Journal of Strength and Conditioning Research最新文献

Abstract: Weng, Y-H, Huang, T-S, Chang, C-Y, Yang, J-L, Chen, W-S, and Lin, J-J. Soft tissue glenohumeral internal rotation deficit revealed detailed musculoskeletal factors of baseball players. J Strength Cond Res 39(2): e129-e134, 2025-Glenohumeral internal rotation deficit (GIRD) remains contentious regarding its role in shoulder injuries. Soft tissue GIRD (ST-GIRD), reflecting soft tissue changes, may offer a more precise understanding of the injury mechanism. This study investigates correlations between ST-GIRD, self-perceived function/performance, and musculoskeletal factors in baseball players, comparing them with traditional GIRD measurements. Subjects completed the Kerlan-Jobe Orthopedic Clinic self-report questionnaire for function and performance. Soft tissue GIRD, adjusted for humeral retrotorsion, was calculated. Eighty baseball players from various levels were recruited. Kerlan-Jobe Orthopedic Clinic scores significantly correlated with ST-GIRD ( r = 0.307, p = 0.046) but not with GIRD ( r = 0.164, p = 0.161). Soft tissue GIRD significantly correlated with scapula root of spine alignment ( r = -0.303, p = 0.023) but not with GIRD ( r = -0.069, p = 0.614). Higher correlation coefficients were found between acromiohumeral distance and posterior capsule thickness with ST-GIRD ( r = -0.241 and 0.236, respectively) than with GIRD ( r = 0.183 and 0.122, respectively). Soft tissue GIRD offers more detailed musculoskeletal insights than GIRD, showing improved correlations with function/performance, scapular alignment, acromiohumeral distance, and posterior capsule thickness. This supports the notion that internal rotation deficiency is associated with increased posterior capsule thickness and decreased acromiohumeral distance. These results provide coaches and health care practitioners a more detailed way to monitor function and performance of baseball players.

Abstract: Wilson, PJ, Roe, G, and Kiely, J. How do they decide? Performance support staff perceptions of decision-making in elite-sport environments. J Strength Cond Res 39(2): 192-199, 2025-Decision-making is a critical component of performance support staff responsibilities, yet research exploring staff perceptions relating to key facets of decision-making is lacking. This study aimed to explore perceptions of performance support staff relating to; the importance of decision-making in their role, the value of team decision-making, strategies to enhance decision-making skills, monitoring the process and outcome of decisions, and the obstacles to good decision-making within their professional contexts. A mixed-methods approached was used to explore perceptions of decision-making in 191 performance support staff (male staff = 179, female staff = 12) working in professional ( n = 147) or international ( n = 44) sport. Performance support staff reported decision-making as extremely important to their role; however, only 31% had received formal decision-making education and revealed underdeveloped decision-making capabilities within their organizations as a barrier to good decision-making. Most performance support staff conveyed that team decision-making is a valuable endeavor and augments decision outcomes; yet articulated dysfunctional team dynamics as an obstacle to good decision-making in their environments. Largely, performance support staff reported an absence of organizational strategy and workflow systems and processes for tracking and making decisions, respectively, whereas only 22% had a consistent reviewing and updating process. When making decisions, performance support staff faced several different cognitive biases and were challenged by the environmental pressures . The perspectives documented here suggest that performance support staff would likely benefit from undertaking evidence-based training and implementing scientifically informed strategies to enhance decision-making processes within their organizations.

