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Effects of ingesting carbohydrate and branched-chain amino acids on markers of skeletal muscle protein synthesis of the insulin-PI3K-mTOR signal transduction pathways in response to a bout of heavy resistance exercise.

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dc.contributor.advisor Kreider, Richard B., 1962-
dc.contributor.advisor Willoughby, Darryn Scott, 1963-
dc.contributor.author Ferreira, Maria Pontes.
dc.contributor.other Baylor University. Dept. of Health, Human Performance and Recreation. en
dc.date.copyright 2008-08
dc.identifier.uri http://hdl.handle.net/2104/5230
dc.description.abstract Purpose: To determine if activity of the MAPK-ERK or PI3K-mTOR insulin signaling pathway is increased in response to an acute lower body resistance exercise (RE) bout and supplemental BCAA + CHO or CHO ingestion. Methods: 27 recreationally trained males (20.9 y; 81.8 kg) were randomly assigned to a group: BCAA (30 g) + CHO (350 g), CHO (350 g) or placebo CON. Participants performed 4 sets of leg press and extensions at 80% 1RM to failure. Supplements were ingested at 3 time points: 30 min prior to RE, and immediately pre- and post-RE. Venous blood was sampled at baseline (Pre); 30 min post-exercise; 2 h post-exercise, and 6 h post-exercise for serum glucose and insulin. Blood variables were transformed to percent change values and analyzed by a 3 x 4 repeated measures MANOVA. Muscle biopsies were obtained at baseline, 30 min post-exercise, 2 h post-exercise and 6 h post-exercise for ERK1/2, IRS, Akt/PKB, GSK, mTOR, 4E-BP1, and P70S6K. Skeletal muscle variables were transformed to percent change values and analyzed by 3 x 4 repeated measures MANOVA. Univariate ANOVAs were utilized as follow-up tests to the MANOVA for select variables. Results: MANOVA results demonstrate a significant group x time interaction for insulin and glucose (P<.05). Despite a nearly 3 fold-increase of insulin over fasting baseline measures in the CHO groups as compared to the placebo group, neither BCAA + CHO or CHO significantly increased any of the muscle variables. Univariate analysis demonstrated significant group x time interaction for Akt/PKB phosphorylation (p=0.039) suggestive of a group effect. The following muscle variables demonstrated by MANOVA a significant time effect: IRS (p=.054); Akt/PKB (p=0.011); ERK1/2 (p=0.026); p70S6K (p=0.038). A time trend for mTOR (p=0.089) was noted. No significant effects were found for GSK and 4E-BP above baseline or among groups. Summary: The results indicate that RE but not BCAA + CHO or CHO increased the phosphorylation status of IRS, AKT/PKB, p70S6K and ERK above baseline levels (p<.05) with trends for group x time interaction for Akt/PKB and trend for mTOR activation. Phosphorylation of GSK and 4E-BP was not influenced by the RE and supplementation protocol. en
dc.rights Baylor University theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact librarywebmaster@baylor.edu for inquiries about permission. en
dc.subject Isometric exercise -- Physiological aspects. en
dc.subject Carbohydrates -- Physiological effect. en
dc.subject Branched chain amino acids -- Physiological effect. en
dc.subject Proteins -- Synthesis. en
dc.subject Musculoskeletal system -- Physiology. en
dc.subject Dietary supplements -- Physiological effect. en
dc.title Effects of ingesting carbohydrate and branched-chain amino acids on markers of skeletal muscle protein synthesis of the insulin-PI3K-mTOR signal transduction pathways in response to a bout of heavy resistance exercise. en
dc.type Thesis en
dc.description.degree Ph.D. en
dc.rights.accessrights Baylor University access only en
dc.contributor.department Health, Human Performance and Recreation. en


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