Step-reduction in Older Men and Women

Study Overview
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Brief Summary
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This study investigates the effects of two weeks of reduced daily ambulation and a subsequent return to normal physical activity on metabolic health of older adults.

Detailed Description
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Aging results in a progressive loss of muscle mass that is accelerated by periods of muscular disuse, common for older adults during hospitalization or convalescence from illness. Transient physical inactivity has been shown to cause muscular atrophy and impairments in insulin sensitivity in both younger and older adults. However, the recovery capacity of older adults after such physical inactivity remains unknown. This study aims to determine the impact of two weeks of daily step reduction to ≤1000 steps per day, an experimental model mimicking short-term physical inactivity, on glycemic control in older adults and further investigate whether older adults are able to recover from the consequences of this inactivity simply by returning to their habitual activity for 14 days.

Official Title
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The Influence of Acute Physical Inactivity on Metabolic Function in Older Men and Women

Conditions
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Older Adults, Reduced Physical Activity

Intervention / Treatment
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* Behavioral: Normal Daily Steps
* Behavioral: Step-Reduction
* Behavioral: Return to Normal Daily Steps


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Non-smoker Exclusion Criteria: Use of assistive walking devices Chronic use of analgesic or anti-inflammatory drugs History of neuromuscular problems or muscle and/or bone wasting disease Acute or chronic illness including cardiac, pulmonary, liver or kidney abnormalities, uncontrolled hypertension, insulin or non-insulin dependent diabetes or other metabolic disorders Daily use of statins, particularly simvastatin and atorvastatin Use of medications known to affect protein metabolism Normally complete fewer than 3000 steps per day

Ages Eligible for Study
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Minimum Age: 65 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: Change in physical activity for older adults<br>Older adult participants undergo alterations in daily ambulation by completing Normal Daily Steps for one week, followed by a two-week Step-Reduction and a subsequent Return to Normal Daily Steps for two weeks | Behavioral: Normal Daily Steps<br>* Complete normal daily ambulation for one week<br>Behavioral: Step-Reduction<br>* Reduce daily ambulation to fewer than 1000 steps per day for two weeks<br>Behavioral: Return to Normal Daily Steps<br>* Increase daily ambulation to 100% of normal daily step-count for two weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Insulin Sensitivity | Assessed via Matsuda ISI | Measured at the end of each behavioural intervention (Week 1, Week 3, Week 5) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in lean tissue mass | Assessed via Dual Energy X-Ray Absorptiometry | Measured at the end of each behavioural intervention (Week 1, Week 3, Week 5) | 
| Change in Peak Isometric Maximal Voluntary Leg Extension Strength | Assessed via muscle dynamometry | Measured at the end of each behavioural intervention (Week 1, Week 3, Week 5) | 
| Change in Muscle Protein Synthesis | Obtained via vastus lateralis muscle biopsy | Measured at the end of each behavioural intervention (Week 1, Week 3, Week 5) |