Rhythmic arm swing enhances patterned locomotor-like muscle activity in passively moved lower extremities

Abstract

The use of driven gait orthosis (DGO) has drawn attention in gait rehabilitation for patients after central nervous system (CNS) lesions. By imposing a passive locomotor-like kinematic pattern, the neural mechanisms responsible for locomotion can be activated as in a normal gait. To further enhance this activity, discussions on possible intervention are necessary. Given the possible functional linkages between the upper and lower limbs, we investigated in healthy subjects the degree of modification in the lower limb muscles during DGO-induced passive gait by the addition of swing movement in the upper extremity. The results clearly showed that muscle activity in the ankle dorsiflexor TA muscle was significantly enhanced when the passive locomotor-like movement was accompanied by arm swing movement. The modifications in the TA activity were not a general increase through the stride cycles, but were observed under particular phases as in normal gaits. Voluntary effort to swing the arms may have certain effects on the modification of the muscle activity. The results provide clinical implications regarding the usefulness of voluntary arm swing movement as a possible intervention in passive gait training using DGO, since ordinary gait training using DGO does not induce spontaneous arm swing movement despite its known influence on the lower limb movement.

Keywords: Arm swing; Lokomat; locomotor‐like EMG; passive stepping.

Figure 1

The experimental apparatus and the tasks used. Each subject walked passively in the DGO and kept his lower extremities relaxed throughout the session, with different tasks for the upper extremities. In the first experiment, the subject walked without (left panel) and with (right panel) arm swing. In the second experiment, he walked with the arms swinging while wearing different loads on both wrists.

Figure 2

Representative EMG waveforms for the muscles investigated and the joint movements during gait cycles in both the upper and lower extremities. Each waveform represents the ensemble average of gait cycles over 30 sec. Gray waveforms are those without arm swing; black lines are those with arm swing.

Figure 3

Comparisons of mean EMG values in each muscle investigated between the with/without arm swing conditions. Error bars: standard deviations (SD). Statistically significant difference *P < 0.05.

Figure 4

Representative EMG waveforms for the muscles investigated and the joint movements during gait cycles in both the upper and lower extremities under different weight loads (0, 0.75, 1.5, and 2.25 kg) applied to the wrists of the swinging arms. Each waveform represents the ensemble average of gait cycles over 30 sec.

Figure 5

Mean EMG values in each muscle investigated among different conditions of arm swinging (accompanying different weight loads at the wrist). Error bars: SD. Statistically significant main effect §P < 0.05

Figure 6

Relationship between muscle activity in the upper extremity (aDEL) and the ankle dorsiflexor TA muscle under arm swing with different weights applied at the wrist (0, 0.75, 1.5, and 2.25 kg) in the 10 subjects. There was statistically significant correlation with P < 0.001.