Assessment on the usual physical activity in overweight and obese adolescents

OBJECTIVES:To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation. METHODS:Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit and assessed usual physical activity. RESULTS:56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 +/- 2.3 vs 52.3 +/- 2.5 bpm, p < 0.001). However, the variations in BP did not supply reliable assessment of usual physical activity. The activity questionnaire had been filled in satisfactorily by 72% of subjects. In 95% of cases, the classification of subjects as S or A by the step-test agreed with the classification based on the questionnaire. CONCLUSION:The step-test provided the rapid and reliable assessment of usual physical activity of the children (from 6-7 years of age) in 95% of cases during a routine consultation (30 min), and the activity questionnaire enabled the doctor to check the conclusions of the step-test and recommend to the parents physical activities adapted to the physical capacities of their children.