Journal of Strength and Conditioning Research最新文献

Abstract: Kuhlman, NM, Jagim, AR, Jones, MT, Feit, MK, and Fields, JB. A comparison of match external load demands across women's collegiate field sports. J Strength Cond Res 39(2): 234-241, 2025-Historically, soccer (SOC), lacrosse (LAX), and field hockey (FH) have been grouped together as "field sports" due to their intermittent nature of match play and similar physiological demands. However, questions have emerged regarding potential variations in demands between sports. The purpose of this study was to compare external match workloads between collegiate women's SOC, LAX, and FH, and examine within-sport positional differences. Athletes (SOC: n = 15; LAX: n = 15; FH: n = 14) wore a global positioning system device during all matches throughout a competitive season. External load metrics included in the analysis were total distance (TD), sprint distance (SD), accelerations (>3 m·s -2 ), sprint efforts (SE), player load (PL), PL per minute (PL/min), top speed (m·s -1 ), and distances covered in select speed zones. Soccer performed higher external load volumes (TD, PL) ( p ≤ 0.025) but incurred lower intensities (SD, SE, accelerations) ( p < 0.001) compared with LAX and FH. Within-sport positional differences were apparent in SOC ( p < 0.001-0.018), LAX ( p < 0.001-0.045), and FH ( p < 0.001-0.004). However, FH exhibited more positional variance in external load metrics compared with SOC or LAX. Field hockey midfielders covered greater volumes (TD, PL) compared with attackers and defenders ( p < 0.001), while attackers sustained greater intensities (SD, SE, top speed) compared with midfielders and defenders ( p < 0.004). Results indicate that there are significant differences in external workload parameters between sports and across positions. Practitioners should tailor sport-specific and position-specific programs to match demands, and future research should explore the proposed categorizations of LAX as a "fast collision invasion sport," FH as a "fast contact invasion sport," and SOC as a "slow contact invasion sport."

Abstract: Padrón-Cabo, A, Lorenzo-Martínez, M, De Dios-Álvarez, V, Rey, E, and Solleiro-Durán, D. Effects of a short-term detraining period on the physical fitness in elite youth soccer players: a comparison between chronological age groups. J Strength Cond Res 39(2): e149-e154, 2025-The aim of this study was to examine the effects of a 2-week in-season training cessation on neuromuscular and endurance performance in 2 different age groups of elite youth soccer players. A total of 30 players belonging to the under-15 (U15, n = 17) and under-17 (U17, n = 13) age groups of a Spanish professional soccer academy participated in the study. The following tests were assessed before and after the training cessation period: squat jump (SJ), countermovement jump (CMJ), 20-m sprint with 5-m and 10-m split times, modified 505 change of direction, and 30-15 Intermittent Fitness Test (30-15 IFT). The results showed significant and similar performance impairments between the 2 age groups in SJ ( p = 0.020), CMJ ( p = 0.044), 20-m sprint ( p < 0.001), and 30-15 IFT ( p < 0.001). The U17 players evidenced greater impairment than the U15 players in 5-m ( p = 0.006) and 10-m ( p = 0.002) sprint performance. However, there was no significant change ( p = 0.070) in the players' change of direction performance. These findings provide valuable information for strength and conditioning coaches, suggesting the need for targeted interventions to mitigate the effects of detraining on neuromuscular and endurance performance during short-term in-season training cessation periods in elite youth soccer players. Special attention should be paid to maintaining sprint performance during short-term detraining periods in U17 players.

Abstract: Faricier, R, Fleitas-Paniagua, PR, Iannetta, D, Millet, GY, Keir, DA, and Murias, JM. Time spent near maximal oxygen uptake during exercise at different regions of the severe-intensity domain. J Strength Cond Res 39(2): e106-e114, 2025-This study applied the critical power (CP) model and several bouts of constant-power exercise within different regions of the severe-intensity domain to determine whether there exists an optimal intensity to maximize time spent near V̇ o2 peak. Subjects visited the laboratory 9 times. After a ramp-incremental test to determine V̇ o2 peak and peak power output (PO peak ), 9 active individuals (5 females) performed 4 constant-power bouts to task failure between 65 and 100%PO peak to estimate CP and total finite work above CP (W'). Subjects then completed 4 additional exhaustive trials predicted to result in task failure in ∼3, 6, 9, and 12 minutes. Time spent at V̇ o2 peak was calculated as the duration at which V̇ o2 ≥ 95% of the trial-specific V̇ o2 peak. The level of significance set for the study was p < 0.05. Mean CP and W' were 201 ± 48 W and 17.6 ± 8.4 kJ, respectively. For each bout, time to task failure was 2.7 ± 0.5, 6.3 ± 0.6, 9.5 ± 1.2, and 13.1 ± 3.1 minutes for the 3-, 6-, 9-, and 12-minute conditions. Time spent at V̇ o2 peak during the 3-minute trial (45 ± 22 seconds) was shorter than during the 9-minute (204 ± 104 seconds; p = 0.002) and 12-minute trials (260 ± 155 seconds; p < 0.001). The 6-minute trial (117 ± 46 seconds) had shorter ( p = 0.005) time spent at V̇ o2 peak compared with the 12-minute trial. At least when performing single bouts of exercise, intensities closer to CP (i.e., those sustainable for ∼9 minutes or longer) seem preferable compared with POs in the upper regions of the severe-intensity domain to maximize time at V̇ o2 peak.

