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Kathleen F. Janz and Shelby L. Francis

Although there is strong and consistent evidence that childhood and adolescent physical activity is osteogenic, the evidence concerning its sustained effects to adult bone health is not conclusive. Therefore the value of interventions, in addition to beneficial bone adaptation, could be exposure to activities children enjoy and therefore continue. As such, interventions should provide skills, pleasure, and supportive environments to ensure continued bone-strengthening physical activity with age. Until the dose-response as well as timing of physical activity to bone health is more fully understood, it is sensible to assume that physical activity is needed throughout the lifespan to improve and maintain skeletal health. Current federal guidelines for health-related physical activity, which explicitly recommend bone-strengthening physical activities for youth, should also apply to adults.

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Shelby L. Francis, Ajay Singhvi, Eva Tsalikian, Michael J. Tansey, and Kathleen F. Janz


Determining fitness is important when assessing adolescents with type 1 diabetes mellitus (T1DM). Submaximal tests estimate fitness, but none have been validated in this population. This study cross-validates the Ebbeling and Nemeth equations to predict fitness (VO2max (ml/kg/min)) in adolescents with T1DM.


Adolescents with T1DM (n = 20) completed a maximal treadmill test using indirect calorimetry. Participants completed one 4-min stage between 2.0 and 4.5 mph and 5% grade (Ebbeling/Nemeth protocol). Speed and grade were then increased until exhaustion. Predicted VO2max was calculated using the Ebbeling and Nemeth equations and compared with observed VO2max using paired t tests. Pearson correlation coefficients, 95% confidence intervals, coefficients of determination (R2), and total error (TE) were calculated.


The mean observed VO2max was 47.0 ml/kg/min (SD = 6.9); the Ebbeling and Nemeth mean predictions were 42.4 (SD = 9.4) and 43.5 ml/kg/min (SD = 6.9), respectively. Paired t tests resulted in statistically significant (p < .01) mean differences between observed and predicted VO2max for both predictions. The association between the Ebbeling prediction and observed VO2max was r = .90 (95% CI = 0.76, 0.96), R 2 = .81, and TE = 6.5 ml/kg/min. The association between the Nemeth prediction and observed VO2max was r = .81 (95% CI = 0.57, 0.92), R 2 = .66, and TE = 5.6 ml/kg/min.


The Nemeth submaximal treadmill protocol provides a better estimate of fitness than the Ebbeling in adolescents with T1DM.

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Brad R. Julius, Amy M.J. O’Shea, Shelby L. Francis, Kathleen F. Janz, and Helena Laroche

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 (r s = .35) and daughters (r s = .27). Self-reported maternal PA time spent with one of their children was significantly correlated with the WE MVPA of all children (r s = .21) and children aged 8–10 (r s = .22) and with the WD MVPA of all children (r s = .15), children aged 8–10 (r s = .23), aged 11–12 (r s = .52), and daughters (r s = .37), and inversely correlated to the WD sedentary time of all children (r s = −.21), children aged 8–10 (r s = −.30), aged 11–12 (r s = −.34), daughters (r s = −.26), and sons (r s = −.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.

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Katie R. Hosteng, Jacob E. Simmering, Linnea A. Polgreen, James F. Cremer, Alberto M. Segre, Shelby L. Francis, Kara M. Whitaker, Philip M. Polgreen, and Lucas J. Carr

Background: Regular physical activity is crucial for healthy aging, but older adults are the least active age group. This study explored the feasibility, acceptability, and efficacy of a multilevel mHealth intervention for increasing physical activity of older adults living in a retirement community. Methods: Participants included 54 older adults (mean age = 81.2 y, 77.8% female, 98.1% white) living in a retirement community. Participants received a Fitbit Zip and access to a multilevel mHealth physical activity intervention (MapTrek Residential) for 8 weeks. Physical activity (in steps per day) and intervention compliance (days worn) were measured objectively with the Fitbit for 12 weeks (8-wk intervention plus 4-wk follow-up). Psychosocial outcomes (social support, self-efficacy, and outcome expectations) were assessed at baseline and 8 weeks. Acceptability outcomes were assessed with an open-ended process evaluation survey and focus groups. Descriptive statistics and linear mixed models were used to examine intervention effects. Results: Participants increased daily steps from 5438 steps per day at baseline (95% CI, 4620 to 6256) to 6201 steps per day (95% CI, 5359 to 7042) at week 8 (P < .0001) but this was not maintained at 12 weeks (P = .92). Conclusions: Our multilevel mHealth physical activity intervention was effective for increasing physical activity older adults over 8 weeks. Additional research focused on maintaining physical activity gains with this approach is warranted.