Journal of Strength and Conditioning Research最新文献

{"title":"Correlation Between Muscle Strength, Swing Speed, Batting Statistics, and Body Composition Parameters in High School Baseball Players: A Retrospective Observational Study.","authors":"Kenta Suzuki, Yasuaki Mizoguchi, Fumihiko Kimura, Kazuki Fujisaki, Daiki Yokoyama, Toby Hall, Kiyokazu Akasaka","doi":"10.1519/JSC.0000000000004984","DOIUrl":"10.1519/JSC.0000000000004984","url":null,"abstract":"<p><strong>Abstract: </strong>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.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e135-e141"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142568971","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":"Physiological, Physical, and Psychological Determinants of Success During the Naval Special Warfare Screener Selection Course.","authors":"Brian J Martin, Martin Wright, Varun Patel, Adam Susmarski, Mita Lovalekar, Jennifer N Forse, Meaghan E Beckner, Andrew K Ledford, Bradley C Nindl","doi":"10.1519/JSC.0000000000004979","DOIUrl":"10.1519/JSC.0000000000004979","url":null,"abstract":"<p><strong>Abstract: </strong>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.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e162-e170"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869492","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":"Collegiate Male Athlete Attitudes Toward Male and Female Strength and Conditioning Coaches.","authors":"Katrina Taylor, Shealene J Little","doi":"10.1519/JSC.0000000000005022","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005022","url":null,"abstract":"<p><strong>Abstract: </strong>Taylor, K, and Little, SJ. Collegiate male athlete attitudes toward male and female strength and conditioning coaches. J Strength Cond Res 39(2): 277-280, 2025-Sports have long been male dominated, but there have been recent increases in the involvement of women in athletic administration and athlete support, that is, strength and conditioning. However, more is needed to know about the attitudes of male athletes toward female strength and conditioning coaches (SCCs) in the collegiate setting. This study aimed to determine differences in male student-athlete attitudes toward male and female SCCs and the factors associated with these perceptions. Male student-athletes (n = 89) volunteered to complete a survey that included the Modified Attitude of Athletes toward Male versus Female Coaches questionnaire and demographic information. Data were analyzed using t tests and one-way analysis of variance as appropriate, with an alpha level set at 0.05. Subjects reported more positive attitudes toward male SCCs (105.74 ± 19.34) than female SCCs (101.96 ± 22.68; p = 0.02, η2 = 0.24). There were no differences in perceptions because of year in school (p = 0.74, d = 0.02) or history of female mentors (p = 0.05, d = 0.49). However, male student-athletes with \"extremely close\" maternal relationships (104.98 ± 23.15) reported more favorable perceptions of female SCCs than those with less close relationships (96.25 ± 22.71; p = 0.049, d = 0.41). Findings from the study suggest that male student-athletes perceive male SCCs more positively than female SCCs. Factors such as previous relationships and mentors may influence these perceptions; however, further research is needed in a more diverse sample. Understanding these differential attitudes may help coaches and athletes improve relationship dynamics between male student-athletes and female SCCs. Future research should focus on strengthening these relationships to optimize training in collegiate settings.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 2","pages":"277-280"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143059245","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":"Position-Specific Differences in Speed Profiles Among National Football League Scouting Combine Participants.","authors":"Zachary M Gillen","doi":"10.1519/JSC.0000000000004958","DOIUrl":"10.1519/JSC.0000000000004958","url":null,"abstract":"<p><strong>Abstract: </strong>Gillen, ZM. Position-specific differences in speed profiles among NFL scouting combine participants. J Strength Cond Res 39(2): e121-e128, 2025-This study examined the relationships between speed profiles and athletic