Browsing by Subject "Leucine -- Physiological effect."
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Item The effects of branched-chain amino acid and leucine ingestion on the ERK1/2 MAP kinase signal transduction pathway in conjunction with an acute bout of heavy resistance exercise.(2007-12-03T17:51:50Z) Campbell, Bill.; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Purpose: To determine if leucine or BCAA ingestion increases the activation of the ERK1/2 MAPK pathway greater than that which resistance exercise (RE) elicits alone; to determine a possible mechanism for a BCAA or leucine induced ERK1/2 MAPK pathway via IRS-1 and SHP-2. Methods: 30 males (22.5yrs; 81.1kg) were randomly assigned to 1 of 3 groups: Leucine (60mg/kg/bw), BCAA (120mg/kg/bw), or placebo. Subjects performed 4 sets of leg press and leg extension at 80% 1RM to failure. Supplementation was ingested at 3 time points: 30 minutes prior to RE, and immediately pre- and post-RE. Venous blood was sampled at baseline; 30min later, immediate post-exercise, 30min post-exercise; 2hrs post-exercise, and 6hrs post-exercise for serum glucose, insulin, GH, and IGF-1. Muscle biopsies were sampled at baseline, and 30min post, 2hr post, and 6hr post-exercise for MEK1, ERK1/2, IRS-1, and SHP-2. Skeletal muscle variables were transformed to delta values and analyzed via a 3 (group) x 4 (time points) repeated measures MANOVA. Univariate ANOVAs (Bonferroni adjusted) were conducted as follow-up tests to the MANOVA. Post-hoc tests of the interaction effects demonstrated in the ANOVA were investigated via an independent samples T-test. Results: Neither BCAA or leucine increased the secretion of the 4 serum variables. A group x time interaction relative to ERK1/2 activation indicated that the BCAA group was significantly elevated at the 2hr post and 6hr post time points in comparison with the Leucine (p < .05) and Placebo groups (p < .001). A group x time interaction for IRS-1 activation indicated that the Leucine group was significantly elevated at 2hr post and 6hr post in comparison with the BCAA (p < .05) group. No group x time interactions were observed for MEK1 or SHP-2. Summary: BCAA supplementation increased the phosphorylation status of ERK1/2 in conjunction with RE at 2 and 6 hours post-exercise. Leucine supplementation did not have any effect on ERK1/2 activation.Item The effects of heavy resistance exercise in combination with orally administered branched-chain amino acids or leucine on insulin signaling and Akt/mTOR pathway activity in active males.(2007-12-03T18:51:46Z) La Bounty, Paul.; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Purpose: To determine if activity of the insulin signaling pathway is increased during lower body resistance exercise due to supplemental BCAA or leucine ingestion. Methods: 30 recreationally trained males (22.5yrs; 81.1kg) were randomly assigned to 1 of 3 groups: Leucine (60mg/kg/bw), BCAA (120mg/kg/bw), or non-caloric placebo. Participants performed 4 sets of leg press and leg extension at 80% 1RM to failure (at least 8 reps). Supplements were ingested at 3 time points: 30 minutes prior to RE, and immediately pre- and post-RE. Venous blood was sampled at baseline (Pre); immediate pre- and post-exercise, 30 minutes post-exercise; 2hours post-exercise, and 6 hours post-exercise for serum glucose, insulin, GH, and IGF-1. Muscle biopsies were obtained at baseline, and 30 minutes post, and 2 and 6 hours post-exercise for IRS-1, Akt, mTOR, 4E-BP1, and P70-S6K. Skeletal muscle variables were transformed to delta values and analyzed using a 3 (group) x 4 (time points) repeated measures MANOVA. Univariate ANOVAs (Bonferroni adjusted) were utilized as follow-up tests to the MANOVA. Post-hoc tests of the interaction effects demonstrated in the ANOVA were analyzed using independent samples T-tests. Results: Neither BCAA or leucine significantly increased any of the 4 serum