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.
Kathleen F. Janz and Shelby L. Francis
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.