Maximal lipid oxidation during exercise (Lipox_(max)): From physiological measurements to clinical applications. Facts and uncertainties

摘要

There is an intensity of exercise that elicits a maximal oxidation of lipids and has been termed Lipox_(max), Fatox_(max)or Fat_(max). The measurement of Lipox_(max) by graded exercise calorimetry appears to be a reproducible measurement, although modifiable by several physiological conditions (training, previous exercise or meal). Its measurement closely predicts what will be oxidized over 45-60 minutes of low to medium intensity training performed at the corresponding intensity. It might be a marker of metabolic fitness, and reflects mitochondrial respiration. Lipox_(max) is related to catecholamine status and the growth-hormone IGF-I axis. Its changes are related to alterations in muscular levels of citrate synthase, and to the mitochondrial ability to oxidize fatty acids. A meta-analysis shows that training at this level is efficient for reducing fat mass, sparing fat-free mass, increasing the ability to oxidize lipids during exercise, reducing blood glucose and HBA1c in type2 diabetes, and decreasing circulating cholesterol.