Background

Parkinson’s disease (PD) may influence the oxygen (O₂) cost of walking as an indicator of walking efficiency. There is limited information regarding O₂ cost of walking across different speeds in PD and the associated influence of weight status. This study examined the O₂ cost of treadmill walking across different speeds in PD as a function of normal weight and overweight status based on body mass index (BMI).

Methods

The sample included 30 persons with PD who had mild to moderate bilateral motor symptoms (Hoehn and Yahr stages 2-3). BMI was calculated from height and weight (kg·m⁻²) measured with a scale and stadiometer, and persons were classified as normal weight (≤25kg·m⁻²; n=10) or overweight (>25kg·m⁻²; n=20). Participants performed three 6-minute bouts of treadmill walking with a 4-minute rest period between bouts. The three bouts were 0.5mph slower than normal comfortable pace (NCP), NCP, and 0.5mph faster than NCP. O₂ cost of walking was measured by indirect calorimetry and calculated based on net relative O₂ consumption and speed (ml·kg⁻¹·m⁻¹). We conducted a 2×3 mixed-factor ANOVA to examine differences in O₂ cost of walking between weight status groups (normal weight and overweight) across the speeds (slower, NCP, faster).

Results

The values for O₂ cost of walking at slower, NCP, and faster speeds were 0.25, 0.22, and 0.21, respectively. The ANOVA indicated no significant interaction between BMI status groups and speeds on O₂ cost of walking. There were significant differences in O₂ cost of walking as a function of treadmill speed; O₂ cost was lowest with faster speed, and highest with slower speed. There was no main effect of BMI status on O₂ cost of walking.

Conclusions

Weight status based on BMI may not influence the O₂ cost of walking overall or across different speeds in persons with PD. Persons with PD may walk more efficiently at faster speeds, whereas less efficiency at slower speeds could possibly result from directing relatively more energy towards maintaining balance.