2018 Volume 64 Issue Suppl.1 Pages 117
Introduction: It is known that the increased intramyocellular lipid (IMCL) levels observed in obese subjects are closely associated with Insulin resistance in skeletal muscle. Interestingly, some reports suggested low intensity exercise (LIE) decreased IMCL and improved insulin resistance. On the other hand, a few reports showed vigorous intensity exercise (VIE) improved insulin resistance, although increased IMCL level. However, it is unknown whether exercises intensity is reflect to lipid alterations and insulin sensitivity (IS). The aim of this study was to clarify role of exercise intensity on changes in lipid composition and insulin resistance in skeletal muscle.
Methods: We recruited 20 Japanese men with moderate insulin resistance (HOMA-R > or=1.6). Subjects were randomly assigned to LIE (40% VO2 peak) group or VIE (70% VO2 peak) group. Each group performed LIE or VIE with ergometer for 5 consecutive days. Target energy expenditure of exercise was set at 300 kcal/day. Before and 3-day after completion of each exercise protocol, insulin resistance was evaluated by hyperinsulinemic euglycemic clamp and IMCL was measured by 1H-MRS. In addition, IMCL was also evaluated immediately after the exercise at day 5. Lipidomics in skeletal muscle were measured by hyperinsulinemic-euglycemic clamp and liquid chromatographymass spectrometry, respectively.
Results: As a result of exercise, IRI decreased in LIE group and body fat percentage and HDL-C decreased in VIE group (Table-1). Both exercise protocol similarly improved insulin resistance by ~20%. In both group, IMCL level was slightly decreased by 10~20% immediately after exercise at day 5. Although IMCL level was recovered to baseline value at 3-day after last bout of exercise in LIE group, IMCL level in VIE group increased twofold from baseline. When lipid composition change was compared before exercises and 3 days after exercise, in phosphatidylcholine (C32: 0, C36: 3), phosphatidylethanolamine (C36: 1, C36: 3) and lysophosphatidylethanolamine (C18: 1), it increased by 20% or more in LIE, although little change in VIE.
Conclusions: Exercise effects on insulin sensitivity and lipid composition in muscle vary with intensity.