Journal of Strength and Conditioning Research最新文献

{"title":"Effects of High-Intensity Progressive Resistance Training Combined With Self-Talk on Muscle Strength and Functional Performance in Older Adults.","authors":"Vittoria Ferrando, Francesco Mirabelli, Marco Panascì, Denise Sofrà, Piero Ruggeri, Emanuela Faelli, Ambra Bisio","doi":"10.1519/JSC.0000000000005115","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005115","url":null,"abstract":"<p><strong>Abstract: </strong>Ferrando, V, Mirabelli, F, Panascì, M, Sofrà, D, Ruggeri, P, Faelli, E, and Bisio, A. Effects of high-intensity progressive resistance training combined with self-talk on muscle strength and functional performance in older adults. J Strength Cond Res XX(X): 000-000, 2025-In older people, muscle mass and functional capacity decline, affecting balance, and gait control. In this population, resistance training (RT) improves muscle strength, counteracting this physiological decline. In younger individuals, cognitive strategies like motivational self-talk have been successfully integrated with RT to enhance its effectiveness. This study aimed to compare the effects of a high-intensity progressive RT with positive motivational self-talk against RT alone on muscle strength and functional performance in older adults. Twenty-eight healthy older people were divided into resistance training self-talk (RT-ST) group and RT group. The RT-ST group mentally repeated positive motivational phrases during lower-limb exercises, whereas the other group performed RT alone. The 4-week protocol included biweekly sessions, consisting of warm-up, a high-intensity resistance exercise, and cooldown. Handgrip strength, 1 repetition maximum (1RM), 30-second chair stand (30 s-CS), and time up and go (TUG) tests were conducted before (PRE), immediately after (POST), and 2 weeks after follow-up (FU) of the intervention. One repetition maximum significantly increased from PRE to POST (p ≤ 0.001) and FU (p ≤ 0.05) in both groups. The 30 s-CS significantly improved only in the RT-ST group at FU (p ≤ 0.001), with higher values compared with the RT group at POST (p ≤ 0.05) and FU (p ≤ 0.05). Time up and go test duration decreased in both groups (p ≤ 0.001), with RT-ST completing the test faster than RT (p ≤ 0.05). Incorporating positive motivational self-talk into a high-intensity progressive RT program led to significant improvements in functional performance, suggesting that its benefits go beyond improving muscle strength and may positively impact the activities of daily living in older adults.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Retrospective Analysis of Grip and Index Finger Strength, Job-Specific Scenario, and Shooting Performance in Incumbent Law Enforcement Personnel and Cadets.","authors":"Robert G Lockie, Michael A Young, Sarah N Lanham, Robin M Orr, J Jay Dawes, Thomas R Nagel","doi":"10.1519/JSC.0000000000005028","DOIUrl":"10.1519/JSC.0000000000005028","url":null,"abstract":"<p><strong>Abstract: </strong>Lockie, RG, Young, MA, Lanham, SN, Orr, RM, Dawes, JJ, and Nagel, TR. Retrospective analysis of grip and index finger strength, job-specific scenario, and shooting performance in incumbent law enforcement personnel and cadets. J Strength Cond Res 39(4): e581-e588, 2025-This study investigated grip and index finger strength, and scenario performance, of incumbent deputy sheriffs/police officers. All personnel (incumbents; n = 15) and cadets ( n = 44) completed a job-specific scenario (step-ups, jumping jacks, sprawls, strikes, drags, carries, simulated fight) for time. Dominant grip strength (DGS) and nondominant grip strength (NDGS) and dominant index finger strength (DIFS) nondominant index finger strength (NDIFS) were measured pre- and postscenario. Incumbents and cadets then completed a 6-steel plate shooting test. Steel time (time to hit all plates) and number of shots required were recorded. Between-group differences in scenario time, steel time, and shots fired were analyzed by a univariate analysis of covariance (ANCOVA) ( p < 0.05; covariates: sex, age). Relationships between grip and index finger strength with scenario variables were derived with partial correlations controlling for sex and age ( p < 0.05; incumbents and cadets analyzed separately). A repeated measures ANCOVA ( p < 0.05; covariates: sex, age) investigated between-group differences in grip and index finger strength, and whether there were changes postscenario. Cadets completed the scenario faster than the incumbents ( p = 0.045). The incumbent group had a nonsignificant 71% faster steel time and required 40% fewer shots, and experienced a decrease in DGS and NDGS ( p ≤ 0.013) postscenario. Pre- and post-DGS and NDGS, pre-DIFS, and post-NDIFS significantly related to scenario time for the cadets ( r = -0.311 to -0.503). Incumbents had fitness limitations that affected scenario time but demonstrated better shooting skills. Even with grip strength decreases postscenario, incumbents likely had sufficient strength to complete the shooting task. Cadets may be more reliant on general fitness when completing job-specific scenarios because they require further skill development.