Children-Adult Comparisons of VO₂And HR Kinetics During Submaximum Exercise

Oxygen uptake (VO₂) and heart rate (HR) kinetics for submaximum exercise were compared in prepubescent boys (mean age ±SD = 10.2 ± 1.28 years, N = 21) and adult men (30.0 ± 5.64 years, N = 21). Standard open circuit spirometric techniques were used to determine VO₂ and a bipolar ECG was used to measure HR. The kinetics of VO₂ and HR were determined for each subject using graphic procedures. Subjects performed submaximum exercise on the bicycle ergometer at an intensity of 42 ± 1.3% (mean ± SE) of VO₂ max for the children and 39 ± 0.7% of VO₂ max for the adults (p =.07). There were no group differences in VO₂ t½ (children t½ = 18.5 ± 0.75 sees and adults t½ = 17.4 ± 0.39 sees, p =.18) and HR t½ (children t½ = 11.4 ± 1.86 sees and adults t½ = 13.6 ± 1.66 secs, p =.38). These data suggest that children and adults do not differ in cardiorespiratory adjustments during low intensity exercise. This is in contrast to suggestions of other investigators that children have a faster cardiovascular adjustment to exercise.