Two Weeks of Reduced Activity and Skeletal Muscle Health in Older Men

Summary

Muscle size declines at around 0.5-1% per year after 50 years of age, with muscle strength declining up to twice as fast as muscle size. This may eventually lead to loss of independence if tasks of daily living become too strenuous to be performed safely. Short periods of bed rest cause very rapid loss of muscle size and strength, and studies using healthy older participants have shown that age increases vulnerability to this muscle loss. However, it is unlikely that healthy individuals would be faced with periods of bed rest unless suffering a severe illness. In light of this, recent evidence has shown that even just reducing walking to less than 1,500 steps per day for two weeks caused 4% loss of leg muscle in over 65 year olds. This amount of activity is roughly the equivalent of being housebound, something that may become more common into older age, for example due to prolonged bad weather, or minor injury or illness.

This study will investigate what causes such stark muscle loss during two weeks of reduced activity, and the impact on skeletal muscle function and size, as well as balance, body composition, and other indicators of general health such as how the body responds to food or exercise. Importantly, exercise strategies that could reduce muscle loss during a period of reduced activity will also be investigated.

In brief, three groups of 10 older men (aged 65-80 years) will undertake two weeks of reduced physical activity by limiting their daily steps to \<1,500/day. All groups will then undertake a re-training exercise programme to ensure that any losses in muscle strength or size are regained. One of the groups will be a control, whereby they will undertake the step-reduction intervention and re-training, but no protective exercise before or during the step-reduction intervention. This group will allow us to achieve our primary objective of determining the influence of two weeks of reduced physical activity on muscle strength and size in healthy older males. The two other groups will undertake either four weeks of strength exercise training before the step-reduction intervention, or daily home based exercise 'snacking' during the step-reduction intervention. The potential protective benefits of the exercise interventions in reducing the impact of two weeks of reduced activity on muscle strength and size, and any effect on how muscle is re-gained afterwards, will be compared to the 'control' group.

Conditions

• Muscular Atrophy

Interventions

BEHAVIORAL

Step-reduction

Participants will reduce the number of steps they take each day to less than 1, 500 for two weeks, using a pedometer to monitor their daily step count.

BEHAVIORAL

Pre-training

Participants will attend 10 strength training exercise sessions over a four week period prior to the step-reduction intervention. These exercise sessions will be focused on lower limb strength, fully supervised and will be progressive.

BEHAVIORAL

Exercise snacking

Participants will perform three bouts of five minutes of exercise each day during the two week step-reduction intervention. These will consist of five discrete exercises, each performed continuously for one minute, with one minute of rest between each exercise. These exercises will be non-supervised, and require no specialist equipment.

Sponsors & Collaborators

• University of Bath

  lead OTHER

Principal Investigators

• Keith Stokes, PhD · University of Bath

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

65 Years

Max Age

80 Years

Sex

MALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2015-07-31

Primary Completion

2017-10-31

Completion

2017-10-31

Countries

• United Kingdom

Study Locations