Which method should be chosen to estimate the oxygen cost of walking in post-stroke individuals?

Background: The oxygen cost of walking (Cw) represents the energy expenditure involved in walking, which is a major concern when quantifying physical activity in stroke. Recent studies have reported that Cw may be estimated accurately with a prediction equation using the self-self-selected walking speed (S).

Research Question: To evaluate the validity of Cw estimates according to different modalities of S measurements (10-m walking test, 6-minute walking test, GaitRite system).

Methods: Twenty-one stroke individuals in subacute phase who were able to walk without human aid were included. Cw was estimated from the walking speed measured during a 10-m walking test, a 6-minute walking test and a recording on a GaitRite system. The values of the Cw estimates were compared to those measured by a respiratory gas exchange analyzer (Metamax3b).

Results: The findings showed that there is no significant difference between the Cw measured by Metamax3b and the Cw estimates regardless of the modalities used to measure S (Fvalue = 0.02; pvalue = 0.99). The mean bias between Cw measured by the Metamax3b and those estimated using the different S measurement modalities was less than 2.5 % of the mean Cw value. Test retest reliability was excellent with an intraclass correlation coefficient higher than 0.95.

Significance: in stroke survivors who are able to walk independently without human aid, the use of a 10-m walking test, a 6-minute walking test or a GaitRite recording can be considered validated for estimating Cw.