Loss of strength contributes more to physical disability after stroke than loss of dexterity

OBJECTIVE: The major contributors to physical disability after stroke are considered to be the negative impairments of loss of dexterity (defined here as loss of the ability to co-ordinate muscle activity in the performance of any motor task) and loss of strength. The aims of this study were: (1) to determine the relative contributions of strength and dexterity to function during recovery after stroke; and (2) to determine the predictive value of initial strength, dexterity and function on long-term function after stroke. DESIGN: A longitudinal descriptive study. SETTING: The inpatient and outpatient rehabilitation departments of two metropolitan hospitals. SUBJECTS: Twenty-two patients undergoing rehabilitation after acute stroke participated. MAIN OUTCOME MEASURES: Strength and dexterity of the elbow flexors and extensors were measured, along with arm function, at 3, 5, 7, 9, 11, 15, 19, 23 and 27 weeks after stroke. RESULTS: Standard multiple linear regression analysis demonstrated that strength and dexterity in total contributed significantly to function at all times (r2 = 0.66-0.82, p < 0.0001). Furthermore, strength always made an additional separate contribution to function (r2 = 0.05-0.26, p < 0.05). Function at week 3 was the best clinical predictor of function at week 27 (r2 = 0.55, p < 0.001). CONCLUSIONS: Loss of strength is a more significant contributor than loss of dexterity to physical disability after stroke. This suggests that, where significant weakness is present, exercise designed to increase strength will be required to decrease disability.