Journal of Strength and Conditioning Research最新文献

Abstract: Trecroci, A, Cavaggioni, L, Rossi, A, Bongiovanni, T, Invernizzi, PL, Formenti, D, and Longo, S. Self-regulated learning assessment in young soccer players: beyond competitive levels. J Strength Cond Res 39(1): e56-e61, 2025-This study explores self-regulated learning (SRL) among young soccer players, transcending the traditional focus on competitive levels. One hundred twenty-four soccer players of regional and provincial levels from under 14 to under 17 age groups voluntarily participated in the study and were combined into a single group. A median-split method based on total time performance was used to separate players into low performers (LPs) and high performers (HPs) from a 90° change of direction dribbling test. The self-regulation of learning-self-report scale for sport practice (SRL-SRS-SP) with a 5-factor solution (planning, reflection, effort, self-efficacy, and self-supervision) and 31 items was used. The score was based on a 1-5 Likert scale. The level of significance was set at p -value < 0.05. The SRL-SRS-SP total score by HP players differed significantly from that of LP players ( p = 0.015). Regarding each subscale, HP players showed significantly higher scores than LP players ( p = 0.011) for planning, whereas no differences were observed for the remaining factors ( p ≥ 0.05). The main observation of this study revealed that HP soccer players had a greater level of engagement in the learning process with a remarkable ability to plan for specific improvement than LP peers. This suggests that the competitive level might not be the sole determinant of differences in SRL. Therefore, strength and conditioning coaches should emphasize metacognitive and motivational components because of their crucial role in enhancing technical and physical performance.

Abstract: Lewis, A, Rattray, B, and Flood, A. Does cathodal preconditioning enhance the effects of subsequent anodal transcranial direct current stimulation on corticospinal excitability and grip strength? J Strength Cond Res 39(1): e1-e12, 2025-Inconsistent effects of transcranial direct current stimulation (tDCS) on corticospinal excitability (CSE) and exercise performance are commonly reported. Cathodal preconditioning, involving cathodal tDCS delivered before anodal tDCS over the same region, may enhance changes in CSE and exercise beyond that resulting from anodal tDCS alone. This study aimed to investigate whether the effects of anodal tDCS on CSE and isometric grip strength can be enhanced by cathodal preconditioning. Thirty-five healthy subjects aged 19-37 years completed a familiarization session followed by 4 stimulation conditions presented in a randomized cross-over design across 4 separate sessions. tDCS doses were applied at 2 mA over the primary motor cortex for 10 minutes. Corticospinal excitability was assessed using 120% of resting motor threshold and an input/output curve of motor evoked potentials of the first dorsal interosseous. Grip strength was evaluated as time to exhaustion (TTE) in a sustained isometric contraction. Relative to conventional sham stimulation, TTE was significantly increased by 15% after conventional anodal tDCS. Corticospinal excitability increased in response to tDCS, but this effect did not differ across conditions. Cathodal preconditioning before anodal stimulation did not increase CSE or grip strength beyond that seen in the other stimulation conditions. Our findings did not reveal any significant impact of stimulation type on CSE. Notably, anodal tDCS led to a significant improvement in grip strength endurance. However, cathodal preconditioning did not seem to increase the effect of subsequent anodal stimulation on CSE nor grip strength.

