Journal of Strength and Conditioning Research最新文献

Abstract: Moraga-Maureira, E, González, JA, and García-Ramos, A. Velocity-based strength assessment in youth athletes: Effects of maturation stage and repeated testing on reliability. J Strength Cond Res XX(X): 000-000, 2026-Resistance training in youth, once clouded by misconceptions about safety and development, is now widely endorsed for its role in enhancing health, motor performance, and athletic skills-highlighting the need for reliable assessment protocols to guide its implementation. This study aimed to evaluate the reliability of velocity-based strength assessment protocols in youth athletes and to examine how testing frequency (1 to 4 sessions) and maturation stage (pre-/circa- vs. postpeak height velocity [PHV]) influence their consistency. Thirty-four young male athletes-16 pre-/circa-PHV (age = 13.2 ± 0.8 years) and 18 post-PHV (age = 15.1 ± 1.0 years)-completed 1 familiarization session followed by 4 identical testing sessions. The testing protocol involved 4 incremental loading conditions during the squat exercise. Velocity values at fixed absolute loads showed acceptable absolute (coefficient of variation [CV] ≈ 7.0%) and moderate relative reliability (intraclass correlation coefficient [ICC] ≈ 0.67), whereas load-velocity relationship variables demonstrated acceptable absolute (CV ≈ 9.1%) and good relative reliability (ICC ≈ 0.75). Younger athletes (CV ≈ 7.6%) demonstrated reliability indices comparable with those observed in post-PHV athletes (CV ≈ 8.3%). Although reliability was acceptable from the first session (CV ≈ 9.5%), progressive improvements were observed in subsequent sessions (CV ≈ 8.8 and 6.2%). These findings support the use of both velocity at fixed loads and load-velocity profiling in youth athletes, suggesting that these protocols can be reliably implemented from as early as 12 years of age, provided that athletes are adequately familiarized with the procedures.

Abstract: Bowie, JS, Sterczala, AJ, Kraemer, WJ, Maresh, CM, Comstock, B, Muñoz, CX, McKenzie, AL, Volek, JS, and Lee, EC. Acute heavy resistance exercise protocol increases extracellular heat shock protein without changes in associated cytokines. J Strength Cond Res XX(X): 000-000, 2026-The purpose of this investigation was to characterize changes in extracellular HSP70 (eHSP70) and associated cytokines (interleukin 1 beta, interleukin-6, interleukin 10, interleukin 12, p70, and tumor necrosis factor alpha) in response to a stressful acute heavy resistance exercise protocol (AHREP). Healthy, resistance-trained men (n = 10, 24 ± 5 years, 176.8 ± 5.5 cm, 84.65 ± 12.78 kg, 17.6 ± 6.3% body fat, 145 ± 18 kg back squat 1 repetition maximum) completed an AHREP (6 × 10 back squat). Blood samples were collected before exercise (PRE), immediately post (IP), and at 15, 30, 60, and 120 minutes, and 24, 48, and 72 hours postexercise. White blood cell (WBC) count was measured with automated hematology, cytokines were measured with flow cytometry, and eHSP70 was measured by ELISA. Data were analyzed with repeated measures analysis of variance, with significant main effects further examined using post hoc pairwise t-tests. Extracellular HSP70 levels increased after exercise (PRE 0.39 ± 0.24 vs. IP 0.57 ± 0.37 vs. ng·mL-1, p < 0.05) sustained to 15 minutes postexercise (0.52 ± 0.35 ng·mL-1, p < 0.05) before returning to baseline at 30 minutes (0.424 ± 0.315 ng·mL-1, p > 0.05). White blood cell shifts (PRE 6 ± 2 vs. IP 11 ± 4 cells·103·μL-1, p < 0.001) were coincident with postexercise increases in chemoattractant cytokine IL-8 (PRE 4.77 ± 2.73 vs. IP 6.38 ± 3.53%, p < 0.05). We demonstrate that a sufficiently stressful resistance training protocol can activate pathways typically associated with aerobic exercise and heat exposure. The AHREP evokes a similar cardiovascular stress to aerobic protocols, which similarly increase eHSP70.

