Aging, Energy Malnutrition Protein, Muscle Atrophy
Conditions
Keywords
Muscle protein synthesis, Ageing, Dietary protein, Disuse
Brief summary
In healthy middle-aged men and women, what is the effect of dietary energy restriction and energy surplus on daily muscle protein synthesis rates and muscle morphology, compared to energy balance, during free-living and immobilisation?
Detailed description
Background Age related muscle tissue loss, which is associated with a number of negative health outcomes is partially caused by blunted muscle protein synthesis rates (MPS) in response to food ingestion, which is exacerbated by muscle disuse. Concomitantly, consuming an energy balanced diet appears to become more challenging with advancing age, due to a reduction in appetite. Of concern is that the impact of energy intake on muscle protein metabolism during ageing is poorly characterised. Objective To determine daily MPS and muscle morphology in response to differing energy intakes, in free-living conditions and during immobilisation. Methods Healthy middle-aged volunteers will consume a hypocaloric, energy-balanced, or hypercaloric diet (providing 1.4 g.kg.day protein) over a three-day free-living period, and a three day period of single leg immobilisation. Deuterium oxide and MRI scans will be used to measure daily MPS and muscle size, respectively. Value The study will determine the effect of energy intake per se on daily muscle protein synthesis rates and muscle size, in free-living and immobilised conditions. This will inform how energy provision modulates tissue loss with ageing, and how this interacts with the catabolic stress of muscle disuse.
Interventions
OTHEREnergy status
Varying conditions of energy intake, thereby manipulating whether participants are in a state of energy restriction, balance, or surplus.
Sponsors
University of Exeter
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
35 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
Age 35-65 Healthy Non-smoker Recreationally active
Exclusion criteria
Any diagnosed metabolic impairment (e.g. type 1 or 2 Diabetes) Any diagnosed cardiovascular disease or hypertension Elevated blood pressure at the time of screening. (An average systolic blood pressure reading of ≥150mmHg over two or more measurements and an average diastolic blood pressure of ≥90mmHg over two or more measurements.) Chronic use of diabetic medication. A personal or family history of epilepsy, seizures or schizophrenia. Allergic to mycoprotein / Quorn, penicillin, or cow's milk. Any musculoskeletal injury that may impair their use of crutches. Any diagnosed severe digestive illness. Any diagnosed severe autoimmune disease. Any diagnosed cancer. Any metal fragments in the eyes, a pacemaker, or metal implants in the body that preclude MRI scanning.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Muscle protein synthesis (MPS) | 6 days (3 days free-living, 3 days immobilised) | Daily muscle protein synthesis rates, expressed as fractional synthetic rate (FSR) (%/day) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Muscle morphology. | 3 day immobilisation phase. | Changes in muscle size, measured via MRI scanning, during immobilisation. |
Countries
United Kingdom
Outcome results
None listed