Journal of Strength and Conditioning Research最新文献

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: Saini, AS, Sharma, SK, Kushwah, GS, Phukan, MI, McCabe, C, and Thapa, RK. Effects of three different volumes of in-water warm-up protocols in acute physiologic responses and 100 m swimming performance across all strokes. J Strength Cond Res XX(X): 000-000, 2025-This study examined the effects of 3 in-water warm-up (WU) protocols of varying volumes (600, 1,200, and 1,800 m) on acute physiologic responses and 100-m swimming performance across all strokes. Forty male national-level swimmers (21.0 ± 2.0 years) participated in a randomized crossover study, performing each WU protocol followed by a 100-m time trial in their respective strokes. Physiologic metrics, including blood lactate, temperature, heart rate, and rating of perceived exertion (RPE), were recorded. A repeated measures ANOVA was used to investigate the effects of the 3 protocols on physiologic and swimming performance across all the strokes. Results showed that the regular WU (1,200 m) led to significantly faster times in backstroke (65.56 ± 1.14 seconds vs 67.02 ± 1.20 seconds), breaststroke (70.73 ± 0.94 seconds vs 72.73 ± 0.94 seconds), and butterfly (58.64 ± 0.77 seconds vs 60.53 ± 0.86 seconds) than the long WU (1,800 m) (p < 0.05). For the butterfly, the short WU (600 m) also resulted in significantly better swimming performance than the long WU. No significant differences were observed in freestyle performance among the 3 WU protocols, nor were there differences in heart rate across all strokes (p > 0.05). Higher blood lactate and tympanic temperatures were observed after regular WU, while RPE was lowest after the short WU. This study emphasizes the importance of optimizing WU volumes based on stroke-specific demands in swimming. In addition, it also suggests practitioners to be cautious about using heart rate as a sole marker of WU effectiveness in swimming.

Abstract: Maestroni, L, Turner, A, Read, P, Bettariga, F, Fenu, G, Rosalia, A, Guastella, M, and Bishop, C. Inter-limb asymmetry data in athletes with anterior cruciate ligament reconstruction: A comparison of different equations to interpret between-limb difference data. J Strength Cond Res XX(X): 000-000, 2025-Between-limb performance and biomechanical differences (i.e., interlimb asymmetries) after anterior cruciate ligament (ACL) reconstruction are monitored and reported during rehabilitation and at the time of return to sport. However, different asymmetry equations can alter the magnitude and consistency of the asymmetry. Fifty-three amateur athletes (16 women; 37 men; 28.5 ± 6.7 years; 177.1 ± 6.5 cm; 75.3 ± 10.8 kg) at a median of 28.1 months post-ACL reconstruction completed a strength and vertical jump assessment including 5 repetition maximum (RM) box squat, rear foot elevated split squats, leg extension and countermovement jump (CMJ), single-leg CMJ, and single-leg drop jump. Large significant differences (ƞ2 = 0.14-0.44) were found between unilateral equations for each variable assessed, and between bilateral equations (ƞ2 = 0.17-0.34) for CMJ concentric and eccentric impulse asymmetries. Small to large significant pairwise differences were present between each equation and variable in unilateral tasks (d = 0.46-2.30). For the CMJ, large significant pairwise differences were also found between most equations for CMJ concentric and eccentric impulse asymmetry (d = 0.99-3.04). We recommend the use of the Standard Percentage Difference (with direction) formula for unilateral tasks and the Bilateral Asymmetry Index 1 for bilateral tasks.

