Triglyceride metabolism in exercising muscle.

Triglycerides are stored within lipid droplets in skeletal muscle and can be hydrolyzed to produce fatty acids for energy production through β-oxidation and oxidative phosphorylation. While there was some controversy regarding the quantitative importance of intramyocellular triglyceride (IMTG) as a metabolic substrate, recent advances in proton magnetic resonance spectroscopy and confocal microscopy support earlier tracer and biopsy studies demonstrating a substantial contribution of IMTG to energy production, particularly during moderate-intensity endurance exercise. This review provides an update on the understanding of IMTG utilization during exercise, with a focus on describing the key regulatory proteins that control IMTG breakdown and how these proteins respond to acute exercise and in the adaptation to exercise training. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.