F-2-14-06
ISOKINETIC CLOSED KINETIC CHAIN STRENGTH TESTING OF THE KNEE
Kenji Kawamura (Kibi International University, Okayama, Japan)
Objective: The optimal rehabilitation program following anterior cruciate ligament (ACL) reconstruction remains controversial. The objective of this study was to assess isokinetic open versus closed kinetic chain testing of the knee and to develop an optimal testing method and rehabilitation program for the knee joint that can accomplish specific functional requirements effectively without inducing harmful side effects.
Methods: Forty - two healthy young subjects with ages between 18 to 34 years performed isokinetic open and closed kinetic chain exercises. CYBEX 6000 isokinetic dynamometer was used to measure open and closed concentric torque generated by the right lower extremity. Each subject was instructed to exert maximal voluntary effort in extension for three repetitions in both of the two settings. An angular velocity of 60 deg/sec was used. The two isokinetic measures of interest in this investigation Were peak torque (PT) and joint angle at which peak torque is reached (JAPT). The EMG activity from eight muscles was monitored simultaneously for each exercise using surface electromyography. The muscles selected were the gluteus maximus, rectus femoris, vastus medialis, vastus lateralis, medial hamstring, lateral hamstring, medial gastrocunemius and the lateral gastrocunemius.
Results: Isokinetic open and closed kinetic chain testing resulted in similar torque-angle curve patterns. There were strong and significant (p<0.0001) correlations between PT of the isokinetic closed kinetic chain testing and that of the open kinetic chain testing. There was no significant difference between JAPT of the isokinetic closed kinetic chain testing and that of the open kinetic chain testing. EMG showed that only quadriceps groups were active during open kinetic chain testing while all the muscles of the lower extremity were active during closed kinetic chain testing.
Conclusions: Isokinetic closed kinetic chain testing of the knee can be reliable, and has strong and significant correlation with classical isokinetic open kinetic chain testing. From a biomechanical perspective, they are safer and produce stresses that are potentially less of a threat to healing structures.
F-2-14-07
ESTIMATION OF THE RELATIONSHIP BETWEEN SURFACE ELECTRICAL MUSCLE STIMULATION AND JOINT TORQUES USING AN ARTIFICIAL NEURAL NETWORK MODEL
Kazuhisa Domen, Yasuharu Koike, Mitsuo Kawato (ATR Human Information Processing Research Laboratories, Kyoto, Japan)
Functional Electrical Stimulation (FES) produces active movements in paralyzed limbs. With classical control methods, however, each stimulus pattern has to have a template of a specific electromyographic pattern recorded from healthy subjects; this does not allow the trajectory to be modified without changing a template. In order to develop an FES control system in which we can modify the trajectory simply by changing kinematic variables, we examined the relationship between surface electrical stimulation and joint torques using an artificial neural network model (ANN).
The flexion and extension of an elbow joint on a horizontal plane were examined for two healthy subjects. The biceps brachii and triceps brachii were stimulated with surface electrodes with various stimulus patterns both under static and dynamic conditions. Data was collected using a force sensor under the static conditions and an OPTOTRAK position sensing system under the dynamic conditions.
The ANN successfully constructed a forward dynamics model of the human arm. Information was obtained of a non-linear relationship between the stimulation and produced muscle torque, with satisfactory accuracy under both conditions. Conclusion: The ANN could construct a forward dynamics model of the human arm with FES. Our method can be applied to a more accurate FES control system which will enable natural movements to be produced.