Abstract: Jagim, AR, Horswill, CA, Dobbs, WC, Twohey, EE, Tinsley, GM, Fields, JB, and Jones, MT. Minimum wrestling weight for high school girls wrestling: Time to revisit minimal body fat percent. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to determine whether an alternative body fat percentage (BF%) could be established as a safer margin for minimal wrestling weight (MWW) determination by evaluating the distribution of BF% and MWW values naturally occurring for high school girls wrestling. Data from the 2022-2023 high school season were retrospectively analyzed. In total, 33,321 female wrestlers completed skinfold (SKF) assessments or bioelectrical impedance analysis (BIA) in accordance with sport governing body mandates for weight certification. Frequency statistics and descriptive analysis were performed to compute normative MWW and BF% profiles. Body fat percentage thresholds of 12% (12MWW) and the BF% value defining the lowest fifth percentile were used to determine the resulting MWW and minimum weight class for each method. The median ± interquartile range for BF% was 28.3 ± 9.2%. There was a difference (p < 0.001) in BF% values between BIA (28.4 ± 6.8%) and SKF (29.4 ± 7.6%), but a trivial effect size (ES = 0.14). The fifth percentile for BF% was 19%, which was used for alternative MWW determination (19MWW). 12MWW and 19MWW were 11.2 ± 6.4 kg (p < 0.001; ES = 1.8) and 8.6 ± 7.7 kg (p < 0.001; ES = 1.1) lower than the body mass of the wrestlers at the time of weight certification. Nearly all BF% values were above the 12% threshold currently used to determine MWW. Current body weights were more than 9.1 kg above MWW values for both 12MWW and 19MWW. Increasing the minimum BF% threshold from 12 to 19% would affect a small percentage of wrestlers and improve the margin of safety for those intent on achieving a lower weight class.

Abstract: Cowley, N, Nicholson, V, Timmins, R, Munteanu, G, Wood, T, García-Ramos, A, Owen, C, and Weakley, J. The effects of percentage-based, rating of perceived exertion, repetitions in reserve, and velocity-based training on performance and fatigue responses. J Strength Cond Res XX(X): 000-000, 2024-This study assessed the effects of percentage-based training (%1RM), rating of perceived exertion (RPE), repetitions in reserve (RIR), and velocity-based training (VBT) on (a) acute kinematic outputs, perceptions of effort, and changes in neuromuscular function during resistance training; and (b) neuromuscular fatigue and perceptions of soreness 24 hours after exercise. In a randomized crossover design, 15 subjects completed a %1RM, RPE, RIR, and VBT training condition involving a fatiguing protocol followed by 5 sets of the free-weight back squat and bench press at 70% of 1 repetition maximum. Subjects returned at 24 hours to assess neuromuscular fatigue and perceived soreness. Percentage-based training and RPE allowed the smallest volume loads, with %1RM prescription causing sets to be regularly taken to failure. Alternatively, RIR and VBT allowed greater maintenance of training volume. Velocity-based training had the most accurate training prescription, with all sets being within 5% of the intended starting velocity, while the RPE and %1RM prescriptive methods caused subjects to train with loads that were increasingly inaccurate. The RPE prescriptive method had the lowest reported values for differential RPE while the %1RM had the greatest change across the session. At no point were there between-group differences in measures of neuromuscular fatigue or perceived soreness. These findings demonstrate that autoregulatory prescriptive methods can be used to mitigate the risk of training to failure, ensure accurate training prescription that can maintain training volume, and enhance within-training kinematic outputs without altering neuromuscular fatigue or perceptions of soreness.

Abstract: Calaway, C, Walls, K, Levitt, H, Caplan, J, Mann, B, Martinez, K, Gastaldo, R, Haq, I, and Signorile, JF. Velocity-based-training frequency impacts changes in muscle morphology, neuromuscular performance, and functional capability in persons with Parkinson's disease. J Strength Cond Res 39(1): 99-106, 2025-Velocity-based training (VBT) positively impacts muscle morphology and performance in persons with Parkinson's disease (PD); however, optimal training frequencies for VBT in patients with PD remain undetermined. Changes in ultrasound-determined muscle thickness (MT) and echo intensity (EI)-derived muscle quality of the rectus femoris (RF) and vastus lateralis (VL), neuromuscular performance, and functional capacity were examined following 2 VBT frequencies (2-3 d·wk -1 ) using 30% velocity loss thresholds for 12 weeks. Neuromuscular performance was assessed using computerized pneumatic resistance machines. For each variable, 2 (time) × 2 (group) repeated-measures analyses of variance (ANOVA) were used to determine significant main effects and interactions. Significant time effects were seen for MT and EI of all muscles ( p < 0.05). Muscle thickness improvements included right VL (RVL) (0.171 ± 0.065 cm; p = 0.019), left VL (LVL) (0.214 ± 0.101 cm; p = 0.049), right RF (RRF) (0.194 ± 0.077 cm; p = 0.023), and left RF (LRF) (0.318 ± 0.109 cm; p = 0.010). For EI, improvements occurred in RVL (-18.688 ± 3.600; p = <0.001), LVL (-10.959 ± 4.894; p = 0.040), RRF (-9.516 ± 3.537; p = 0.016), and LRF (-9.018 ± 3.444; p = 0.019). Time effects were seen for leg-press 1-repetition maximum and peak power ( p < 0.01) and habitual walking speed ( p = 0.022), with a group by time interaction for maximal gait speed favoring the 3 d·wk -1 condition (∆0.15 m·s -1 , p = 0.002). The results indicate that VBT at 2 or 3 d·wk -1 can significantly improve muscle morphology, neuromuscular performance, and functional capability in patients with PD; however, improvements in maximal gait speed require 3 d·wk -1 . These findings provide flexibility when developing exercise prescriptions for patients with PD.

