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 57[13]y and median [IQ range] BMI 33.3[30.8 to 35.3]kg·m^-2. The VO₂pk on the ITM vs ICE was 2268[574] vs 1775[430]ml·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[101] versus 29[15]kcal) and moderate (178[100] versus 85[59]kcal) 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.

Conclusion Contrary to current guidelines, walking might be the preferred training modality for achieving the combination of weight loss and increased cardiorespiratory fitness in obese adults with OSA.

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Abstract S125 Figure 1

A comparison of the energy expenditure between weight-unsupported (treadmill) and -supported (cycling) exercise in obese adults with OSA