Acute EPOC response in women to circuit training and treadmill exercise of matched oxygen consumption

Abstract

The purpose of the study was to evaluate the effects of circuit training (CT) and treadmill exercise performed at matched rates of oxygen consumption and exercise duration on elevated post-exercise oxygen consumption (EPOC) in untrained women, while controlling for the menstrual cycle. Eight, untrained females (31.3±9.1 years; 2.04±0.26 l min⁻¹ estimated VO_2max; BMI=24.6±3.9 kg/m²) volunteered to participate in the study. Testing was performed during the early follicular phase for each subject to minimize hormonal variability between tests. Subjects performed two exercise sessions approximately 28 days apart. Resting, supine energy expenditure was measured for 30 min preceding exercise and for 1 h after completion of exercise. Respiratory gas exchange data were collected continuously during rest and exercise periods via indirect calorimetry. CT consisted of three sets of eight common resistance exercises. Pre-exercise and exercise oxygen consumption was not different between testing days (P>0.05). Thus, exercise conditions were appropriately matched. Analysis of EPOC data revealed that CT resulted in a significantly higher (p<0.05) oxygen uptake during the first 30 min of recovery (0.27±0.01 l min⁻¹ vs 0.23±0.01 l min⁻¹); though, at 60 min, treatment differences were not present. Mean VO₂ remained significantly higher (0.231±0.01 l min⁻¹) than pre-exercise measures (0.193±0.01 l min⁻¹) throughout the 60-min EPOC period (p<0.05). Heart rate, RPE, V_E and RER were all significantly greater during CT (p<0.05). When exercise VO₂ and exercise duration were matched, CT was associated with a greater metabolic disturbance and cost during the early phases of EPOC.