Publication:

合併補充支鏈胺基酸與瓜胺酸對高強度阻力訓練後發力率無顯著影響

目的：阻力運動會誘發中樞疲勞，可能原因之一是大腦血清素濃度增加。色胺酸是合成血清素的前驅物，補充支鏈胺基酸可能減少色胺酸進入大腦，減少血清素合成，進而減緩中樞疲勞；補充瓜胺酸可能可以協助移

除運動中所產生的氨。本研究探討合併補充支鏈胺基酸和瓜胺酸對下肢高強度阻力訓練誘發之疲勞的影響，以等長下肢中段拉 (isometric mid-thigh pull)發力率做為肌肉疲勞的指標，並探討可能的生化機轉。方法：以 10 名有阻力訓練經驗的健康男性大學生為對象，採隨機單盲交叉設計，每位受試者皆接受 2 次測試，以 85% 一次反覆最大重量 (1 repetition maximum)進行深蹲訓練，每組 5 次，共 5 組，於阻力訓練前、訓練後立即、訓練後24小時，分別進行等長下肢中段拉測試。AA 測試於訓練前補充支鏈胺基酸 0.1 g/kg 及瓜胺酸 0.025 g/kg， PLA 測試則補充安慰劑。結果： PLA 測試訓練後等長下肢中段拉最大力量發力率較訓練前有降低的趨勢(p=0.083)，而在 50, 90, 150, 200 毫秒之發力率及最大力量在二次測試間均無顯著差異。二次測試訓練前後血漿氨濃度均無顯著差異；PLA 測試血漿尿素濃度在訓練後顯著低於基準值， AA 測試血漿尿素濃度則在各時間點則無顯著差異。結論：在本研究的阻力訓練期間，氨合成並未顯著增 加，而補充瓜胺酸可能增加訓練期間的尿素循環，移除了在阻力訓練期間代謝支鏈胺基酸所產生的氨，使得 AA 測試訓練後的血漿氨濃度維持與訓練前

相同；但即使有此效果，補充支鏈胺基酸與瓜胺酸仍對阻力訓練後之疲勞無顯著影響。

Purpose: Resistance exercise can induce central fatigue. One of the mechanisms of central fatigue is the increase in cerebral serotonin. Tryptophan is the precursor for serotonin synthesis. Supplementation of branched-chain amino acids may reduce the cerebral uptake of free tryptophan, which may prevent central fatigue. Citrulline may remove the ammonia synthesized during exercise. The aim of this study was to investigate the effect of supplementation of branched-chain amino acids and citrulline on fatigue induced by high-intensity resistance training in the lower limbs. The rate of force development in isometric mid-thigh pull (IMTP) was used as the indicator for muscular fatigue. The potential biochemical mechanisms of the supplementation were also examined. Design and Methods: The subjects were 10 healthy male college students with experience in strength training. The study used the single-blind cross-over design with each subject participating in 2 trials. The resistance training contained 5 sets of 5 repetitions of squat at the intensity of 85% 1 RM. IMTP was performed before, immediately after, and 24 hr after the resistance training. In the AA trial, the subjects consumed 0.1 g/kg branched-chain amino acids and 0.025 g/kg citrulline before the training. In the PLA trial, the subjects consumed placebo. Results: The rate of force development at the maximal force in IMTP showed a tread of decrease after the training in the PLA trial (p=0.083). There was no significant difference in the rate of force development at 50, 90, 150, and 200 ms in the AA and PLA trials. Plasma ammonia concentrations were similar before and after the training in both trials. Plasma urea concentration was significantly decreased after the training in the PLA trial, while they remained unchanged in the AA trial. Conclusions: The resistance training did not result in excess ammonia production. However, supplementation of citrulline may increase urea cycle during the training, which could remove the excess ammonia production from oxidation of branched-chain amino acids. Despite this potential effect, the supplementation of branched-chain amino acids did not affect the fatigue induced by resistance training.