Background Weight loss and improving cardiorespiratory fitness are key treatment outcomes for obese individuals with Obstructive Sleep Apnoea (OSA). We investigated the total energy expenditure and cardiorespiratory response to weight supported (cycling) and unsupported (walking) at two different intensities.
Methods Individuals with treated OSA and a BMI >30 kg/m2 performed an incremental cardiopulmonary exercise test on a cycle ergometer (ICE) and a treadmill (ITM) with expired gas analysis to determine the peak oxygen uptake (VO2pk). Participants completed two endurance tests on each modality matched at 80% and 60% of the highest VO2pk determined by the incremental tests. The cardiorespiratory responses were measured and total energy expenditure was estimated from the VO2.
Results 16 participants (8 male) completed all six tests: mean [SD] age 57y and median [IQ range] BMI 33.3[30.8 to 35.3]kg·m-2. The VO2pk on the ITM vs ICE was 2268 vs 1775ml·min-1, respectively. Participants endured treadmill walking at 80% and 60% VO2pk for four and nearly three times as long, respectively, compared to cycling with similar cardiovascular responses. The pattern of energy expenditure during rest, exercise and recovery at matched intensities (Figure 1) was similar between modalities at matched intensities.
Total energy expenditure during treadmill walking was greater than cycling at both high (158 versus 29kcal) and moderate (178 versus 85kcal) intensities. For a thrice weekly exercise regimen of at least moderate intensity, treadmill exercise would typically result in a total of 388 and 277 kcal/week greater energy expenditure than cycle exercise at 80% and 60% VO2pk, respectively.