Can Supplemental Leucine Offset Disuse-induced Muscle Atrophy?

Summary

Ageing is associated with a gradual decline in muscle mass that is detrimental to both physical function and metabolic health, increasing the risk of morbidity and mortality. The loss of protein muscle mass with ageing is poorly understood, but it may partly relate to inactivity/disuse (i.e. during injury or hospitalization). Periods of inactivity/disuse blunt the ability of muscle to grow (termed anabolic blunting), leading to a loss of muscle mass and strength. An accumulation of these periods over a lifetime promotes the devastating loss of muscle protein mass and strength seen with ageing.

Disuse-induced muscle loss is underpinned by a blunted muscle anabolic response to protein nutrition. Supplementing the diet with the amino acid leucine may offer a potential solution to alleviate muscle mass and strength loss during disuse. In fact, leucine is suggested to promote muscle protein growth and reduce muscle protein loss during disuse in rats, but this is yet to be shown in humans. Accordingly, the proposed study will investigate whether leucine supplementation can offset muscle and strength loss during short-term disuse.

Twenty-four healthy (non-obese, non-diabetic, non-smokers) men aged 18-35 years will initially complete a lower-limb strength assessment and undergo a body composition scan three days later. The following morning, participants will be randomly assigned to ingest either 5g of leucine (n=12) or a caloric-matched placebo (n=12) with each meal over a 7 d period of a single-leg immobilisation. Immediately following immobilisation participants will undergo another body composition scan. Additionally, a stable isotope infusion will be combined with serial muscle biopsies from the thigh of each leg to determine the measure rates of muscle protein synthesis in the fasted state and in the 'early' and 'late' phase of feeding. A day later, the assessment of muscle strength will be repeated.

Conditions

• Muscle Disuse Atrophy

Interventions

DIETARY_SUPPLEMENT

Leucine

Participants will ingest 15g of leucine supplementation/day during the immobilisation period. Leucine supplementation will be administered in powdered form (Infinit Nutrition, Canada) and participants will be required to consume 5g of leucine mixed with 250-300 ml of water during each meal. Leucine is a dietary supplement according to the US FDA. This supplementation protocol has been demonstrated in humans (Murphy et al., 2016, AJCN) with no reported side effects. The quantity of leucine supplementation falls well within the safe limits outlined by Rasmussen et al. (2016). Infinit Nutrition Leucine is in compliance with banned substances requirements as espoused by the World Anti-Doping Agency. Infinit Nutrition Leucine is not a medicinal product.

DIETARY_SUPPLEMENT

Placebo

Participants will ingest 15g of placebo supplementation/day during the immobilisation period. Placebo supplementation will be administered in powdered form and participants will be required to consume 5g of placebo supplementation mixed with 250-300 ml of water during each meal (3x/day). Placebo supplementation will contain 5g of non-essential amino acids (Infinit Nutrition, Canada) and will be calorically matched to the leucine supplementation.This supplementation protocol has been demonstrated previously in humans, with no reported side effects (Murphy et al., 2016, AJCN).

Sponsors & Collaborators

• University of Birmingham

  lead OTHER

Principal Investigators

• Leigh Breen, PhD · University of Birmingham

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

35 Years

Sex

MALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2017-03-01

Primary Completion

2019-02-01

Completion

2019-05-01

Countries

• United Kingdom

Study Locations