How strongly is aerobic capacity correlated with walking speed and distance after stroke? Systematic review and meta-analysis

Background: Restoration of walking capacity, as reflected by walking speed and walking distance, is a primary goal after stroke. Peak aerobic capacity (peak oxygen consumption [VO₂peak]) is suggested to be correlated with walking capacity after stroke. Although the strength of this correlation is unclear, physical therapy programs often target walking capacity by means of aerobic training. Purpose: The purpose of this systematic review was to summarize the available evidence on the correlation between VO₂peak and walking capacity. Data Sources: The databases MEDLINE, CINAHL, EMBASE, Cochrane Library, and SPORTDiscus were searched up to May 2014. Study Selection: Cross-sectional studies reporting correlation coefficients between VO₂peak and walking capacity in stroke were included, along with longitudinal studies reporting these correlation coefficients at baseline. Data Extraction: The methodological quality of the studies was assessed using a checklist of 27 items for observational research. Information on study design, stroke severity and recovery, and assessments and outcome of VO₂peak and walking capacity, as well as the reported correlation coefficients, were extracted. Data Synthesis: Thirteen studies involving 454 participants were included. Meta-analyses showed combined correlation coefficients (r_ɱ) for VO₂peak and walking speed and forVO₂peak and walking distance of .42 (95% credibility interval=.31, .54) and .52 (95% credibility interval=.42, .62), respectively. Limitations: The studies included in the present review had small sample sizes and low methodological quality. Clinical and methodological diversity challenged the comparability of the included studies, despite statistical homogeneity. Relevant data of 3 studies could not be retrieved. Conclusions: The strength of the correlation ofVO₂peak with walking speed was low and moderate for VO₂peak and walking distance, respectively, indicating that other factors, besides VO₂peak, determine walking capacity after stroke.