Abstract

Isometric Protocol as a Useful Tool for Evaluating Flexor and Extensor Torques of the Paretic Foot in Post-Stroke Patients

Author(s): Ewa Chlebus, Agnieszka Warenczak, Marta Jokiel, Ewa Breborowicz, Magdalena lanczak Trzaskowska, Przemyslaw Lisinski

Background

Stroke has detrimental effects on locomotors performance of the ankle joint. Reduced force generation abilities of flexor and extensor muscles in the paretic foot resulting in deteriorated ankle stability and motor quality.

Aim

Stroke patients experience weakening of extensor and flexor muscles in the paretic foot. For certain muscles the degree of weakening depends on foot-shank position so different foot positions would result in different extensor-flexor torque ratios. Further the following parameters were measured:

• Peak Torque (PT), Average Torque (AVGT), and AVGT/BW obtained with isometric testing in three foot-shank positions (15° flexion, 0° neutral position, -15° extension) and generated by extensors and flexors of paretic, non-paretic and in healthy volunteers.

• The ratio of AVGT generated by foot extensors to the same values generated by flexors in paretic, non-paretic, and healthy foot in three test positions (15° flexion, 0° neutral position, -15° extension)

Materials and methods

Patients with hemiparesis (No=34) were examined. The control group consisted of 34 healthy volunteers. There were no differences between the groups in terms of age, weight and height. The following parameters were measured: Peak Torque (PT), Average Torque (AVGT), and AVGT/BW. The relationship between extensor and flexor performance was determined by agonist/antagonist ratio, i.e. the ratio of average extensor torque to average flexor torque.

Results

PT, AVGT, and AVGT/BW values of paretic foot extensors differed from those recorded in the control group. As for the non-paretic limb, differences were found only in neutral foot positioning. PT, AVGT, AVGT/BW values of paretic foot flexors differed from the results of healthy subjects. The agonist/antagonist ratio of the paretic foot was different from the results of healthy subjects.

Conclusions

Early after stroke, significant weakening of extensors and flexors occurs in both lower extremities. The paretic limb is marked by abnormal agonist/antagonist ratio.