Influence of muscle mass and work on post-exercise glucose and insulin responses in young untrained subjects.

The 18 h post-exercise glucose and insulin responses of six male and six female subjects were measured following one- or two-leg cycling to determine the influence of muscle mass involvement and work. Each subject performed three exercise trials on a Cybex Met 100 cycle ergometer: (1) two-leg exercise for 30 min at 60% of the two-leg VO2 max; (2) one-leg exercise for 30 min at 60% of one-leg VO2 max; and (3) one-leg exercise (one-leg TW) at 60% of the one-leg VO2 max with the total work performed equal to that of the two-leg trial (duration approximately 50 min). These trials were preceded by 2 days of inactivity and followed by an 18 h post-exercise 75 g oral glucose tolerance test (OGTT). The glucose response during the baseline OGTT demonstrated that the subjects had normal glucose tolerance with fasting serum glucose levels of 5.1 mM, and 1 and 2 h serum glucose less than 7.8 mM, respectively. The 18 h post-exercise glucose responses were significantly lower following the two-leg trial (P < 0.05), with the area under the curve values being 129.9 mM h-1 less than the resting control level. The 18 h post-exercise insulin AUC response of the two-leg trial was significantly lower than either of the one-leg responses (14.7 pM below the one-leg and 5.0 pM below the one-leg TW) but was not associated with a change in C-peptide. The 18 h post-exercise insulin levels of the one-leg and one-leg TW trials were above or near the resting control values, but were not accompanied by a significant change in C-peptide. In conclusion, the data presented here show that the amount of muscle tissue utilized during an exercise bout can influence both the glucose and insulin responses, whereas the amount of total work employed during the exercise had no effect on either of these parameters.

Effects of resistance exercise on glucose tolerance in normal and glucose-intolerant subjects.

This study was conducted to determine whether improvements in glucose tolerance could be observed after a single bout of resistance exercise in young (27.1 +/- 1.24 yr) control subjects, older (53.3 +/- 1.7 yr) patients with non-insulin-dependent diabetes mellitus (NIDDM), and older (50.7 +/- 1.9 yr) age-matched control subjects. Each subject was screened for fitness level and any contraindications to exercise before inclusion in the study. A 75-g oral glucose tolerance test was administered 2 wk after the subjects were screened, and the subjects were familiarized with the exercise equipment. The maximum weight that could be lifted with one repetition was determined on seven Nautilus machines that utilized the upper and lower body. After a 48-h rest period, a 3-set x 10-repetition protocol based on the subject's one repetition maximum was completed by each participant on each machine. Eighteen hours after the lifting protocol, a second oral glucose tolerance test was administered. There was no change in the pre- to post-exercise glucose levels in any of the treatment groups, but the total insulin responses (area under the curve) of the young control and NIDDM groups were significantly lower after exercise: from 6.93 +/- 0.8 x 10(3) to 5.38 +/- 0.65 x 10(3) pM in the young control group and from 9.83 +/- 1.95 x 10(3) to 7.77 +/- 1.50 x 10(3) pM in the NIDDM group. The postexercise C-peptide levels were unchanged in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)