JONATHAN C. McLEOD, STUART M. PHILLIPS*
* Corresponding Author
McMaster University, Department of Kinesiology, Hamilton, Canada

Abstract

The age-related loss in skeletal muscle mass and strength, collectively referred to as sarcopenia, is measurable in the sixth decade of life with mass being lost at ~0.8% annually and strength at ~1-3% per year beginning for most in their fourth decade of life. The reduction in muscle mass and strength with advancing age are associated with many chronic diseases, mobility impairments and even mortality. The acute regulation of skeletal muscle mass is via fluctuations in muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Here we briefly examine the evidence for several nutritional strategies (dietary protein, leucine and omega-3 polyunsaturated fatty acids) that may aid in mitigating the negative effects of sarcopenia.

INTRODUCTION

Aging is accompanied by the progressive loss of skeletal muscle mass, strength, and function: sarcopenia. Sarcopenia is measurable in the sixth decade of life and it is estimated that muscle loss proceeds at a rate of ~0.8% annually past 55 years old (1), whilst losses in muscle strength and power occur more rapidly at rates of 1-3% and 4-8% per year, respectively (2,3). Sarcopenia is prognostic for mobility disability, chronic disease risk, reduced quality of life, and mortality (4). Given that the world population is aging at an unprecedented rate, and that by the year 2050, the proportion of the world’s population over the age of 65 will nearly double from 12% to 22% (5), reducing the prevalence of sarcopenia or mitigating its progression, would greatly enhance the health span, and quality of life, of older adults (5).

To a large extent, skeletal muscle mass is governed by changes in muscle protein synthesis (MPS) and muscle protein breakdown (MPB). MPS is a graded, saturable process that is sensitive to various exogenous stimuli, such as resistance exercise and the provision of essential amino acids (EAA), via hyperaminoac ...