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SummaryWe aimed to establish jump power cut-offs for the composite outcome of either sarcopenia (EWGSOP2) or dysmobility syndrome using Asian and Caucasian cohorts. Estimated cut-offs were sex specific (women: < 19.0 W/kg; men: < 23.8 W/kg) but not ethnicity specific. Jump power has potential to be used in definitions of poor musculoskeletal health.PurposeWeight-corrected jump power measured during a countermovement jump may be a useful tool to identify individuals with poor musculoskeletal health, but no cut-off values exist. We aimed to establish jump power cut-offs for detecting individuals with either sarcopenia or dysmobility syndrome.MethodsAge- and sex-matched community-dwelling older adults from two cohorts (University of Wisconsin-Madison [UW], Korean Urban Rural Elderly cohort [KURE], 1:2) were analyzed. Jump power cut-offs for the composite outcome of either sarcopenia defined by EWGSOP2 or dysmobility syndrome were determined.ResultsThe UW (n = 95) and KURE (n = 190) cohorts were similar in age (mean 75 years) and sex distribution (68% women). Jump power was similar between KURE and UW women (19.7 vs. 18.6 W/kg, p = 0.096) and slightly higher in KURE than UW in men (26.9 vs. 24.8 W/kg, p = 0.050). In UW and KURE, the prevalence of sarcopenia (7.4% in both), dysmobility syndrome (31.6% and 27.9%), or composite of either sarcopenia or dysmobility syndrome (32.6% and 28.4%) were comparable. Low jump power cut-offs for the composite outcome differed by sex but not by ethnicity (< 19.0 W/kg in women; < 23.8 W/kg in men). Low jump power was associated with elevated odds of sarcopenia (adjusted odds ratio [aOR] 4.07), dysmobility syndrome (aOR 4.32), or the composite of sarcopenia or dysmobility syndrome (aOR 4.67, p < 0.01 for all) independent of age, sex, height, and ethnicity.ConclusionSex-specific jump power cut-offs were found to detect the presence of either sarcopenia or dysmobility syndrome in older adults independent of Asian or Caucasian ethnicity.

Limited research has examined long-term training adaptations in elite Deaf athletes. This three-year longitudinal observational study characterized anthropometric and physical performance changes in the Polish Deaf National Basketball Team preparing for the Deaflympics (2019–2021). Eleven male athletes (age 26.9 ± 6.3 years) underwent annual assessments of body composition and performance, including countermovement jumps (CMJ, ACMJ), spike jump (SPJ), sprint speed (0–5 m, 0–20 m), and estimated VO₂max. A control group of physically inactive Deaf students ( n  = 15; age 21.1 ± 1.6 years) was also evaluated. Friedman ANOVA revealed stable body composition across seasons ( p  > 0.05; W = 0.01–0.22), except for a moderate increase in left-leg fat-free mass ( p  = 0.025; W = 0.33). While jump performance remained unchanged ( p  > 0.05; d = 0.18–0.32), sprint performance declined significantly (0–5 m: χ²(2) = 20.18, p  < 0.001; 0–20 m: χ²(2) = 14.59, p  = 0.001). Compared with inactive peers, players demonstrated superior physical capacity, including higher fat-free mass (d = 2.12), greater jump power (d = 3.46), and faster sprint times (d = − 1.03 to − 1.07), with a mean 2021 VO₂max of 47.3 ± 6.1 ml·kg⁻¹·min⁻¹. In conclusion, these elite athletes maintained morphology and power but showed declining sprint performance, likely due to COVID-19 disruptions. This study provides the first longitudinal evidence of performance trajectories in elite Deaf basketball players, underscoring the need for individualized, acceleration-focused monitoring to sustain long-term neuromuscular performance.

