Difference in Upper Extremity Spinal Motor Neuron Excitability and Function during Walking and Stepping in Place

[Purpose] We analyzed F-waves obtained during walking and stepping in place by healthy subjects to investigate changes in upper extremity spinal motor neuron excitability. [Subjects] Twenty-six healthy subjects were evaluated before, during, and after walking and stepping in place. [Methods] We recorded F-waves from the Abductor Pollicis Brevis muscle of the upper extremity before, during and after walking and stepping in place. [Results] F-wave persistence significantly increased during walking compared to persistence before and after walking. There was no significant change in F/M amplitude ratio and F-wave latency values during walking when compared to before and after walking. All parameters of F-waves demonstrated a statistically significant increase during stepping in place when compared to before and after stepping in place. [Conclusion] These findings indicate that upper extremity spinal motor neurons excitability increases during stepping in place, but only the firing frequency of the upper extremity a motor neuron increases during walking. Our findings suggest that seemingly similar movements such as walking and stepping in place are neurophysiologically distinct. Therefore, caution is required when working with neurologically impaired individuals, and it is important to be aware of the impact of each exercise.