Abstract: Bishop, C. Using ratio data in strength and conditioning: component parts hold the key. J Strength Cond Res 39(2): e176-e179, 2025-In strength and conditioning, ratio data are made up of more than 1 component part and are now commonplace in both research and practice, with an abundance of metrics from strength and jump testing being used as part of the ongoing monitoring process. Given these data have been used for many years, their inherent issues may not be obvious to all practitioners. However, ratio data often exhibit greater measurement error than their individual component parts. In addition, monitoring alterations in ratio data also presents challenges, given there is more than 1 way that the resultant test score can change. This brief review provides some practical examples to illustrate these challenges but also some viable solutions to guide practitioners on how the concurrent monitoring of ratios and their component parts can help guide decision-making in day-to-day practice.

Abstract: Modric, T, Clemente, FM, Versic, S, Chmura, P, Andrzejewski, M, Kryściak, J, and Sekulic, D. Environmental heat stress detrimentally affects match running performance of elite soccer teams competing in the UEFA Champions League. J Strength Cond Res 39(2): e142-e148, 2025-This study aimed to examine the effect of environmental heat stress (EHS), defined by wet-bulb globe temperature (WBGT), on match running performance (MRP) while controlling for match-related contextual factors. For this purpose, 2 approaches were implemented: (a) the MRP in heat stress nonrisking environment (NoEHS) (WBGT <22° C) and heat stress risking environment (EHSrisk) (WBGT ≥22° C) were compared and (b) changes in MRP according to the 1° C increase in WBGT were evaluated. Data on MRP were collected using an optical tracking system from all teams ( n = 32) in all UEFA Champions League matches ( n = 125) during the 2022-23 season. Metrics included total distance (TD), low-intensity (LIR), moderate-intensity (MIR), and high-intensity running (HIR) distances. Results indicated that less TD (108.84 vs. 110.71 km; Cohen's d [ d ] = 0.53), MIR (15.91 vs. 17.09 km; d = 0.85), and HIR (8.75 vs. 9.23 km; d = 0.46) were covered in matches played in EHSrisk compared with the NoEHS. Further investigation indicated that for every 1° C increase in WBGT, TD averagely decreased by 0.16 km ( d = -0.48), MIR by 0.13 km ( d = -1.09), and HIR by 0.06 km ( d = -0.69). These findings demonstrated decreased overall and intensive workload during the matches in EHSrisk, suggesting the detrimental effect of EHS on match volume and intensity in elite soccer. When EHS risk is anticipated, consideration of playing and recovery strategies should be implemented by coaches to achieve tactical goals while minimizing physical strain during a match.

Abstract: Baena-Raya, A, Robles-Ruiz, J, Pérez-Castilla, A, Pareja-Blanco, F, and Rodríguez-Pérez, MA. Effects of light versus very heavy resisted sprint training on multidirectional speed in semi-professional soccer players. J Strength Cond Res 39(2): e155-e161, 2025-The purpose of this study was to evaluate the effects of an 8-week resisted linear sprint training (RST) program with 2 loading conditions (light vs. very heavy) on linear sprint (LS), curve sprint (CS), and change of direction (COD) performance in young soccer players. Thirty-eight male under-19 soccer players were assessed for 30-m LS, CS, and modified 505 COD tests. Players were randomly allocated into 3 groups: control ( n = 18), light ( n = 10), and very heavy RST ( n = 10). Light and very heavy RST groups performed RST with external loads resulting in a 25 and 75% velocity loss from the player's maximal LS velocity, respectively. The control group did not perform any sprint training. Significant group × time interactions were observed for LS, CS, and COD performances ( p < 0.05). The control group showed no performance improvement. Both RST groups showed significant improvements in LS at 10-, 20-, and 30-m ( p ≤ 0.03; effect size [ES] ≥ 0.62), whereas no significant changes were observed for the split times ( p > 0.05). CS performance was significantly increased by the 2 RST groups ( p ≤ 0.03; ES ≥ 0.60), except for light RST on CS right side at 17-m ( p = 0.09; ES = 0.46). Change of direction performance was only significantly enhanced by the very heavy RST group ( p ≤ 0.001; ES ≥ 0.80). No significant changes between RST groups were observed. In conclusion, using both light and very heavy RST can enhance LS and CS performance, whereas very heavy RST is recommended to optimize COD performance in young soccer players.