•Elevated serum γ-glutamyl transferase (GGT) activity signals oxidative stress.•Elevated serum GGT was associated with low jump power in adults aged ≥50 y.•Serum GGT levels showed a negative association with low handgrip strength.•The relationship persisted after adjustment for age, sex, lean mass, and body fat.•Serum GGT may act as a marker of muscle function. Elevated serum γ-glutamyl transferase (GGT), a hepatic cholestasis or liver damage marker, has been associated with low lean mass and adiposity. However, whether serum GGT can predict muscle function in adults remains unclear. The aim of this study was to determine whether an elevated serum GGT is associated with low peak weight-corrected jump power (JP) and low handgrip strength (HGS). This study included 662 individuals aged ≥50 y in the final cohort (women, 86%; mean age, 64.8 y). The primary outcome was low peak weight-corrected JP defined as <23.8 W/kg and <19W/kg in men and women, respectively, and the secondary outcome was low HGS (<28 kg in men; <18 kg in women). Participants with low JP had a higher GGT level, older age, lower HGS, and higher body fat than those without low JP. Serum GGT showed a negative association with JP (adjusted β = –1.16, P = 0.005) and HGS (adjusted β = –0.92, P = 0.018). One log-unit increment in GGT was associated with elevated odds of low JP (adjusted odds ratio [aOR] 2.13, P = 0.002) after adjustment for age, sex, lean mass, and body fat percentage, particularly in individuals without hepatic steatosis (aOR, 2.30) versus those with hepatic steatosis (aOR, 0.80; Pinteraction = 0.020). Elevated serum GGT was associated with low muscle function in adults independent of age, muscle mass, and adiposity, indicating that serum GGT may play a role as an independent marker of muscle function.

SummaryIn a community-dwelling elderly cohort (Korean Urban Rural Elderly), low peak jump power was associated with elevated odds of dysmobility syndrome and its components, independent of age and comorbidities. Jump power measurement improved discrimination of individuals with dysmobility syndrome when added to conventional risk factors.IntroductionDysmobility syndrome was proposed to encompass the risks affecting musculoskeletal outcomes. Jump power measurement is a safe, reproducible high-intensity test for physical function in elderly. However, the relationship between jump power and dysmobility syndrome remains unknown.MethodsA total of 1369 subjects (mean 71.6 years; women, 66%) were analyzed from a community-based cohort. Dysmobility syndrome was defined as the presence of ≥ 3 factors among falls in the preceding year, low lean mass, high fat mass, osteoporosis, low grip strength, and low timed get-up-and-go (TUG) performance. Subjects were grouped into tertiles of jump power relative to weight based on sex-stratified cutoffs (32.4 and 27.6 W/kg in men; 23.9 and 19.9 W/kg in women) or into the failed-to-jump group.ResultsThe prevalence of dysmobility syndrome was 20% overall, increasing from the highest (T1) to lowest (T3) jump power tertile (1, 11, 15% in men; 11, 16, 39% in women) and the failed-to-jump group (39% in men; 48% in women). Low jump power or failed-to-jump was associated with elevated odds of dysmobility syndrome (T3 vs. T1, adjusted odds ratio [aOR] 4.35, p < 0.001; failed-to-jump vs. T1, aOR 7.60, p < 0.001) and its components including falls, low lean mass, high fat mass, and poor TUG performance but not osteoporosis after adjustment for covariates. Jump power modestly discriminated dysmobility syndrome (area under the curve [AUC], 0.71, p < 0.001), which improved discriminatory performance when added to conventional risk factors (AUC, from 0.75 to 0.79, p < 0.001).ConclusionsLow peak jump power was associated with elevated odds of dysmobility syndrome and its components, independent of age and comorbidities.

Aims: This cross-sectional study aimed to analyze the relevance of musculoskeletal fitness for identifying low physical functioning in community-dwelling older women. Methods: Sixty-six older women (73.62 ± 8.23 yrs old) performed a musculoskeletal fitness assessment of the upper and lower limbs. A handheld dynamometer was used to evaluate upper-limb muscle strength through a handgrip (HG) test. Lower-limb power and force were assessed from a two-leg countermovement vertical jump (VJ) on a ground reaction force platform. Physical functioning was assessed subjectively using the Composite Physical Function (CPF) questionnaire and objectively by daily step count measured by accelerometry and gait speed/agility assessed by the 8-Foot Up-and-Go (TUG) test. Logistic regressions and ROC curves were carried out to define odds ratios and ideal cutoff values for discriminatory variables. Results: VJ power showed the ability to identify low physical functioning when evaluated through the CPF (14 W/kg, 1011 W), gait speed/agility (15 W/kg, 800 W), or daily accumulated steps (17 W/kg). Considering that VJ power was normalized for body mass, the increase of 1 W/kg corresponds to a decrease of 21%, 19%, or 16% in the chance of low physical functioning when expressed by these variables, respectively. HG strength and VJ force did not show a capacity to identify low physical functioning. Conclusions: The results suggest that VJ power is the only marker of low physical functioning when considering the three benchmarks: perception of physical ability, capacity for mobility, and daily mobility.