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e581-e588"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142729824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Associations of Handgrip Strength, Walking Pace, and Genetic Risks With Incident Arrhythmias.","authors":"Panpan He, Ziliang Ye, Mengyi Liu, Yuanyuan Zhang, Chun Zhou, Yanjun Zhang, Sisi Yang, Xianhui Qin","doi":"10.1519/JSC.0000000000005036","DOIUrl":"10.1519/JSC.0000000000005036","url":null,"abstract":"<p><strong>Abstract: </strong>He, P, Ye, Z, Liu, M, Zhang, Y, Zhou, C, Zhang, Y, Yang, S, and Qin, X. Associations of handgrip strength, walking pace, and genetic risks with incident arrhythmias. J Strength Cond Res 39(4): e589-e597, 2025-We quantified the associations of handgrip strength and walking pace with incident arrhythmias using Cox proportional hazards models with hazards ratios (HRs). The study included 487,673 subjects, with an average age of 56.4 years, 54.8% female, and free of baseline arrhythmias from the UK Biobank prospective study. Handgrip strength was assessed by a dynamometer. Low handgrip strength was defined as less than 27 kg in men and 16 kg in women. Walking pace was self-reported as slow, average, or brisk. The arrhythmia categories involved incident atrial fibrillation (AF), incident ventricular arrhythmias, and incident bradyarrhythmia, respectively. Over a median follow-up duration of 12.4 years, 28,967 (5.9%), 4,061 (0.8%), and 11,741 (2.4%) subjects developed incident AF, incident ventricular arrhythmias, and incident bradyarrhythmia, respectively. Compared with those with low handgrip strength, the adjusted HRs (95% confidence interval [CI]) of incident AF, ventricular arrhythmias, and bradyarrhythmia in subjects with normal handgrip strength were 0.76 (95% CI: 0.73.-0.79), 0.75 (95% CI: 0.67.-0.84), and 0.80 (95% CI: 0.74.-0.85), respectively. Compared with those with a slow walking pace, subjects with a brisk walking pace had significantly lower risks of incident AF (HR, 0.56; 95% CI: 0.53.-0.58), ventricular arrhythmias (HR, 0.52; 95% CI: 0.45.-0.59), and bradyarrhythmia (HR, 0.63; 95% CI: 0.59.-0.68). In addition, the inverse associations of handgrip strength and walking pace with AF were significantly stronger among those with a lower genetic risk of AF (both p interaction <0.001). In conclusion, handgrip strength and walking pace were inversely associated with incident arrhythmias. The inverse associations for incident AF were stronger in those with a lower genetic risk of AF.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e589-e597"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reliability and Accuracy of Stryd to Detect Changes in Vertical Displacement of the Center of Mass While Running.","authors":"Matthew Somma, Michael A Lawrence","doi":"10.1519/JSC.0000000000005038","DOIUrl":"10.1519/JSC.0000000000005038","url":null,"abstract":"<p><strong>Abstract: </strong>Somma, M and Lawrence, MA. Reliability and accuracy of Stryd to detect changes in vertical displacement of the center of mass while running. J Strength Cond Res 39(4): 414-417, 2025-The purpose of this study was to determine if Stryd can reliably and accurately detect changes in vertical displacement of the center of mass (VCoM) that are produced when cadence was increased by 5 and 10%. A secondary purpose of this investigation was to determine the interlimb reliability of Stryd for VCoM and cadence. Twenty healthy individuals (5 males, 15 females; age: 24.5 ± 1.5 years; mass: 67.1 ± 12.2 kg; height: 1.66 ± 0.01 m) were fitted for motion capture and 2 Stryd devices. After warm-up, subjects ran at a self-selected speed on the treadmill for each condition (self-selected, +5%, and +10% cadence) while VCoM and cadence were collected simultaneously from Stryd and motion capture. Reliability between the Stryd devices on different limbs was excellent for both cadence (intraclass correlation coefficient [ICC] = 0.999, p < 0.001) and VCoM (ICC = 0.993, p < 0.001). Cadence was not significantly different between the Stryd device and motion capture ( p = 0.153). Stryd produced significantly ( p < 0.001) smaller values for VCoM regardless of condition, with average differences ranging between 4.4 and 4.6 cm. A linear regression revealed that Stryd predicted 50.7% of variation in motion capture VCoM ( p < 0.001). Stryd can reliably measure both cadence and VCoM regardless of which limb it is placed on, as indicated by the near-perfect agreement between Stryd devices, and the Stryd device can detect and predict changes in VCoM. However, Stryd consistently underestimates VCoM, which can be corrected by using a linear regression equation.