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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. [ABSTRACT FROM AUTHOR]

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.

BackgroundThere is an increasing consensus on the relevance of musculoskeletal fitness for health throughout the life cycle, requiring evaluation approaches and description of results capable of characterizing different age groups and body sizes. This study aimed to describe the musculoskeletal fitness of young Portuguese people aged 10–18 through handgrip strength (HGS) and vertical jump power (VJP) and investigate differences between the sexes.MethodsThe sample included 736 participants (359 girls recruited from schools. HGS (kg) was assessed using a handheld dynamometer, and VJP (W) was assessed using a force platform; both measurements were standardized for body mass.ResultsHigher HGS and VJP were observed in boys than in girls from 13 years old (13 years: p ≤ 0.05; 14–18 years: p ≤ 0.001), with no significant differences before this age. The percentile distributions of HGS and VJP are described for each sex using the lambda, mu, sigma (LMS) method. The pattern of development of these variables as a function of age is presented.ConclusionsHandgrip strength and vertical jump power show differences between the sexes from 13 years of age and similar trajectories to populations in other countries in the same age group.

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Background: The countermovement jump (CMJ) is a valid and reliable test of lower extremity (LE) muscle power. However, the CMJ may not be appropriate during early-stage rehabilitation of injuries. Functional muscle strength tests (FMSTs) could evaluate LE muscle power with lower joint reaction forces. Hypothesis: The lateral step-up test (LSUT), 5 times sit to stand (5×STS), and 30-s chair stand test (30CST) could predict CMJ jump height (JHt) and jump peak power (JPow). Study Design: Cross-sectional study. Level of Evidence: Level 2. Methods: Eighty-one young adults performed 3 CMJs to measure JHt and JPow using an electronic jump mat and speed analyzer. Participants also performed three FMSTs: 1 trial of the LSUT and a modified trial of LSUT touching the ground with the heel only (MLSUT); 2 trials of the 5×STS; and 2 trials of the 30CST, in a randomized order. Spearman rho correlations and hierarchal multiple linear regressions were used to determine whether FMST performances predicted JHt and JPow, after controlling for sex, body height, and body mass. Results: 30CST, LSUT, MLSUT, sex, body mass, and body height were significantly associated with JHt (P < 0.05). LSUT, sex, body height, and body mass were significantly associated with JPow (P < 0.05). Hierarchical regression analyses showed that the 30CST significantly predicted JHt (P < 0.01) and JPow (P = 0.03), independent of sex, body height, and body mass. Conclusion: 30CST performance predicted JHt and JPow in young adults. Clinical Relevance: The 30CST is easy to perform, requires equipment found readily in clinics, and predicts LE muscle power. This test could be used to track progress during the early stages of LE injury rehabilitation. [ABSTRACT FROM AUTHOR]

Introduction: A paucity of research exists examining the importance of muscle morphological and functional characteristics for elite female sprint performance. Purpose: This study aimed to compare lower body muscle volumes and vertical jumping power between elite and subelite female sprinters and assess the relationships of these characteristics with sprint race and acceleration performance. Methods: Five elite (100 m seasons best [SBE100], 11.16 ± 0.06 s) and 17 subelite (SBE100, 11.84 ± 0.42 s) female sprinters underwent: 3T magnetic resonance imaging to determine the volume of 23 individual leg muscles/compartments and five functional muscle groups; countermovement jump and 30 m acceleration tests. Results: Total absolute lower body muscle volume was higher in elite versus subelite sprinters (+15%). Elite females exhibited greater muscle volume of the hip flexors (absolute, +28%; relative [to body mass], +19%), hip extensors (absolute, +22%; relative, +14%), and knee extensors (absolute, +21%), demonstrating pronounced anatomically specific muscularity, with relative hip flexor volume alone explaining 48% of sprint performance variability. The relative volume of five individual muscles (sartorius, gluteus maximus, adductor magnus, vastus lateralis, illiopsoas) were both distinct between groups (elite > subelite) and related to SBE100 (r = 0.553–0.639), with the combination of the sartorius (41%) and the adductor magnus (17%) explaining 58% of the variance in SBE100. Elite female sprinters demonstrated greater absolute countermovement jump power versus subelite, and absolute and relative power were related to both SBE100 (r = −0.520 to −0.741) and acceleration performance (r = 0.569 to 0.808). Conclusions: This investigation illustrates the distinctive, anatomically specific muscle volume distribution that facilitates elite sprint running in females, and emphasizes the importance of hip flexor and extensor relative muscle volume. [ABSTRACT FROM AUTHOR]

