Journal of Strength and Conditioning Research最新文献

Abstract: Benítez-Muñoz, JA, Fleitas-Paniagua, PR, Murias, JM, and Cupeiro, R. Changes in blood lactate concentration during a step incremental test do not predict changes in substrates oxidation through the training season. J Strength Cond Res XX(X): 000-000, 2025-The aim of the present work was to determine whether changes in blood lactate concentration [La-] between 2 different points of a training season would allow to predict changes in fat oxidation (FatOx) or carbohydrate oxidation (CHOx) in men and women. Fourteen men and 10 women performed a step incremental exercise test on a cycle ergometer at 2 points of the training season (spring and fall). Blood lactate concentration was measured during the final 30 seconds of each step and immediately after task failure, while mean FatOx and CHOx during the last minute of each stage was estimated using indirect calorimetry. Subsequently, the difference between the 2 points of the training season at each common power output during the incremental test was calculated for [La-] (Δ[La-]), FatOx (ΔFatOx), and CHOx (ΔCHOx). The significant level was set at p < 0.05. The results showed [La-] was strongly and inversely associated with FatOx (men: -0.821 ± 0.112; women: -0.914 ± 0.038) and strongly and positively associated with CHOx (men: 0.937 ± 0.027; women: 0.945 ± 0.032) at each point of the training season. Contrary, a broad range of correlations were determined for the relationship between Δ[La-] and ΔFatOx (men: -0.207 ± 0.531; women: -0.384 ± 0.502) or ΔCHOx (men: 0.292 ± 0.427; women: 0.324 ± 0.475). In conclusion, assessing [La-] alone might be considered as an effective way to indirectly assess substrate oxidations as long as [La-], FatOx, and CHOx during the incremental test remain stable throughout the training season. Contrary, the novel and most important finding is changes in [La-] do not predict changes in substrate oxidations as the training season progresses.

Abstract: Gonçalves Dias, W, Benvenutti Bueno de Camargo, J, Volpi Braz, T, Rodrigues Batista, D, Oenning Col, L, Prestes, J, and Ricardo Lopes, C. A comparison between synergist and nonsynergist resistance training schemes in recreationally trained men. J Strength Cond Res XX(X): 000-000, 2025-The aim of the present study was to compare the effects of 2 different resistance training (RT) schemes (synergist [SN] and nonsynergist [NS]) on both muscle strength and hypertrophy outcomes in recreationally trained subjects. The sample included 22 men that were assigned to 2 experimental groups: NS (push/pull and pull/push exercises, n = 12; age: 20.5 ± 2.3 years; total body mass: 75.1 ± 8.2 kg; height: 179.8 ± 7.8 cm; experience in RT: 2.4 ± 1.4 years) and SN (pull/pull and push/push exercises, n = 10; age: 22.1 ± 3.2 years; total body mass: 82.7 ± 11.7 kg; height: 175.0 ± 7.0 cm; experience in RT: 3.2 ± 1.5 years). Muscle thickness assessments of the triceps brachialis, biceps brachialis, pectoralis major, and one repetition-maximum testing in the bench press and lat pull-down exercises were performed before and after the 8-week intervention period. The total load lifted during each week also was calculated. Both groups displayed significant increases in muscle strength and thickness (NS and SN, p < 0.05), with no significant difference observed between the groups for the dependent variables assessed (all p > 0.05). Therefore, the present study suggests that individuals aiming to increase muscle strength and size may benefit from both training schemes, taking into account personal preferences.

