Continuous resistance training alters exercise‐induced MMPs activation and expression of ECM components

Abstract

Recent studies indicate that matrix metalloproteinases (MMPs) and skeletal muscle extracellular matrix (ECM), especially basal lamina, components play a role in muscle mass regulation, although the effects of resistance training (RT) on those proteins are unclear. Thus, the purpose of the study was to investigate the effects of RT on activities and protein expression of MMPs and ECM. Ten male SD rats were divided into 1‐exercise bout (1B) or 18‐exercise bouts (18B) group. This study was conducted in conformance with the FASEB Statement of Principles for the use of animals in research and education. The right gastrocnemius muscle was isometrically trained via percutaneous electrical stimulation (maximum contraction for 5 sec × 5, 5 sets) every other day, whereas the left leg served as a control. MMP‐2 and MMP‐9 activities (via gelatin zymography) were increased 10 min after acute exercise with no change in expression of tissue inhibitors of metalloproteinases in 1B group. However, repeated bouts attenuated exercise‐induced MMPs activation in 18B group. MMPs expressions were significantly higher in trained muscles. RT increased β1‐integrin expression but not the other ECM proteins. Our results suggest that resistance exercise activates MMPs during initial phase of RT but this response is attenuated with continuation of RT.This study was supported by grant from Meiji Yasuda Life Foundation of Health and Welfare.