Responses of non-obese white children to treadmill exercise

Objective: To determine the response to maximal treadmill exercise with the Bruce protocol in a cohort of healthy non-obese American children and adol escents. Study design: A retrospective review of treadmill exercise studies on 347 w hite American children (188 boys, 159 girls) aged 5 to 18 years was perform ed with metabolic criteria to verify maximal exercise effort. Data on exerc ise endurance time, heart rate, blood pressure, and metabolic variables wer e assessed and compared between age groups and sexes by unpaired t testing and analysis of variance. Results: Exercise endurance time was lower in all age groups when compared with earlier published data. Girls had a lower endurance time than boys at all ages. There was no significant difference in maximum heart rate with re spect to age or sex. The maximum systolic blood pressure and diastolic bloo d pressure increased with increasing age in both boys and girls. Boys had s ignificantly higher maximum systolic blood pressure and diastolic blood pre ssure after 13 years of age. The maximum absolute oxygen consumption and in dexed oxygen consumption showed similar trends for both sexes. Conclusion: Lower exercise endurance times are seen despite physiologic evi dence of maximal effort, raising the possibility that cardiovascular condit ioning is reduced in contemporary American children.