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"414-417"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142877392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revamping Pace Distribution: A Case Study on Elevating the Men's 400 m Track and Field Japanese National Record After 32 Years.","authors":"Yoshihiro Chiba, Kentaro Sato, Takaya Yoshimoto, Hayato Ohnuma, Ryo Yamanaka, Kyohei Takahashi, Kai Kobayashi, Takeo Matsubayashi, Yohei Takai","doi":"10.1519/JSC.0000000000005032","DOIUrl":"10.1519/JSC.0000000000005032","url":null,"abstract":"<p><strong>Abstract: </strong>Chiba, Y, Sato, K, Yoshimoto, T, Ohnuma, H, Yamanaka, R, Takahashi, K, Kobayashi, K, Matsubayashi, T, and Takai, Y. Revamping pace distribution: A case study on elevating the men's 400 m track and field Japanese national record after 32 years. J Strength Cond Res 39(4): e610-e615, 2025-Many studies have investigated the 400-m sprint, and the optimal pacing strategy is subject to debate. Little information is available regarding the effects of changes in the pacing strategy on running speed and spatiotemporal variables in the official 400-m race. This case study analyzed changes in running speed and spatiotemporal variables of a Japanese elite long sprinter who set a new Japanese national record in the 400-m race by modifying his pace distribution based on the analysis of his previous races and the performances of world-class long sprinters. To revamp his pace distribution, 25 preceding races (ranging from 45.47 to 46.95 seconds) were analyzed, spanning from June 2015 to June 2023. The independent variables were the 50-m split time, average running speed, percentage of the 50-m split time relative to the 400-m record, step length, and step frequency. K.S. broke his own record by modifying the pacing distribution based on the development of his previous race and the world-class long sprinters. The modified pacing strategy increased running speed in the 200- to 300-m section. Step lengths were longer throughout the 400 m, and step frequencies were higher in the last 200 m than before the alteration in the pace distribution. Modifying the pacing strategy from leading to driving may enhance the personal records of long sprinters. This improvement is attributed to the maintenance of longer step lengths over the entire 400-m range and an increase in the step frequency in the last 200 m.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e610-e615"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of the Load-Velocity Relationship Variables to Discriminate the Level of Fatigue Induced by Multiple Sets of the Hexagonal Barbell Deadlift Exercise.","authors":"Deniz Şentürk, Zeki Akyildiz, Danica Janicijevic, Amador García-Ramos","doi":"10.1519/JSC.0000000000005037","DOIUrl":"10.1519/JSC.0000000000005037","url":null,"abstract":"<p><strong>Abstract: </strong>Şentürk, D, Akyildiz, Z, Janicijevic, D, and García-Ramos, A. Sensitivity of the load-velocity relationship variables to discriminate the level of fatigue induced by multiple sets of the hexagonal barbell deadlift exercise. J Strength Cond Res 39(4): 407-413, 2025-This study aimed to evaluate changes in load-velocity (L-V) relationship variables (L 0 , v 0 , and A line ) after different fatigue protocols and to determine their correlation with changes in 1 repetition maximum (1RM). After determining the hexagonal barbell deadlift (HBD) 1RM, 27 resistance-trained men randomly completed 3 sessions that only differed in the activity performed between 2 incremental loading tests that were performed at the beginning (presession) and end (postsession) of the session: (a) control protocol: no training; (b) moderate-fatigue protocol: 5 sets of the HBD exercise at 70% 1RM performing half the maximum possible number of repetitions; and (c) high-fatigue protocol: 5 sets of the HBD exercise performed to failure against the 70% 1RM. Significance was set at an alpha level of 0.05. The reduction of 1RM ( p < 0.001), v 0 ( p = 0.014), and A line ( p < 0.001) at postsession was greater for the high-fatigue protocol, followed by the moderate-fatigue protocol, and finally the control protocol. The changes in L 0 did not differ between the fatigue protocols ( p = 0.372). The percent change in the 1RM at postsession was significantly correlated with the percent change in A line ( r = 0.714) and L 0 ( r = 0.540), but not with the percent changes in v 0 ( r = 0.177). These results suggest that the L-V relationship variables offer a highly sensitive and practical solution for fatigue monitoring.