Abstract: McClean, ZJ, da Silva Torres, R, Herzog, W, Pasanen, K, Lun, V, and Jordan, MJ. The influence of sport representation and attitudes toward strength training on neuromuscular performance profiles in university athletes: Part I-Male athletes. J Strength Cond Res XX(X): 000-000, 2025-Strength, power, and plyometric testing are essential to evaluate neuromuscular performance in athletes. However, this approach creates datasets with numerous outcome measures that can lead to challenges for interpretation and establishing relevant performance benchmarks for preseason testing and performance-readiness after injury. The idea that athlete performance profiles exist within a larger population has been suggested, but limited research has explored this concept or suggested methodologies for delineating relevant profiles. Exploring the existence of neuromuscular performance profiles in university athletes while accounting for the influence of the sport environment and psychosocial factors, such as attitudes toward strength training, may support more athlete-specific neuromuscular benchmarks. Healthy male university athletes ( n = 272) from 5 sports completed a comprehensive neuromuscular performance testing battery and a questionnaire that included assessment of attitudes toward strength training. Unsupervised machine learning applied to the body weight-normalized neuromuscular performance dataset, along with Fisher's exact tests, was used to examine differences in attitudes toward strength training across clusters (alpha = 0.05). Five profiles were identified, including a high strength/high power/braking-dominant jump strategy cluster with a large ice hockey representation and a high strength/high power/fast jump strategy cluster consisting mostly of field-sport athletes. Differences in attitudes toward training were noted across profiles ( p < 0.05); for instance, athletes in a low-strength/low-power profile tended to prefer training in a more private training environment ( p = 0.023). These results may help inform neuromuscular performance benchmarks in male university athletes, while the psychosocial characteristics of these profiles may provide insight into increasing strength training engagement in this population.

Abstract: Kassiano, W, Costa, B, Kunevaliki, G, Lisboa, F, Prado, A, Alves, L, Tricoli, I, Stavinski, N, Francssuel, J, and Cyrino, ES. Comparison of muscle hypertrophy and strength adaptations induced by back squat and leg extension resistance exercises. J Strength Cond Res XX(X): 000-000, 2025-Exercise selection affects muscular adaptations (e.g., strength gains and muscle hypertrophy). The purpose of this study was to compare changes in strength and muscle size between the back squat and leg extension resistance exercises. Sixty-three untrained young women were randomly allocated to perform the Smith machine back squat (SQ, n = 30) or leg extension (LE, n = 33) exercises. Subjects performed 3 sets of 8-12 repetitions maximum (RM) per session, 2 d·wk -1 , for 8 weeks. Muscle thickness of the rectus femoris (RF) and vastus lateralis (VL) was measured at the proximal, middle, and distal sites. Strength was assessed through 3 repetitions maximum (3RM) tests in the back squat (3RM-SQ) and leg extension (3RM-LE) exercises. The LE experienced greater increases in the 3 RF sites (proximal: +11.4% vs. +2.0%; middle: +12.3% vs. +5.7%; distal: 17.5% vs. +7.9%; all p < 0.001). Conversely, the SQ showed greater increases in VL at the distal site (+18.2% vs. +11.2%; p < 0.001). Smith machine back squat induced greater increases in 3RM-SQ (+46.7 vs. 21.3%; p < 0.001), but no between-group difference was observed in 3RM-LE increases (SQ = +19.8% vs. LE = +23.4%; p = 0.824). Based on our results, the leg extension induce greater rectus femoris hypertrophy, while the back squat promotes greater vastus lateralis hypertrophy, particularly at the distal site. The back squat training seems to be more effective for increasing squat strength, but both exercises are likely similarly effective for increasing leg extension strength.

Abstract: Fahey, JT, Comfort, P, and Ripley, NJ. Force plate derived isometric mid-thigh pull data in girls youth and adult soccer players: a comparison between age groups. J Strength Cond Res XX(X): 000-000, 2025-Expression of maximal and rapid force (i.e., force at 250 ms) is important for sporting success. Despite growing participation rates, injury risk in women soccer remains high. Furthermore, relative strength does not seem to change across age groups with no current data on rapid force production. This study was designed to report net and relative net isometric midthigh pull (IMTP) peak and rapid force for girls youth soccer players. Ninety-four youth soccer players, categorized into Foundation Development Phase (FDP; U11-U12, n = 21, 10.9 ± 0.6 years, 42.8 ± 7.6 kg, 1.49 ± 0.08 m), Youth Development Phase (YDP; U13-U15, n = 35, 13.6 ± 1.0 years, 54.8 ± 7.9 kg, 1.60 ± 0.06 m), and Professional Development Phase (PDP; n = 38, U16-U21, 16.2 ± 1.1 years, 63.4 ± 6.8 kg, 1.67 ± 0.06 m) performed the IMTP. Moderate-to-large differences were observed between FDP vs. YDP and PDP for net peak force, relative net peak force, and relative net force at 250 ms, with no differences between YDP and PDP players, respectively. Small-to-moderate increases in relative net peak force were observed between FDP vs. YDP and PDP. The results of this study highlight that maximal and rapid relative strength plateaus with increasing age. This could be problematic for players aiming to transition to senior and international standards of women's football and warrants further investigation. Practitioners should design strength and conditioning programs to enhance maximal and rapid relative strength to physically prepare youth players for the increased match-demands associated with increasing age and competition.

