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

Area of Science:

• Exercise Physiology
• Sports Science
• Weight Management

Background:

• Rating of perceived exertion (RPE) and respiratory exchange ratio (RER) are linked to acute exercise responses.
• Long-term adaptations in RPE and RER with exercise training are less understood, particularly concerning weight loss outcomes.

Purpose of the Study:

• To investigate how RPE and RER adapt over 24 weeks of exercise training.
• To compare these adaptations between individuals who did and did not achieve expected weight loss (compensators vs. noncompensators).
• To examine the relationship between RPE, RER, training intensity, and weight loss achievement.

Main Methods:

• 110 participants (49±12 yr) underwent 24 weeks of supervised exercise (8 or 20 kcal·kg body wt⁻¹·wk⁻¹).
• Participants were categorized as noncompensators or compensators based on % expected weight loss (%EWL).
• RPE, RER, heart rate, and %V̇o₂peak were measured at baseline, week 12, and week 24.

Main Results:

• RPE and RER decreased from baseline to week 12, then stabilized, irrespective of weight compensation.
• Noncompensators exhibited higher RPE relative to heart rate, partly due to higher %V̇o₂peak.
• Both RPE and %V̇o₂peak positively predicted %EWL, independent of other factors.

Conclusions:

• Individual adaptations in perceived exertion are associated with achieving expected weight loss in overweight/obese individuals.
• Higher relative perceived exertion and self-selected training intensity correlate with greater weight loss.
• Understanding individual exercise intensity and behavioral responses can enhance exercise-based weight management strategies.