The Journal of Bone and Joint Surgery, Vol 64, Issue 6 896-899, Copyright © 1982 by Journal of Bone and Joint Surgery, Inc
Energy costs of walking in lower-extremity plaster casts
RL Waters, J Campbell, L Thomas, L Hugos and P Davis
The energy cost of walking with axillary crutches and each of three types
of plaster casts (long, short, and cylinder) on the lower extremity was
measured in twenty normal adult men. The knee and ankle joints were
immobilized unilaterally in the neutral positions. Oxygen uptake was
measured using a modified Douglas-bag technique. Heart rate, respiratory
rate, and step frequency were telemetered from transducers that were
attached to the subjects. When walking and bearing full weight on a cast
without the use of crutches, the average rates of energy expenditure for
subjects wearing the three varieties of casts did not significantly differ
from the value for normal walking. Velocity, however, was reduced depending
on the extent of immobilization. The average velocity of the subjects was
fifty-six meters per minute in a long cast, sixty-four meters per minute in
in a cylinder cast, and seventy meters per minute in a short cast, compared
with seventy-eight meters per minute without immobilization of the limb.
The subjects' average oxygen cost per meter was 0.24 milliliter per
kilogram in a long cast, 0.20 milliliter per kilogram in a cylinder cast,
and 0.19 milliliter per kilogram in a short cast, compared with 0.15
milliliter per kilogram for normal walking. Using a unilateral
non-weight-bearing swing-through gait, the average rate of oxygen uptake
for subjects wearing the three types of casts did not differ from the mean
value without a cast (21.2 milliliters per kilogram per minute). All values
were at least 60 per cent higher than the average for normal level walking.