Forearm Immobilization, Metabolic Health, and Nutrition

University of Exeter24 enrolled

Overview

The present study will investigate the impact of dietary branched chain amino acid restriction on muscle atrophy, insulin sensitivity and muscle protein synthesis following short-term forearm immobilization

Twenty-four healthy young volunteers will undergo 2 days of forearm immobilization in combination with either a branched chain amino acid restricted diet or a control diet. Before and after immobilization, they will receive a stable isotope tracer infusion (5.5 h) combined with repeated blood and muscle sampling under insulin clamp conditions, in order to measure insulin sensitivity and muscle protein synthesis in the fasted and fed state.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Enrollment

Conditions

Healthy

Interventions

Forearm immobilizationBEHAVIORAL

Two days of forearm immobilization

Eligibility

Sex: ALLMin age: 18 YearsMax age: 40 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Males and females 18-40 years of age * Body mass index between 18.5 and 30 kg/m2 Exclusion Criteria: * Smoking * Any diagnosed metabolic impairment (e.g. type 1 or 2 diabetes) * Any diagnosed cardiovascular disease * Hypertension (≥140 mmHg systolic and/or ≥90 mmHg diastolic) * Chronic use of any prescribed or over the counter pharmaceuticals (excluding oral contraceptives and contraceptive devices) * Regular use of nutritional supplements * Currently involved in a structured progressive resistance training programme (\>3 times per week) * A personal or family history of thrombosis, epilepsy, seizures or schizophrenia * Any previous motor disorders or disorders in muscle and/or lipid metabolism * Known hypokalaemia * Presence of an ulcer in the stomach or gut and/or strong history of indigestion * Known severe kidney problems * Pregnant or breastfeeding * Unable to give consent

Locations (1)

University of Exeter

Exeter, Devon, United Kingdom

Outcomes

Primary Outcomes

Forearm glucose uptake

Insulin sensitivity, measured as forearm glucose uptake, under hyperinsulinaemic-euglycaemic conditions

Time frame: Hyperinsulinaemic-euglycaemic clamps are performed before and immediately after 2 days of forearm immobilisation. Forearm glucose uptake is measured during the steady state period of the clamp.

Secondary Outcomes

Muscle protein synthesis rates

Muscle protein synthesis rates are measured using an intravenously infused stable isotope labelled amino acid tracer, combined with repeated blood and muscle tissue sampling.

Time frame: During 3 hours of hyperinsulinaemic-euglycaemic clamped conditions before and after 2 days of immobilisation

Intramuscular BCAA concentration

Intramuscular BCAA concentration measured using mass spectrometry

Time frame: Before and after 3 hours of hyperinsulinaemic-euglycaemic clamped conditions

BCAA concentrations between forearm arterialized venous and deep venous blood

Arterialized venous-deep venous forearm balance of BCAA, in the fasted state and during a hyperinsulinaemic-euglycaemic clamp

Time frame: Fasted and during the steady-state phase of the insulin clamp (i.e. last 30 minutes)

Whole-body substrate oxidation

Whole-body substrate oxidation measured using indirect calorimetry

Time frame: Hyperinsulinaemic-euglycaemic clamps are performed before and immediately after 2 days of forearm immobilisation. Whole-body substrate oxidation is measured before the commencement of, and during the steady state period of the clamp (last 30 minutes)

Data from ClinicalTrials.gov

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