Dynamic muscle strength training in stroke patients: effects on knee extension torque, electromyographic activity, and motor function.

The effects of training with isokinetic maximal voluntary knee extensions were studied in stroke patients. Two groups of 10 patients each trained twice a week for 6 weeks. One group trained exclusively eccentric movements and the other exclusively concentric movements. The effects were evaluated from the following tests before and after the training period. The maximal voluntary strength in concentric and eccentric actions of the knee extensor and flexor muscles was recorded together with surface electromyography at constant velocities of 60, 120, and 180 deg.s-1 on three different days. The body weight distribution on the legs while rising and sitting down was measured with two force plates. The self-selected and maximal walking speeds and the swing to stride ratio of the paretic leg were measured. After the training period, the knee extensor strength had increased in eccentric and concentric actions in both groups (p < .05). The eccentric and the concentric strength in the paretic leg relative to that of the nonparetic leg increased in the eccentrically trained group (p < .05) but not in the concentrically trained group. The restraint of the antagonistic muscles in concentric movements increased after concentric (p < .05) but not eccentric training. A nearly symmetrical body weight distribution on the legs in rising from a sitting position was noted after eccentric (p < .05) but not concentric training. Changes in walking variables were not significantly different between the groups. Eccentric knee extensor training was thus found to have some advantages as compared to concentric training in stroke patients.

Long-term effects of auditory feedback training on relearned symmetrical body weight distribution in stroke patients. A follow-up study.

Long-term effects of auditory kinetic feedback on relearned symmetrical body weight distribution while rising and sitting down were studied in stroke patients. Thirty patients were re-tested on average 33 months after having trained with and without auditory feedback. Body weight distribution on the legs was measured with two force plates. At re-test there was a decrease from 48% to 39% of body weight distribution (%BWD) on the paretic leg in rising and in sitting down in the patients in the auditory feedback group (p < 0.001). In the control group the decrease was from 44 to 39% BWD on the paretic leg (p < 0.05) in rising and from 44 to 42% BWD (n.s.) in sitting down. The symmetrical body-weight distribution, acquired after auditory feedback training, was not consistent over time. Movement time, however, was significantly reduced in the auditory feedback group (p < 0.05). Possible reasons for the findings are discussed.

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

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.

Vertical ground reaction force feedback to enhance stroke patients' symmetrical body-weight distribution while rising/sitting down.

A force platform with an auditory output consisting of two electronic balances was used to reinforce symmetrical body-weight distribution in stroke patients. Forty patients randomly assigned to an experimental group or a control group practised rising and sitting down for 15 min, thrice daily, 5 days a week for 6 weeks. The experimental group but not the control group received ground reaction force feedback through the auditory output. Vertical ground reaction forces under each foot were measured with two force plates. Mean difference in improvement of body weight distribution on the paretic leg was 13.2 +/- 10.7 (M, SD) per cent total body weight in the experimental group and 5.1 +/- 6.7 per cent in the control group in rising (p < 0.01) and 12.7 +/- 7.5 per cent total body weight and 4.6 +/- 6.6 per cent in sitting down tests (p < 0.001). The patients in the experimental group achieved in average close to a symmetrical body-weight distribution while rising and sitting down. Improvements in physical performance and sit-stand tests were greater in the experimental group (p < 0.05 and p < 0.01, respectively). No differences were seen in improvement in performance of activities of daily living. Symmetry in body-weight distribution in rising and sitting down correlated with high scores in physical performance, motor function in rising, and with functional ability.

Body weight-bearing while rising and sitting down in patients with stroke.

Distribution of body weight on the two legs while rising and sitting down was examined in 42 subacute stroke patients and 16 healthy adults during both spontaneous movement and following instruction directed at even weight distribution. Vertical floor reaction forces were measured by two force plates. There was a difference between patients and controls in the tested motor tasks--the patients favoured their nonparetic leg. However, body weight distribution was less asymmetric when patients tried to rise and sit down evenly compared to spontaneous rising/sitting down (p less than 0.001). Patients' own estimation of distribution of body weight documented on a visual analogue scale, correlated with actual body weight distribution while rising (rs = 0.36) but not while sitting down. To motivate stroke patients to pay attention to their ability to distribute body weight evenly while rising and sitting down and to create and use adequate self-reports seems a necessary commitment in a rehabilitation programme in order to avoid the learned nonuse syndrome.