Leucine-enriched Nutraceutical and Attenuating Muscle Loss

Overview

This leucine-enriched protein gummy (as a gummy bar/slab) will be studied to address age-related loss of muscle mass and strength/function in older persons. The product is small volume (approximately 35 g per serve) and low energy (approximately 100 kcal per serve). It is easy to chew and swallow with the consistency of a firm Jello. In addition, it contains an effective dose of leucine in a high-quality protein matrix consisting of milk proteins. Understanding the efficacy of this product on changes in levels of blood amino acids and the molecular signaling required to enhance muscle growth will provide helpful insight for the suggestion of supplemental use.

General experimental design: Pre-testing will require participants to become familiarized with performing maximal voluntary isometric contractions, as well as touring the laboratory facilities. Participants will be asked to complete dietary records for three days to determine habitual caloric intake. The experimental trial will be conducted in three phases. A baseline run-in phase (Phase 1) during which participants will consume a diet matching their estimated energy requirement to put them in a weight-stable phase. Energy requirements will be estimated using the Harris Benedict equation using an appropriate physical activity factor based on interview responses to a standard activity questionnaire. Participants will then be assigned to either the comparator group (n=10) or leucine-enriched protein food group (n=10). For the subsequent 10d (Phase 2), participants will undergo a period of step reduction (\< 1000 steps.d-1) whilst in a 500 kcal.d-1 deficit that will be adjusted for the reduced physical activity due to the step reduction. The reason for inducing an energy deficit is to mimic a situation where older individuals will be both physically inactive and 'undernourished', such as during home-bound periods of sickness or while in hospital. After completing Phase 2, participants will then return to their normal step count (from measured habitual steps pre-intervention) under energy balanced conditions for 10d that will serve as a recovery phase, Phase 3. We will complete assessments of body composition, leg lean mass, maximal voluntary isometric strength, measures of physical performance, and rate of force development will be made. Skeletal muscle biopsies will be obtained for biochemical analysis. At these time points, maximal voluntary isometric force, maximal leg press strength, a battery of physical performance measures and body composition will once again be obtained.

Conditions

Interventions

Eligibility

Locations (4)

Outcomes