UBC Reports | Vol. 48 | No. 3 | Feb. 7, 2002

Study flexes muscles

Rehabilitation Sciences researchers will seek to discover how muscles recover after weightlessness and lack of use

Skiers, hikers and astronauts may all benefit from an investigation launched recently by UBC Rehabilitation Sciences researchers.

The first study of its kind in North America, it aims to discover how wasted and weakened muscles recover from prolonged periods of weightlessness.

"Our study findings have significant implications for how we treat astronauts returning to Earth from the international space station," says principal investigator Donna MacIntyre, an associate professor of Physical Therapy. "Results will also influence therapies for injuries from skiing, hiking or motor vehicle accidents where there are bone fractures."

More than 40 people will take part in the three-year controlled clinical study, a joint life science project of the Canadian Space Agency, Vancouver General Hospital (VGH) and UBC.

MacIntyre will be working with co-investigators Asst. Prof. Janice Eng and Asst. Prof. Darlene Redenbach, both experts in physical therapy at the School of Rehabilitation Sciences.

Half of the study participants are patients who have been non-weight bearing for at least six weeks. Types of injury will vary, but most patients will have been immobilized because of broken legs or torn Achilles tendons at the heel. The remaining participants will form the control group.

Rate of muscle recovery will be assessed for all 40 participants while they engage in a standardized physiotherapy program that can last from six weeks to three months. Exercises include knee and ankle movements, weight lifting, balancing moves and aerobic exercise.

Testing patients' muscle strength, fatigue and balance will take place at the Rehabilitation Research Laboratory of the GF Strong Rehabilitation Centre using a machine that resembles an airplane cockpit and provides video displays of muscle strength. Another machine tests patients' ability to maintain balance.

"The body's muscles are microscopically damaged when they are not exposed to gravity and forced to carry the body's weight. This can happen when you are confined to bed, use crutches to keep a broken leg off the ground or spend lengthy periods in space," says MacIntyre.

Scientists estimate that the body's muscles are damaged after 30 days of bed rest with muscle mass declining by eight per cent in the thigh and four to five per cent in the calf. There can be a 20 per cent decrease in leg strength after only two weeks of bed rest.

Muscle biopsies from astronauts show some loss of muscle mass after five days of weightlessness with significant damage after 11 days.

Patients will also be treated in the physiotherapy department at VGH. Researchers will conduct biochemical blood testing and analysis to determine extent of muscle injury and inflammation at the muscle injury lab at the School of Rehabilitation Sciences. Analysis of study results will also take place at UBC.