Abstract: Curtis, M, Kupperman, N, Westbrook, J, Weltman, AL, Hart, J, and Hertel, J. Neuromuscular performance and the intensity of external training load during the preseason in National Collegiate Athletic Association Division I men's collegiate basketball players. J Strength Cond Res 39(1): 54-61, 2025-The aim of the study was to determine whether acute changes in neuromuscular performance can be detected through countermovement jumps (CMJs) conducted pre- and postpractice sessions in conditions of high or low intensity measured by microsensors technology. Using an observational repeated measures design, data were collected from 10 male collegiate basketball players. Countermovement jump data were collected before and after practice exposures over 4 weeks of preseason. Select CMJ kinetics were compared in conditions of high and low training load intensity to detect neuromuscular performance changes in displacement of the center of mass and kinetics. Kinetic measures were categorized as output, underpinning, and strategy-related variables. We investigated "output" defined as displacement (jump height [JH]), "underpinning" defined as force-related (mean eccentric force, mean concentric force, force at zero velocity), and "strategy" defined as time-related (countermovement depth [CMD], eccentric duration (EccDur), concentric duration [ConcDur]) variables. There were significant condition × time interactions in CMJ variables namely eccentric mean force (EccForce), force at zero velocity (Force@0), CMDepth, EccDur, and ConcDur. In conditions of high intensity, players had significant, but small decreases in EccForce and Force@0, with small increases in CMD, EccDur, and ConDur, respectively. However, there were no significant decreases in JH. High-intensity practice exposures did not impact neuromuscular performance specific to "output," suggesting that collegiate basketball athletes can maintain JH despite alterations in "underpinning" and "strategy-related" variables. This could have relevance in understanding how fatigue associated with higher-intensity training exposures may potentially alter jump strategy and force production capacities due to external load intensity in collegiate basketball athletes.

Abstract: Tinsley, GM, Meyer, MK, Ptak, SM, Yu, D, Provost, JA, Hansen, NJ, and Carbuhn, AF. Body composition changes over a collegiate playing career in NCAA Division I women's soccer players. J Strength Cond Res 39(1): e40-e55, 2025-Although body composition is known to influence success in organized sport, the longitudinal body composition changes produced by sport specialization are not well characterized for women's soccer. To address this need, this study reports the body composition changes of NCAA Division I women's soccer players over their entire collegiate playing career. Serial dual-energy x-ray absorptiometry (DXA) scans were performed throughout players' involvement in collegiate women's soccer. Analyses of all players with multiple DXA scans (n = 80) and players with ≥3 years of DXA data (n = 17) were performed using linear mixed-effects models that included effects of time, playing position, game minutes, and interactions. In all athletes (n = 80; 2.1 ± 1.2 years of participation), significant increases in bone mass (1.4%), total lean mass (1.7%), and fat-free mass index (0.3 kg·m-2) occurred. These changes coincided with increased arm and leg bone mass, increased lean mass in all regions, and decreased body fat percentage and leg fat mass. In athletes with ≥3 years of collegiate data (n = 17; 3.5 ± 0.4 years of participation), larger increases in bone mass (3.0%), bone mineral density (2.2%), total lean mass (2.5%), fat-free mass index (0.4 kg·m-2), and segmental bone and lean mass were observed. Larger decreases in body fat percentage and leg fat mass were also noted. Although playing position was related to body composition characteristics, changes in outcomes were generally unrelated to position or game minutes. In summary, beneficial changes in multiple aspects of body composition were observed over years of participation in a collegiate women's soccer program.

Abstract: Barillas, SR, Lloyd, RS, Pedley, JS, and Oliver, JL. Different external cues elicit specific kinetic strategies during a drop jump in well-trained adolescent soccer players. J Strength Cond Res 39(1): e30-e39, 2025-The purpose of this study was to examine how different external cues that focus on jump height and ground contact time influence kinetic outcomes from a drop jump (DJ) in well-trained young soccer players. Following familiarization, 21 adolescent male soccer players performed 2 DJ trials under 4 different cue conditions: a height cue instructed subjects to jump to the ceiling, a ground contact cue instructed subjects to get off the ground as fast as possible, a combined condition joined both cues together, whereas a neutral cue with no external focus was used as a control condition. The height and contact time cues elicited specific kinetic responses that were significantly different to other conditions (p < 0.05); the height cue increasing impulses (d = 1.17-1.21) and jump height (d = 0.68), with the contact cue shortening ground contact time (GCT) (d = 1.27), increasing vertical stiffness (d = 1.48) and increasing force (d = 1.20-1.36). When combining the height and contact cue, a combination of significant (p < 0.05) kinetic responses were also observed, albeit to a lesser effect. Specifically, the combined cue increased impulse (d = 0.71-0.76) and jump height (d = 0.57) compared with a contact cue and a height cue, increased reactive strength index (d = 0.34), force (d = 0.69-0.83), and vertical stiffness (d = 0.75) while also reducing GCT (d = 0.69). Practitioners working with well-trained adolescent soccer players can use different external cues to effectively influence the kinetic strategies employed during a DJ.

