Dietary Strategies to Promote Muscle Protein Anabolism in the Elderly

Summary

Aging is associated with the loss of lean muscle mass, termed sarcopenia. Food intake and in particular the ingestion of protein or amino acids has been shown to be a powerful stimulus to promote net muscle protein anabolism. However this anabolic response following a meal-like protein bolus seems to be blunted in the elderly as compared to young adults.

The first aim of this proposal is to investigate the post-prandial muscle protein synthesis rates in young and elderly men in response to a meal-like protein bolus after a period of rest or physical activity (study A). The rest trial (REST) will act as a proof-of-principle study to examine the blunted protein synthetic response in the elderly, and as a control trial in comparison with the exercise trial (EXC) to establish the surplus value of physical activity prior to protein intake on muscle protein synthesis.

The second aim of this proposal is to determine the surplus value of an increased quantity of the ingested protein bolus (study B). Large amounts of protein (40 and 60 g) will be compared to a meal-like amount of protein (20 g) as a means to maximize plasma amino acid availability and/or to stimulate muscle protein anabolism.

The third aim of this proposal is to study the differences in quality of the ingested protein bolus (study C). Instead of significantly increasing the quantity of the protein bolus, we will also apply a more practical approach to augment skeletal muscle protein synthesis rates; modifying the digestibility or amino acid composition of a meal-like protein bolus.

Conditions

• Sarcopenia

Interventions

DIETARY_SUPPLEMENT

Protein/Amino Acids

Casein Whey Leucine

OTHER

Physical exercise

The physical exercise protocol will consist of low intensity cycling and light resistance-type exercise; after 5 minutes of self-paced cycling, subjects will perform 6 sets of 10 repetitions on the horizontal leg press machine (Technogym BV, Rotterdam, The Netherlands) and 6 sets of 10 repetitions on the leg extension machine (Technogym BV, Rotterdam, The Netherlands). The first 2 sets of both resistance exercises will be performed at 40% of the subjects' 1RM. Sets 3-4, and 5-6 will be performed at 55% and 75% of 1RM, respectively, with 2 minutes rest intervals between sets.

Sponsors & Collaborators

• National Nutrition and Food Technology Institute

  collaborator OTHER

• Maastricht University Medical Center

  lead OTHER

Principal Investigators

• Luc van Loon, Phd · Maastricht University

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

85 Years

Sex

MALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2007-12-31

Primary Completion

2010-11-30

Completion

2010-11-30

Countries

• Netherlands

Study Locations