Uncertain association between maximal fat oxidation during exercise and cardiometabolic risk factors in healthy sedentary adults.

The present work examines the relationships between maximal fat oxidation during a graded exercise test (MFO), the intensity of exercise that elicits MFO (Fatmax), and traditional cardiometabolic risk factors in healthy, sedentary adults. A total of 119 (81 women) young, sedentary adults (22.1 ± 2.2 years old), and 71 (37 women) middle-aged, sedentary adults (53.4 ± 4.9 years old) participated in the current study. Systolic and diastolic blood pressures were determined following standard procedures. Plasma glucose, insulin, total cholesterol, high-density lipoprotein cholesterol and triglycerides were determined in a fasted state and the homeostatic model assessment of insulin resistance index and low-density lipoprotein cholesterol levels subsequently calculated. A sex and age group-specific cardiometabolic risk Z-score was also calculated for each subject based on waist circumference, systolic and diastolic blood pressure, plasma glucose, high-density lipoprotein cholesterol and triglycerides. MFO and Fatmax were determined using a walking graded exercise test using indirect calorimetry. No clear association was seen of MFO and Fatmax with any cardiometabolic risk factor (all P≥0.05), except for a weak, inverse association between Fatmax and the fatty liver index (P=0.027). Similarly, neither MFO nor Fatmax was apparently associated with the cardiometabolic risk Z-score (all P≥0.05). The current findings suggest an uncertain association of MFO and Fatmax during a graded exercise test with the cardiometabolic profile of healthy, sedentary adults.HighlightsThe study of the physiological mechanisms that trigger the onset of metabolic disorders has received considerable attention in recent years, with changes in MFO and Fatmax being highlighted as a potential key factor.This work shows that MFO and Fatmax during a graded exercise test are not associated with the cardiometabolic profile in sedentary, healthy adults.Further studies are needed to elucidate which other physiological disorders are related to cardiometabolic risk.