performance measurements from the National Football League (NFL) Scouting Combine, and position-specific differences in speed profiles. Subjects included NFL Scouting Combines participants with valid scores for the 40-yard dash, as well as the 10- and 20-yard splits of the 40-yard dash ( n = 2,156). Subjects were divided into the following position groups: defensive backs (DBs, n = 421), defensive linemen (DL, n = 356), linebackers (LBs, n = 261), offensive linemen (OL, n = 354), running backs (RBs, n = 217), tight ends (TEs, n = 122), quarterbacks (QBs, n = 108), and wide receivers (WRs, n = 317). Performance measures included 40-yard dash time (with 10- and 20-yard split times), bench press repetitions to failure, vertical jump height, broad jump distance, pro-agility time, and L-cone drill time. The 40-yard dash and its splits calculated vmax , τ , and amax to reflect speed profiles. One-way analysis of variances examined position-related differences. Pearson's product moment correlation coefficients examined relationships between performance measures and speed profile variables. Skill positions (DB and WR) had the greatest vmax and amax , and lowest τ , followed by big skill positions (LB, RB, TE, QB), followed by DL, then OL with the lowest vmax and amax , and highest τ . For skill and big skill positions, vmax , τ , and amax exhibited greater relationships with combine measures, whereas OL generally had the lowest relationships. The position-specific differences in this study demonstrate potential areas of strength and weakness for certain positions. This may help guide strength and conditioning coaches desiring to improve position-specific speed and acceleration capabilities for American football players.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e121-e128"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142349024","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":"Diaphragm Function in Elite Weightlifters With and Without Chronic Low Back Pain and its Impacts on Sports Performance.","authors":"Emma Feng Ming Zhou, Arnold Yu Lok Wong, Juhua Peng, Guohui Lin, Tao Wen, Jianhui Fang, Chufeng Zhou, Siu Ngor Fu","doi":"10.1519/JSC.0000000000004976","DOIUrl":"10.1519/JSC.0000000000004976","url":null,"abstract":"<p><strong>Abstract: </strong>Zhou, EFM, Wong, AYL, Peng, J, Lin, G, Wen, T, Fang, J, Zhou, C, and Fu, SN. Diaphragm function in elite weightlifters with and without chronic low back pain and its impacts on sports performance. J Strength Cond Res 39(2): e115-e120, 2025-The aim of this study was to compare diaphragm function between elite weightlifters with and without chronic low back pain (LBP) and to explore the associations between diaphragm function and sports performance. Forty-nine elite weightlifters aged 16-26 years were recruited, including 29 women (16-25 years, mean ± SD = 19.93 ± 2.70 years) and 20 men (16-26 years, mean ± SD = 20.95 ± 2.68 years). Of these, 23 subjects had chronic LBP. Diaphragm thickness and excursion were assessed using ultrasonography, and maximal inspiratory pressure (MIP), measured with POWERbreathe KH2, served as indicators of diaphragm contractility and strength, respectively. Sports performance was gauged through maximal snatch and clean and jerk lifts. Group differences and performance correlations were analyzed with consideration for confounders. The significance was set at p ≤ 0.05. Weightlifters with chronic LBP demonstrated significantly lower diaphragmatic contractility: diaphragm thickening fraction (by 21%; mean difference [MD] = 0.09, p = 0.04, Cohen's d = 0.69) and diaphragm excursion (by 18%; MD = 0.99, p < 0.01, Cohen's d = 0.89) compared with non-LBP controls. In addition, MIP was positively related to snatch ( r = 0.34, p = 0.02) and clean and jerk ( r = 0.43, p < 0.01) lifts. This study revealed that elite weightlifters with chronic LBP exhibit reduced diaphragm contractility, and inspiratory muscle force output (primary diaphragm) was associated with lifting performance. Incorporating diaphragm strengthening into training and rehabilitation might enhance performance and aid in LBP management, offering a dual benefit for athletes.