(A) Spontaneous muscle activity in participants with SCI over time compared to neurologically intact participants at rest. (B) Spontaneous muscle activity in participant number 2 during the relaxation period over time. (A) Averaged RMS ± SD for each muscle at rest are presented for participants with SCI and neurologically intact participants. The number of muscles with spontaneous activities, frequency and the amplitude of the motor unit firing were increased in participants with SCI during first and second assessment. These involuntary activities were reduced over time (Ax 3 and Ax 4) in participants with SCI. (B) An example of spontaneous muscle activities at rest in one participant with SCI. The frequency and the amplitude of the motor unit firing were increased over time in LPM. But the high level of spontaneous activity in LOP were cleared completely in the following assessments. Similar activity was seen in ROP in the second Ax which was cleared in the fourth Ax. In addition, the spontaneous muscle activity was only observed in RA in fourth Ax. RMS: root mean square, DPI: days post injury, LOP: left opponens pollicis, LPM: left pectoralis major, Ax: assessment.