支鏈胺基酸增補對單次運動後記憶力、注意力與腦氧含量之影響

本研究探討一次高劑量支鏈胺基酸增補對耐力運動後生理、生化代謝之影響，及支鏈胺基酸、中樞疲勞、腦血氧含量與認知學習記憶力、注意力之關聯。本雙盲研究召募大學體育系之健康男生20人 (22 ± 2歲) 計數平衡後，分成二組：控制組 (安慰劑組, 麥芽糊精40克/次) 10名、實驗組 (支鏈胺基酸組, 支鏈胺基酸 40克/次；白胺酸54%, 異白胺酸19%, 纈胺酸27%) 10名，交叉前、後各僅增補1次，增補當日進行1小時之耐力跑步，運動強度70~75% 最大保留心跳率。增補前、後與運動前、後均採血與取尿，以測量血液生化值：葡萄糖、乳酸、胺基酸、血清素與肌酸激酶濃度；及收集尿液參數：比重、吸光值、酸鹼值、肌酸酐、尿素氮與5-羥基引朵醋酸濃度。並以近紅外線光譜儀與認知測驗 (工作記憶力、選擇注意力與分散注意力測驗)，探討支鏈胺基酸增補與耐力運動對腦部前額葉血氧飽和變化與認知學習記憶力與注意力之影響。統計分析後，研究結果發現支鏈胺基酸增補可維持耐力運動後恢復期血漿葡萄糖、麩醯胺酸、丙胺酸、纈胺酸、白胺酸、支鏈胺基酸與總受測胺基酸濃度，並利於維持體內氮之平衡。相較於無支鏈胺基酸增補者，支鏈胺基酸增補降低血漿游離色胺酸與支鏈胺基酸比值 (p < .05)，降低運動後血清血清素 (p < .05) 和尿液5-羥基引朵醋酸 (p < .05) 濃度，且增加運動後恢復期選擇注意力和分散注意力測驗執行時，前額葉含氧血紅素和總血紅素之百分變化率 (p < .05)，同時也提升選擇注意力之表現。相較於支鏈胺基酸增補者，麥芽糊精增補提升運動前工作記憶力之表現 (p < .05)，於運動後之恢復期也提升組內分散注意力之表現 (p < .05)。綜上所述，支鏈胺基酸增補有助於減少中樞疲勞的傾向，且有利於認知測驗執行時，腦血流量與血氧運送，提升了選擇注意力之表現。

關鍵字

血清素； 5-羥基引朵醋酸；中樞疲勞；前額葉氧合作用；認知表現

並列摘要

To investigate the influences of acute branched-chain amino acid (BCAA) supplementation and endurance exercise on amino acid metabolism, cerebral functions of memory and attention, and prefrontal cortex oxygenation, a double-blind, counter-balanced, and cross-over study was undertaken. Twenty healthy male athletes (22 ± 2 y) were recruited and divided into two groups: placebo group (n = 10, maltodextrin 40 g/bout) and BCAAs group (n = 10, BCAAs 40 g/bout; leucine 54%, isoleucine 19%, valine 27%). On the testing day, the participants performed 1 hour running with an intensity of 70~75% heart rate reserved maximum. Blood and urine samples were collected before and after both the supplementation and endurance running. Blood concentrations of glucose, lactate, selective amino acids, 5-hydroxytryptamine (5-HT) and creatine kinase were measured. In addition to urinary specific gravity, absorbance and pH value, urinary concentrations of creatinine, urea nitrogen and 5-hydroxyindoleacetic acid (5-HIAA) were also determined. Cognitive tests (working memory, selective attention and divided attention) and functional Near-Infrared Spectroscopy were employed to understand the effects of BCAA supplements and endurance exercise on cerebral functions of memory and attention, and oxygenation. After statistical analysis, the plasma homeostasis of glucose, glutamine, alanine, valine, leucine, BCAAs and total selective amino acid concentrations were maintained with BCAA supplement, and also the nitrogen metabolism of the body at recovery. Compared with the placebo group, BCAA supplement reduced the ratio of f-tryptophan (f-TRP)/BCAAs (p < .05), the concentrations of serum 5-HT (p < .05), and urinary 5-HIAA (p < .05) after endurance running. It also increased oxygenation of the prefrontal cortex during the selective attention and divided attention tests at recovery (p < .05), along with a significant performance improvement on the selective attention test. Maltodextrin supplement improved the performance on the working memory test before running (p < .05), and enhanced the performance on the divided attention test at recovery (p < .05). Branched-chain amino acid supplementation tended to reduce central fatigue, and increase cerebral blood flow and blood oxygen delivery during cognitive tests, which enhanced the performance on the selective attention test after a bout of exercise.