Abstract: Kilit, B, Chmura, P, Arslan, E, Soylu, Y, and Radziminski, Ł. Effects of 2 combined training protocols on the aerobic and anaerobic fitness, technical skills, and psychophysiological responses in young soccer players. J Strength Cond Res 39(1): 86-93, 2025-The study compared the effects of combining small-sided soccer games (SSGs) with high-intensity interval training (HIIT) and repeated sprint training (RST) on aerobic and anaerobic fitness, technical skills, and psychophysiological responses in young soccer players. Thirty-two male, adolescent, soccer players (aged 13.5 ± 0.3 years) were randomly divided into either the SSGs + HIIT group ( n = 16) or the SSGs + RST group ( n = 16) for combined training 3 times per week for 6 weeks. The players in the SSGs + HIIT group performed 12-18 minutes of runs at intensities (90-95%), whereas the players in the SSGs + RST group consisted of 3-4 sets of 5-7 times 15-m shuttle sprints (all-out efforts). Both training groups played 4 bouts of 2-a-side or 4-a-side SSGs with various game formats at 2-day intervals. Psychophysiological responses were determined during and after all training sessions. Before and after training interventions, the following physical performance tests were used: 5- to 30-m sprint time, countermovement jump, triple-hop distance, zigzag agility with the ball and without the ball, repeated sprint ability (RSA), 30-15 Intermittent Fitness Test, 3 corner run test, speed dribbling ability (SDA), Yo-Yo Intermittent Recovery Test Level 1, and Y-balance test. Our main findings were that the SSGs + RST group demonstrated greater improvement in 5-m sprint time, SDA time, and RSA in the meantime compared with the SSGs + HIIT ( p ≤ 0.05, d values ranging from 1.50 to 2.25). Moreover, the SSGs + RST group showed greater improvement in agility test responses ( p ≤ 0.05, d values ranging from 2.13 to 2.34) than the SSGs + HIIT group. However, the SSGs + HIIT induced higher perceived exertion, mental effort, and lower greater physical enjoyment meaningfully compared with the SSGs + RST ( p ≤ 0.05, d values ranging from 6.04 to 6.67). In conclusion, these results demonstrate that the SSGs + RST is an effective training program to improve young soccer players' speed and agility-based performance responses.

Abstract: Jiang, G, Tan, X, Zou, J, and Wu, X. A 24-week combined resistance and balance training program improves physical function in older adults: a randomized controlled trial. J Strength Cond Res 39(1): e62-e69, 2025-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 community-dwelling adults aged 60-74 years were randomly assigned to an RT (n = 22), RBT (n = 22), or control (n = 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 = 0.017; p < 0.001, respectively), maximum walking speed (p = 0.014; p < 0.001), upper extremity (p = 0.013; p = 0.009) and lower extremity (p = 0.009; p < 0.001) muscle strength, and spirometry (p = 0.043; p = 0.018) were significantly improved at 24 weeks compared with the control group. Only the RBT group showed significant improvement in normal walking speed (p = 0.002). Compared with the RT group, the RBT group showed additional significant improvements in dynamic balance (p = 0.001) and lower limb muscle strength (p = 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: Yang, Y-R, Chen, C, Pan, C-H, Yen, S-Y, and Cheng, C-F. Effects of half-time re-warm-up with core strength exercises on subsequent agility and power performance in basketball players. J Strength Cond Res 39(1): 62-69, 2025-This study investigated the effects of half-time re-warm-up (RW) comprising core strength exercise (CSE) on basketball players' subsequent power and change of direction (COD) performance. Twelve male collegiate basketball players were recruited to perform 3 conditions--CSE RW on a stable platform (STA) or an unstable platform (USTA) and passive rest (control, CON)--in randomized, counter-balanced order after a modified Loughborough intermittent shuttle test (LIST). The COD and power performance tests were administered before the LIST and after the interventions. Heart rate (HR) was continuously measured during each trial. Results showed significantly lower changes in T-test time in STA compared with CON (p < 0.05). Changes in countermovement jump height in STA were significantly higher than those in CON (p < 0.05). During the isometric midthigh pull test, changes in the maximum rate of force development (RFD) (p < 0.05), RFD in the range of 0-90 milliseconds (p < 0.05), 0-150 milliseconds (p < 0.05), 0-200 milliseconds (p < 0.05), and 0-250 milliseconds (p < 0.05), in STA were significantly higher than those in CON. In addition, RFD in the range of 0-150 milliseconds (p < 0.05) and 0-250 milliseconds (p < 0.05) in USTA was significantly higher than that in CON. The mean HR during USTA was significantly higher than that in STA and CON (p < 0.05). These findings indicated that CSE RW during halftime might prevent power and COD performance decline in the second half of a game, with practical implications for coaches and players.

