The Visual3D software also filtered,
integrated, normalized, and determined
the peak and mean EMG
activity for each muscle. Specifically,
after adjustment for direct current bias
and baseline noise, the EMG data were
digitally filtered (60-Hz notch; Butterworth
10-Hz high-pass and 350-Hz
low-pass filters), full-wave rectified,
and integrated over 0.01-second intervals.
Processed EMG signals were normalized
and expressed as a percentage
of the maximum recorded within a
0.05-second moving window average
of either the MVC or any of the sit-tostand
transfer trials. Because the
signals were normalized to any
maximum muscle contraction that
occurred during testing, EMG data
were expressed as a percentage
of maximum voluntary contraction
(% MVC).