The purpose of this study was to determine whether metabolic cost is similar in overweight and normoweight children when workload during exercise on a cycle-ergometer is adjusted relative to an objectively determined second ventilatory threshold (VT2) or the maximal workload (Pmax). The tests were conducted every 2 years: first at the age of 10 years and the third test at around the age of 14 years. The levels of maximal oxygen consumption (VO(2)max), Pmax, and the VT2 were determined by means of graded tests on a cycle ergometer. The main test consisted of two 6-minute exercises of submaximal constant intensity (below and above VT2) performed on a cycle ergometer, with a 4-minute recovery between efforts. The workload during cycling was adjusted individually for each participant and adjusted to the values determined in the graded test: workload at VT2 and Pmax. Physiological response (absolute and relative to free-fat mass oxygen uptake, heart rate, pulmonary ventilation, tidal volume, and breathing frequency) is similar in overweight and normoweight boys when workload on a cycle ergometer is adjusted to VT2. The only significant intergroup difference was seen in relative to body mass oxygen intake.
Keywords: body composition; exercise physiology; obesity; oxygen uptake; physical activity; ventilatory threshold.