Rising and sitting down in stroke patients. Auditory feedback and dynamic strength training to enhance symmetrical body weight distribution.

Abstract

The purpose was to study vertical ground reaction force feedback and dynamic knee extensor training used to enhance stroke patients' symmetrical body weight distribution while rising and sitting down. Sixteen healthy subjects and 51 stroke patients participated in the studies. Two vertical strain gauge force transducers attached to two force-measuring platforms were used to measure body weight distribution over the lower limbs. An auditory feedback device, specially developed for training body weight distribution on the paretic leg, employed two electronic balances sensing vertical forces from each foot, separately. Torque of maximal voluntary eccentric and concentric knee extensor and flexor actions at 30, 60, 120, 180 and 240 deg/s was recorded with an isokinetic dynamometer together with surface electrodes from the quadriceps and hamstring muscles. When instructed to rise with even body weight on each lower limb, the stroke patients loaded the paretic leg more than when rising habitually, indicating that stroke patients have a latent motor capacity. Stroke patients' own estimations on visual analogue scales of body weight distributed on the paretic leg correlated with measured loading of the paretic leg in rising. After six weeks of training with auditory feedback of vertical ground reaction forces in the acute phase after stroke, the patients improved their loading of the paretic leg compared to a control group. The patients distributed body weight over the lower limbs nearly symmetrically while rising and while sitting down. The peak torque was not greater, however, than in the control group, rising with an asymmetrical body weight distribution. This implies that the patients after feedback training were better at using the knee extensor torque of the paretic leg to attain symmetrical body weight distribution over the lower extremities. Changes in improvement of physical performance and sitting to standing were greater than in the control group. No differences between groups were seen in performance of activities of daily living. Body weight distribution over the limbs in rising and in sitting down was re-tested on average 33 months after end of training. The symmetrical weight distribution after feedback training was not maintained over time. Knee extensor strength improved after six weeks of eccentric and concentric training, starting on average 27 months after stroke. The increase in strength was related to enhanced activation of agonist EMG activity. Eccentric training seems to be superior to concentric training with reference to a) improved body weight distribution over the lower limbs in rising, to b) increased knee extension torque and to c) increased agonist EMG activity without a concomitant, augmented EMG activity of the antagonistic knee flexor muscles. It was concluded that stroke patients have a latent motor capacity, that six weeks auditory feedback training promotes symmetrical body weight distribution which, however, is not consistent over time and that isokinetic eccentric training is superior to concentric training with reference to weight distribution in rising, knee extension torque and EMG activity.