To evaluate normal healthy persons without spasticity to observe normal findings of the elbow stretch reflex using a newly developed, portable, hand-driven spasticity-measuring system.
Thirty normal persons without any disease involving the central or peripheral nervous system were enrolled in this study. The portable hand-driven isokinetic system is able to measure the joint angle, angular velocity, electromyographic (EMG) signals, and torque during elbow passive extension-flexion. One set of 10 passive elbow extension and flexion movements was performed for data acquisition at each angular velocity, including 60, 90, 120, 150 and 180 degrees per second (°/sec). Electromyographic data were collected from the biceps brachii and the triceps brachii. Torque data were collected from sensors around the wrist.
We were able to detect EMG activity and torque in all subjects by using the new portable hand-driven isokinetic system. EMG activity and torque increased with incremental increase of angular velocities. The joint angle of maximal EMG activity according to different angular velocities did not show any significant difference (116°-127° in elbow extension and 37°-66° in elbow flexion). The joint angles of maximal torque according to different angular velocities were not significantly different either.
Using the portable hand-driven isokinetic system on the elbows of normal subjects, we were able to obtain expected results. By considering our normal findings of the elbow stretch reflex using this system, we propose that the various aspects of spasticity-related data can be measured successfully.
Citations
Objective: To determine whether muscle fatigue affects knee joint proprioception.
Method: Thirty healthy subjects (18 male and 12 female) with an average age of 22.1 years were selected for this study. Angular errors were measured to test propriocetive function in the knee joint. In a sitting position, the subject's dominant leg was passively positioned to the 45o knee flexion stimulus point for 2∼4 second, while the subject concentrated on this position, the leg was passively returned to the 90o flexion position, afterward the subject was asked to duplicate the stimulus point actively. The difference, in degrees between the stimulus point and the reproduced point is an angular error. All subjects were blindfolded and underwent proprioception measurement before and after the muscle fatigue. Isokinetic exercises performed at 180 degree/sec on the Cybex Orthotron II(Cybex, a division of Lumex, Inc. USA) were used to induce the muscle fatigue. All subjects performed an isokinetic exercise with their dominant leg. Exercise was continued until 50% of the initial peak torque was reached. When the subjects were fatigued to less than 50% of the initial peak torque, the isokinetic exercises were discontinued. Then we immediately retested the proprioception using the same method.
Results: The mean and standard deviation of the angular error increased from 2.79⁑1.17o to 6.40⁑3.42o after muscle fatigue.
Conclusion: The proprioception significantly decreased after the muscle fatigue(p＜0.001). This result suggests that the muscle fatigue must be considered when an injured professional athlete a patient with fatigable disease is set in a rehabilitation program. Further studies are required to determine the physiological mechanisms of the role of muscle fatigue for the decreasing proprioception.
Objective: To investigate the torque curves and heart rate responses to isometric, eccentric and concentric isokinetic exercises with a maximal voluntary contraction of the right knee and elbow joints in 30 healthy men(26.6⁑2.2 years).
Method: Subjected performed the eccentric and concentric isokinetic exercises with 10 repetitions at 60o/sec, while performing the isometric exercises at a joint angle of 60 degrees for the same period of time with Cybex 6000. Peak torque, angle of peak torque, and total work were measured and the flexor-to-extensor ratios of peak torque were calculated.
Heart rates were recorded simultaneously at rest and immediately after the exercise, and the time required to return to the resting heart rate level was also recorded for each exercise session.
Results: Peak torque and total work for the eccentric exercise were significantly higher than those for the concentric exercise(p＜0.01) of the knee and elbow joints. Eccentric peak torques for flexors and extensors of the knee joint occurred at a significantly longer muscle length than the concentric peak torques(p＜0.01).
Flexor-to-extensor ratios of a peak torque of the knee joint between the eccentric and concentric isokinetic exercises did not show a significant difference.
Torques at a joint angle of 60 degrees were highest in the eccentric isokinetic exercise, followed in the order by isometric, and then concentric isokinetic exercises of the knee joint(p＜0.01), and concentric torque at a joint angle of 60 degrees was significantly lower than those of the eccentric and isometric exercises of the elbow joint.
The increase in heart rate and the time of returning to the resting heart rate level were independent of the size of the contracting muscle mass and the types of exercise. The increment ratio for the heart rate was 70.4⁑23.6%.
Conclusion: In conclusion, the response of heart rate to the exercise is not influenced by the contracting muscle mass or the types of exercise in a short duration of maximal voluntary contraction, implying that special precautionary measures are not required for the isometric, eccentric and concentric isokinetic exercises.
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