Abstract: Kieser, J, Langford, M, Stover, E, Tomkinson, GR, Clark, BC, Cawthon, PM, and McGrath, R. Absolute agreement between subjective hand squeeze and objective handgrip strength in adults. J Strength Cond Res 39(1): 16-23, 2025-Despite handgrip strength (HGS) being considered a convenient muscle strength assessment, HGS lacks routine measurement in sports medicine and healthcare settings because barriers such as time and lack of instrumentation may exist. Alternatives to circumvent these barriers should be sought. This study examined the absolute agreement of a subjective estimate of strength capacity on objectively measured HGS in adults aged 18-84 years. We also evaluated the test-retest reliability of an electronic handgrip dynamometer as a secondary purpose. There were 4 trained interviewers (i.e., assessors) who were assigned completely at random to subject laboratory visits occurring on 2 separate days. Trained interviewers carefully positioned their fingers into the hand of each subject before asking them to squeeze their fingers with maximal effort, and interviewers estimated each subject's HGS. An electronic handgrip dynamometer objectively measured HGS. Intraclass correlation coefficients (ICCs) were used for the analyses. The analytic sample included 100 subjects (age: 48.0 ± 20.2 years; 61% women). Poor agreement between mean objective HGS and averaged subjective hand squeeze was observed (ICC: 0.47; 95% confidence interval [CI]: 0.40-0.53). However, there was moderate agreement between dynamometer-derived maximal HGS and the most accurate HGS estimate (ICC: 0.75; CI: 0.65-0.86). An excellent test-retest reliability was found for mean (ICC: 0.97; CI: 0.95-0.98) and maximal HGS with the electronic dynamometer (ICC: 0.97; CI: 0.96-0.98). Trained interviewers performing subjective hand squeezes can approximate objective HGS with adequate accuracy, which could be useful when time and handgrip dynamometry access are lacking. Expanded interviewer training and testing may help with implementation.

Abstract: Gonzalo-Skok, O and Bishop, C. Effects of maturation on the magnitude and direction of asymmetry in jumping and change of direction speed in young elite football players. J Strength Cond Res 39(1): 70-78, 2025-Physical performance is often affected by maturation in young athletes and provides an interesting challenge to optimize performance. The present study analyzed whether maturation affects directional dominance, chronological age, body mass, and biological age predictors and assessed between chronological or biological age-group differences in young footballers. One hundred eight elite male players (U-15 to U-19) were tested on bilateral vertical and unilateral vertical and horizontal jumping, sprinting (40 m), and change of direction (COD) ability over single and multiple CODs (times and the percentage-based COD deficit [%CODD]). Almost half of the players (45%) at post-peak height velocity (PHV) showed consistency in the direction of asymmetry (jumping and COD). Ten-meter sprint time was the main predictor to explain the %CODD. Standing height affects unilateral horizontal jumping, and peak speed and unilateral horizontal jumping were the main predictors for unilateral vertical jumping. Post-PHV reported significantly (p < 0.05, effect size [ES] = 0.76-1.50) greater vertical and horizontal jumping, and linear and COD speed performance than mid-PHV. Significant differences (p < 0.05) in jumping, sprinting, and COD performance were found between U-15 and the rest of groups. Furthermore, the U-16 group showed a significant difference (p < 0.05) to the U-19 (for peak speed) and U-18 groups (for 40-m sprint and peak speed). Significantly (p = 0.04, ES = 0.47) lower %CODD asymmetries were found in mid-PHV compared with post-PHV. The study highlights the impact of maturation on the direction of asymmetry, tending to show the same weak side as maturation increases (i.e., older, and more experienced and mature players). Finally, decreasing between-limbs asymmetry should be considered during maturation, especially as greater football specialization.

