Role of Exercise Intensity on Intramyocelluar Lipid Level After Exercise in Subjects with Moderate Insulin Resistance

Abstract

It is known that the increased intramyocellular lipid (IMCL) levels observed in obese subjects are closely associated with Insulin resistance (IR) in muscle. Interestingly, some reports suggested low intensity exercise (LIE) decreased IMCL and improved IR. On the other hand, a few reports showed vigorous intensity exercise (VIE) improved IR, but increased IMCL level. This phenomenon is a reminiscent of endurance-trained athletes, who possess a high oxidative capacity and enhanced insulin sensitivity, also have higher IMCL content known as athlete's paradox (AP). From these findings, we hypothesized exercise intensity is one of the determinants of AP. To test this hypothesis, we recruited 15 men with moderate insulin resistance (HOMA-R >1.6) and randomly assigned to LIE (40% VO2 peak) or VIE (70% VO2 peak) group. Each group performed ergometer for 5 consecutive days. Before and 3-day after completion of protocol, IR was evaluated by glucose clamp and IMCL was measured by 1H-MRS. The IMCL was also evaluated immediately after the exercise at day 5. Both exercise protocol improved IR. In both group, IMCL level was not significantly changed after exercise at day 5. Although IMCL level was recovered to baseline value at 3-day after last bout of exercise in LIE group, that in VIE group increased twofold from baseline (Fig). These data suggested exercise intensity is a determinant of change of IMCL. (Figure Presented).