Study of Inactivity on Metabolism of Elderly Muscles

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

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.

Study Overview

• Status: Completed
• Conditions: Sarcopenia
• Intervention / Treatment: Behavioral: Step reduction

• Study Type: Interventional
• Enrollment (Actual): 10
• Phase: Phase 1

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Hamilton, Ontario, Canada, L8S 4K1
      • McMaster University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 60 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Step Reduction; Step reduction: Take less than 1500 steps/d; No disease	Behavioral: Step reduction; taking less than 1500 steps/d; Other Names: Sedentary behaviour

What is the study measuring?

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

Collaborators and Investigators

• Sponsor: McMaster University

Study record dates

Study Major Dates

• Study Start: September 1, 2011
• Primary Completion (Actual): September 1, 2012
• Study Completion (Actual): December 1, 2012

Study Registration Dates

• First Submitted: July 19, 2011
• First Submitted That Met QC Criteria: March 21, 2013
• First Posted (Estimate): March 26, 2013

Study Record Updates

• Last Update Posted (Actual): February 25, 2020
• Last Update Submitted That Met QC Criteria: February 21, 2020
• Last Verified: March 1, 2013

More Information

Terms related to this study

• Keywords: insulin sensitivity; muscle; sarcopenia; muscle protein synthesis; whey protein; protein; leg strength; reduced activity; step reduction; whole body protein
• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Neuromuscular Manifestations; Pathological Conditions, Anatomical; Muscular Atrophy; Atrophy; Sarcopenia
• Other Study ID Numbers: 267