Abstract: Sudlow, A, Pommerell, F, Galantine, P, Del Sordo, G, Boyas, S, Rahmani, A, Robichon, J, Samozino, P, Duché, P, and Peyrot, N. Effects of dribbling constraints on sprint acceleration performance according to maturity status in handball players. J Strength Cond Res XX(X): 000-000, 2025-The aim was to determine the effects of dribbling and maturation in handball players on sprinting horizontal force production capacities. One hundred sixteen male handball players participated (10-39 years). Split times and continuous velocity-time data were collected using a radar in sprinting and dribbling conditions. Samozino's method was applied to obtain horizontal force-velocity relationship parameters (Pmax, F0, v0, SFV) and technical variables (RFmax, DRF). Somatic maturity was determined from peak height velocity (PHV). Statistical significance for all tests was set at an alpha level p < 0.05. Interaction effects were observed for split times revealing that, at all distances, each maturity group decreased in performance when dribbling and that maturation effects persisted in both conditions (p < 0.05, d = 0.33-3.83). No interaction effects were observed for any of the mechanical outputs but decreases in all outputs were observed in the dribbling condition, all maturity groups combined (p < 0.002, d = 0.36-0.90). Greater relative change in performance was observed for Pre-PHV vs. Post-PHV and Adults at almost all distances (p < 0.05, d = 0.59-0.93). No effects of maturation were observed for any of the mechanical outputs. Dribbling in handball has effects on horizontal force capacities with reductions in Pmax primarily due to greater losses in v0 than F0, suggesting that improvement in dribbling proficiency leads to smaller decreases in propulsive force production capacities.

Abstract: Barrera-Domínguez, FJ, Scott Talpey, Almagro, BJ, and Molina-López, J. Effect of individualized training based on change of direction deficit on speed performance in basketball players. J Strength Cond Res XX(X): 000-000, 2025-Linear and changes of direction (COD) speed are considered key performance determinants in basketball. The aim of this study was to analyze the effect of an individualized COD deficit-based training program on linear speed and COD efficiency, and performance in basketball players. In addition, the differences in linear speed and COD performance between 2 time periods (4 and 8 weeks) with this training were analyzed. Thirty-six male basketball players (age, 21.4 ± 3.23 years; height, 1.87 ± 0.07 m; body mass, 83.6 ± 7.83 kg) were divided into an intervention group (INT, n = 18), who performed an individualized COD deficit-based training, and a control group (CON, n = 18), who underwent a nonindividualized multidirectional repeated sprint training program. Both groups performed the intervention 2 days per week. Baseline, 4-week, and 8-week assessments included 10 meters linear speed and COD (5 + 5 meters at 45°, 90°, and 180° cut) tests. An improvement in multidirectional speed efficiency was observed from 4 weeks in the INT group (effect size [ES] ≥ 1.61, p < 0.01), with no change in the CON group. After 8 weeks, significant improvements were observed in the INT players' mean speed performance (mean difference [MD] -0.09, ES = 0.34, p < 0.01), with COD180° showing the greatest changes (MD ≤ -0.18, ES ≥ 0.44, p < 0.01). In conclusion, an individualized COD deficit-based training program improved speed performance after 8 weeks, with changes in multidirectional speed efficiency after first 4 weeks. Given basketball's unpredictable and multidirectional nature, strength and conditioning coaches should seek the optimal trade-off between the linear and multidirectional speed demands on their players.