Abstract: Henderson, FJ and Shimokochi, Y. Inertial one-leg squat training and drop jump biomechanics in athletes with anterior cruciate ligament reconstruction after return to sport. J Strength Cond Res 39(2): 156-164, 2025-Athletes with anterior cruciate ligament reconstruction (ACLR) display altered jumping mechanics persisting long after returning to sport (RTS). We investigated the effects of flywheel rear leg elevated (Bulgarian) split squat (RLESS) training on single-leg drop jump (SLDJ) biomechanics in athletes with ACLR after RTS. Eleven competitive athletes with unilateral ACLR (546 ± 270 days postsurgery) performed 16 sessions of 1 set of deep knee flexion RLESS until failure in the reconstructed leg (REC) using a flywheel. Using motion capture and force plates, jump height and leg joint contribution were calculated during a 30-cm SLDJ, alongside peak vertical ground reaction force (vGRF), lower extremity joint peak angle, displacement, work, peak internal moment, and peak power. After training, the jump height increased in REC ( p < 0.05) but not the intact leg (INT), although the jump height in REC remained lower than that in INT. Reconstructed leg knee contribution increased, whereas REC hip contribution decreased, so no bilateral difference remained after training. Although jump height remained unchanged in INT, several kinematic and kinetic variables changed significantly. Vertical ground reaction force showed no significant difference while asymmetry in internal knee varus moment disappeared, suggesting that some risk factors of ACL injury were reduced. Therefore, athletes with ACLR show persistent deficits in jumping performance, but adding 8 weeks of flywheel RLESS in REC can safely improve performance and restore normal joint contribution. Besides, coaches should be aware of possible changes in jumping mechanics in INT despite unchanged jumping performance when monitoring athletes with ACLR.

Abstract: Suzuki, K, Mizoguchi, Y, Kimura, F, Fujisaki, K, Yokoyama, D, Hall, T, and Akasaka, K. Correlation between muscle strength, swing speed, batting statistics, and body composition parameters in high school baseball players: a retrospective observational study. J Strength Cond Res 39(2): e135-e141, 2025-Body composition has emerged as a pivotal factor influencing baseball player performance. The purpose of this study was to examine the relationships between muscle strength, swing speed, batting statistics, and body composition in high school baseball players. This retrospective study evaluated 29 high school baseball players included critical parameters related to body composition (body fat percentage, lean body mass [LBM], fat mass index [FMI], and fat-free mass index [FFMI]), muscle strength (bench press, squat, deadlift), batting statistics (batting average, on-base percentage, slugging percentage, on-base plus slugging), and swing speed. These metrics were gathered using a body composition analyzer (Omron HBF-701; Omron Healthcare Co., Kyoto, Japan). After the correlation analysis with body composition, a subsequent multivariate analysis was conducted. Multivariate regression analysis identified LBM ( p < 0.05, p < 0.01) as a significant predictor for bench press and swing speed, FFMI for squat ( p < 0.01), and FMI for deadlift ( p < 0.05). No significant association was found between body composition and batting statistics. Lean body mass has been identified as an important contributing factor to swing speed, suggesting the need for body composition management among high school baseball players and coaches to enhance performance and functionality. However, no association was found between batting statistics and body composition. Therefore, it is suggested that high school baseball players prioritize the development of technical skills over swing speed and muscle strength to improve batting statistics.

Abstract: Martin, BJ, Wright, M, Patel, V, Susmarski, A, Lovalekar, M, Forse, JN, Beckner, ME, Ledford, AK, and Nindl, BC. Physiological, physical, and psychological determinants of success during the naval special warfare screener selection course. J Strength Cond Res 39(2): e162-e170, 2025-The Naval Special Warfare (NSW) screener is an arduous, 24-h course conducted at the Naval Academy in Midshipmen aspiring to enter the Navy's Sea, Air, and Land program. The purpose was to assess and characterize the physiological stress imposed during the 24-hour screener and identify physical, physiological, and psychological differences between finishers and nonfinishers. Forty-eight male Midshipmen between the ages of 18 and 26 years (height = 177.5 ± 6.8 cm, mass = 77.0 ± 5.3 kg, percent body fat = 7.54 ± 2.7%) participated. Before 4-6 weeks of the screener, subjects performed a battery of physical measures, questionnaires, and a cold pressor test (CPT). Blood was collected at baseline, post-CPT, and pre- and postscreener to assess the effects of the screener and differences between finishers and nonfinishers. A total of 48 Midshipmen started the screener, 37 finishers and 11 nonfinishers. Logistic regression revealed that 4 measures significantly increased the likelihood of finishing. A higher likelihood of finishing the screener was observed with Midshipmen with greater height (∼5 cm, p = 0.036), higher anaerobic power (∼0.5 W·kg -1 , p = 0.036), greater low-back endurance (∼17 s, p = 0.039), and faster swim times (∼1 minute, p = 0.001). Dehydroepiandrosterone (DHEA) and serum cortisol were both lower after the CPT in finishers ( p = 0.042 and 0.004, respectively) but were not different in nonfinishers. Dehydroepiandrosterone and the DHEA:salivary cortisol ratio were lower postscreener in finishers vs. nonfinishers (-70% and -133%, p = 0.008 and 0.001, respectively). In conclusion, this study presents novel findings regarding differences between finishers and nonfinishers of the NSW screener and how a 24-h event of particularly intense stressors affects biomarkers in a select group of Naval Academy Midshipmen.