Abstract: Naclerio, F, Larumbe-Zabala, E, Chapman, M, Gonzalez-Frutos, P, and Triplett, NT. Comparable workout output by using velocity feedback or perceived exertion in male and female recreationally resistance trained individuals. J Strength Cond Res XX(X): 000-000, 2025-We compared an objective (velocity feedback [VEL]) vs. a subjective (rating of perceived exertion [RPE]) autoregulatory method to estimate velocity drop thresholds associated with low (10%), moderate (20%) metabolic fatigue, and muscular endurance (40%) during continuous sets in the back squat (BSQ) exercise using either 50% or 75% of the 1 repetition maximum (1RM). After five sessions of familiarization and determining the 1RM, 19 male subjects (24.5 ± 6 years) and 9 female subjects (30.4 ± 8 years) underwent two identical 6-day testing sessions over 2 weeks (12 sessions) using the VEL (first 6 sessions) or the RPE method (last 6 sessions). The assessments of velocity thresholds and relative loads were randomized for each 6-day testing period. The average velocity (AV) and the OMNI-RES (0-10) scale scores were measured for every repetition of each set. Under VEL, sets ended after completing two consecutive repetitions below the target threshold. A linear mixed-effects model setting velocity thresholds, method, and their interaction as fixed effects, and subjects as random components, was conducted. Although no significant differences between methods were identified for the percentage of velocity decrease and the total number of repetitions completed per set, compared with VEL, under the RPE method, fewer repetitions were completed below the thresholds for both 50 and 75% 1RM (p < 0.01 and g > 1 in all cases). In conclusion, both methods, VEL and RPE, seem useful for estimating velocity changes during continuous sets of BSQ. However, the RPE method allowed for fewer unnecessary repetitions when squatting until 10, 20, and 40% of velocity decrease.

Abstract: Iglesias-Soler, E, Fariñas, J, Rúa-Alonso, M, Rial-Vázquez, J, Nine, I, and Revuelta-Lera, B. Shorter set configurations attenuate performance loss and lactatemia during resistance training in postmenopausal women: A randomized crossover trial (CARE project). J Strength Cond Res XX(X): 000-000, 2025-Menopause is a stage of life associated with a decline in muscle mass and strength, which underscores the importance of resistance training (RT) for preserving neuromuscular function in women. This study analyzed the effect of set configuration (SC) in RT sessions on lactatemia, mechanical performance, and neuromuscular fatigue in postmenopausal women. Fifty physically active postmenopausal women performed, in randomized order, 3 resistance sessions consisting of 4 exercises: leg press (LP), bench press (BP), prone leg curl, and lateral pull-down. The sessions were matched for load intensity (12 repetition maximum), volume (36 repetitions per exercise), and work-to-rest ratio, but differed in SC: 9 sets of 4 repetitions (4S), 6 sets of 6 repetitions (6S), and 4 sets of 9 repetitions (9S). A linear velocity transducer recorded concentric velocity and power in each repetition of LP and BP. Intraset and session-level velocity loss and power loss were calculated. Lactatemia and explosive performance in LP and BP were assessed before and after each session. Data were analyzed using linear mixed models. 4S improved mechanical performance and attenuated intraset and session velocity loss and power loss, while eliciting smaller increases in lactatemia than other configurations. Within each configuration, velocity and power loss were significantly higher in BP than in LP. Similar reductions in explosive performance were observed across all sessions. In conclusion, SC modulates both mechanical performance and glycolytic involvement in postmenopausal women. Exercise-specific differences highlight the need for caution when using fixed velocity- and power-loss thresholds to estimate effort in this population.

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: Boccia, G, Serranò, S, Bonelli, B, La Torre, A, and Pavei, G. The scaling factor between jump height and ground contact time in drop jumps: A linear relationship at the individual level. J Strength Cond Res XX(X): 000-000, 2025-The extent to which jump height scales with changes in ground contact time (GCT) remains unknown. Establishing this relationship would enable more accurate comparisons of rebounds with different GCTs. Currently, to reliably compare reactive strength index (RSI) values, it is necessary to consider only those with similar contact time parameters. Elite young track and field athletes performed drop jumps from a 40 cm box under 3 distinct instructional conditions: (a) trade-off strategy-minimizing GCT while maximizing jump height; (b) maximizing jump height; (c) minimizing GCT. A hierarchical linear regression model was applied, with GCT and sex (male/female) as independent variables and jump height as the dependent variable. Compared with the trade-off condition, focusing on short GCT led to a 21-millisecond reduction in GCT (p < 0.0001) but also a 5.9-cm decrease in jump height (p < 0.0001). Conversely, prioritizing jump height increased jump height by 4.8 cm (p < 0.0001) but prolonged GCT by 49 milliseconds (p < 0.0001). However, RSI remained unaffected by instructions (p = 0.567). A significant main effect of GCT on jump height was observed (β = 0.154; p < 0.00001). The full model, incorporating random and fixed effects, accounted for 94% of the variance in jump height. At the individual level, our findings confirm a linear relationship between GCT and jump height. This relationship underscores the importance of considering the GCT-jump height trade-off when assessing drop jump performance and highlights the need for evaluations across various GCT ranges rather than relying solely on 1 jump strategy.

