Evidence of a Logarithmic Relationship Between Motor Capacity and Actual Performance in Daily Life of the Paretic Arm Following Stroke

Objective: To examine the associations between actual performance in daily life and function, capacity and self-perceived performance of the paretic upper limb following stroke.Population: Seventeen individuals with stroke.Outcome measures: Correlation coefficients between actual performance (measured with the Stroke-Upper Limb Activity Monitor), function (Fugl-Meyer Assessment), capacity (Action Research Arm test) and self-perceived performance (ABILHAND questionnaire).Results: High correlations were found between actual performance and function (r=0.75; 95% confidence interval (CI): 0.42-0.90), and capacity (r =3270.71; 95% CI: 0.35-0.89), whereas a moderate correlation was found between actual performance and self-perceived performance (r=0.64; 95%, CI: 0.21-0.86). For the relationship between actual performance anti both function and capacity, logarithmic regression explained more variance than did linear regression.Conclusion: The present study provides first evidence of the existence of a non-linear relationship between actual performance, function and capacity of the paretic upper limb following stroke. The results indicate that function and capacity need to reach a certain threshold-level before actual performance also starts to increase. Because of the small sample size of the present study caution is needed when generalizing these results.