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"407-413"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scenario and Shooting Performance in Incumbent Deputy Sheriffs/Police Officers, Cadets, and Cadets Who Worked in Custody/Corrections Facilities.","authors":"Robert G Lockie, Michael A Young, Sarah N Lanham, Robin M Orr, J Jay Dawes, Thomas R Nagel","doi":"10.1519/JSC.0000000000005058","DOIUrl":"10.1519/JSC.0000000000005058","url":null,"abstract":"<p><strong>Abstract: </strong>Lockie, RG, Young, MA, Lanham, SN, Orr, RM, Dawes, JJ, and Nagel, TR. Scenario and shooting performance in incumbent deputy sheriffs/police officers, cadets, and cadets who worked in custody/corrections facilities. J Strength Cond Res 39(4): e616-e619, 2025-Job-specific fitness of law enforcement personnel can decline during their careers. Personnel could offset fitness deficiencies with greater skill and knowledge. Cadets in certain counties may work in custody/corrections before their training academy. This study used archival data to compare job-specific scenario performance of incumbent deputy sheriffs/police officers (INC; n = 15), cadets entering academy (CAD; n = 19), and cadets entering academy after working in custody/corrections facilities (CADCUST; n = 25). Subjects completed a scenario (step-ups, jumping jacks, sprawls, strikes, drags, sandbag carries, and a simulated fight) as fast as possible followed by a firearms test where they had to hit 6 steel plates. Steel time (time to hit all plates) and number of shots required were recorded. Univariate analysis of covariances, with sex and age as covariates and Bonferroni post hoc analyses, derived between-group differences in all variables ( p < 0.05). The CAD group completed the scenario faster than the INC group ( p = 0.011). Though not significant, the INC group did have the fastest steel time and lowest number of shots. The CADCUST group completed the scenario 10% slower than the CAD group, was 138-366% slower in steel time, and needed 61-100% more shots than the other groups. The INC group likely had fitness limitations that affected scenario performance but demonstrated better shooting skills. The CADCUST group was slower than the CAD group in the scenario and performed worst in the shooting test. Cadets who work in custody/corrections facilities before academy may require fitness and skill interventions while INC should attempt to maintain their fitness during their career.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e616-e619"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142877401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Normalizing and Standardizing Physical Fitness by Sex, Age, and Body Size in Brazilian Children and Adolescents: A PROESP-BR Study.","authors":"João Francisco de Castro Silveira, Cézane Priscila Reuter, Eivind Aadland, Lars Bo Andersen, Alan Michael Nevill, Júlio Brugnara Mello, Anelise Reis Gaya","doi":"10.1519/JSC.0000000000005042","DOIUrl":"10.1519/JSC.0000000000005042","url":null,"abstract":"<p><strong>Abstract: </strong>de Castro Silveira, JF, Reuter, CP, Aadland, E, Andersen, LB, Nevill, AM, Mello, JB, and Gaya, AR. Normalizing and standardizing physical fitness by sex, age, and body size in Brazilian children and adolescents: A PROESP-BR study. J Strength Cond Res 39(4): e598-e609, 2025-The study aimed to use allometric modeling to identify how body size dimensions should be exponentiated to normalize physical fitness variables. It also aimed to provide reference values to standardize physical fitness into z-scores by sex, age, and body size dimensions. Cross-sectional data from 95,691 Brazilian children and adolescents (52,747 males; 55.1%; aged 6-18 years) were analyzed, including physical fitness tests (abdominal endurance, agility, cardiorespiratory fitness, flexibility, lower and upper limbs power, and speed) and anthropometric measures (arm span, body mass, and height). Allometric modeling was applied, and statistical significance was determined using p values less than 0.05. Results revealed that taller individuals with longer levers generally performed better in physical fitness tests (p ≤ 0.007), regardless of biologic sex and chronologic age, except for flexibility tests where shorter individuals with longer upper limbs performed better (p ≤ 0.001). The impact of greater body mass varied depending on whether the test required the individual to carry his/her own weight. Among females, performance in weight-bearing/carrying tests peaked at middle adolescence and declined thereafter, while among males, performance steadily increased with age. In conclusion, the present study provided reference equations to calculate z-scores independent from biologic sex and chronologic age and dimensionless to body size variables, and also suggested how arm span, body mass, and height could be exponentiated for use in the denominator of a physical fitness scaled ratio or index.