variables. A group x time interaction for IRS-1 phosphorylation demonstrated that the leucine group was significantly elevated at 2hr post and 6hr post when compared to the BCAA group (p < .05). A group x time interaction for 4E-BP1 phosphorylation demonstrated that the leucine and BCAA groups were both elevated at the 2hr post in comparison with the placebo (p < .05). BCAA was significantly greater than leucine at 6 hours (p < .05) as well. No interactions were observed for Akt, mTOR, or P70-S6K. Summary: The results indicate that BCAA and leucine supplementation with RE increased the phosphorylation status of 4E-BP1 at 2 hours post-exercise and the BCAA group increased the phosphorylation of 4E-BP1 greater than leucine (p < .05) at 6 hours post-exercise.Item Effects of ingesting branched chain amino acids and carbohydrate on myostatin signaling and markers of myogenesis in response to a bout of heavy resistance exercise.(2008-10-14T19:34:44Z) Li, Rui, 1972-; Kreider, Richard B., 1962-; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Purpose: To determine if co-ingestion of carbohydrate (CHO) with branchedchain amino acids (BCAA) or leucine (Leu) downregulates the myostatin signaling pathway and upregulates the makers of myogenesis to a extent greater than that which resistance exercise elicits alone; to explore a possible mechanism for a CHO-BCAA or CHO-Leu induced the modification of myostatin pathway and the activation of myogenesis. Methods: 31 males (22.5yrs; 81.1kg) were randomly assigned to 1 of 3 groups: CHO-BCAA (maltodextrin 1.5 g/kg/bw, BCAA 120mg/kg/bw), CHO-Leucine (maltodextrin 1.5 g/kg/bw, Leu 60mg/kg/bw) and CHO alone (maltodextrin 1.5 g/kg/bw). A control group ingesting placebo (450 ml Crystal Light®) was employed from the previous study using the same study design in the same lab. Subjects performed 4 sets of leg press and leg extension at 80% 1RM to failure. Supplementation was ingested at 3 time points: 30 minutes prior to RE, and immediately pre- and post-RE. Venous blood was sampled at baseline; 30min later, immediate postexercise, 30min post-exercise; 2hr post-exercise, and 6hr post-exercise for serum glucose, insulin, IGF-1, myostatin, myostatin propeptide, follistatin and FLRG. Muscle biopsies were sampled at baseline, and 30min post, 2hr post, and 6hr post-exercise for myostatin, ActRIIB, p21cip, p27kip, myoD, myf-5, myogenin and MRF-4 mRNA expression. Serum variables were expressed in delta values as percent change and analyzed via a 4 (group) × 6 (time points) repeated measures MANOVA. Muscle variables were analyzed as CT ratio for relative mRNA expression via a 4 (group) × 4 (time points) repeated measures MANOVA. Univariate ANOVAs (Bonferroni adjusted) were conducted as follow-up tests to the MANOVA. Post-hoc tests of the interaction effects demonstrated in the ANOVA were investigated via an independent sample T-test. Results: CHO-BCAA, CHO-Leu and CHO alone significantly increased blood glucose and serum insulin levels combined with resistance exercise. Either CHO-BCAA or CHO-Leu enhanced serum insulin to a greater extent compared with CHO alone, nonetheless no statistically significance indicated. None of the CHO-BCAA, CHO-Leu or CHO alone, compared with placebo, modified serum IGF-1, myostatin and its inhibitors. Regarding muscle samples, a univariate group × time interaction relative to myogenin mRNA expression indicated that the CHO-Leu group was significantly upregulated at the 6hr post time point in comparison with the Placebo group (p < .05). No group × time interactions were observed for the myostain signaling molecules and other myogenic regulatory factors except myogenin. Summary: CHO-Leu supplementation upregulated the myogenin mRNA expression in conjunction with resistance exercise at 6hr post-exercise. Co-ingestion of BCAA or Leu had no effect on the inhibition of myostatin signaling at pre- and post-translational level.