The Influence Of Non-exercise Physical Activity During Aerobic Exercise On Cardiometabolic Risk Factors

Abstract

PURPOSE: To determine the impact of changes in non-exercise physical activity on changes in cardiometabolic risk factors in participants performing aerobic exercise training. METHODS: Obese adults (N=25) were randomized to an aerobic training group or an aerobic training and increasing non-exercise physical activity group. Both groups performed supervised aerobic training (50%-75% VO2 max) for 24 weeks at a dose of 12 kcals per kg per week. Non-exercise physical activity (total steps, minutes in low, moderate to vigorous [MVPA] physical activity) was quantified during the entire intervention using Fitbit One accelerometers (removed during supervised exercise sessions). Cardiometabolic assessments included lipids, glucose, insulin, 2-hour glucose/insulin from an oral glucose tolerance test, fitness, and body composition measures (% body fat, weight, and waist circumference). Linear regression models were run with change in the cardiometabolic variable as the dependent variable and baseline value, age, race, sex, supervised exercise time, adherence to exercise dose, change in non-exercise physical activity variables (change in total steps, minutes in light intensity and minutes in MVPA) as predictor variables. RESULTS: Change in total steps was a significant predictor for change in weight (r2= 0.17, p=0.04), percent weight loss (r2= 0.18, p=0.03, waist circumference (r2=0.31, p=0.004), triglycerides (r2= 0.30, p=0.01) and relative fitness (r2= 0.19, p=0.03). Change in total steps approached significance as a predictor for absolute fitness (p=0.052) and body fat (p=0.059). Change in minutes in low intensity was a significant predictor of the change in 2-hour glucose (r2= 0.20, p=0.03). Change in MVPA was not associated with change in any cardiometabolic variables (all ps>0.05). Change in non-exercise physical activity did not predict changes in glucose, insulin, 2-hour insulin, low density lipoprotein, high density lipoprotein, total cholesterol, or lean mass levels (all ps>0.05). CONCLUSIONS: Change in non-exercise physical activity outside of aerobic training was associated with changes in several cardiometabolic variables. Increasing total steps or minutes in low intensity may represent a clinical target to maximize the health benefits of aerobic exercise training in obese adults.