Fatness is not a factor of fitness: analysis of cardiorespiratory data from healthy children over an 8-year period

Abstract

AbstractPurposeTo evaluate exercise performance and body mass index in healthy children over an 8-year period in order to determine whether cardiorespiratory fitness has decreased relative to changes in body mass index in our patient population.MethodThis study is a retrospective review of anthropometric and cardiorespiratory fitness data from our hospital's Exercise Physiology Laboratory's database on 1201 healthy children (6–18 years) with structurally normal hearts who performed one cycle ergometry test between 1999 and 2006. Subjects were stratified by gender and age. Body mass index was compared between 1999–2002 (Early Group) and 2003–2006 (Late Group) and with national averages. Exercise outcome variables were maximal oxygen consumption, anaerobic threshold, physical working capacity indexed to body weight. Analysis of variance was used to detect differences between groups for each outcome variable.ResultsBody mass index was not significantly different from national data (p-value equals 0.79) or between groups. A negative trend (p-value greater than 0.15 less than 0.20) was observed among most indices of exercise performance between Early and Late Groups. Significantly lower anaerobic threshold was found among males between Early and Late Group (25.7 plus or minus 0.9 versus 23.4 plus or minus 1.6 millilitres per kilogram per minute, p-value less than 0.01), and in physical working capacity among females between Early and Late Groups (2.9 plus or minus 0.1 versus 2.7 plus or minus 0.1, p-value less than 0.05).ConclusionsCardiorespiratory fitness in males and working capacity in females declined over time independent of body mass index. This suggests that other measures may need to be evaluated for promotion of overall cardiovascular health.