Although the concentric isokinetic muscle
strength testing could not definitely reveal that the
experimental group performed greater quadriceps
muscle strength than control group, 6MWD may
explain the greater improvement. Ostchega and
colleagues57 indicated that there was a linear
relationship between knee extensor strength,
isokinetic muscle strength, and timed walk
performance. Therefore, greater improvement of
6MWD in the experimental group may reveal greater
quadriceps muscle strength than in the control group.
Knee flexion ROM improved significantly in
the experimental group while the control group did
not. Although there was no significant difference
between groups at each time point, degree of knee
flexion ROM in the experimental group increased
over time from baseline to the 12th week, whereas
the control group remained the same as baseline
measurements. The results reveal the beneficial
effect of the exercise program on knee flexion ROM.
In the experimental group, ESs of knee flexion ROM
in both knees improved from a small to medium
level at the completion of the intervention. In both
groups, changes in knee extension ROM indicated
a little difference from a normal value41 and showed
no statistically significant. One possible reason was
that all eligible participants had mild to moderate
severity of knee symptoms. Therefore, their knee
joints would have little or no deformity.