Abstract: Tallis, J, Bolt, L, Morris, OR, Suchomel, TJ, and Eustace, SJ. Between session reliability of traditional and temporal bilateral and unilateral dynamic strength index calculations and association with sprint and change of direction performance. J Strength Cond Res XX(X): 000-000, 2025-The present study aimed to (a) evaluate the between session reliability of traditional and temporal based bilateral and unilateral dynamic strength index (DSI); (b) determine the association between DSI and sprint and change of direction performance in participants clustered by DSI root metrics. Thirty-eight recreationally active male participants (age: 23.4 ± 3.4 years) completed 20-m sprints, 5-0-5 change of direction test, bilateral and unilateral countermovement jumps (CMJ), and isometric midthigh pulls (IMTP) on 2 occasions. Vertical ground reaction force profiles were assessed to determine traditional DSI (DSIT), DSI based on mean force achieved after 100 milliseconds (DSI100), 150 milliseconds (DSI150), the entire CMJ propulsive phase (DSIP), and CMJ propulsive impulse (DSII). Bayesian interclass correlation coefficients and multiple linear regression after K-means clustering were used to analyze the data. Between session reliability of DSI was poor-moderate (interclass correlation coefficient [ICC] = 0.24-0.76) and highest for DSIT measures, albeit with some uncertainty (95% Higher Density Intervals [HDI]: 0.53-0.87). Bilateral temporal based DSI reliability was greater compared with unliteral equivalents, and temporal based DSI calculated for the nondominant limb, and those determined over a small-time epoch for the dominant limb were poor. There was limited association across DSI measures and straight-line 20-m sprint and 5-0-5 change of direction performance test. DSI100 for the dominant side had the strongest association with the performance outcomes (R2 = 0.33-0.36) and was improved in participants that expressed higher CMJ peak propulsive force. Dynamic strength index should be used with caution with respect to exercise prescription for the intention of improving tasks requiring rapid horizontal center of mass translation.

Abstract: Fields, JB, Jones, MT, Kitts, SE, King, EL, and Jagim, AR. Relationships between disordered eating, body dissatisfaction, and low energy availability in women collegiate athletes. J Strength Cond Res XX(X): 000-000, 2025-Women collegiate student-athletes face unique challenges regarding nutrition, body image, and athletic performance, increasing their risk for low energy availability (LEA), disordered eating (DE), and body dissatisfaction (BID). However, limited data exist exploring LEA, DE, and BID across a variety of women's sports. Therefore, the purpose of this study was to evaluate the prevalence of and relationships among LEA risk, DE behaviors, and BID in women collegiate athletes from multiple sports. Division I, II, and III women student-athletes (n = 115) participated in this cross-sectional, descriptive study. Athletes completed the low energy availability for females questionnaire (LEAF-Q), eating attitudes test (EAT-26), muscularity-oriented eating test (MOET), and body dissatisfaction items from the eating disorder examination questionnaire (EDE-Q) to assess LEA risk, DE behaviors, and BID, respectively. Sixty-four percentages of athletes were at risk for LEA, with the highest prevalence in volleyball (100%), wrestling (68%), lacrosse (67%), and cross country (57%). However, only 8% of athletes were classified at risk for eating disorders. Notably, 81 and 84% of athletes reported body weight and shape dissatisfaction, respectively, which was strongly associated with disordered eating behaviors (EAT-26: r = 0.707; MOET: r = 0.723, p < 0.001). These results show a high prevalence of LEA risk and BID across athletes, with DE behaviors strongly linked to body image concerns. Despite a high LEA risk among athletes, clinical eating disorder risk remained low, suggesting that undereating may often be unintentional. Targeted interventions focused on nutritional education, body image, and psychological support are critical for improving health and performance outcomes among collegiate women student-athletes.