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