Abstract: Edgington, HCA, Lambert, AJ, Sophocleous, V, Waterworth, SPW, Barker, JT, Liew, BXW, and McManus, CJ. Blood flow restriction does not impair ankle proprioception in healthy male adults. J Strength Cond Res XX(X): 000-000, 2026-Blood flow restriction (BFR) training has been widely used to enhance muscle strength and hypertrophy at low loads, yet its impact on proprioception, particularly ankle joint position sense (JPS), is not fully understood. This study assessed the effect of BFR on ankle proprioception in 30 healthy male subjects, who were randomly assigned to control (n = 10), sham (n = 10), and BFR (n = 10) groups. Joint position sense was evaluated using constant error (CE) and variable error (VE) during passive ankle plantarflexion before, during, and after the intervention. The BFR group underwent 80% arterial occlusion pressure, whereas the sham group received minimal pressure. Results indicated a significant effect of the group on CE (p = 0.016), with subjects in the control group overshooting the target angle more than those in the BFR group. However, no significant differences in CE were found between the BFR and sham groups (p > 0.05). Variable error showed a significant effect of time point (p = 0.048), but no interaction effect with the group was observed. These findings suggest that BFR does not impair ankle JPS accuracy or consistency in healthy males. These results provide evidence that BFR can be safely incorporated into rehabilitation or training contexts without compromising proprioception, making it a valuable option for populations that cannot engage in high-load resistance training. Future studies should expand on these findings by exploring varied populations and refining BFR protocols for optimal proprioceptive function.

Abstract: Jeremy, R, Ben, S, and Robin, O. The effect of a daily undulating periodization program on the physical performance of trainee tactical police officers. J Strength Cond Res XX(X): 000-000, 2026-Specialist tactical police officers, like Special Weapons and Tactics (SWAT) teams, require exceptional muscular strength, power, speed, and aerobic fitness. However, physical training is often constrained by demanding operational schedules and competing tactical priorities. The aim of this study was to determine the effects of a daily undulating periodization (DUP) program on specialist tactical police officer trainee fitness. A within-subjects, repeated measures, cohort study was conducted with eight police officers undergoing specialist training (29.3 ± 5.5 years, 180.6 ± 6.0 cm, 85.4 ± 7.4 kg). They were assessed before and after a 12-week DUP training cycle consisting of planned varied resistance training sessions emphasizing hypertrophy, max strength, and power development, implemented across 5 days each week to optimize recovery and adaptation. Outcomes included measures of strength (e.g., deadlift, bench press, and pull-up), lower limb peak velocity and power (loaded counter movement jump [CMJ]), and anaerobic (Repeated Anaerobic Sprint Test [RAST]) and aerobic (the Maximum Aerobic Speed [MAS]) fitness. Significant improvements in strength (pull-ups and split squat, p < 0.001) and CMJ peak velocity and power output in the unloaded, 20-kg load, and 40-kg load conditions (p = 0.005-0.04) were found. Significant improvements in the RAST for total time, average power, and maximum power (p = 0.02) along with MAS (p = 0.006) and maximal oxygen uptake (V̇o2 max) (p = 0.006) were identified. A DUP program might be an effective method of enhancing the physical fitness required in specialist police officers for the performance of their occupational tasks within their workplace constraints. A DUP program may elicit positive anaerobic and aerobic fitness changes with concurrent increases in lower limb power and strength measures in police officers undergoing specialist police tactical training.

Abstract: Tuğrul, E, Darandeli, A, Tuğrul, F, Knicker, AJ, Soylu, AR, and Ertan, H. Supportive progressive resistance training combined with adjuvant hypofractioned radiation therapy improves shoulder complex muscle strength in women with breast cancer. J Strength Cond Res XX(X): 000-000, 2026-Despite its benefits, radiation therapy (RT) causes a range of side effects that adversely affect individuals undergoing breast cancer (BC) treatment. Exercise is considered a simultaneous treatment alongside radiation therapy to mitigate side effects and to facilitate effective recovery in patients. The aim of this study was to investigate the effects of progressive resistance training (PRT) combined with adjuvant hypofractionated radiation therapy (HFRT) on shoulder complex muscle strength and muscle activation in patients with BC. Thirty-one patients with BC were assigned to either an exercise group (EG, n = 15) or a control group (CG, n = 16). EMG and force signals were recorded while the patients performed isokinetic shoulder internal and external rotation with their surgery limb and the contralateral limb at angular velocities of 1.047 rad/s and 2.094 rad/s. Common terminology criteria for adverse events (CTCAE) were used to evaluate the side effects of HFRT. Torque and EMG data for pre- and postintervention were compared between the 2 groups using linear mixed models. The torque produced during shoulder internal and external rotation at all angular velocities showed significantly greater improvement in EG compared with CG (p < 0.0001). Group and time interaction was statistically significant for mean functional control ratio (FCR) and maximal voluntary contraction torque values (p < 0.0001). Similarly, group and time interaction was statistically significant for peak EMG values (p < 0.0001). There was no statistically significant difference in CTCAE between the EG and the CG (p > 0.05). PRT combined with adjuvant HFRT is effective in increasing shoulder complex muscle strength, and FCR in women with BC.

