Reduced Muscle Oxidative Capacity During and After Exercise in Older Adults With Obesity

Abstract Objective Obesity and physical activity are two major factors affecting aerobic performance in older adults. The underlying mechanisms of the causes are still unknown. Oxidative capacity, muscles’ maximal capacity to utilize oxygen, is a part of aerobic performance. Muscle oxygen level (SmO2), a measure of oxidative capacity, reflects the balance between oxygen delivery and oxygen demand. When oxygen delivery surpasses oxygen demand, SmO2 increases, which indicates higher oxidative capacity. This study aimed to identify the influence of obesity and physical activity level on SmO2 changes during and after short exercise. Methods This is a cross-sectional study. SmO2 changes during and after a bilateral heel-raise (BHR) test were measured in 60 community-dwelling older adults (≥ 60 years old) in four groups: inactive obese, active obese, inactive non-obese, and active non-obese. Inactive is defined as performing less than 150 minutes/week moderate-intensity activity. Results The inactive obese group took a longer time for SmO2 drop during the BHR test, had a lower SmO2 level at the end, and recovered slower after the test than all other groups. Especially, compared with the active non-obese group, this group exhibited significantly poorer SmO2 recovery one minute after the test, 5.3% less (p=.036). The active obese group’s oxidative capacity was similar to the inactive non-obese group, although lower than the active non-obese group. Discussion To prevent physical decline in older adults with obesity, regular exercise has been recommended. This study substantiated this from a hemodynamics viewpoint. Older adults with obesity need 150+ minutes/week moderate-intensity exercise.