Effect of Light Resistance Exercise after Ingestion of a High-Protein Snack on Plasma Branched-Chain Amino Acid Concentrations in Young Adult Females

Abstract

SummaryWe have previously reported the preventive effects of light resistance exercise (voluntary tower climbing exercise) after ingestion of a high-protein snack (HPS) on muscle loss in glucocorticoid-injected rats. However, such studies have not been performed in humans. In this cross-over study, we examined the effect of light resistance exercise after ingestion of HPS on plasma branched-chain amino acid (BCAA) concentrations in humans. Seven healthy young adult females (aged 22.1 Ϯ 1.2 y) participated in this study. They were assigned to either an exercise group or a control group. Seven days after the first experiment, they were crossed over to the opposite intervention. The subjects ingested HPS (15 g protein, 18 g sugar) 3 h after breakfast (basal meal). The plasma BCAA concentrations increased at 30 min after HPS ingestion. The subjects in the exercise group performed light resistance exercise (15 min dumbbell exercise using 300 g brown-rice-filled fabric dumbbells) when the plasma BCAA concentrations were increased (60 min after the snack ingestion). The control group maintained a resting position during the experiment. Changes in the plasma BCAA concentrations between 60 and 90 min after HPS ingestion increased continuously in the control group ( ϩ 27 mol/L) but decreased in the exercise group ( Ϫ 37 mol/L). Therefore, light resistance exercise after HPS ingestion may be effective for utilization of plasma BCAA in humans. Key Words high-protein snack, light resistance exercise, branched-chain amino acids, muscular blood flow, dumbbell exercise Moderate exercise and protein intake are essential for maintaining and increasing skeletal muscle mass. Many studies have been conducted on the timing of exercise and protein or amino acid intake for efficiently increasing skeletal muscle mass ( 1 -5 ). In particular, branched-chain amino acid (BCAA) accounts for about 35% of the essential amino acids that constitute muscle protein ( 6 ), and leucine has been investigated for its protein anabolic and insulin-like effects ( 7 , 8 ).We have previously reported that the serum amino acid concentrations are not significantly increased after ingestion of basal meals, whereas the concentrations are rapidly increased after high-protein snack (HPS) ingestion in rats ( 9 ). It was considered that ingestion of HPS approximately 3 h after the basal meals is an effective method to supply muscles with sufficient amounts of amino acids ( 10 ).To examine whether the ingestion of HPS is effective in supplying amino acids to muscle and suppressing muscle loss, we have previously studied this phenomenon in glucocorticoid-injected rats ( 9 , 11 ). We found that muscle loss cannot be suppressed by providing HPS alone without light resistance exercise ( 9 , 11 ).In this study, we examined the effect of light resistance exercise after HPS ingestion 3 h after a basal meal on plasma BCAA concentrations and estimated whether the ingestion of HPS and light resistance exercise was effective for utilization of BCAA in humans. SUBJECTS AND ME...

Chronic Effect of Light Resistance Exercise after Ingestion of a High-Protein Snack on Increase of Skeletal Muscle Mass and Strength in Young Adults

“…However, it is difficult for the elderly to continue heavyload exercise on a daily basis. Recent studies have reported that even light resistance exercise such as lowspeed muscle flexing and extending exercise (10), is effective in increasing muscle mass and strength by restricting blood flow (9): this study used a dumbbell exercise devised by Suzuki that can be practiced even by the elderly (3,5,6). Movements in this exercise are very slow, with the subject's muscle blood flow being restricted by holding the light dumbbells (300 g) and adducting the wrists, which promotes protein synthesis and excretion of growth hormones (11).…”

“…Further, to determine whether the above effect could be observed in humans, we investigated changes in plasma branched-chain amino acid (BCAA) concentrations to determine whether light resistance exercise (dumbbell exercise) performed with high plasma BCAA concentrations resulting from ingestion of HPS 3 h after a basal meal is effective in the promotion of amino acid utilization by peripheral tissues ( 3 ). HPS ingested 3 h after a basal meal increased the plasma BCAA concentrations.…”

Effect of Intermittent Blood Volume Fluctuation of Light Resistance Exercise after Ingestion of the High-Protein Snacks on Plasma Branched-Chain Amino Acid Concentrations in Young Adults

“…It is thought that the climbing exercise in rats also causes intermittent blood volume fluctuation in muscle tissues, similar to that which arises during dumbbell exercise in human subjects ( 4 ).…”

“…Performing dumbbell exercise in half-crouching position, with the upper body angled forwards, grasping the dumbbells firmly, twisting the wrists inward, and keeping them curled ( 5 , 6 ) resulted in reduced blood volume in the antebrachial and femoral muscles during exercise and sudden increase in blood volume during the interval period between exercise sets ( 4 ). It is thought that the climbing exercise in rats also causes intermittent blood volume fluctuation in muscle tissues, similar to that which arises during dumbbell exercise in human subjects ( 4 ).…”

“…The performance of voluntary tower climbing exercise ( 3 ) as light-resistance exercise after ingestion of the HPS, producing intermittent blood volume fluctuation in muscle tissue, resulted in increased muscle mass in glucocorticoid-injected rats. In addition, light-resistance exercise (dumbbell exercise) during a period of elevated plasma branched-amino acid (BCAA) concentration following the HPS which was taken 3 h after the basal meals seemed also effective in promoting the utilization of BCAA in human subjects ( 4 ).…”