Isometric Muscle Function of Knee Extensors and the Relation With Functional Performance in Patients With Stroke

Abstract Gerrits KH, Beltman MJ, Koppe PA, Konijnenbelt H, Elich PD, de Haan A, Janssen TW. Isometric muscle function of knee extensors and the relation with functional performance in patients with stroke. Objective (1) To examine the isometric strength, speed, and fatigue resistance of the knee extensors of the paretic limb and nonparetic limb in patients with stroke and compare these with able-bodied subjects. (2) To relate the contractile properties with different indices of functional performance. Design Case-control study. Setting Rehabilitation center research laboratory. Participants Eighteen stroke patients and 10 able-bodied controls. Interventions Not applicable. Main Outcome Measures Maximal voluntary torque (MVT), maximal rate of torque development, time to maximal rate of torque development, half relaxation time (½RT), and fatigue index. Scores on the Functional Ambulation Category scale, Berg Balance Scale, and Rivermead Mobility Index as well as distance walked during the six-minute walk test were obtained. Results MVT of the paretic leg was lower than of the nonparetic leg ( P P P P r =0.49–0.64; P Conclusions Apart from bilateral weakness, knee extensors in patients with stroke showed a lower rate of torque development and relaxation (both paretic and nonparetic leg) and lower fatigue resistance (paretic leg only) than controls, which in part may be a consequence of changes within the muscles. Strength and fatigue resistance relate to functional performance, indicating that these muscle properties should be addressed during rehabilitation. However, future research is needed to elucidate the efficacy of exercise programs.