When citing an abstract from the 2009 Annual - Society for ...

Abstract: Many activities of daily living, ranging from holding a telephone to carrying
shopping, are critically dependent on stable low-level voluntary contractions with a constant
force output. Force steadiness has been measured previously after stroke, but only over short
intervals such as 5-20s. We investigated force stability over a more functionally relevant duration
in hemiplegic stroke subjects. 10 subjects (between 1-13 years post stroke, mean 6.5 years; aged
37-72) sat with the knee of the test leg extended to 120° and the ankle at the mid-point of passive
range of motion. Dorsiflexion maximum voluntary contraction force was measured in this
position during three brief (2-3 s) trials. Subjects then produced either 5 or 10% of their
maximum and once established, the target force was held for 6 minutes under different
conditions including during a distraction task, and with and without visual feedback. Trials on
each side were separated by 10 min rest, with the less affected side tested before the more
affected side. Thus any learning or training effect occurred on the less affected side. Surface
EMG was recorded from tibialis anterior, peroneus longus and triceps surae and quantified for
each condition as the magnitude of the RMS processed signal. Force stability was measured as
the mean square error from the target force. Significant differences in force stability were seen
between sides (p