Determinants of fat oxidation during exercise in healthy men and women: a cross-sectional study

2003.—The aim of the present study was to establish fat oxidation rates over a range of exercise intensities in a large group of healthy men and women. It was hypothesised that exercise intensity is of primary importance to the regulation of fat oxidation and that gender, body composition, physical activity level, and training status are secondary and can explain part of the observed interindividual vari-ation. For this purpose, 300 healthy men and women (157 men and 143 women) performed an incremental exercise test to exhaustion on a treadmill [adapted from a previous protocol (Achten J, Venables MC, and Jeukendrup AE. Metabolism 52: 747–752, 2003)]. Substrate oxidation was determined using indirect calorimetry. For each indi-vidual, maximal fat oxidation (MFO) and the intensity at which MFO occurred (Fatmax) were determined. On average, MFO was 7.8 0.13 mg kg fat-free mass (FFM)1 min1 and occurred at 48.3 0.9% maximal oxygen uptake (V ˙ O2 max), equivalent to 61.5 0.6 % max