Journal of Strength and Conditioning Research最新文献

Abstract: da Silva, LSL, Gonçalves, LdS, Alves Campos, PH, Benjamim, CJR, Tasinafo Júnior, MF, de Lima, LCR, Bueno Júnior, CR, and Alves, CPdL. Comparison between eccentric vs. concentric muscle actions on hypertrophy: a systematic review and meta-analysis. J Strength Cond Res 39(1): 115-134, 2025-Different physiological mechanisms of sarcomere activity during eccentric (ECC) and concentric (CON) muscle actions led to investigations into muscle hypertrophy outcomes, but conclusions remain elusive. We aimed to investigate the effects of ECC vs. CON muscle actions on muscle hypertrophy in apparently healthy adults through a systematic review with meta-analysis. The searches were conducted on EMBASE, MEDLINE, Cochrane Library, Web of Science, Scopus, and SPORTDiscus databases. To be eligible for inclusion, studies had to: (a) be randomized/controlled trials; (b) investigate the effects of CON vs. ECC resistance training programs in apparently healthy adults; (c) assess hypertrophy outcomes using direct imaging for cross-sectional area, muscle thickness, or muscle volume. A total of 15,778 studies were identified, and 26 (682 subjects included in the meta-analysis) met the inclusion criteria. The main findings indicated no statistical difference between ECC vs. CON on hypertrophy measurements (0.285 [95% CI: -0.131 to 0.701]; p = 0.179; I2: 84.4%; GRADE: very low). Subgroup meta-analysis analyzing possible hypertrophy outcome moderators as age (18-59 years old and ≥60 years old) and weeks of intervention duration (>8 weeks) did not reveal differences between ECC vs. CON. Subgroup analysis revealed an effect favoring the ECC for the upper limb muscles (p = 0.018), ≤8 weeks of intervention (p = 0.046), muscle thickness assessment (p = 0.0352), and isokinetic contraction (p = 0.0251). Our findings suggest similar hypertrophy between ECC and CON muscle actions in apparently healthy adults. However, it appears that the muscles of the upper limbs, shorter interventions, hypertrophy assessment method, and the contraction type may favor ECC muscle actions.

Abstract: Mann, JB, Cowley, N, and Weakley, J. The role of speed, change of direction, and momentum by position and starting status in Division 1 collegiate football players. J Strength Cond Res 39(1): 41-47, 2025-This study (a) investigated differences between big, mid, and skill positions in sprint and change of direction times and momentum; (b) compared starting and nonstarting athletes; and (c) investigated whether thresholds can be developed to distinguish between starting and nonstarting Division 1 collegiate football athletes. Data from 496 collegiate football players who completed the 40-yard dash, pro-agility, and L drill were analyzed. Momentum was calculated using body mass and the average velocity during each test. To assess differences between positions and starters and nonstarters, data were analyzed using linear mixed models with effect size ±95% confidence intervals. Receiver operating characteristic (ROC) curves were generated to determine whether a cutoff value could be used to distinguish starters from nonstarters. Significant differences for both time and momentum were found between positional groups and starters and nonstarters for all tests in all positions. Starting skill position players tended to have greater differences in sprint or change of direction times and starting big players had greater sprint momentum. However, it should be noted that all ROC curves demonstrated relatively poor predictive value. Collectively, these findings demonstrate that bigger, faster players are preferentially selected in collegiate Division 1 football and there may be value in coaches collecting and assessing different outcome measures (e.g., sprint times and sprint momentum) depending on the positional group of the player. Finally, it should be acknowledged that setting binary thresholds to guide selection decisions is ill-advised and that speed, change of direction, and momentum are only one piece of the performance puzzle.

Abstract: Fontanetti, G, Barreto, RV, Junior, RC, Marangoni, V, Denadai, BS, Greco, CC, and Lima, LCR. The use of the self-selected rest interval method is as effective for optimizing postactivation performance enhancement in elite athletes as employing the best fixed rest interval. J Strength Cond Res 39(1): 10-15, 2025-This study investigated whether the adoption of a self-selected recovery interval (SSI) is more effective than the use of a fixed recovery interval (FRI) to elicit postactivation performance enhancement (PAPE). Ten male professional volleyball athletes (20.6 ± 1.5 years; 92.8 ± 4.9 kg; 195 ± 8 cm) participated in 3 experimental sessions, in random order, following familiarization with countermovement jump (CMJ) exercises and determination of the load for 5-repetition maximum (5RM: 146 ± 27 kg) squat exercise. The 3 experimental sessions consisted of (a) control session (CON), with measurement of CMJ height 4 minutes before and 2, 4, 6, 8, and 10 minutes after subjects rested while sitting in a chair without performing any preactivation (PA) protocol; (b) session with FRI, with measurement of CMJ height 2, 4, 6, 8, and 10 minutes after performing a PA exercise consisting of 5 squats with 5RM load; and (c) session with SSI, with evaluation of CMJ height once after performing the PA adopting a SSI based on a readiness scale. No significant differences were found between CMJ height in the CON session. Countermovement jump height was higher (p < 0.05) than the baseline measurement at minutes 4, 6, and 8 post-PA in the FRI session, for the best CMJ performance during the FRI session, and after the PA in the SSI session. No significant differences were found between the heights of the best CMJ in the FRI session (49.2 ± 6.8 cm) and post-PA in the SSI session (49.6 ± 6.6 cm). Therefore, adopting FRI and SSI is equally effective in eliciting PAPE in elite athletes. Despite being as effective as adopting FRI to elicit PAPE, SSI is more intuitive and easily applicable in contexts where PAPE can be implemented.

