Does Endurance Training Protect From Lipotoxicity?

Modest regular exercise and reduction of die-tary fat halves the risk of developing type 2diabetes. In overt type 2 diabetes, higherlevels of exercise training improve glycemic control, whereas the impact of diet and optimal dietary composition are presently unknown (1). Thus, one can assume that intensive exercise protects from diet-induced insulin resistance. Intravenous lipid infusion is an estab-lished model to increase plasma free fatty acids (FFAs) and induce insulin resistance (2,3). Although plasma FFAs and intramyocellular lipid (IMCL) inversely correlate with insulin sensitivity in sedentary humans, athletes store more IMCL despite greater insulin sensitivity. This has been termed the “athletes ’ paradox ” (4). In this issue of Diabetes, Phielix et al. (5) hypothesize that, relative to their untrained counterparts, the high ox-idative capacity of endurance-trained athletes attenuates lipid-induced insulin resistance during hyperinsulinemic