Physical performance was assessed by three
components including physical function, quadriceps
muscle strength, and range of motion of the knee.
Physical function was assessed by distance walked
in the 6-Minute Walk Test. Quadriceps muscle
strength was determined by knee extension peak
torque during the concentric isokinetic muscle
strength testing. The CON-TREX MJ, a multi-joint
module dynamometer (CMV AG, Dubendorf,
Switzerland) was employed to measure concentric
isokinetic muscle strength conducted by a trained
technician at a university medical school. Test speed
was set at 60 degrees per second (600/sec) with 2
sets of 3 maximal repetitions and joint angle was
set to yield the actual 60 degrees of knee move-
ment. Range of motion (ROM) of the knee was
measured using a universal goniometer after comple-
tion of the isokinetic muscle strength testing.
Protocol for knee flexion and extension ROM
measurement was described elsewhere.41