Abstract: Sánchez-Jiménez, JL, Javaloyes, A, Peña-González, I, Moya-Ramón, M, and Mateo-March, M. Pacing strategy and workload distribution as determinants of success in one-day monument cycling races. J Strength Cond Res XX(X): 000-000, 2026-This study examines workload distribution and pacing strategies in professional cyclists who finished in the top 5 compared with those ranked 6th-30th in Monument races. Power output data from 30 professional male cyclists and a total of 42 race files were analyzed across Milan-San Remo, the Tour of Flanders, Paris-Roubaix, Liège-Bastogne-Liège, and Il Lombardia (2021-2023), which are the 5 most prestigious 1-day "Monument" races in professional cycling. Top-5 cyclists exhibited a lower-body mass index (p = 0.021) and a higher compound score (p = 0.034) than top 6-30 finishers. A repeated-measures ANOVA showed significant differences in accumulated workload across power zones (p < 0.001), with zone 4 being the only zone where top-5 cyclists significantly outperformed others (p = 0.017; ES = 0.7). In addition, top-5 cyclists expended significantly more energy in zone 4 during the third quarter of the race (p = 0.022), suggesting greater fatigue resistance. A multiple discriminant analysis confirmed zone 4 workload as the primary predictor distinguishing between groups (λ = 0.896; p = 0.037), correctly classifying 71.2% of cases. These findings highlight the role of submaximal endurance and physiological durability in Monument race success. Differences in pacing strategies, particularly the ability to sustain higher zone 4 efforts in decisive race phases, may be key to achieving top performance.

Abstract: Dello Stritto, E, Sánchez-Valdepeñas, J, Romagnoli, R, and Piacentini, MF. Validation of a velocity perception scale for the bench press: Accuracy in velocity perception and %1RM perception across multiple loads. J Strength Cond Res XX(X): 000-000, 2026-The aim of this study was to validate a velocity perception scale specific for the bench press to help subjects accurately perceive the execution velocity of each repetition. In addition, we investigated whether subjects were also able to estimate the lifted %1RM and whether this estimation was more or less accurate than their perception of velocity (PV). Twenty healthy males completed 4 familiarization sessions with the velocity perception scale and 3 testing sessions, where they performed 7 different loads per session in a random order (velocity ranging from 1.10 m·s-1 to 0.20 m·s-1). For each repetition, the real velocity (Vr) measured, the perceived velocity (Vp) and the perceived %1RM (%1RMp) were registered. Pearson's correlation (r) and the coefficient of determination (R2) demonstrated high values across all 3 days for both Vp-Vr (r = 0.94-0.95; R2 = 0.89-0.90) and %1RMp-measured %1RM (r = 0.89-0.92; R2 = 0.80-0.85). The reliability of Vp was assessed using intraclass correlation coefficient (ICC) model 2, form 1, and showed good values for each load used, ranging from ICC = 0.77-0.84 across the 7 loads. Perception of velocity accuracy was determined using the DeltaScore, defined as the difference between Vp and Vr (DeltaScore = Vp - Vr). Subsequently, %1RMp was converted into velocity using individual load-velocity relationships, leading to the creation of DeltaRM defined as the difference between %1RMp (converted to velocity) and Vr (DeltaRM = %1RMp - Vr). This conversion enabled a direct comparison between the accuracy of the DeltaScore (Vp - Vr) and DeltaRM (%1RMp - Vr) via Bland-Altman plots, which consistently revealed a lower error for the DeltaScore. In conclusion, Vp proved to be a very stable parameter across the 3 days, and subjects were able to accurately discriminate even small velocity variations resulting from the use of 7 different loads during bench press.

