Zitat:
J Sci Med Sport. 2001 Dec;4(4):431-46.
Influence of weight training exercise and modification of hormonal response on skeletal muscle growth.
Tarpenning KM, Wiswell RA, Hawkins SA, Marcell TJ.
Department of Exercise Sciences, Uniersity of Southern California, Los Angeles, USA.
To investigate the influence of carbohydrate (CHO) consumption on the acute hormonal response, and chronic adaptation to weight lifting exercise, two studies were conducted. Following a four-hour fast, seven young men (21.3 +/- 3.5 y) performed (on two occasions) a nine-station weight lifting protocol, completing 3 sets of 10 repetitions at 75% of 1RM (series 1). Randomly assigned, one session included the ingestion of a non-caloric placebo, and the other, a 6% CHO solution. For series 2, two groups of young men (21.3 +/- 1.5 y) participated in 12 weeks of progressive resistance weight training. Training for one group included the ingestion of a non-caloric placebo, and the other, a 6% CHO solution. In series 1, weight lifting exercise with CHO ingestion significantly (p < 0.05) elevated blood glucose and plasma insulin levels above baseline, as well as that occurring with the placebo. This resulted in a significant blunting of the cortisol response (7% with CHO compared to 99% with placebo). These findings indicate that CHO consumption during weight lifting exercise can modify the acute hormonal response to exercise. With series 2, CHO consumption continued to blunt the cortisol response to exercise during the twelve weeks of training. This is in contrast to significantly elevated cortisol levels observed for the placebo control group. Corresponding with the modified response patterns were differences in muscle growth. Weight training exercise with CHO ingestion resulted in significantly greater gains in both type I (19.1%) and type II (22.5%) muscle fibre area than weight training exercise alone. The difference in the cortisol response accounted for 74% of the variance (r = 0.8579, p = 0.006) of change in type I muscle fibre area, and 52.3% of the variance (r = 0.7231, p = 0.043) of change in type II muscle fibre area. These findings suggest that the modification of the cortisol response associated with CHO ingestion can positively impact the skeletal muscle hypertrophic adaptation to weigh training.
Mir persönlich hat Maltodextrin während des Trainings (was damals allerdings nicht länger als 60-90min dauerte) allerdings herzlich wenig gebracht (außer, dass ich immer fetter geworden bin). Bei Trainingseinheiten, die 2h dauern, nehme ich dagegen auch gern einen
Zitat:
Eur J Appl Physiol Occup Physiol. 1990;61(1-2):5-10.
Glycogen and triglyceride utilization in relation to muscle metabolic characteristics in men performing heavy-resistance exercise.
Essen-Gustavsson B, Tesch PA.
Swedish University of Agricultural Sciences, Faculty of Veterinary Medicine, Department of Medicine and Surgery, Uppsala.
Nine bodybuilders performed heavy-resistance exercise activating the quadriceps femoris muscle. Intermittent 30-s exhaustive exercise bouts comprising 6-12 repetitions were interspersed with 60-s periods for 30 min. Venous blood samples were taken repeatedly during and after exercise for analyses of plasma free fatty acid (FFA) and glycerol concentration. Muscle biopsies were obtained from the vastus lateralis muscle before and after exercise and assayed for glycogen, glycerol-3-phosphate, lactate and triglyceride (TG) content. The activities of citrate synthase (CS), lactate dehydrogenase, hexokinase (HK), myokinase, creatine kinase and 3-hydroxyacyl-CoA dehydrogenase (HAD), were analysed. Histochemical staining procedures were used to assess fibre type composition, fibre area and capillary density. TG content before and after exercise averaged (SD) 23.9 (13.3) and 16.7 (6.4) mmol kg-1 dry wt. The basal triglyceride content varied sixfold among individuals and the higher the levels the greater was the change during exercise. The glycogen content decreased (P less than 0.001) from 690 (82) to 495 (95) mmol kg-1 dry wt. and lactate and glycerol-3-phosphate increased (P less than 0.001) to 79.5 (5.5) and 14.5 (7.3) mmol kg-1 dry wt., respectively, after exercise. The HK and HAD/CS content respectively correlated with glycogen or TG content at rest and with changes in these metabolites during exercise. FFA and glycerol concentrations increased slightly (P less than 0.001) during exercise. Lipolysis may, therefore, provide energy during heavy-resistance exercise of relatively short duration. Also, storage and utilization of intramuscular substrates appear to be influenced by the metabolic profile of muscle.
Gruß