The influence of age, sex and cardiorespiratory fitness on maximal fat oxidation rate

• Published in: Applied physiology, nutrition, and metabolism Vol. 46; no. 10; pp. 1241 - 1247
• Main Authors: Frandsen, J, Amaro-Gahete, F.J, Landgrebe, A, Dela, F, Ruiz, J.R, Helge, J.W, Larsen, S
• Format: Journal Article
• Language: English
• Published: 1840 Woodward Drive, Suite 1, Ottawa, ON K2C 0P7 NRC Research Press 01.10.2021; Canadian Science Publishing NRC Research Press
• Subjects: Absorptiometry, Photon; Adipose Tissue - metabolism; Adult; Age; Age Factors; Age groups; Aging; Calorimetry, Indirect; Cardiorespiratory Fitness; Cardiovascular system; Cross-Sectional Studies; Demographic aspects; Exercise; Exercise physiology; Exercise Test; fat oxidation; Female; Gender differences; Health aspects; Humans; Lipid metabolism; Lipid peroxidation; Male; Maximum oxygen consumption; Mens health; Middle Aged; Oxidation; Oxidation-Reduction; oxydation des graisses; Physical fitness; Physiological aspects; Physiological research; Respiration; Respiratory physiology; sex; Sex Factors; sexe; vieillissement; Womens health; Denmark; sexe; oxydation des graisses; aging; fat oxidation; sex; vieillissement
• ISSN: 1715-5312; 1715-5320
• DOI: 10.1139/apnm-2021-0080

Fat oxidation decreases with age, yet no studies have previously investigated if aging affects the maximal fat oxidation rate (MFO) during exercise in men and women differently. We hypothesized that increased age would be associated with a decline in MFO and this would be more pronounced in women due to menopause, compared with men. In this cross-sectional study design, 435 (247/188, male/female) subjects of varying ages performed a DXA scan, a submaximal graded exercise test and a maximal oxygen uptake test, to measure MFO and cardiorespiratory fitness (CRF) by indirect calorimetry. Subjects were stratified into 12 groups according to sex (male/female), age (<45, 45–55 and >55 years), CRF (below average and above average). Women aged <45 years had a higher MFO relative to fat free mass (FFM) (mg/min/kg) compared with men, regardless of CRF. However, there were no differences in MFO (mg/min/kg FFM) between men and women, in the groups aged between 45–55 and >55 years. In summary, we found that women aged <45 years display a higher MFO (mg/min/kg FFM) compared with men and that this sexual divergence is abolished after the age of 45 years. Novelty: Maximal fat oxidation rate is higher in young women compared with men. This sex-related difference is attenuated after the age of 45 years. Cardiorespiratory fitness does not influence this sex-related difference.