Plantarflexor muscle activity during a change in walking speed on a treadmill: Comparison between Parkinson’s and unimpaired controls

Purpose

To compare plantarflexor muscle activity between Parkinson’s and control participants during a change in walking speed while walking on a self-paced treadmill

Approach

Participants, (n=14) included a control (n= 8, aged 31.7 (+/-17.9 years) and a Parkinson’s (n= 6, aged 67.3 +/-11.57 years) group. All participants were asked to walk on an interactive treadmill synchronised to a virtual reality scene showing a forest walk. The treadmill was self-paced meaning speed was automatically controlled by the participant’s position which was tracked by a motion capture system (VICON, Oxford Metrics, Oxford, UK). Participants increased their speed in response to a visual instruction projected onto the screen. Immediately before and then during the speed change electromyography (EMG) electrodes captured the activity of gastrocnemius and soleus muscles. Differences in contraction duration and muscle work (area under the curve, AUC) were compared before and during the speed change

Outcomes

Results: Walking speed increased, in response to instruction for the Parkinson’s (+ 0.38 m/s) group and control (+ 0.83m/s). With proportionate increases in gastrocnemius duration in Parkinson’s group(5%) on the side that swing first and(7%) on the contralateral side while the control group showed a decrease (2%, 3%) on both sides respectively. Soleus activity, however, differed between the groups. While the Parkinson’s group increased (26%) activity on the side that swung first and decreased (-1%) on the contralateral side the opposite pattern was observed in control group (swing side decreased (5%) and stance side increased (6%). Finally, there was an increase (10.5%) in the work of soleus (stance side) in the control group, no other differences in AUC were noted

Conclusion(s): In this study of muscle activity during walking speed modulation, the activity of gastrocnemius changed according to expectations for increasing walking speed in both control and Parkinson’s groups. The difference in soleus activity, however, suggests a different pattern of motor control was applied in Parkinson’s, which may impair the ability to change speed. Further, larger scale, studies are warranted to test this hypothesis.

Cost and savings

No further information. 

Implications

There are no direct implications for gait rehabilitation in Parkinsons from this study which was designed as a pilot. The interesting findings do merit further research and. PWP showed that they are able to change their speed while walking on a self-paced treadmill. It seems that the study needs further work to find a better result on plantarflexor activation during walking on the treadmill

Top three learning points

No further data. 

Funding acknowledgements

I would like to thank and acknowledge the Kuwait Civil Service Commission that supported me and funded this study.