Oxygen uptake and heart rate kinetics of body mass-based squat exercise in children and adults

This study aims to clarify oxygen uptake (VO2) and heart rate (HR) kinetics of body mass-based squat exercise (SQBM) with relation to age. Fourteen healthy adults and 19 healthy children performed SQBM 200 times as well as an incremental loaded bicycle test to determine maximal VO2 and HR. The V O2 and HR during SQBM were normalized to maximal VO2 (%V O2peak) and HR (%HRmax), respectively. Electromyograms (EMGs) were recorded from the vastus lateralis, rectus femoris, vastus medialis and biceps femoris muscles from the right leg. In the VO2 and HR during SQBM, the time constant in children was faster than adults, whereas the physiological load (%VO2peak and %HRmax) was almost the same between children and adults. In both groups, %VO2peak was significantly related to %HRmax during SQBM. The slope of the %VO2peak-%HRmax relationship was 0.92 for children, and 0.73 for adults. The current results demonstrate that, compared to adults, the rise in VO2 and HR after initiation of SQBM is faster in children, and the physiological load during SQBM partially depends on individual maximal aerobic capacity.