Endurance training protocol and longitudinal performance assays for Drosophila melanogaster

One of the most pressing problems facing modern medical researchers is the surging levels of obesity, with the consequent increase in associated disorders such as diabetes and cardiovascular disease (1-3). An important topic of research into these associated health problems involves the role of endurance exercise as a beneficial intervention. Exercise training is an inexpensive, non-invasive intervention with several beneficial results, including reduction in excess body fat (4), increased insulin sensitivity in skeletal muscle (5), increased anti-inflammatory and antioxidative responses (6), and improved contractile capacity in cardiomyocytes (7). Low intensity exercise is known to increase mitochondrial activity and biogenesis in humans (8) and mice, with the transcriptional coactivator PGC1-α as an important intermediate (9,10). Despite the importance of exercise as a tool for combating several important age-related diseases, extensive longitudinal genetic studies have been impeded by the lack of an endurance training protocol for a short-lived genetic model species. The variety of genetic tools available for use with Drosophila, together with its short lifespan and inexpensive maintenance, make it an appealing model for further study of these genetic mechanisms. With this in mind we have developed a novel apparatus, known as the Power Tower, for large scale exercise-training in Drosophila melanogaster (11). The Power Tower utilizes the flies' instinctive negative geotaxis behavior to repetitively induce rapid climbing. Each time the machine lifts, then drops, the platform of flies, the flies are induced to climb. Flies continue to respond as long as the machine is in operation or until they become too fatigued to respond. Thus, the researcher can use this machine to provide simultaneous training to large numbers of age-matched and genetically identical flies. Additionally, we describe associated assays useful to track longitudinal progress of fly cohorts during training.