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.
Exercise ; Healthy Volunteers ; Joints ; Knee* ; Leg ; Methods ; Muscle Fatigue* ; Muscle Tonus ; Quadriceps Muscle ; Rehabilitation*

PURPOSE: This study examined the effects of horse riding simulator exercise on the thickness changes in the transverse abdominis in normal adults. METHODS: Forty-five healthy adults were recruited and randomized to a horseback riding simulation exercise group (n=15), a sling exercise group (n=15), and a trunk stabilization exercise group (n=15). A horseback riding simulator offers the indoor experience of horseback riding and mimics the rhythmic movement of horseback riding, thereby provided a virtual environment, such as riding a real horse on the front screen. The velocity of the horse riding simulator exercise was regulated within the subject's ability to control the exercise on the horse riding simulator. A sling exercise group performed sling exercise under the inspection of the experimenter. In the trunk stabilization exercise group, the subjects were instructed to perform the exercise accurately and pause the session when pain occurred during the intervention. The subjects in each group carried out the interventions three times per week for six weeks. The thickness of the transverse abdominis was measured using a pressure biofeedback unit and the ultrasound. RESULTS: Significant differences in the thickness of transverse abdominis within the groups were observed between before and after the interventions. On the other hand, there were no differences in the parameters among the groups. CONCLUSION: Horse riding simulator exercise can be an alternative to trunk stabilization exercise by increasing the thickness of the transverse abdominis in healthy adults.
Adult ; Biofeedback, Psychology ; Hand ; Horses ; Humans ; Ultrasonography