Abstract: Mann, JB, Cowley, N, and Weakley, J. The role of speed, change of direction, and momentum by position and starting status in Division 1 collegiate football players. J Strength Cond Res 39(1): 41-47, 2025-This study (a) investigated differences between big, mid, and skill positions in sprint and change of direction times and momentum; (b) compared starting and nonstarting athletes; and (c) investigated whether thresholds can be developed to distinguish between starting and nonstarting Division 1 collegiate football athletes. Data from 496 collegiate football players who completed the 40-yard dash, pro-agility, and L drill were analyzed. Momentum was calculated using body mass and the average velocity during each test. To assess differences between positions and starters and nonstarters, data were analyzed using linear mixed models with effect size ±95% confidence intervals. Receiver operating characteristic (ROC) curves were generated to determine whether a cutoff value could be used to distinguish starters from nonstarters. Significant differences for both time and momentum were found between positional groups and starters and nonstarters for all tests in all positions. Starting skill position players tended to have greater differences in sprint or change of direction times and starting big players had greater sprint momentum. However, it should be noted that all ROC curves demonstrated relatively poor predictive value. Collectively, these findings demonstrate that bigger, faster players are preferentially selected in collegiate Division 1 football and there may be value in coaches collecting and assessing different outcome measures (e.g., sprint times and sprint momentum) depending on the positional group of the player. Finally, it should be acknowledged that setting binary thresholds to guide selection decisions is ill-advised and that speed, change of direction, and momentum are only one piece of the performance puzzle.

Abstract: Fontanetti, G, Barreto, RV, Junior, RC, Marangoni, V, Denadai, BS, Greco, CC, and Lima, LCR. The use of the self-selected rest interval method is as effective for optimizing postactivation performance enhancement in elite athletes as employing the best fixed rest interval. J Strength Cond Res 39(1): 10-15, 2025-This study investigated whether the adoption of a self-selected recovery interval (SSI) is more effective than the use of a fixed recovery interval (FRI) to elicit postactivation performance enhancement (PAPE). Ten male professional volleyball athletes (20.6 ± 1.5 years; 92.8 ± 4.9 kg; 195 ± 8 cm) participated in 3 experimental sessions, in random order, following familiarization with countermovement jump (CMJ) exercises and determination of the load for 5-repetition maximum (5RM: 146 ± 27 kg) squat exercise. The 3 experimental sessions consisted of (a) control session (CON), with measurement of CMJ height 4 minutes before and 2, 4, 6, 8, and 10 minutes after subjects rested while sitting in a chair without performing any preactivation (PA) protocol; (b) session with FRI, with measurement of CMJ height 2, 4, 6, 8, and 10 minutes after performing a PA exercise consisting of 5 squats with 5RM load; and (c) session with SSI, with evaluation of CMJ height once after performing the PA adopting a SSI based on a readiness scale. No significant differences were found between CMJ height in the CON session. Countermovement jump height was higher (p < 0.05) than the baseline measurement at minutes 4, 6, and 8 post-PA in the FRI session, for the best CMJ performance during the FRI session, and after the PA in the SSI session. No significant differences were found between the heights of the best CMJ in the FRI session (49.2 ± 6.8 cm) and post-PA in the SSI session (49.6 ± 6.6 cm). Therefore, adopting FRI and SSI is equally effective in eliciting PAPE in elite athletes. Despite being as effective as adopting FRI to elicit PAPE, SSI is more intuitive and easily applicable in contexts where PAPE can be implemented.