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Purpose: To estimate temporal trends in broad jump performance for United States youth, a marker of muscular fitness and health. Method: Electronic databases, topical systematic reviews, and personal libraries were systematically searched for studies reporting descriptive standing broad jump data for apparently healthy United States youth (age 10-17 years). Temporal trends at the sex-age level were estimated using sample-weighted regression models associating the year of testing to mean jump performance, with national trends standardized to the year 1985 using a post-stratified population-weighting procedure. Results: Collectively, there was a small increase of 12.6 cm (95%CI: 12.5 to 12.7) or 7.9% (95%CI: 7.1 to 8.6) in 65,527 United States youth between 1911 and 1990. Increases were greater for girls (change in means [95% CI]: 17.1 cm [16.9 to 17.3]; 11.4% [10.7 to 12.2]) compared to boys (change in means [95% CI]: 8.5 cm [8.3 to 8.7]; 4.6% [3.8 to 5.4]), but did not differ between children (10-12 years) and adolescents (13-17 years). Increases in broad jump performance were not always uniform across time, with steady and progressive increases observed for boys and children, respectively, and a diminishing rate of increase observed for girls and adolescents. Conclusions: Muscular fitness is a good marker of health, so greater broad jump performance from 1911 to 1990 may reflect corresponding changes in health. Routine assessment of broad jump performance may be useful to monitor trends in health and muscular fitness of United States youth due to its practicality, scalability, and predictive utility.

Anthropometry is important for predicting sports performance. While 3-dimensional (3D) body scanners increase the feasibility of anthropometric assessment, reliability data on athletes are lacking. The aim of this study was to determine the test-retest reliability of a portable, single-camera 3D body scanning system (Styku S100) to assess circumferences, and whole-body and segmental surface areas and volumes of athletes. Forty-nine (19 males) athletes were scanned 6 times (two sessions of three scans). The Styku scanner demonstrated nearly perfect reliability. Systematic errors were negligible (mean standardized bias [95%CI]: scan 1 vs. 4, 0.04 [0.02, 0.06]), random errors were negligible (mean standardized typical error [95%CI]: scan 1 vs. 4, 0.14 [0.10, 0.17]), and test-retest correlations were nearly perfect (mean intra-class correlation coefficient [95%CI]: scan 1 vs. 4, 0.98 [0.97, 0.99]). Single-camera 3D body scanning systems may provide practitioners and researchers with a feasible tool to evaluate body size and shape.

The aims of this systematic review and meta-analysis were to evaluate the effect of photobiomodulation (PBM) on musculoskeletal pain in injured athletes and to determine if the effects of PBM allowed injured athletes to return to play faster. Electronic databases (MEDLINE Complete, CINAHL, and SPORTDiscus, PubMed, Web of Science, and Embase) were systematically searched (up to and including November 7, 2023) for peer-reviewed randomized controlled trials (RCTs) meeting criteria. Six RCTs, representing 205 competitive and recreational athletes with a mean age of 24 years, were included in the analysis. There were 6 intervention groups using standard physical therapy (n = 1), placebo PBM (n = 4), and aloe gel (n = 1) lasting between 10 minutes and 8 weeks in duration. The level of significance set for the study was p < 0.05. Overall, the use of PBM indicated a positive effect on pain reduction for PBM vs. control groups, standardized mean differences = 1.03, SE = 0.22, 95% confidence intervals = [0.43-1.63], p = 0.0089, but the 2 RCTs found evaluating the effect of PBM on time to return to play after injury in athletes do not support a benefit. Allied healthcare professionals may use PBM to reduce pain, thus allowing an athlete to return to their normal bio-mechanical movement faster; however, limited evidence suggests that PBM does not reduce time to return to play after an injury. [ABSTRACT FROM AUTHOR]

Background: Digit ratio (2D:4D), a putative marker of prenatal testosterone, is a negative correlate of sports, athletic, and fitness performance. Objectives: To describe the relationship between 2D:4D and vertical jump performance in athletes. Methods: Sixty‐one Division I American Football players from a Midwestern U.S. university had their 2D:4D measured digitally and their vertical jump performance measured using jump mechanography. The primary outcome was jump height, with secondary outcomes depicting jump execution also recorded. Linear relationships between 2D:4D and vertical jump performance were quantified using partial correlations adjusted for age, height, mass, and ethnicity. Results: 2D:4D was a statistically significant weak negative correlate of jump height (partial r [95% confidence interval]: −0.26 [−0.48, −0.01]), indicating that athletes with lower 2D:4Ds (i.e., relatively longer 4th digits) jumped higher. Relationships with jump execution variables were negligible to weak and negative, but not statistically significant. Conclusions: The significant relationship between 2D:4D and jump height probably reflects both the long‐term organizational and short‐term activational benefits of testosterone. Therefore, 2D:4D may be a useful indicator of explosive strength among young athletes. [ABSTRACT FROM AUTHOR]

Background: Digit ratio (2D:4D), a marker of prenatal testosterone exposure, is a weak negative correlate of sports/athletic/fitness performance. While numerous studies have examined the relationship between 2D:4D and physical fitness, there has never been a comprehensive study that has synthesized studies examining relationships between 2D:4D and muscular fitness. Objectives: To systematically review and meta‐analyze the relationship between 2D:4D and muscular fitness measured as handgrip strength (HGS). Methods: We systematically searched five electronic databases, reference lists, topical systematic reviews/meta‐analyses, and personal libraries in November 2020. Peer‐reviewed, cross‐sectional studies that reported Pearson's correlation coefficients between objectively measured 2D:4D and HGS were included. We used random‐effects meta‐analysis to estimate the pooled correlation and the 95% confidence interval (95%CI), and moderator analyses to estimate the influence of sex and age. Results: Data from 22 studies, representing 5271 individuals from 11 countries ranging in (mean) age from 10.4 to 58.0 years, were included. Overall, there was a weak negative correlation between 2D:4D and HGS (r = −0.15, 95%CI = –0.20 to −0.09), indicating that individuals with low 2D:4Ds had high HGS. We found substantial heterogeneity between studies (Q = 123.4, p <.0001; I2 = 74%), but neither sex (Q = 0.003, p =.96) nor age (Q = 0.46, p =.50) significantly moderated the pooled correlation. Conclusions: We found a weak negative relationship between 2D:4D and HGS, which showed substantial heterogeneity between studies, but was neither moderated by sex nor age. Our finding probably reflects both the long‐term (organizational) and short‐term (activational) benefits of testosterone. [ABSTRACT FROM AUTHOR]