Study of Inactivity on Metabolism of Elderly Muscles

Study Overview
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Brief Summary
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Skeletal muscle mass declines with inactivity (casting is a good example) and increases with activity (such as weightlifting). Whether muscle mass increases or decreases, is determined by whether more new proteins within muscle are made than are broken down. The investigators know that feeding protein increases the synthesis of new proteins but that the response of older muscles to protein feeding is blunted compared with the young. This resistance of the elderly to muscle building stimuli may be the primary reason that muscle mass is lost in aging. The investigators also know that periods of muscle disuse such as casting result in a person's muscle shrinking due, the investigators believe, to a lower rate of synthesis of new muscle proteins. Age-related muscle loss begins around 50 years old and proceeds at approximately 1% for every year after. Elderly persons would likely fare well with advancing age if their muscle loss were simply linear; however, a rate of muscle loss of 1% annually is a 'population view' and does not represent what occurs during short periods of muscle disuse (i.e. during hospitalization or illness), which occur with increasing frequency in elderly persons. During periods of disuse, the resistance of elderly muscles to protein nutrition may be worsened. The investigators will measure how quickly new proteins are made at rest and after protein feeding in elderly men, before and after a 14 day period of reduced activity brought on by having people reduce their daily step count.

Official Title
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Influence of Reduce Daily Step Count on Muscle Protein Metabolism in Older Persons

Conditions
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Sarcopenia

Intervention / Treatment
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* Behavioral: Step reduction


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or Female Aged 60 to 80 years old Non-smoker Generally healthy and can tolerate the resistance exercise and protein drink Exclusion Criteria: Allergies to whey protein Health problems such as: heart disease, rheumatoid arthritis of the knee joint, diabetes, poor lung function, uncontrolled hypertension, or any health conditions that might put participants at risks for this study Failed an exercise stress test Taking metformin and/or other medications for the control of blood glucose even though one might not be classified as diabetic Taking prescribed blood thinners such as warfarin and heparin but excluding aspirin Taking medications for lung and kidney conditions but excluding medication for asthma that is under control

Ages Eligible for Study
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Minimum Age: 60 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Step Reduction<br>Step reduction: Take less than 1500 steps/d No disease | Behavioral: Step reduction<br>* taking less than 1500 steps/d<br>* Other names: Sedentary behaviour;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fractional synthetic rate (FSR) of myofibrillar muscle protein | rate of making new muscle proteins | over 5h | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood amino acid concentrations | concentration of amino acids in blood | over 5h | 
| Intramuscular signalling protein status | phosphorylation of key signalling proteins | over 5h | 
| Insulin sensitivity via blood sampling | measure of insulin concentration | over 5h | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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sarcopenia, muscle, reduced activity, insulin sensitivity, protein, step reduction, muscle protein synthesis, whey protein, leg strength, whole body protein