Aerobic Exercise in the Fasted State: the Effects on Energy Metabolism in Healthy Adults

There are a number of factors that can affect energy metabolism in the context of aerobic exercise and potentially play a role in the increase of aerobic capacity. Reliance on fat oxidation is one such factor and strategies are sought to maximise adaptations in enhancing this metabolic switch. A strategy that has been explored in recent years is the nutritional pattern of the fasted state. With aerobic exercise and the fasted state harnessing congruent energy metabolism pathways, this literature review aimed to investigate an important interplay between aerobic exercise in the fasted state and potential benefits for energy metabolism. The hypothesis, ‘aerobic exercise in the fasted state will enhance energy metabolism in healthy adults’, was tested through an evaluation of energy metabolism patterns with aerobic exercise in the fasted state. A review of the relevant literature since 2005 relating to the healthy adult population was undertaken, resulting in the critical appraisal of 21 articles. The findings from this review support metabolic switching in fasted state aerobic exercise, demonstrating preferential reliance on fat oxidation, enhanced glucose metabolism and mitochondrial activity, all of which is coordinated through pathways regulated by nuclear hormone receptors. Fasted state aerobic exercise can be considered beneficial for enhanced energy metabolism in both the general and athlete population.