The Effects of Jendrassik Maneuver on the T-reflex and the H-reflex of Soleus Muscle

OBJECTIVE: To investigate the effects of Jendrassik maneuver on latency and amplitude of the T-reflex and H-reflex of the soleus muscle in normal adults. METHOD: The T-reflex and H-reflex tests were performed on sixty normal adults with standardized technique using the soleus muscle. The shortest latency and the largest peak-to-peak amplitude were chosen for representative values. RESULTS: The results were as follows: 1) There was a significant difference in latency of the T-reflex between with and without Jendrassik maneuver. 2) The increment ratio of the amplitude with Jendrassik maneuver was 88% in the T-reflex and 18% in the H-reflex. There were a significant difference in the amplitude of both reflexes between with and without Jendrassik maneuver. 3) A high correlation was present between the latency of H- & T-reflex and the length. CONCLUSION: According to these results, we suggest that Jendrassik maneuver primarily increases the sensitivity of muscle spindles and decreases the presynaptic inhibition of the Ia terminals at cortical, subcortical and spinal levels. Jendrassik maneuver can be a useful tool in cases of clinically decreased or absent deep tendon reflex.

Study of Upper Extremity Strength Using Jamar Dynamometer, Pinch Gauge, and Multiple Work Simulator in Normal Subjects

OBJECTIVE: To evaluate the components for vocational rehabilitation program including the strengths and job simulation, and to provide the data of the upper extremity strengths for a successful return to work. METHOD: Sixty normal untrained subjects(male 30, female 30) were examined for the grip and pinch strengths using Jamar dynamometer and Preston pinch gauge, and the strengths of five simulated tasks using work simulation of Cybex 6000 Testing and Rehabilitation System(Cybex, Division of Lumex, inc., USA). RESULTS: The values during the tasks were significantly different in males compared to females(p<0.01). Strengths of the right upper extremity by Jamar dynamometer, Preston pinch gauge, gripping device, T-handle(radial direction), and flutted knob(radial direction) were significantly different compared to the left(p<0.01). Grip strengths between Jamar dynamometer and gripping device of Cybex were highly correlated(p<0.01). All the measured values were significantly correlated with both weight and height(p<0.01). CONCLUSION: The results of this study can be used as a baseline data for the vocational rehabilitation in patients with a disability of upper extremity.