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 4","pages":"e598-e609"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reliability and Sensitivity of Using Isometric Strength and Sprint Speed Measures in Adolescent Female Athletes.","authors":"Jamie Salter, Dale Forsdyke, Zoe Dawson, Jacob Rymer, Luke Walsh, Peter Mundy","doi":"10.1519/JSC.0000000000005029","DOIUrl":"10.1519/JSC.0000000000005029","url":null,"abstract":"<p><strong>Abstract: </strong>Salter, J, Forsdyke, D, Dawson, Z, Rymer, J, Walsh, L, and Mundy, P. Reliability and sensitivity of using isometric strength and sprint speed measures in adolescent female athletes. J Strength Cond Res 39(4): 418-426, 2025-The aim of this study was to establish the reliability and sensitivity of isometric mid-thigh pull (IMTP) and sprint speed (5 m, 40 m, and maximal sprint speed) in adolescent women, before exploring the stability of this across maturation to provide maturity-specific benchmarks. A total of 147 female athletes (age: 13.8 ± 2.8 years; stature: 157.1 ± 13.1 cm; body mass: 51.2 ± 15.3 kg; percentage of predicated adult height: 94.3 ± 6.6) performed IMTP and sprint trials on 2 occasions, separated by 7 days. Within- and between-session reliability was determined using intraclass correlation coefficient (ICC), coefficient of variation, and Bland-Altman limits of agreement, with sensitivity detected by signal-to-noise ratios for small (SWC 0.2 ) and moderate (SWC 0.5 ) worthwhile change. A between-group analysis of variance and Cohen's d -effect sizes determined differences between biological maturity groups (pre-, mid-, and post-peak height velocity [PHV]). All isometric strength and sprint performance markers demonstrated either \" moderate \" or \" acceptabl e\" within-session reliability, except for time to peak force (PF) and 40 m sprint. Despite metrics all having \" high \" or above ICC (0.55-0.98), only PF offered a \" good \" sensitivity when using SWC 0.2 , with most offering better sensitivity with SWC 0.5 . Noise was higher between sessions, resulting in \" poor \" signal-noise ratios, likely associated with the bias favoring retest trials. Reliability and sensitivity findings were consistent across maturational stages, demonstrating either \" moderate \" or \" acceptable \" reliability. There were clear differences between maturity groups for all measures, particularly between mid-PHV and post-PHV. Practitioners can be assured that IMTP and sprint performance measures are reliable within this population but require thorough familiarization processes before confidence in interpreting meaningful changes.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"418-426"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strength, Rate of Force Development, and Force Control Evaluations to Quantify Upper-Limbs Asymmetries Agreement in Professional Male Volleyball Players.","authors":"Samuel D'Emanuele, Gennaro Boccia, Veronica Zardo, Valter Durigon, Federico Schena, Cantor Tarperi","doi":"10.1519/JSC.0000000000005025","DOIUrl":"10.1519/JSC.0000000000005025","url":null,"abstract":"<p><strong>Abstract: </strong>D'Emanuele, S, Boccia, G, Zardo, V, Durigon, V, Schena, F, and Tarperi, C. Strength, rate of force development, and force control evaluations to quantify upper-limbs asymmetries agreement in professional male volleyball players. J Strength Cond Res 39(4): 466-473, 2025-Asymmetries are known to vary based on the nature of the sport and differ between individuals and the tests used. We explored interlimb asymmetries in muscle function among 13 national-level male volleyball players (24 ± 3 years; 87 ± 7 kg; 194 ± 7 cm; 19 ± 2 hours training/week), aiming to determine whether these asymmetries are muscle specific and consistent across various metrics. Subjects underwent assessments for elbow extensors and flexors in both limbs, including maximal contractions to assess the maximal voluntary force (MVF), submaximal ballistic contractions measuring Rate of Force Development (RFD peak ), Scaling Factor (RFD-SF), and evaluations of Approximate Entropy (ApEn), Coefficient of Variations, and Detrended Fluctuation Analysis (DFAα) during sustained contractions. Repeated-mixed ANOVA within and between-factors assessed each metric's differences between muscle groups and limbs. Kappa coefficients (K) were calculated to determine the levels of agreement for the direction of asymmetry among muscle groups and different metrics at the individual level. Our findings revealed that asymmetries were muscle specific, with statistical significance observed only in flexors MVF (12%, p = 0.007, d = 0.68). The asymmetry direction agreement between metrics was null for all parameters except for MVF, which resulted in slight ( K = 0.022) and fair ( K = 0.308) for ApEn. The agreement between RFD peak vs MVF ( K = 0.386) was fair, slight between RFD peak vs RFD-SF ( K = 0.141), and null when comparing RFD peak with ApEn and DFAα. At the individual level, no consistent performance advantage was found for either limb, despite volleyball's partial asymmetrical nature, emphasizing the importance of creating personalized training based on the muscle/limb of interest and the parameter to be improved (i.e., maximum strength or RFD).</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"466-473"},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}