Abstract: Altug, T, Soyler, M, Aydin, AS, Celik, S, and Taber, CB. Effects of kinetic- and kinematic-oriented change-of-direction training on anterior cruciate ligament risk factors in elite soccer players under fatigue. J Strength Cond Res XX(X): 000-000, 2026-This study investigated the effects of repeated change-of-direction (COD) drills on body composition and performance outcomes in elite U17 soccer players, examining fatigue-induced changes in anterior cruciate ligament (ACL) injury risk mechanisms. Twenty-eight male athletes (age: 16.8 ± 0.6 years; height: 167.4 ± 2.3 cm; body mass: 63.50 ± 2.19 kg; fat mass (FM): 5.31 ± 0.90 kg; fat-free mass (FFM): 58.20 ± 0.84 kg) were randomly assigned to either a kinetic group emphasizing resistance-based force production or a kinematic group targeting agility and COD mechanics. A 12-week in-season intervention was conducted, with pretest and posttest evaluations of heart rate (HR), blood lactate (LA), rating of perceived exertion (RPE), FM, FFM, COD time, and shuttle sprint (SS) performance. Significant group × time interactions were observed for FM (F (1, 26) = 6.07, p = 0.021, η2 = 0.189), SS (F (1, 26) = 5.75, p = 0.024, η2 = 0.181), and RPE (F (1, 26) = 13.52, p = 0.001, η2 = 0.342), favoring the kinetic group. These athletes exhibited greater reductions in FM, smaller increases in sprint time, and elevated RPE, indicating improved fatigue tolerance. No interaction effects were found for COD, HR, or LA, but the kinetic group exhibited more effective within-group adaptation to training-induced fatigue. Overall, kinetic-based COD training may support neuromuscular and metabolic adaptation under fatigue, while kinematic approaches may better preserve movement quality. A combined approach may mitigate fatigue-related ACL injury risk during competition.

Abstract: Ocaña-García, Á, Herrero-Atiénzar, JM, López-Gullón, JM, Bonacasa, B, and Bayonas-Ruiz, A. A velocity-based approach to variable resistance training in the bench press: repetitions to failure and level of effort. J Strength Cond Res XX(X): 000-000, 2026-This study analyzed the use of elastic bands in the bench press exercise within a velocity-based training approach to explore its application in variable resistance training (VRT) in regard to the level of effort methodology. Therefore, we aimed to (a) investigate the intersubject and intrasubject variability in the number of repetitions to failure (nRM) across 3 one-repetition maximum percentages (%1RM) and 2 load configurations using elastic bands: 25% (B25) and 50% (B50) of the load from bands; (b) examine the relationship between the number of repetitions completed and velocity loss reached; (c) assess the mean propulsive velocity associated to each %1RM and elastic bands contribution; and (d) study the influence of the subject's strength level on these parameters. After determining the individual 1RM, 26 subjects with low (n = 9), medium (n = 9), and high (n = 8) relative strength levels completed 2 rounds of nRM tests against their 60, 70, and 80% 1RM with B25 and B50 configurations in the bench press. Number of repetitions to failure increased with band contribution (B50 > B25, p < 0.01) and showed moderate intersubject variability (coefficients of variation = 16%) and very low intrasubject (SEM ≤ 1.4 repetitions) variability for all the strength levels, %1RM, and band contributions analyzed. A very high correlation (R2 = 0.910-0.935) between the number of repetitions completed and the percentage of velocity loss reached (from 5 to 65%) was found. These findings support the use of the level of effort as a reliable and practical tool for programming VRT.

Abstract: Brown, GA, Shaw, BS, and Shaw, I. Sex-based performance differences in shot put, javelin, and long jump among U.S. youth athletes aged 10 and under. J Strength Cond Res XX(X): 000-000, 2025-Controversy currently exists over whether sex-based differences necessitate sex-segregated youth sports. This study examined sex-based performance differences in shot put, javelin throw, and long jump among athletes aged 10 years and under using data from USA Track & Field (USATF) Regional Junior Olympic Championships. Performance records from all 15 USATF regions for the 2022, 2023, and 2024 Regional Junior Olympic Championships were analyzed. Distances recorded in shot put, javelin throw, and long jump for male and female athletes in the 8-and-under and 9-10-year-old age groups were compared using 2-sample t-tests (p < 0.05). Hedges' g was calculated to determine effect sizes. Percentile analyses (10th-95th) were also conducted for each sex and event. Males significantly outperformed females in all 3 events across both age groups (p < 0.0001). Effect sizes were large for javelin (Hedges' g = 1.138 and 1.099) and shot put (g = 0.730 and 0.741), and medium for long jump (g = 0.429 and 0.473). Male performance advantages ranged from 8 to 55% depending on event and age group. Percentile analyses revealed consistent male advantages across the entire performance distribution, suggesting inherent sex-based trends regardless of ability level. These findings demonstrate clear sex-based performance differences in throwing and jumping events among prepubertal athletes. Although physical activity levels may contribute to these differences, anatomical and physiological factors likely play a significant role. Coaches, parents, and sport governing bodies should consider these sex-based performance trends when developing training programs, setting expectations, and establishing age-group competition structures for youth athletes.