13 male subjects were studied and placed in 3 groups. Each group exercised one leg with sprint (S), or endurance (E) training and the other leg oppositely or not at all (NT). Oxygen uptake (Vo2), heart rate and blood lactate were measured for each leg separately and for both legs together during submaximal and maximal bicycle work before and after 4 weeks of training with 4-5 sessions per week. Muscle samples were obtained from the quadriceps muscle and assayed for succinate dehydrogenase (SDH) activity, and stained for myofibrillar ATPase. In addition, eight of the subjects performed after the training two-legged exercise at 70% Vo2 max for one hour. The measurements included muscle glycogen and lactate concentrations of the two legs as well as the blood flow and the a-v difference for O2, glucose and lactate.
PIEHL, K., S. ADOLFSSON and K. NAZAR. Glycogen storage and glycogen synthetase activity in trained and untrained muscle of man. Acta physiol. scand. 1974. 90. 779-788. Bilateral biopsies from "one-leg" trained subjects were analysed for glycogen content ( G ) , total glycogen synthetase activity (GST), synthetase I-form (GSI) and hexokinase (HK). Histochemical estimations were made of G, GST and GSI in slow twitch (ST) and fast twitch ( F T ) muscle fibres. Samples from the trained ( T ) and the untrained ( U ) legs were taken before and after acute exhaustive exercise and at different intervals during a 46 h recovery period when a carbohydrate enriched diet was given. Prior to exercise G levels were higher
To find out to what extent body composition affects glucose tolerance, blood glucose (BG) and insulin (IRI) responses to a 100-g oral glucose tolerance test (OGTT) were compared in 10 male body builders, 11 untrained lean control subjects, and 11 mildly obese men, all of similar age (19-35 years). In comparison with the remaining two groups, the body builders had the lowest percentage of fat, although their lean body mass (LBM) in absolute terms did not differ from that in obese subjects. Both BG and IRI concentrations during the OGTT were the lowest in body builders, medium in controls, and the highest in obese men. The differences in glucose tolerance between the groups were also demonstrated by comparison of the subjects' BG levels during the OGTT with the respective mean BG values obtained in a reference group of 42 healthy nonobese men aged from 20 to 55 years. The data indicate that body builders show better glucose tolerance and improved insulin action in comparison with untrained, nonobese subjects of similar age and body weight. Lean body mass in absolute terms cannot, however, be considered as a sole determinant of the insulin action in the body since in mildly obese subjects glucose tolerance was considerably reduced in spite of the fact that their LBM was similar to that in body builders. Either muscle hypertrophy or reduced adiposity may account for the beneficial effects of body building on glucose metabolism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.