Abstract: Gonzalo-Skok, O and Bishop, C. Effects of maturation on the magnitude and direction of asymmetry in jumping and change of direction speed in young elite football players. J Strength Cond Res 39(1): 70-78, 2025-Physical performance is often affected by maturation in young athletes and provides an interesting challenge to optimize performance. The present study analyzed whether maturation affects directional dominance, chronological age, body mass, and biological age predictors and assessed between chronological or biological age-group differences in young footballers. One hundred eight elite male players (U-15 to U-19) were tested on bilateral vertical and unilateral vertical and horizontal jumping, sprinting (40 m), and change of direction (COD) ability over single and multiple CODs (times and the percentage-based COD deficit [%CODD]). Almost half of the players (45%) at post-peak height velocity (PHV) showed consistency in the direction of asymmetry (jumping and COD). Ten-meter sprint time was the main predictor to explain the %CODD. Standing height affects unilateral horizontal jumping, and peak speed and unilateral horizontal jumping were the main predictors for unilateral vertical jumping. Post-PHV reported significantly (p < 0.05, effect size [ES] = 0.76-1.50) greater vertical and horizontal jumping, and linear and COD speed performance than mid-PHV. Significant differences (p < 0.05) in jumping, sprinting, and COD performance were found between U-15 and the rest of groups. Furthermore, the U-16 group showed a significant difference (p < 0.05) to the U-19 (for peak speed) and U-18 groups (for 40-m sprint and peak speed). Significantly (p = 0.04, ES = 0.47) lower %CODD asymmetries were found in mid-PHV compared with post-PHV. The study highlights the impact of maturation on the direction of asymmetry, tending to show the same weak side as maturation increases (i.e., older, and more experienced and mature players). Finally, decreasing between-limbs asymmetry should be considered during maturation, especially as greater football specialization.

Abstract: Feeney, KA, Melton, BF, Ryan, GA, Bland, HW, and Butler, CR. The association between body composition and performance on military fitness tests. J Strength Cond Res 39(1): 94-98, 2025-Body composition and physical testing are important considerations for military personnel. However, limited research exists on the potential relationship between these 2 factors. The purpose of this retrospective cohort study was to examine the correlations between several body composition measures and performance on the components of 2 separate fitness tests in Air Force special warfare candidates. Within the cohort of candidates, 1,036 completed body composition testing, 1,002 completed a calisthenic-based fitness test, and 562 completed a fitness test designed to mimic occupational tasks. Analysis of Pearson correlations indicated that the calisthenic-based test weakly favored candidates with lower body mass and body fat levels on the lower end of that found within the cohort studied, while a higher score on the occupational-based test was linked to higher body mass index (BMI) and skeletal muscle mass (SMM) and lower absolute and relative body fat levels. Individual components of the occupational-based test favored different body composition relationships. A large negative association was seen between the farmer's carry time and SMM (r = -0.53) and a moderate negative association between farmer's carry time and body mass (r = -0.46), p < 0.01. The weight lifted during 3-RM deadlift demonstrated moderate positive associations with body mass (r = 0.49), BMI (r = 0.50), and SMM (r = 0.49), p < 0.01. These results suggest that individuals in physically active military roles should maximize SMM while managing body fat levels.

Abstract: Watson, A, Murray, A, Coughlan, D, Wells, J, Ehlert, A, Xu, J, Turner, A, and Bishop, C. Understanding training load in golf: A survey of swing coaches, performance practitioners, and medical staff. J Strength Cond Res 39(1): e20-e29, 2025-The present study aimed to investigate the current opinions and practices of golf coaches, performance practitioners, and medical staff working in golf, on the topic of monitoring training load in the sport. A cross-sectional, explorative survey was undertaken, which included specific questions for each subgroup using a combination of Likert scale and "Yes" or "No" questions. A total of 89 practitioners completed the survey with 23 being golf coaches, 35 being performance practitioners, and 31 being medical practitioners. Results showed that virtually all technical coaches and support staff practitioners agreed on the importance of monitoring training load in golf. However, our findings identified a noticeable gap between what is current opinion and what is actually done in day-to-day practice, relating to training load monitoring in the sport. Although the majority of coaches and practitioners are in agreement with the value of assessing load in golf, the number that actually monitor and collect data relating to this is substantially lower. Therefore, further consideration and research is undoubtedly required on this topic to help inform and change current practice in golf.

