Individual Variability in Waist Circumference and Body Weight in Response to Exercise.

This study aimed to determine the magnitude of exercise-induced individual variability for waist circumference (WC) and body weight change after accounting for biological variability and measurement error. Determinants of response variability were also considered. Participants (53 ± 7.5 yr) were 181 adults (61% women) with abdominal obesity randomized to the following: control; low-amount, low-intensity exercise (LALI); high-amount, low-intensity exercise (HALI); or high-amount, high-intensity exercise (HAHI) for 24 wk. Unstructured physical activity was measured by accelerometer. The variability in response to exercise for WC and body weight (SDR) was isolated by subtracting the SD values for the change scores in the exercise group from that of the control group. The variability of response due to exercise (SDR) for change in WC was 3.1, -0.3, and 3.1 cm for LALI, HALI, and HAHI groups, respectively. Corresponding values for body weight were 3.8, 2.0, and 3.5 kg for LALI, HALI, and HAHI, respectively. The high-amount exercise groups yielded the highest proportion of individuals with a clinically meaningful response. No variables predicted the response to exercise (P > 0.05). Substantial variability in response to standardized exercise was observed for change in both WC and body weight after accounting for the variability not attributed to exercise. Potential determinants of the interindividual variability in response to exercise remain unclear.