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e115-e120"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546117","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 Between Relative Lower and Upper Body Strength and Hyperinsulinemia in US Adults: 1999-2002 and 2011-2014 NHANES.","authors":"James R Churilla, William R Boyer, Michael R Richardson, Charles C Williams","doi":"10.1519/JSC.0000000000004974","DOIUrl":"10.1519/JSC.0000000000004974","url":null,"abstract":"<p><strong>Abstract: </strong>Churilla, JR, Boyer, WR, Richardson, MR, and Williams, CC. Associations between relative lower and upper body strength and hyperinsulinemia in U.S. Adults: NHANES 1999-2002 and 2011-2014. J Strength Cond Res 39(2): e171-e175, 2025-Skeletal muscle (SM) is an insulin-sensitive tissue that aids in glucose homeostasis. Insulin resistance leads to chronic hyperglycemia and type 2 diabetes. Previous evidence suggests that greater SM strength and size improve insulin dynamics. The primary aim of this study was to examine the association(s) between relative lower and upper body strength and hyperinsulinemia in a nationally representative sample of US adults. Samples of adult (≥50 years) subjects in the 1999-2002 ( N = 1,097) and adults (≥20 years) in the 2011-2014 ( N = 2,576) National Health and Nutrition Examination Survey were used in the analyses. Significance was set at p ≤ 0.05 for regression models. Quartiles (Q) of relative lower body strength (RLBS [N·BMI -1 ]) and relative grip strength (RGS [kg·BMI -1 ]) were created. Hyperinsulinemia was calculated using the weighted 75th percentile of log-fasted insulin among adults without diabetes. Inverse dose-response relationships were found for decreasing prevalence estimates of hyperinsulinemia by increasing Q of both RLBS and RGS. Similar dose-response associations were revealed for increasing Q of both RLBS and RGS and mean insulin concentrations. Following adjustment for demographic and lifestyle variables, subjects in Q2, Q3, and Q4 of RLBS were found to have significantly lower odds of hyperinsulinemia (OR 0.58 [ P = 0.05], OR 0.38, OR 0.22 [ p < 0.05 for both], respectively). Subjects in Q2, Q3, and Q4 of RGS were also found to have lower odds of hyperinsulinemia (OR 0.30; OR 0.14; OR 0.05 [ p < 0.0001 for all]), respectively. These data suggest RLBS and RGS may both be favorably associated with insulin homeostasis.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e171-e175"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142568970","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":"High-Fatigue Dynamic Resistance Exercise Induces Significant Hypoalgesia Effect.","authors":"Riley Hogge, Madison Mascheri, Dimitri Shurik, William J Hanney, Abigail W Anderson","doi":"10.1519/JSC.0000000000004985","DOIUrl":"10.1519/JSC.0000000000004985","url":null,"abstract":"<p><strong>Abstract: </strong>Hogge, R, Mascheri, M, Shurik, D, Hanney, WJ, and Anderson, AW. High-fatigue dynamic resistance exercise induces significant hypoalgesia effect. J Strength Cond Res 39(2): 165-172, 2025-Although dynamic resistance exercise is a recommended treatment for patients with musculoskeletal pain, optimal intensity to create hypoalgesia has not been established. Response to exercise may also be affected by biopsychosocial factors that modulate pain response. The first purpose was to compare the immediate effects of a high-fatigue/exertion leg extension, low-fatigue/exertion leg extension, and control condition on pressure pain threshold (PPT) applied to the quadriceps (local effects) and trapezius (systemic effects). The second purpose was to examine if psychological and pain sensitivity factors affected response to exercise. As a within-subject design, subjects completed psychological questionnaires, a control condition, and a 1-repetition maximum (1RM) during the first session. Subjects attended 2 more sessions where they completed 3 sets of a leg extension exercise at 50% of their 1RM until they reached a fatigue level of high fatigue (8/10 on the Borg CR-10) or low fatigue (3/10) with a randomized session order. A within-subject repeated-measures ANOVA was conducted (significance set at p < 0.05). High-fatigue exercise produced significantly higher PPT at the quadriceps than quiet rest after each set ( F [6,162] = 3.25, p < 0.01, partial eta 2 = 0.11). During low-fatigue exercise, individuals with an efficient endogenous pain inhibitory capacity displayed significantly higher PPT at the trapezius ( F [2.14, 55.61] = 3.31, p = 0.03, partial eta 2 = 0.11). Lower fear of pain was moderately associated with greater PPT increases at the trapezius ( r = -0.38, p = 0.04). Although high-fatigue exercise produces immediate local hypoalgesia, systemic hypoalgesia is affected by variability in pain inhibition and fear of pain.