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Incorporation of the vertical jump (VJ) test in health-related fitness batteries is predicated on the availability of prediction equations to accurately estimate VJ power. The purpose was to develop and validate a generalizable equation to estimate VJ power from VJ height, body mass, age, and sex in 10- to 18-year-olds. The sample (N = 529) performed a VJ test and had VJ power assessed via mechanography. Validation and cross-validation groups were randomly formed to assess accuracy. Results indicated that estimates of VJ power from VJ height and body mass were accurate (R = 0.93, SEE = 275 Watts). Age and sex did not add substantially to the model. Upon cross-validation, accuracy was maintained. The newly developed model was more accurate than previously published equations. The following equation provides accurate and feasible estimates of VJ power (Watts) = -1354.820 + (35.455*VJ[cm]) + (43.942*body mass[kg]). This equation provides a feasible way to estimate power in field-based settings.

We developed age- and sex-specific smoothed percentiles for vertical and long jump, as well as vertical jump power, in healthy 10-18 year olds (n = 529, 47.1% female). Jump height and distance were measured and vertical jump power was assessed via mechanography. LMS regression was used to create smoothed age-specific reference curves, separated by sex. Pearson correlations between the jumps ranged from r = 0.22 to 0.64, varying by age and sex. Comparing medians, younger males had slightly higher values for vertical and long jump compared to females. Vertical jump power was more comparable between the sexes. For all measures, differences between the sexes become more pronounced at ages associated with the transition into adolescence. Growth model coefficients are reported for calculation of Z-scores. The growth curves can be used to compare samples, track lower body power, and link tests of fitness to athletic performance or health-related outcomes.

We developed plank test standards, based on trunk lean mass-to-fat mass (LM/FM) ratio, in a sample of healthy Portuguese 10--18 year olds (n = 474, 46.4% female). Height and weight were measured and muscular endurance was assessed using the prone plank test. Trunk LM/FM ratio was determined using dual-energy x-ray absorptiometry. Plank standards were derived using receiver operator characteristic curves. Approximately 90% of youth with sufficient trunk LM/FM ratio were categorized into the desirable zone of plank time. Roughly two-thirds of those with trunk LM/FM ratio [less than or equal to] 5th percentile were identified within the undesirable zone. The odds of low trunk LM/FM were 6.5 times greater for those in the undesirable zone of plank compared those scoring above the cutpoint (independent of age, sex, or weight status). The standards provided here can be used to identify low trunk LM/FM ratio, which may have implications for balance and spinal health in youth.

Using a sample of healthy youth (n = 466, 10 to 18 yr), we report the predictive utility of vertical jump power (VJ Power, W) for predicting bone strength. We measured VJ Power using mechanography and an indicator of bone strength, i.e., height-adjusted total bone mineral content less head (TBLH BMC, g), using DXA. Growth curve models were used to convert VJ Power to age- and sex-specific percentiles/Z-scores. Associations were examined using receiver operator characteristic curve analysis, i.e., area-under-the-curve (AUC), as well as sensitivity (Se) and specificity (Sp) for Desirable, Marginal, and Low groups based on VJ Power percentiles. The AUC was 0.84 for TBLH BMC [less than or equal to] -2.0 Z-score from VJ Power percentiles. Se for Marginal and Low groups were 71.4% and 42.9%, respectively. Sp for Marginal and Low groups were 85.2% and 95.1%, respectively. The results suggest the utility of using VJ Power percentiles for assessing bone strength.

This study summarized protocols in the "Lisbon Study for the Development and Evaluation of Musculoskeletal Fitness Standards in Youth" and assessed associations between fitness assessments and health outcomes. The sample was 529 children and adolescents (10 to 18 yr). The fitness assessments included handgrip, vertical jump, long jump, plank, and lower body power. The health outcomes were total body and hip bone mineral content, hip bone mineral density, and total body lean tissue mass. Correlation analyses examined associations unadjusted and adjusted for size and maturity. After adjustment, in females, vertical jump, long jump, and lower body power were associated with all health outcomes (r = 0.22 to 0.55, p < 0.05). In males, all fitness assessments were associated with all health outcomes (r = 0.17 to 0.64, p < 0.05). Musculoskeletal fitness assessments including non-invasive and easy-to-measure field assessments are associated with important muscle and bone health outcomes in youth.

This study examined the predictive validity of musculoskeletal fitness tests for identifying sarcopenia in youth. The sample was 529 participants age 10 to 18 years. Indices included: total lean body mass (LBM) normalized for height (LBM index, LBMI, kg/m2), appendicular LBMI (aLBMI, kg/m[superscript 2]), and LBM to fat body mass (FBM) ratio (LBM/FBM). Lean and fat tissue were measured via DXA. The cutoff value for sarcopenia was -- 2.0 standard deviations [less than or equal to] mean for age and sex. Fitness was assessed using handgrip, plank, and vertical jump tests. Variables were standardized using the lambda-mu-sigma (LMS) method. By sex, analysis included the area under the curve (AUC), sensitivity (Se), and specificity (Sp). The ROC curves for aLBMI was highly accurate (AUCs [greater than or equal to] 0.90, Se and Sp = 86-88%) for vertical jump and moderately accurate for handgrip (AUCs = 0.87-0.88, Se and Sp = 71-75%). Fitness tests can be used to identify pediatric sarcopenia.

