Adaptations to exercise in compensators and noncompensators in the E-MECHANIC Trial

Abstract

Adaptations to exercise in compensators and noncompensators in the E-MECHANIC Trial. J Appl Physiol 129: 317–324, 2020. First published July 16, 2020; doi:10.1152/japplphysiol.00826.2019.—Rating of perceived exertion (RPE) and respiratory exchange ratio (RER) have previously been associated with acute exercise compensation. This study examined adaptations in the RPE and RER with long-term exercise training in individuals who did (noncompensators) and did not (compensators) lose the expected amount of weight. Participants (n = 110, 71.8% women, means ± SD; age 49 ± 12 yr) completed 24 wk of supervised exercise training at 65– 85% V O2peak to achieve a prescribed dose of 8 kcal·kg body wt 1·wk 1 (8 KKW) or 20 KKW. Participants were categorized as noncompensators (n = 55) or compensators (n =55) based on the percent of expected weight loss (%EWL) achieved. Changes in RPE and RER during exercise over time (baseline, week 12, week 24) were compared by weight compensation category. Individual %EWL in relation to RPE, RER, and training intensity (%V O2peak) was evaluated over the same time period. RPE and RER for a given workload decreased from baseline to week 12 and stabilized through week 24, regardless of weight compensation (time P < 0.0001). Noncompensators had a higher RPE relative to heart rate, which was partly explained by higher %V O2peak. RPE and %V O2peak both positively predicted %EWL, independent of age, sex, and exercise dose. Training intensity and RPE were positively associated with weight loss on the individual level, warranting further investigation into self-selection in exercise-based programs. Understanding individual heterogeneity in training intensity and behavioral responses may improve future weight management efforts that involve exercise.