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"165-172"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142729714","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":"Effects of Different Stretching Modalities on the Antagonist and Agonist Muscles on Isokinetic Strength and Vertical Jump Performance in Young Men.","authors":"Samuel Montalvo, Matthew P Gonzalez, Martin S Dietze-Hermosa, Armando Martinez, Sergio Rodriguez, Manuel Gomez, Nicholas Cubillos, Gabriel Ibarra-Mejia, Erik Tan, Sandor Dorgo","doi":"10.1519/JSC.0000000000004937","DOIUrl":"10.1519/JSC.0000000000004937","url":null,"abstract":"<p><strong>Abstract: </strong>Montalvo, S, Gonzalez, MP, Dietze-Hermosa, MS, Martinez, A, Rodriguez, S, Gomez, M, Ibarra-Mejia, G, Tan, E, and Dorgo, S. Effects of different stretching modalities on the antagonist and agonist muscles on isokinetic strength and vertical jump performance in young men. J Strength Cond Res 39(2): 173-183, 2025-Exercise warm-up may include static or dynamic stretching, impacting performance differently. This study investigated the effects of various stretching protocols on isokinetic strength, muscular activity, and vertical jump performance. Sixteen subjects, divided evenly between trained and untrained groups, underwent 8 distinct stretching conditions in random order. Outcomes measured included isokinetic knee extension and flexion torque and power, muscular activity (vastus lateralis, vastus medialis, and biceps femoris), and jump performance (jump height and modified reactive strength index [RSImod]). Responses to the stretching conditions were analyzed using a mixed-methods approach. For isokinetic knee extension, dynamic stretching of both agonist and antagonist (DY-AG-ANT) and combined dynamic agonist with static antagonist stretching (DY-AG ST-ANT) produced significant improvements. Dynamic stretching of both agonist and antagonist increased peak torque by 12.72% and average torque by 30.80%, while DY-AG ST-ANT increased peak torque by 15.61% and average torque by 41.06%. Muscular activity also improved significantly; DY-AG ST-ANT increased EMG activity of the vastus lateralis by 29.43% and vastus medialis by 70.75%. Biceps femoris saw a 33.18% increase with DY-AG and a 22.15% increase with ST-AG. Countermovement jump height improved with DY-AG-ANT (12.6%) and static antagonist (ST-ANT) conditions (11.3%) ( p < 0.05). Dynamic stretching of both agonist and antagonist also enhanced average power knee extension by 32.41%, while ST-AG DY-ANT improved it by 31.09% ( p < 0.05). Dynamic stretching, especially when combined with static stretching, optimizes isokinetic strength, muscular activity, and jump height. Coaches should incorporate dynamic stretching, alone or with static antagonist stretching, to maximize performance.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"173-183"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142502767","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":"The Reliability and Validity of the Rebound Countermovement Jump in National Collegiate Athletic Association Division I American Football Players.","authors":"Scott W Talpey, Micah Drake, Liam Haintz, Anthony Belanger, Mathew W O'Grady, Warren B Young, Peter D Mundy, Lachlan James, Tim J Gabbett, Elizabeth C Gardner","doi":"10.1519/JSC.0000000000004969","DOIUrl":"10.1519/JSC.0000000000004969","url":null,"abstract":"<p><strong>Abstract: </strong>Talpey, SW, Drake, M, Haintz, L, Belanger, A, O'Grady, MW, Young, WB, Mundy, PD, James L, Gabbett, TJ, Gardner, EC. The reliability and validity of the rebound countermovement jump in National Collegiate Athletic Association Division I American football players. J Strength Cond Res 39(2): 200-209, 2025-The purpose of this study was to investigate the reliability and validity of the rebound countermovement jump (R-CMJ), as an alternate test of leg muscle function to the