Energetic Cost of Walking and its Physiological Correlates in Persons with Multiple Sclerosis who have Moderate Mobility Disability

Publication date: Available online 4 July 2018

Source: Archives of Physical Medicine and Rehabilitation

Author(s): Brenda Jeng, Brian M. Sandroff, Robert W. Motl

Abstract

Objective

This study examined aerobic capacity, upper leg muscular strength, and static postural control as correlates of the energetic cost of walking (C_w) in moderate MS mobility disability.

Design

Cross-sectional study

Setting

University-based laboratory

Participants

44 persons with MS (aged 48.43±8.64 years) who have reached a benchmark of moderate mobility disability (i.e., Expanded Disability Status Scale scores between 4.0-6.0) participated in the study.

Main Outcome Measures

C_w was based on (a) net oxygen consumption collected using a portable metabolic unit and (b) walking speed during the 6-Minute Walk (6MW). Participants underwent standard assessments of peak aerobic capacity, upper leg muscular strength, and static postural control.

Results

The data were analyzed using bivariate correlation and linear regression analyses. C_w was inversely correlated with peak oxygen consumption (r=‒.308, p<0.05), peak power output (r=‒.548, p<0.00), and peak torque at 75° knee flexion (r=‒.340, p<0.05), whereas C_w was positively correlated COP area sway (r=0.319, p<0.05), and mediolateral sway velocity (r=.411, p<0.05). 40.3% of variance in C_w was explained by peak power output (β=‒.526, p<0.01) and mediolateral sway velocity (β=.339, p<0.05).

Conclusion

Our findings demonstrate that aerobic power and postural sway may be important correlates of C_w in moderate MS mobility disability. Peak power output reflects a person's physiological functional reserve that is directly relevant for understanding the penalty of walking impairment on the energetic demands of walking. The association between mediolateral postural sway and C_w suggests that mechanical inefficiency controlling the trajectory of the body's center of pressure during ambulation may contribute to the elevated C_w.

https://ift.tt/2KPO9AN