and BIT performed 5 days of 10 3 4 second "all-out" efforts with 30 seconds of recovery. Body composition, blood pressure, countermovement jump (CMJ), 10-m sprint, shuttle run test (SRT), autonomic modulation, self-efficacy, and intention were evaluated before and after training. Sprint interval training elicited a higher %HRpeak, energy expenditure, rating of perceived exertion category ratio 10 scale, and feeling scale than BIT (p, 0.05). SRTdistance was significantly improved in SIT (p = 0.03, d = 0.62), whereas CMJ height was significantly enhanced in BIT (p=0.0014, d=0.72). Self-efficacy progressively worsened for SIT than for BIT as sessions increased, and significant differences were found in 5X week frequency between protocols (p=0.040, d50.79). No differences in intention to engage were detected between the regimens (p. 0.05). No changes were observed in body composition, blood pressure, 10-m sprint, SRTV-O2max, or autonomic variables with training (p. 0.05). Results exhibit that extremely low-volume SIT improved running performance, whereas BIT increased the vertical jump. [ABSTRACT FROM AUTHOR]