Abstract: Gepfert, M, Terbalyan, A, Roczniok, R, and Gołaś, A. The effects of in-season complex contrast training on anaerobic performance metrics in elite female soccer players. J Strength Cond Res XX(X): 000-000, 2025-The aim of this study was to evaluate the effects of in-season complex contrast training (CCT) on speed, power, and anaerobic capacity metrics in elite female soccer players. Twenty-one players participated in a 3-phase study conducted across the postpreparatory period, midseason, and postseason. Testing included countermovement jump, single-leg jump, 5 and 30 m sprints, and the repeated anaerobic sprint test (RAST). Weekly complex training sessions combined resistance exercises with plyometric drills. Significant improvements were observed in anaerobic performance midseason compared with the preparatory phase (RAST 1, p = 0.0073, d [Cohen's d ES] = 0.45; 30 m sprint, p = 0.0073, d = 0.81), followed by performance declines at the end of the season. Peak RAST metrics improved significantly midseason (e.g., RAST 2, p = 0.025, d = 0.81; RAST 3, p = 0.0083, d = 0.95), but no changes were observed for concentric peak velocity ( p = 0.98) or rate of force development ( p = 0.37). The findings demonstrate that complex contrast training effectively enhances power and anaerobic performance during the midseason but may require strategic load management to mitigate late-season fatigue-related declines. A single weekly session of CCT seems sufficient to maintain, and in some instances improve, physical performance across the season. However, without a comparison group, it is unclear whether it is more or less effective than other training methods.

Abstract: Brooks, SG and Dengel, DR. Position-specific longitudinal assessment of total and regional body composition in NCAA Division I football players. J Strength Cond Res XX(X): 000-000, 2025-Position-specific differences in body composition in American football players have been established. How the total and regional composition changes from preseason to postseason by position is unknown. Thus, this study examined longitudinal changes in total and regional body composition in NCAA Division I collegiate football players (CFPs) over a competitive season. A total of 188 male CFPs aged 18-23 (20.7 ± 1.6 years) were included. Body composition was measured using dual X-ray absorptiometry at preseason and postseason. Subjects were grouped into defensive backs, defensive linemen, linebackers, offensive linemen, punters/kickers, quarterbacks, running backs, tight ends, and wide receivers. Repeated-measures ANOVA assessed effects of season and position on total and regional body composition, controlling for player participation status. Post hoc pairwise comparisons determined the magnitude, direction, and significance of changes for each position. There were no changes in total or regional measures of body mass, fat mass, or bone mass across the season, except for arm mass. Significant (p < 0.05) decreases in total lean mass (LM), arm LM, leg LM, and gynoid LM were observed in certain position groups. The results of this study confirm that there is a decrease in total LM during a competitive season in CFPs. This study demonstrates that this loss in LM mainly comes from the leg and gynoid regions of the body and occurs across all positions. This information can be used by strength and nutrition staff to develop new strategies to prevent this LM loss during the season.

Abstract: Chiron, F, Gulören, B, Erblang, M, Poirier, C, Elbaz, M, Servonnet, A, Gaudin, M, Le Coz, C, Lopes, P, Chennaoui, M, Hanon, C, Léger, D, and Thomas, C. Exploring the influence of coherent breathing on psychophysiological stress during a simulated 3-day 400-m race. J Strength Cond Res XX(X): 000-000, 2025-Managing psychophysiological stress is essential for elite athletes, especially during the high-intensity competitive period. Coherent breathing has been proposed as a noninvasive strategy to enhance recovery by modulating autonomic, neuroendocrine, and inflammatory responses. This study investigated the effects of coherent breathing on the autonomic nervous system (ANS), hypothalamic-pituitary-adrenal (HPA) axis regulation, inflammatory response, and sleep parameters in well-trained athletes undergoing repeated supramaximal efforts. Twenty-two athletes (N = 22) were randomly assigned to a control group (CONT, n = 11) or a coherent breathing group (RELAX, n = 11). Over an 8-day protocol simulating competition, athletes completed 3 400-m races. Heart rate variability, salivary biomarkers (alpha-amylase, cortisol, testosterone IL1-β), and sleep parameters were assessed throughout this study. Two-way repeated measure ANOVA revealed that the RELAX group showed significantly increased parasympathetic activity (root mean square of successive difference, p < 0.01) and a more stable cortisol response (p < 0.01) compared with the control group. The RELAX group also exhibited lower IL1-β levels (p < 0.05), longer total sleep duration (p < 0.05), and reduced sleep latency (p < 0.05). No significant differences in athletic performance were observed between groups. Coherent breathing effectively modulates psychophysiological stress by enhancing ANS balance, regulating HPA axis activity, reducing inflammatory responses, and improving sleep quality. This accessible and low-cost intervention may support recovery and resilience in athletes exposed to repeated high-intensity efforts.