Older men can benefit from leucine-enriched essential amino acid supplements
Older men can benefit from leucine-enriched essential amino acid supplements

Leucine-Enriched Amino Acid Ingestion After Resistance Exercise Prolongs Myofibrillar Protein Synthesis and Amino Acid Transporter Expression in Older Men

Overview

Sarcopenia, the loss of muscle mass and strength that occurs with aging, leaves older adults vulnerable to frailty, falls, mobility limitations, and mortality. Ingesting dietary protein or amino acids after engaging in resistance exercise has been identified and validated as an effective strategy for sustaining muscle and mitigating sarcopenia in the aging population. Scientists continue to investigate the specific nutritional factors that yield these muscle-building effects.

Trial Length

Acute metabolic study

Number of Subjects

15

Gender

Male

Age Range

70 - 74

The Goal

Researchers examined the effects of increased leucine ingestion on skeletal muscle myofibrillar protein synthesis, mammalian/mechanistic target of rapamycin complex 1 signaling, and amino acid transporter mRNA expression in older men over a 24-hour period after resistance exercise.

The Results

One hour after performing resistance exercise, participants ingested 10 grams of essential amino acids made up of either 1.85 grams of leucine or 3.5 grams of leucine. Muscle biopsies were taken at rest, and 2, 5, and 24 hours after exercise.

While both groups increased muscle protein synthesis, the mRNA expression of select amino acid transporters, and the p70 S6 kinase 1 phosphorylation initiation factor for the mammalian target of rapamycin complex 1, only the group taking the essential amino acid mixture containing greater leucine content had elevated levels of muscle protein synthesis and mRNA expression at 24 hours after exercise. The enriched leucine also increased the initiation factor 4E binding protein 1 phosphorylation while the lower leucine dose of 1.85 grams did not.Graph showing time course of myofibrillar protein FSR after ingrestion of essential amino acids.Time course of phosphorylation of mTOR after ingestion of 10g essential amino acids.Time course of mRNA expression after 10g esssential amino acids.

Conclusion

Taking an essential amino acid supplement enriched with leucine after performing resistance exercise may lengthen the anabolic response and sensitivity to amino acids in older men.

The Why?

The body’s response to muscle-building mechanisms becomes more subdued with age, which can lead to muscle wasting and a decline in functional status and quality of life. This study shows that an essential amino acid supplement with a high concentration of leucine can help make aging muscle more responsive to the muscle-building effects of exercise and rehabilitation programs when taken after resistance training.

Citation

Dickinson JM, Gundermann DM, Walker DK, et al. Leucine-enriched amino acid ingestion after resistance exercise prolongs myofibrillar protein synthesis and amino acid transporter expression in older men. J Nutr. 2014;144(11):1694-1702. doi:10.3945/jn.114.198671