Role of Various Anthropometric Indicators of Obesity and Physical Activity on Oxygen Uptake and Fat Oxidation during Moderate-Intensity Aerobic Exercise in Adults: A Secondary Analysis

Obesity and physical activity have opposing effects on cardiorespiratory fitness. This study aimed to investigate the impact of obesity measured by various anthropometric indicators and physical activity level on oxygen uptake and fat oxidation during moderate-intensity aerobic exercise in adults. Forty-eight individuals were recruited. Various anthropometric indicators (i.e., body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR)) were measured. Physical activity was assessed using the International Physical Activity Questionnaire (a short version). Total oxygen uptake (VO2tot) and fat oxidation were recorded during 30-minute aerobic exercise at moderate intensity. There were no differences in oxygen uptake and fat oxidation between obese and non-obese groups. Based on obesity and physical activity, VO2tot was significantly different among groups classified by WHR. Inactive obesity had significantly lower VO2tot 28.1% compared to active obesity and 29.2 % compared to active non-obesity. The inactive obesity had a 3.8%, 27.4%, and 4.3% lower fat oxidation than the active non-obesity, as classified by WC, WHR, and WHtR, respectively. However, the differences were not statistically significant. We conclude that active obesity, as measured by WHR, exhibited higher oxygen uptake compared to inactive obesity. Moreover, inactive obesity showed poorer oxygen uptake than active non-obesity.