Physiological response is similar in overweight and normoweight boys during cycling: A longitudinal study

Abstract

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.

The Effect of Body Mass Index on Acute Cardiometabolic Responses to Graded Exercise Testing in Children: A Narrative Review

“…Indirect calorimetry also provides information about the nutrients’ (carbohydrates, lipids, and protein) oxidation, which can be quantified using the RQ, i.e., the ratio of the carbon dioxide removed from the body divided by the oxygen consumed in the tissues [76]. Typical values of RQ range from 0.7 (lipid oxidation) to 1.0 (carbohydrate oxidation); thus, the estimation of RQ for a given exercise characterizes the substrate oxidation [30]. A comparison of BMI groups showed no difference in lipid oxidation during various submaximal loads of a GXT in prepubescent girls, but higher lipid oxidation in obese pubescent girls [77].…”

“…A comparison of BMI groups showed no difference in lipid oxidation during various submaximal loads of a GXT in prepubescent girls, but higher lipid oxidation in obese pubescent girls [77]. However, no difference in RQ was observed between normal-weight and overweight boys [30].…”

“…It should be highlighted that the exercise mode might influence the differences in cardiometabolic responses between normal- and overweight participants in the studies under examination, because the body is supported on a cycle ergometer, in contrast to a treadmill or step, and this might attenuate the effect of BM. In this line, a study on a cycle ergometer reported similar cardiometabolic response to exercise between normal- and overweight children [30]. Furthermore, it has been shown that at similar levels of HR, obese adolescents had had higher VO 2 , energy expenditure, and fat oxidation during exercise on a treadmill than on a cycle ergometer [43].…”

“…Testing aerobic capacity usually takes place either in a laboratory setting or in the field. In a laboratory, exercise testing is performed on calibrated equipment, which might be a treadmill [22,26,27,28,29], a cycle ergometer [30,31,32], or a step [33,34,35,36], whereas in field testing, participants run a certain distance as fast as they can, e.g., 1 mile run/walk [37], or try to cover the longest distance within a given time, e.g., 12 min run/walk [18], or run with an incremental speed as much as they can, e.g., 20 m shuttle run test [17]. The tests conducted in field—where the environmental conditions (e.g., temperature, humidity, wind, and noise) vary and may interfere with the outcome—are less valid and reliable than those conducted in a laboratory [38,39,40].…”