D-16 Thematic Poster - Exercise Training in Cardiac Patients

Abstract

While branched-chain amino acids (BCAA) leucine is known to stimulate the activation of mTOR and protein synthesis, the contribution of leucine supplementation to the adaptive process and performance improvement to eccentric resistance training is unclear. PURPOSE: This study investigated the effect of BCAA on eccentric training efficiency in rats. METHODS: Male Wistar rats of 12 weeks of age were allocated into BCAA-supplemented (n=7), casein -supplemented (CS) (n=8) or non-supplemented (CONT) (n=8) groups. The BCAA group was fed a BCAA solution (1.35 g/kg, valine: leucine: isoleucine = 1:2:1) by oral gavage twice per day, and had free access to water containing BCAA (3% BCAA solution). The CS group was fed isonitrogen casein and CONT group received 1% hydroxypropyl methylcellulose solution (without nitrogen source) administered in the same manner as the BCAA group. Rats achieved one bout of eccentric contractions, elicited by forty intermittent electric stimulations in the tibialis anterior (TA) muscles every other day for 6 weeks. The isometric strength was monitored throughout the training period and assessed 24 hours after the last session in blinded manner. RESULTS: During the first 4 to 9 days of the training, the isometric strength of all groups declined by 57-62% of the initial value but increased consecutively thereafter. In the last two weeks of the training period, the isometric strength in the BCAA group exceeded that of CONT group by 8-10% (p<0.05) but the increase was not significantly different in the CS group compared to the CONT group (by 5-7%). The increase in the post training isometric force was statistically significant in the BCAA (34.0±2.8 mNm, p<0.05) as compared to the CONT group (25.3±1.9 mNm) but was not statistically significant in the CS group (29.1±1.4 mNm). The average cross-sectional area of the fibers with central nuclei was significantly larger in the BCAA (4291±117 μm2) and CS (4116±100 μm2) as compared to the CONT (3763±93 μm2) group. The muscle weight, myogenic regulatory factors, cytoskeletal protein and satellite cells increased significantly over time but there were no significant differences between the groups. CONCLUSION: These results suggest that BCAA supplementation may be an effective tool in facilitating adaptation to training and improve muscle strength.