Electromyography-signal-based muscle fatigue assessment for knee rehabilitation monitoring systems

This study suggested a new EMG-signal-based evaluation method for knee rehabilitation that provides not only fragmentary information like muscle power but also in-depth information like muscle fatigue in the field of rehabilitation which it has not been applied to. In our experiment, nine healthy subjects performed straight leg raise exercises which are widely performed for knee rehabilitation. During the exercises, we recorded the joint angle of the leg andEMGsignals from four prime movers of the leg: rectus femoris (RFM), vastus lateralis, vastus medialis, and biceps femoris (BFLH). We extracted two parameters to estimate muscle fatigue from the EMG signals, the zero-crossing rate (ZCR) and amplitude of muscle tension (AMT) that can quantitatively assess muscle fatigue from EMG signals. We found a decrease in the ZCR for the RFM and the BFLH in the muscle fatigue condition for most of the subjects. Also, we found increases in theAMT for the RFM and the BFLH. Based on the results, we quantitatively confirmed that in the state of muscle fatigue, the ZCR shows a decreasing trend whereas theAMT shows an increasing trend. Our results show that both the ZCR and AMT are useful parameters for characterizing the EMG signals in the muscle fatigue condition. In addition, our proposed methods are expected to be useful for developing a navigation system for knee rehabilitation exercises by evaluating the two parameters in two-dimensional parameter space.

Quantitative assessment test for upper-limb motor function by using EMG and kinematic analysis in the practice of occupational therapy.

This paper proposes a quantitative assessment test of stroke patients' upper limb motor functions during occupational therapy. Conventional assessments are performed based on therapists' observations and subjective judgments which make it hard to recognize the qualitative functional changes. To suggest quantitative function indices, we measured electromyogram and kinematic parameters from 6 stroke patients during the `stacking cones' task and the `ROM arc' task using motion sensors and EMG sensor attached on the brachial, and analyzed motor functions. The selected indices that represent the motor function were the mean of angular velocity, the number of extrema, and the difference between tension of flexor (FCU, FCR and Brachioradialis m.) and extensor ECU, ECR and EDM). We compared the indices of affected and less affected upper limbs of each subject and it showed statistical significance during the given tasks (p<;0.05). Therefore, the quantitative assessment is expected to integrate the process of treatment and evaluation.

Robot-assisted mirroring exercise as a physical therapy for hemiparesis rehabilitation.

The paper suggests a therapeutic device for hemiparesis that combines robot-assisted rehabilitation and mirror therapy. The robot, which consists of a motor, a position sensor, and a torque sensor, is provided not only to the paralyzed wrist, but also to the unaffected wrist to induce a symmetric movement between the joints. As a user rotates his healthy wrist to the direction of either flexion or extension, the motor on the damaged side rotates and reflects the motion of the normal side to the symmetric angular position. To verify performance of the device, five stroke patients joined a clinical experiment to practice a 10-minute mirroring exercise. Subjects on Brunnstrom stage 3 had shown relatively high repulsive torques due to severe spasticity toward their neutral wrist positions with a maximum magnitude of 0.300kgfm, which was reduced to 0.161kgfm after the exercise. Subjects on stage 5 practiced active bilateral exercises using both wrists with a small repulsive torque of 0.052kgfm only at the extreme extensional angle. The range of motion of affected wrist increased as a result of decrease in spasticity. The therapeutic device not only guided a voluntary exercise to loose spasticity and increase ROM of affected wrist, but also helped distinguish patients with different Brunnstrom stages according to the size of repulsive torque and phase difference between the torque and the wrist position.