The relationship between youth-fitness test items related to cardiorespiratory endurance and body composition and health outcomes is well established. Until recent years, the link between musculoskeletal fitness measures and health markers has been less conclusive. The information provided in this article offers evidence of the health links between youth musculoskeletal measures (specifically the grip test, the vertical jump, the long jump, and the plank) and health outcomes. While additional research is necessary, it is safe to say that the new research brings us closer than ever to identifying reliable, valid, practical muscle-fitness test items. Physical education teachers can consider the suggestions provided in this article for using the test items in their classes. [ABSTRACT FROM AUTHOR]

This study examined the associations of moderate-to-vigorous intensity physical activity (MVPA) trajectories in adolescence through young adulthood with adiposity in young adults. Participants from The Iowa Bone Development Study cohort were longitudinally assessed (N = 297; 57% female). Accelerometry-measured MVPA (min/day) at ages 15 through 23 years, and fat mass and visceral adipose tissue mass indices (kg/m.sup.2, g/m.sup.2) derived from dual-energy X-ray absorptiometry scans at age 23 years were analyzed. Latent trajectory analyses classified MVPA into two patterns. Multivariable linear regression analyses showed that being in the high MVPA trajectory group was associated with lower fat mass index z-scores. Individuals who were consistently active with high MVPA (vs. moderately active with decreasing MVPA) during adolescence up until early young adulthood had less accumulation of total body adiposity in young adulthood. This study suggests that adopting a consistently active lifestyle throughout adolescence can result in healthier body composition in young adulthood., Author(s): Minsuk Oh [sup.1] , Dong Zhang [sup.2] , Kara M. Whitaker [sup.1] [sup.3] , Elena M. Letuchy [sup.3] , Kathleen F. Janz [sup.1] [sup.3] , Steven M. Levy [sup.3] [...]

Power has long been considered to be a skill-related fitness component. However, based on recent evidence, a strong case can be made for the classification of power as a health-related fitness component. Additionally, the evidence indicates that performing physical activities that build power is associated with the healthy development of bones (e.g., enhanced bone mass and architecture, reduced fracture risk) and muscles. Tests of power are good proxy measures for bone health, and the evidence provides support for including measures of power in health-related fitness test batteries for youth. The current research literature also supports the inclusion of physical activities that build power in school physical education and athletic programs, community programs, and programs for adults, including older adults.

Evidence strongly supports a positive, causal effect of physical activity on bone strength and suggests long-term benefits of childhood physical activity to the prevention of osteoporosis. The contribution of healthy bone development in youth is likely to be as important to fracture prevention as the amount of late adulthood bone loss. Families, schools (particularly physical education), and communities are key settings for health promotion focused on bone-enhancing physical activity. However, little research has explored the topic of health promotion and physical education as they pertain to bone health, so best practices are not known. Based on our understanding of the literature, we present the top 10 research questions in health promotion and physical education that should be answered to advance bone-enhancing physical activity in children and adolescents.

Purpose: The authors examined the relationship between mother and child activity. Methods: The authors compared moderate–vigorous physical activity (MVPA) and sedentary time of low-income mothers with obesity and their 6- to 12-year-old children on week (WD) and weekend (WE) days. A total of 196 mother–child pairs wore accelerometers simultaneously for a week. Mothers completed questionnaires. Spearman correlation and multivariate regression were used. Results: WE MVPA (accelerometry) was significantly correlated between mothers with children aged 6–7 (rs =.35) and daughters (rs =.27). Self-reported maternal PA time spent with one of their children was significantly correlated with the WE MVPA of all children (rs =.21) and children aged 8–10 (rs =.22) and with the WD MVPA of all children (rs =.15), children aged 8–10 (rs =.23), aged 11–12 (rs =.52), and daughters (rs =.37), and inversely correlated to the WD sedentary time of all children (rs = −.21), children aged 8–10 (rs = −.30), aged 11–12 (rs = −.34), daughters (rs = −.26), and sons (rs = −.22). In multivariate regression, significant associations were identified between reported child–mother PA time together and child MVPA and sedentary time (accelerometry). Conclusions: Mothers may influence the PA levels of their children with the strongest associations found in children aged 6–7 and daughters. Mother–child coparticipation in PA may lead to increased child MVPA and decreased sedentary behavior. [ABSTRACT FROM AUTHOR]

Purpose: Most pediatric physical activity and bone health research has focused on the period immediately around puberty; few have addressed bone structural strength outcomes. This study assessed the magnitude and consistency of the longitudinal relationships between device-measured vigorous-intensity physical activity (VPA) and structural bone strength outcomes across adolescence to emerging adulthood. Methods: Participants with 3 to 5 bone scans between the age of 11 and 19 years were studied (N = 439, 220 females, 1838 records). Dual-energy X-ray absorptiometry scans of the hip (hip structural analysis) and peripheral quantitative computed tomography scans of the tibia were obtained. Outcomes included femoral neck section modulus, femoral neck cross-sectional area, tibial Bone Strength Index, and tibial torsion strength (polar Strength Strain Index). Sex-specific bone mixed growth models were developed using biological age (chronological age − age at peak height velocity) as the time variable, and height, weight, and device-measured VPA as time-varying covariates. Models also included the VPA–biological age interaction. Results: Individual-centered VPA and the VPA–biological age interaction were significantly, positively associated (P <.05) with Bone Strength Index, polar Strength Strain Index, section modulus, and cross-sectional area in males and females, indicating accumulative effects of VPA throughout maturation and beyond. Conclusion: Bone remains responsive to the mechanical loading of physical activity throughout adolescence and into emerging adulthood. Attention should be placed on promoting bone-strengthening physical activity after the prepubertal years when adult exercise patterns are likely formed. [ABSTRACT FROM AUTHOR]