Reduced step length, not step length variability is central to gait hypokinesia in people with Parkinson's disease

Objectives: Previous studies found that people with Parkinson's disease (PD) walked at a slower speed and with significantly shorter stride length and/or increase in variability of stride length than control subjects. The present study aimed to examine whether difference existed in amplitude and variability of step length between control and PD subjects if they walked at a similar speed. Methods: This was a cross-sectional study. Thirteen PD patients and 15 healthy control subjects were instructed to walk at a similar speed on a treadmill under 2 randomized conditions: walking alone (Walko) and walking with digit subtraction of 3 (Walkcalculation). Amplitude of step length (cm), variability of step length (%), and percent accuracy of the calculation task (%) were recorded and analysed. Results: During both Walkoand Walkcalculation, PD patients had significantly shorter step length and larger step length variability than control subjects (p < 0.05). When a cognitive task was added to walking, PD patients showed a significant decrease in step length without further change in step length variability (p < 0.05). Conclusion: As reduced step length persisted when the control subjects walked at a speed similar to that of patients, our finding suggests that PD patients had a fundamental problem in regulating the amplitude of step length during walking.