Assessment of aerobic exercise capacity in obesity, which expression of oxygen uptake is the best?

Although the impact of obesity on exercise performance is multifactorial, excessive fat mass which can impose an unfavorable burden on cardiac function and working muscle, will affect the aerobic exercise capacity. Weight loss strategies, such as bariatric surgery can obviously affect both the body composition and aerobic exercise capacity. Maximal oxygen consumption ( $\dot{\text{V}}$ O_2max) is a widely used important indicator of aerobic exercise capacity of an individual and is closely related to body weight, size and composition. An individual's aerobic exercise capacity may show different results depending on how $\dot{\text{V}}$ O_2max is expressed. The absolute $\dot{\text{V}}$ O_2max and $\dot{\text{V}}$ O_2max relative to body weight are the most commonly used indicators. The $\dot{\text{V}}$ O_2max relative to fat-free mass, lean body mass or skeletal muscle mass are not influenced by adipose tissue. The last two are more useful to precisely distinguish between individuals differing in muscle adaptation to maximum oxygen uptake. The $\dot{\text{V}}$ O_2max relative to body height is used for studying growth in children. With the in-depth study of exercise capacity and body composition in obesity, the relative oxygen uptake has been increasingly reinterpreted.