Abstract: Larsen, S, Zee, Md, and Tillaar, Rvd. The impact of stance width on kinematics and kinetics during maximum back squats. J Strength Cond Res 39(1): 1-9, 2025-This study compared the lower extremity peak net joint moments (NJMs) and muscle forces between wide and narrow stance widths defined as 1.7 and 0.7 acromion width in the last repetition of the concentric phase in 3 repetition maximum back squats. Twelve recreationally trained men (age:25.3 ± 2.9 years, height:179 ± 7.7 cm, body mass:82.8 ± 6.9 kg) volunteered for the study. The NJMs were estimated using inverse dynamics and individual muscle forces with static optimization. The main findings of interest were that the wide stance resulted in statistically smaller knee flexion angles (Cohen's d: 0.9; 95% confidence interval [CI]: -17.96 to -3.18°), knee extension NJMs [d: 1.45; 95% CI: -1.56 to -0.61 Nm·kg-1], and vastii forces [d: 1.3; 95% CI: -27.7 to -0.9.5 N·kg-1] compared with the narrow stance. Moreover, we observed significantly larger hip abduction angles [d: 3.8; 95% CI: 12.04 to 16.86°] for the wide stance. Hence, we suggest that recreationally trained men aiming to optimize muscle forces in the vastii muscles during maximum back squat training should consider adopting a narrow stance.

Abstract: Yanaka, T, Imawaka, T, Kojima, C, Otomo, M, Ohnishi, T, and Hoshikawa, M. Evaluation of trunk oblique muscle activities in baseball batters using T2-weighted magnetic resonance imaging. J Strength Cond Res 39(1): 48-53, 2025-This study investigated abdominal oblique muscle activity using T2-weighted imaging in baseball batting. For this purpose, 17 baseball batters (21.6 ± 2.7 years, 173.9 ± 4.0 cm, 77.5 ± 7.6 kg) performed 100 toss-batting trials. Before and after toss-batting, 3 Tesla magnetic resonance imaging scans were performed to obtain the T2 values of the 4 abdominal external and internal oblique muscle pairs. The results showed that the T2 values of all abdominal oblique muscles were significantly increased after the 100 trials ( p < 0.05), with no differences in these increases between the muscles. The rate of change in the T2 values was 1.0 ± 3.9% and 4.2 ± 5.2% for the external and internal oblique muscles on the pitcher's side and 3.2 ± 5.1% and 0.9 ± 2.5% for the external and internal oblique muscles on the catcher's side, respectively. These findings indicate that the activity levels of all abdominal oblique muscles during baseball battings are similar and lower than those of the agonist muscles used during resistance exercise and sprinting. These findings suggest that baseball batting is a low-intensity exercise of the abdominal oblique muscles, but adequate training of each abdominal oblique muscle may improve batting performance and prevent injury.