CMJ and drop jumps (DJs). Because the first phase of the R-CMJ mimics that of the CMJ, it is hypothesized that variables obtained in phase I of the R-CMJ will be like those of a CMJ. Similarly, because the second phase of a R-CMJ mimics a DJ, it is believed that the variables obtained from phase II will be like those from a DJ. Collegiate male American football players ( N = 46) aged 18-24 years completed CMJs and R-CMJs on a portable force plate. Tests were completed on 3 separate days to determine the repeatability of select variables and to establish their validity. In addition, a subgroup ( N = 20) of players from the cohort completed DJs from both 30 cm (DJ30) and 45 cm (DJ45) to determine the concurrent validity of the variables obtained from the second phase of the R-CMJ. Most variables obtained from the CMJ and R-CMJ phase I were found to be reliable, except for time-to-take-off. The variables from the DJ30, DJ45, and R-CMJ phase II displayed moderate to good reliability; however, all coefficient of variations were >10%. Jump height achieved in the CMJ was significantly greater than that achieved in phase I of the R-CMJ. The reactive strength index was significantly different in the R-CMJ compared with the DJ from both 30 and 45 cm heights. Although the R-CMJ may be inviting for coaches to use owing to its ease and time efficiency, the results of this study highlight that it may not provide a valid representation of an athlete's reactive strength.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"200-209"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142568979","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":"Can Video Annotation Software With Minimal Standardization Be Used as a Back-Up for a Marker-Free Motion Tracking System when Monitoring Barbell Thruster Velocity During a Repeated Circuit?","authors":"Gerald T Mangine, Ashley Hines, Jacob Grazer, Tiffany A Esmat, John McLester","doi":"10.1519/JSC.0000000000004971","DOIUrl":"10.1519/JSC.0000000000004971","url":null,"abstract":"<p><strong>Abstract: </strong>Mangine, GT, Hines, A, Grazer, J, Esmat, TA, and McLester, J. Can video annotation software with minimal standardization be used as a back-up for a marker-free motion tracking system when monitoring barbell thruster velocity during a repeated circuit? J Strength Cond Res 39(2): 147-155, 2025-This study examined the agreement between a marker-free motion tracking system (PERCH) and a free video annotation software (KINOVEA) for measuring barbell thruster velocity using minimal standardization. For a larger placebo-controlled supplement intervention, 10 men (28.7 ± 8.0 years, 175 ± 8 cm, 91.0 ± 12.0 kg) and 10 women (31.3 ± 5.2 years, 167 ± 4 cm, 70 ± 13 kg) completed a circuit of rowing, 6 barbell thrusters (men: 43.1 kg, women: 29.5 kg), and 3 box jumps for \"as many repetitions as possible\" (AMRAP) in either 5 or 15 minutes. Barbell velocity (m × second -1 ) was monitored by PERCH from the frontal plane, whereas all sessions were video recorded from the same view and subsequently analyzed by KINOVEA using natural barbell landmarks. Fifty repetitions were randomly and equally drawn from each participant ( n = 1,000 repetitions) across all workout and supplement conditions. Although Wilcoxon signed-rank test revealed no differences (mean difference = 0.03 m × second -1 , p = 0.332), KINOVEA only explained 2.6% of PERCH variance, and Spearman's correlation analysis of Bland-Altman plots suggested that differences between technologies were exacerbated by the magnitude of velocity ( ρ = -0.62, p < 0.001). Cross-validated, regression analysis using KINOVEA and readily available participant demographics (arm reach and biological sex) improved prediction by 13.4% but agreement remained inconsistent ( ρ = 0.73, p < 0.001). Neither KINOVEA nor KINOVEA combined with participant demographics are interchangeable with PERCH for monitoring barbell velocity during an AMRAP. Still, researchers and athletes might use this free and accessible software as back-up for whenever PERCH fails to detect repetitions, as some information is better than none.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"147-155"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142502764","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}