Wearable sensors have become increasingly popular for assessing athletic performance, but the optimal methods for processing and analyzing the data remain unclear. This study investigates the efficacy of discrete and continuous feature-extraction methods, separately and in combination, for modeling countermovement jump performance using wearable sensor data. We demonstrate that continuous features, particularly those derived from Functional Principal Component Analysis, outperform discrete features in terms of model performance, robustness to variations in data distribution and volume, and consistency across different datasets. Our findings underscore the importance of methodological choices, such as signal type, alignment methods, and model selection, in developing accurate and generalizable predictive models. We also highlight the potential pitfalls of relying solely on domain knowledge for feature selection and the benefits of data-driven approaches. Furthermore, we discuss the implications of our findings for the broader field of sports biomechanics and provide practical recommendations for researchers and practitioners aiming to leverage wearable sensor data for athletic performance assessment. Our results contribute to the development of more reliable and widely applicable predictive models, facilitating the use of wearable technology for optimizing training and enhancing athletic outcomes across various sports disciplines.

Study aim: The aim of the study was to examine biomechanical characteristics of taekwondo athletes comparing kicks and punches with laboratory tests of muscle strength and power. Material and methods: Six male taekwondo athletes participated in this study. Measurements of maximal punching with the rear hand (hook and straight punches) and kicking (Apdolio and Dwit Chagi) force were performed on a boxing dynamometer. Also, the following laboratory tests were performed: jump height and power output in counter movement jump (CMJ) and spike jump (SPJ), muscle strength for 10 muscle groups and force-velocity (F-v) relationship. Results: Mean maximal straight and hook punching forces were 1659.2 ± 254.2 N and 1843.8 ± 453.3 N, respectively. Maxi­mal Apdolio rear leg, Apdolio lead leg and Dwit Chagi rear leg kicking forces were 3541.3 ± 1130.3 N, 3205.3 ± 965.1 N and 3568.0 ± 1306.0 N, respectively. The heights of jumps were 0.501 ± 0.040 m (CMJ) and 0.554 ± 0.034 m (SPJ). A strong cor­relation between the maximal force of a punch and maximal joint torques was observed. Conclusions: The values of kicking forces developed in a simulated fight were lower than the forces developed in the test of individual kicks. Strong relationships were observed between leg power developed in the SPJ and force of individual Apdolio kicks performed with the lead (r = 0.87, p < 0.05) and rear leg (r = 0.74). Based on these findings, it was concluded that maxi­mal joint torques and height of the SPJ could be used as a proxy of kicking force.

Professional basketball players have demanding schedules that, in combination with certain underlying physical characteristics and side-to-side strength and power imbalances, may make them vulnerable to lower extremity injuries. To examine the relationship among skeletal muscle architecture, lower body power, and games missed because of lower extremity injury (%MISS) in professional basketball players. Cross-sectional study. Setting : Human Performance Laboratory. Nine players under contract for Orlando Magic were assessed. We compared athletes who were injured (n = 4, height = 203.2 ± 5.5 cm, mass = 105 ± 7.5 kg, age = 25.0 ± 2.8 years) and those who remained healthy (n = 5, height = 200.2 ± 12.2 cm, mass = 100.1 ± 16.6 kg, age = 22.4 ± 1.9 years) during the season. Bilateral ultrasonographic measurements of muscle thickness, pennation angle, echo intensity, and cross-sectional area of the rectus femoris and vastus lateralis were collected before regular-season play. Subsequently, muscle thickness and pennation angle were used to compute fascicle length. Along with unilateral jumping power, inferences were made upon the magnitude of the relationship between the percentage bilateral difference in these measures and %MISS, as well as between injured and healthy athletes. The data indicated likely relationships between %MISS and age (r = 0.772), and between %MISS and bilateral differences in rectus femoris cross-sectional area (7.8% ± 6.4%; r = 0.657) and vastus lateralis cross-sectional area (6.2% ± 4.8%; r = 0.521), as well as a possible relationship with vastus lateralis muscle thickness (7.9% ± 8.9%; r = 0.444). Echo-intensity differences in the vastus lateralis were greater in injured (8.0% ± 2.4%) versus healthy athletes (3.2% ± 2.0%). Although a 2-fold difference in mean jumping power was observed between injured (26.3 ± 14.9 W) and healthy athletes (13.6 ± 8.7 W), these differences were not statistically significant (P = .20). In the present sample, lower extremity side-to-side differences may be related to an increased risk for lower extremity injury. Future researchers using larger sample sizes need to identify normal versus at-risk ranges for bilateral differences in muscle structure and power of the lower extremities of professional basketball players and athletes in other sports.