Abstract Background Many older adults with physical limitations living in residential care apartments are unable to exercise in a standing position and are at risk for declining in muscle function leading to falls and injury. Novel approaches to achieve exercise benefits are needed. The purpose of this study was to test the effect of semi-recumbent vibration exercise on muscle outcomes in older adults living in residential care apartment complexes (RCACs). Methods A randomized, crossover design was used to examine the effect of semi-recumbent vibration exercise on muscle function and mass among 32 RCAC residents (mean age 87.5 years) with physical limitations. Participants received a randomized sequence of two study conditions: sham or vibration for 8 weeks each separated by a 4-week washout. Before and after the 8 weeks of vibration treatment and sham treatment, muscle mechanography was used to assess muscle function including jump power, weight-corrected jump power, and jump height. Short physical performance battery (SPPB) and handgrip strength were also used to measure muscle function. Bioelectrical impedance spectroscopy was used to estimate skeletal muscle mass. The effect of the vibration treatment on muscle outcomes was analyzed through mixed effects linear regression models. Results Vibration exercise leads to better jump height (p

Background: Many older adults with physical limitations living in residential care apartments are unable to exercise in a standing position and are at risk for declining in muscle function leading to falls and injury. Novel approaches to achieve exercise benefits are needed. The purpose of this study was to test the effect of semi-recumbent vibration exercise on muscle outcomes in older adults living in residential care apartment complexes (RCACs).Methods: A randomized, crossover design was used to examine the effect of semi-recumbent vibration exercise on muscle function and mass among 32 RCAC residents (mean age 87.5 years) with physical limitations. Participants received a randomized sequence of two study conditions: sham or vibration for 8 weeks each separated by a 4-week washout. Before and after the 8 weeks of vibration treatment and sham treatment, muscle mechanography was used to assess muscle function including jump power, weight-corrected jump power, and jump height. Short physical performance battery (SPPB) and handgrip strength were also used to measure muscle function. Bioelectrical impedance spectroscopy was used to estimate skeletal muscle mass. The effect of the vibration treatment on muscle outcomes was analyzed through mixed effects linear regression models.Results: Vibration exercise leads to better jump height (p < .05) compared to sham exercise but also poorer chair rise performance (p = 0.012). Other muscle functions tests and muscle mass parameters showed non-significant changes.Conclusion: This small pilot study showed no conclusive results on the effect of semi-recumbent vibration exercise on muscle function and mass in older adults living in RCAC. However, the promising signals of improved jump performance could be used to power larger studies of longer duration with various vibration doses to determine the benefit of vibration exercise in this physically impaired, high-risk population with few exercise capabilities.Trial Registration: The study is registered at clinicaltrials.gov ( NCT02533063 ; date of first registration 26/08/2015). [ABSTRACT FROM AUTHOR]

Summary: We 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. Purpose: Weight-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. Methods: Age- 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. Results: The 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. Conclusion: Sex-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. [ABSTRACT FROM AUTHOR]

Background: There is an increasing consensus on the relevance of musculoskeletal fitness for health throughout the life cycle, requiring evaluation approaches and description of results capable of characterizing different age groups and body sizes. This study aimed to describe the musculoskeletal fitness of young Portuguese people aged 10-18 through handgrip strength (HGS) and vertical jump power (VJP) and investigate differences between the sexes., Methods: The sample included 736 participants (359 girls recruited from schools. HGS (kg) was assessed using a handheld dynamometer, and VJP (W) was assessed using a force platform; both measurements were standardized for body mass., Results: Higher HGS and VJP were observed in boys than in girls from 13 years old (13 years: p  ≤ 0.05; 14-18 years: p  ≤ 0.001), with no significant differences before this age. The percentile distributions of HGS and VJP are described for each sex using the lambda, mu, sigma (LMS) method. The pattern of development of these variables as a function of age is presented., Conclusions: Handgrip strength and vertical jump power show differences between the sexes from 13 years of age and similar trajectories to populations in other countries in the same age group., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Correia, Zymbal and Baptista.)

The aim of this study was to investigate the use of drop jumps (DJ) to promote post-activation potential (PAP) and to improve the performance of vertical jump (VJ). For that purpose 15 Volleyball male athletes (19,88 ± 1,54 years old), were conducted randomly: (I) a countermovement jump control (CCMJ); (II) 6 sets of DJ, followed by 4 minutes of passive rest and 3 CMJ (PDJ); (III) 5RM Smith Machine squat (SMS), followed by 4 minutes of passive recovery, and then 3 CMJ (PSMS). All activities had an interval of 72 hours between them. Jump height and power were measured with a jump platform. It was observed a significant increase in jump height (P< 0,001) between PSMS and PDJ, concerning CCMJ. Significant higher values of in jump height (p < 0.001) and power (p < 0.001) were also observed for PSMS concerning PDJ. It can be concluded that both interventions (PDJ and PSMS) promoted a PAP that influenced the height of the CMJ. The uses of DJ in training and pre-competitive situations seem to be an effective way to improve performance. [ABSTRACT FROM AUTHOR]

