Physiologic responses to a thermogenic nutritional supplement at rest, during low-intensity exercise, and during recovery from exercise in college-aged women

Abstract

This study examined acute physiologic responses to a thermogenic nutritional supplement at rest, during exercise, and during recovery from exercise in women. Twelve women (mean ± SD age, 22.9 ± 3.1 years) were recruited for this randomized, double-blinded, placebo-controlled, crossover study. Each testing session consisted of 4 phases: 30 min of presupplementation resting, followed by the ingestion of the placebo or thermogenic nutritional supplement; 50 min of postsupplementation resting; 60 min of walking (at 3.2-4.8 km·h-1); and 50 min of postexercise resting. Energy expenditure (EE), oxygen consumption, respiratory exchange ratio (RER), oxygen (O2) pulse, and heart rate (HR) values were recorded during all 4 phases. Systolic (SBP) and diastolic (DBP) blood pressure were recorded during the rest, postsupplementation, and postexercise recovery phases; ratings of perceived exertion (RPE) were recorded only during exercise. There were no significant differences for EE, oxygen consumption, O2 pulse, HR, SBP, or DBP between the supplement and placebo during the presupplementation resting or postsupplementation phases. The RER, however, was higher with the supplement at 30 min postsupplementation. During exercise, EE and O2 pulse were 3%-6% greater with the supplement than placebo; there were no significant differences in RPE. Postexercise, EE, oxygen consumption, and DBP were 3%-7% greater with the supplement than placebo. These findings suggest that a thermogenic nutritional supplement, when combined with exercise, increases metabolic rate but has no effect on the perception of effort and results in only minimal changes in cardiovascular function.