Abstract: Cardoso, F, Costa, MJ, Colaço, P, Vilas-Boas, JP, Pinho, JC, Pyne, DB, and Fernandes, RJ. Ventilatory and perceived ergogenic effects of mandibular forward repositioning during running at maximal oxygen uptake intensity. J Strength Cond Res 39(1): e13-e19, 2025-Wearing an intraoral dental splint may enhance ventilatory function and exercise performance. Nineteen runners performed on a 400-m outdoor track: (a) an incremental protocol to assess the velocity at maximal oxygen uptake (vV̇ o2 max) and (b) 2 square wave bouts wearing 2 intraoral splints (with and without mandibular forward repositioning). The time until exhaustion at vV̇ o2 max (TLimv V̇ o2 max), ventilatory variables, oxygen uptake (V̇ o2 ) kinetics, energetic profiling, perceived exertion and kinematics, were all measured. Ventilatory data were assessed breath-by-breath and perceived exertion evaluated using the Borg 6-20-point scale at the end of TLimv V̇ o2 max bouts. Images were recorded by video cameras (120 Hz) and kinematic measures retrieved using Kinovea. A paired t test was computed for comparison of splints ( p ≤ 0.05). With (vs. without) mandibular forward repositioning, runners increased their TLimv V̇ o2 max by ∼6% ( p = 0.03), coupled with higher ventilation (151 ± 22 vs. 147 ± 23 L·min -1 , p = 0.04), end-tidal oxygen tension (114.3 ± 3.7 vs. 112.9 ± 3.9 mm Hg, p = 0.003), and lower inspiratory time (0.526 ± 0.083 vs. 0.540 ± 0.090 seconds, p = 0.02), despite similar V̇ o2 kinetics (e.g., 49.0 ± 8.7 vs. 47.7 ± 8.6 ml∙kg∙min -1 of fast component amplitude) being observed. The energy expenditure was ∼8% higher ( p = 0.03) with the mandible forward, coupled with lower perceived exertion scores ( p = 0.04). Mandibular forward repositioning was effective in acutely improving running performance at vV̇ o2 max with ergogenic effects on ventilatory and perceived variables.

Abstract: Gereduz Agapito, L, Brownstein, CG, and Maffiuletti, NA. Effects of soccer match-play on muscle strength, physical performance, and perceptual responses in elite female players. J Strength Cond Res 39(1): 79-85, 2025-The purpose of this study was to investigate the impact of actual soccer match-play on muscle strength, physical performance, and perceptual responses in elite female players. Twelve Swiss elite players were tested before (pre), after (post) and 48 hours after a 90-minute soccer match for knee and hip muscle strength, vertical jump height, and sprint time. Perceptual responses were also evaluated up to 72 hours postmatch with a self-reported questionnaire. Muscle strength, jump, and sprint performance were impaired at post compared with pre (p < 0.001), but fully recovered at 48 hours. Percent strength losses were higher for knee flexors (∼20%) compared with both hip adductors (∼12%; p = 0.005) and abductors (8-12%; p < 0.001), and for knee extensors compared with hip abductors (p = 0.013). Regardless of muscle group, strength losses were higher on the dominant than on the nondominant side (p = 0.010). Most perceptual responses were altered after the match (p < 0.001) and some items such as motivation to train and readiness to play remained unrecovered at 72 hours (p < 0.01). Soccer match-play induced a significant decline of knee and hip muscle strength in elite female players that was more marked for knee flexors than for hip muscles. This was accompanied by performance impairments and by altered perceptual responses that still persisted 72 hours after the match. These findings offer implications for the optimization of postmatch recovery strategies in elite female soccer players.

Abstract: Sandau, I and Kipp, K. Prediction of snatch and clean and jerk performance from physical performance measures in elite male weightlifters. J Strength Cond Res 39(1): 33-40, 2025-This study aimed to build a valid model to predict maximal weightlifting competition performance using ordinary least squares linear regression (OLR) and penalized (Ridge) linear regression (penLR) in 29 elite male weightlifters. One repetition maximum (1RM) or 3RM test results of assistant exercises were used as predictors. Maximal performance data of competition and assistant exercises were collected during a macrocycle in preparation for a competition. One repetition maximum snatch pull, 3RM back squat, 1RM overhead press, and body mass were used to predict the 1RM snatch; and 1RM clean pull, 3RM front squat, 1RM overhead press, and body mass were used to predict the 1RM clean and jerk. Model validation was performed using cross-validation (CV) and external validation (EV; random unknown dataset) for the coefficient of determination and root mean square error (RMSE). Results revealed that penLR models present more plausible output in the relative importance of highly correlated predictors. Of note, the 1RM snatch pull is the most relevant predictor for the 1RM snatch, whereas the 1RM clean pull and 3RM front squat are the most relevant predictors for the 1RM clean and jerk. Validation-based absolute predictive error (RMSE) ranged between ≈ 3-9 kg for the 1RM snatch and ≈ 3-7 kg for the 1RM clean and jerk, depending on the model (OLR vs. penLR) and validation procedure (CV vs. EV). In conclusion, penLR models should be used over OLR models to analyze highly correlated predictors because of more plausible model coefficients and smaller predictive errors.