Moderate-to-vigorous physical activity (MVPA) improves aerobic fitness in children, which is usually assessed by maximal oxygen consumption. However, other indices of aerobic fitness have been understudied.
To compare net oxygen (VO2net), net energy consumption (Enet), net mechanical efficiency (MEnet), and lipid oxidation rate in active and inactive children across body weight statuses.
The sample included normal-weight, overweight, and obese children of whom 44 are active (≥30 min of MVPA/d) and 41 are inactive (<30 min of MVPA/d). VO2net, Enet, MEnet and lipid oxidation rate were determined during an incremental maximal cycling test.
Active obese participants had significantly lower values of VO2net and Enet and higher MEnet than inactive obese participants at all load stages. In addition, active obese participants showed a significantly higher lipid oxidation rate compared with inactive obese and active overweight and normal-weight participants. VO2net, Enet, and MEnet were similar across active children, regardless of body weight status.
Thirty minutes or more of MVPA per day is associated with a potentiation of aerobic fitness indicators in obese prepubertal children. Moreover, the indices of aerobic fitness of inactive obese children are significantly different from those of active obese and nonobese ones.