Because muscle damage from eccentric exercise has been associated with alterations in muscle glycogen metabolism, this study determined the effects of exercise on the insulin and glucose responses to an oral glucose tolerance test (OGTT). In a repeated-measures design, 11 subjects undertook either no exercise, 2 min of isokinetic leg exercise, or 50 min of level or downhill running. No exercise was performed and diet was controlled during the 48 hrs after the treatments and before the OGTT. Ratings of muscle soreness and CK activity were significantly elevated 48 hrs after downhill running. Level running also increased CK activity but did not induce muscle soreness. Isokinetic exercise did not affect either one. Blood glucose responses to the OGTT were similar among the treatments. In contrast, the insulin responses to the OGTT following downhill running were significantly increased. These results suggest that eccentric exercise associated with downhill running that results in delayed muscle soreness is associated with the development of a mild insulin-resistant condition.
Sherman is with the School of HPER, Larkins Hall, 337 W. 17th Ave., The Ohio State University, Columbus, OH 43210. Lash is now at the Dept. of Physiology & Biophysics, Indiana U. School of Medicine, Indianapolis, IN 46223. Simonsen lives in Winston-Salem, N.C. Bloomfield is at OSU. Request reprints from W.M. Sherman.