Sarcopenia is considered to be a risk factor for osteoporotic fracture, which is a major health problem in elderly women. In this study, we aimed to investigate the association of sarcopenia, with regard to muscle mass and function, with prevalent vertebral fracture in community-dwelling elderly women. We recruited 1281 women aged 64 to 87 years from the Korean Urban Rural Elderly cohort study. Muscle mass and function were measured using bioimpedance analysis and jumping mechanography. Skeletal muscle index (SMI) and jump power were used as an indicator of muscle mass and function, respectively. Among the participants, we observed 282 (18.9%) vertebral fractures and 564 (44.0%) osteoporosis. Although age, body mass index, and prevalence of osteoporosis increased as both SMI and jump power decreased, prevalence of vertebral fracture increased only when jump power decreased. In univariate analysis, compared with the highest quartile of jump power, the lowest quartile had a significant odds ratio of 2.80 (95% CI 1.79–4.36) for vertebral fracture. This association between jump power and vertebral fracture remained significant, with an odds ratio of 3.04 (95% CI 1.77–5.23), even after adjusting for other risk factors including age, bone mineral density, previous fracture, and cognitive function. In contrast, there was no association between SMI and vertebral fracture. Based on our results, low jump power, but not SMI, is associated with vertebral fracture in community-dwelling elderly Korean women. This finding suggests that jump power may have a more important role than muscle mass itself for osteoporotic fracture.

Background Ageing is associated with sarcopenia, osteoporosis, and increased fall risk, all of which contribute to increased fracture risk. Mechanically, bone strength adapts in response to forces created by muscle contractions. Adaptations can be through changes in bone size, geometry, and bending strength. Muscle mass is often used as a surrogate for muscle force; however, force can be increased without changes in muscle mass. Increased fall risk with ageing has been associated with a decline in muscle power—which is a measure of mobility. The aims of this study were as follows: (i) to investigate the relationship between muscle parameters in the upper and lower limbs with age in UK men and the influence of ethnicity on these relationships; (ii) to examine the relationships between jump force/grip strength/cross‐sectional muscle area (CSMA) with bone outcomes at the radius and tibia. Methods White European, Black Afro‐Caribbean, and South Asian men aged 40–79 years were recruited from Manchester, UK. Cortical bone mineral content, cross‐sectional area, cortical area, cross‐sectional moment of inertia, and CSMA were measured at the diaphysis of the radius and tibia using peripheral quantitative computed tomography. Lower limb jump force and power were measured from a single two‐legged jump performed on a ground‐reaction force platform. Grip strength was measured using a dynamometer. Associations between muscle and bone outcomes was determined using linear regression with adjustments for age, height, weight, and ethnicity. Results Three hundred and one men were recruited. Jump force was negatively associated with age; for every 10 year increase in age, there was a 4% reduction in jump force (P < 0.0001). There was a significant age–ethnicity interaction for jump power (P = 0.039); after adjustments, this was attenuated (P = 0.088). For every 10 year increase in age, grip strength decreased by 11%. Jump force was positively associated with tibial bone outcomes: a 1 standard deviation greater jump force was associated with significantly higher cortical bone mineral content 3.1%, cross‐sectional area 4.2%, cortical area 3.4%, and cross‐sectional moment of inertia 6.8% (all P < 0.001). Cross‐sectional muscle area of the lower leg was not associated with tibial bone outcomes. Both grip strength and CSMA of the arm were positively associated, to a similar extent, with radius diaphyseal bone outcomes. Conclusions Jump force and power are negatively associated with age in UK men. In the lower limb, the measurement of jump force is more strongly related to bone outcomes than CSMA. It is important to consider jump force and power when understanding the aetiology of bone loss and mobility in ageing men.