The authors examined the effect of branched-chain amino acid (BCAA) supplementation on squat-exercise-induced delayed-onset muscle soreness (DOMS) using 12 young, healthy, untrained female participants. The experiment was conducted with a crossover double-blind design. In the morning on the exercise-session day, the participants ingested either BCAA (isoleucine:leucine:valine = 1:2.3:1.2) or dextrin at 100 mg/kg body weight before the squat exercise, which consisted of 7 sets of 20 squats/set with 3-min intervals between sets. DOMS showed a peak on Days 2 and 3 in both trials, but the level of soreness was significantly lower in the BCAA trial than in the placebo. Leg-muscle force during maximal voluntary isometric contractions was measured 2 d after exercise (Day 3), and the BCAA supplementation suppressed the muscle-force decrease (to ~80% of the value recorded under the control conditions) observed in the placebo trial. Plasma BCAA concentrations, which decreased after exercise in the placebo trial, were markedly elevated during the 2 hr postexercise in the BCAA trial. Serum myoglobin concentration was increased by exercise in the placebo but not in the BCAA trial. The concentration of plasma elastase as an index of neutrophil activation appeared to increase after the squat exercise in both trials, but the change in the elastase level was significant only in the placebo trial. These results suggest that muscle damage may be suppressed by BCAA supplementation.

The ratio of equol non-producers in overweight or obese populations might be higher than generally reported. Natural S-equol might have a role in glycaemic control and in the prevention of cardiovascular disease by its effects to lower LDL-C levels and CAVI scores in overweight or obese individuals.

SummaryThe present study was conducted to examine alterations in plasma free amino acid concentrations induced by squat exercise and branched-chain amino acid (BCAA) supplementation in young, untrained female subjects. In the morning on the exercise session day, participants ingested drinks containing either BCAA (isoleucine : leucine : valine ϭ 1 : 2.3 : 1.2) or dextrin (placebo) at 0.1 g/kg body weight 15 min before a squat exercise session, which consisted of 7 sets of 20 squats, with 3 min intervals between sets. In the placebo trial, plasma BCAA concentrations were decreased subsequent to exercise, whereas they were significantly increased in the BCAA trial until 2 h after exercise. Marked changes in other free amino acids in response to squat exercise and BCAA supplementation were observed. In particular, plasma concentrations of methionine and aromatic amino acids were temporarily decreased in the BCAA trial, being significantly lower than those in the placebo trial. These results suggest that BCAA intake before exercise affects methionine and aromatic amino acid metabolism. Key Words squat exercise, branched-chain amino acids, plasma free amino acids, untrained young women It is well known that amino acid metabolism is affected by exercise ( 1 ). In particular, exercise has been shown to promote branched-chain amino acid (BCAA) catabolism in rats and humans ( 2 , 3 ). Therefore, the popularity of BCAAs as a supplement for people who practice sports is growing. However, despite the common use of BCAAs, little information is available with regard to the effects of BCAA intake on the concentrations of plasma components including free amino acids other than the BCAAs. In a recent study, we have found that BCAA supplementation before squat exercise noticeably suppressed the muscle pain that occurred on the next day after exercise and lasted for a few days (delayed-onset muscle soreness (DOMS)) in young, untrained women ( 4 ). In the present study, we examined alterations in the plasma concentrations of free amino acids induced by squat exercise and BCAA supplementation. Materials and MethodsExperiments were conducted essentially as described previously ( 4 ), except for the following points: (i) 12 young, healthy female volunteers who did not exercise in a regular basis participated in this study, (ii) the subjects ingested the test drink containing BCAA mixture or dextrin at 0.1 g/kg body weight, and (iii) blood samples were collected for preparations of plasma and serum before exercise and at several time points after exercise (see below). The compositions of the test drinks were as follows: a BCAA drink (200 mL) containing 5.5 g of a BCAA mixture (isoleucine, leucine, and valine at a ratio of 1 : 2.3 : 1.2 ( 5 )), 1 g instant green tea powder (Ajinomoto General Foods, Tokyo) and 1.2 g nonnutritive sweetener (Pal Sweet, Ajinomoto, Tokyo), and a placebo drink containing the same ingredients as the BCAA drink except for 5.5 g dextrin instead of the BCAAs ( 4 ). The age of the participants was 22.2 Ϯ 0.5 (mean...

We have examined effects of BCAA supplementation on DOMS and muscle fatigue induced by squat exercise in humans. In a previous study, we found that BCAA supplementation before exercise effectively decreased DOMS and muscle fatigue. In the present study, we examined the effects of intake of BCAAs after exercise on DOMS and muscle fatigue using 12 healthy female adults, who did not take regular exercise. The experiment was conducted with crossover and double blind design. A test solution (200 ml) used in this study contained 5.5 g BCAAs (I:L:V = 1:2.3:1.2), and a placebo solution (200 ml) 5.5 g dextrin instead of BCAAs. The squat exercise consisted of 7 sets of 20 squats/set (total 140 squats), with 3 min intervals between each set. During each set, squats were performed every 2 s. Subjects ingested either solution at 0.1 g BCAAs or dextrin/kg BW immediately after squat exercise. DOMS and muscle fatigue were evaluated by a visual analog scale (VAS). These experimental procedures were the same as those in the previous report for BCAA supplementation before exercise. In the present study, DOMS (showing a peak on the 2nd and 3rd days) and muscle fatigue were tended to be less in the BCAA trial than in the placebo trial, but not significantly different between two trials. These results suggest that BCAA supplementation after exercise may not be effective to decrease DOMS and muscle fatigue, compared to the supplementation before exercise.

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