Abstract: Summary: In 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.Introduction: Dysmobility 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.Methods: A 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.Results: The 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).Conclusions: Low peak jump power was associated with elevated odds of dysmobility syndrome and its components, independent of age and comorbidities. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the muscular activation strategies of professional and amateur soccer players during countermovement jump. Twenty male soccer players, consisting of 10 amateurs (age: 22.9±3.1 year, training status: 12.2±3.1 year) and 10 professionals (age: 22.2±2.5year, training status: 13.7±2.7year) volunteered to participate in the study. Dominant leg surface electromyography activities of five muscles were recorded during countermovement jump. In addition, isokinetic strength of knee flexor and extensors, peak and average power were calculated. According to our results, the average countermovement jump heights were calculated for amateurs (37.1±3.12 cm) and professionals (41.3±2.58 cm). Furthermore, gastrocnemius muscle activation occurred significantly higher in professional soccer players than that of the amateur soccer players during propulsion (between -150ms and -120ms) and flight phase (between 150ms and 270ms) (p lt;0,05). Rectus femoris, vastus lateralis, vastus medialis and biceps femoris muscles contraction values were almost similar in both amateur and professional soccer players which their age, training year and muscle strengths are similar. It could be concluded that pre-activation and post landing phase are important for the jumping performance for both groups; however; the high activation of gastrocnemious muscle could be one of the important determinant for the superior jump performance

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

The article focuses on research that examines the relationship between skeletal muscle architecture and rate of injury among players of the U.S. National Basketball Association. Topics of the study include assessment of nine basketball players under contract for the team Orlando Magic, bilateral ultrasonographic measurement of muscle thickness, pennation angle and echo intensity, and the study showing that side to side differences is related to an increased risk for lower extremity injury.

The aim of this study-case was to determine the effects of plyometric training on height of rise, the (maximal) explosive force of legs, the power of the inferior train. The controlled trial that evaluated the effect of plyometric training on four typical vertical height, test were carried out: Counter Movement Jump - CMJ, Continuous Jump with Bent Legs Reference -- CJbref, Continuous Jump with Straight Legs - hCJs, Continuous Jump with Bent Legs - CJb30 sec. Study-case was identified by computerised used Bosco Protocol applied Kistler force platform measurement 9290AD Quattro Jump. The four tests that were performed using Kistler force platform to measure Quatro Jump Bosco Protocol Version 1.0.9.2, gave us the data about the height and jump power and capacity data on neuro-motor recruitment (fast fibers), voluntary effort, fatigue, muscle elasticity effect or stretching. The pooled estimate of the effect of plyometric training o jump height was plyometric training provides a statistically significant and practically relevant improvement in jump height with the mean effect ranging from 3.8 (CJs) to 7.2 (CJb30s). [ABSTRACT FROM AUTHOR]

When compared, full-term prepubertal boys had greater regional bone size, higher total body (TB) bone mineral content (BMC), and regional bone density than preterm boys but higher TB bone content area and regional BMC than late-preterm boys. Implications include follow-up bone assessment and preterm formula feeding in late-preterm boys. This study was conducted to determine whether there are differences in bone mass and size among prepubertal boys born preterm (PT; ≤34 weeks gestation), late-preterm (LP; >34 and ≤37 weeks gestation), and at term (>37 weeks gestation) and to identify factors that are associated with bone mass and size in these children. Total body (TB), spine and hip dual energy X-ray absorptiometry and tibia peripheral quantitative computed tomography measures were obtained on 24 boys aged 5.7 to 8.3 years. In multiple regression analysis adjusting for current weight, height, age, and jump power, term boys had greater cortical thickness ( p = 0.03) and area ( p = 0.01), higher trabecular volumetric bone mineral density ( p = 0.05), TB bone mineral content (BMC; p = 0.007), and hip areal bone mineral density (aBMD; p = 0.01) than PT boys, and higher TB BMC ( p = 0.01), TB bone area ( p = 0.03), hip BMC ( p = 0.02) and aBMD ( p = 0.01), and femoral neck BMC ( p = 0.05) and aBMD ( p = 0.02) than LP boys. There were no differences in activity measures among gestation groups and no group-by-activity interactions. Term boys have greater bone size and mass than PT boys and higher bone mass than LP boys at several bone sites. Activity measures did not differ among gestation groups and did not explain bone differences. [ABSTRACT FROM AUTHOR]