Tendon reflexes elicited using a computer controlled linear motor tendon hammer

We present a novel instrumentation system for studying tendon and spinal reflexes using a commercial linear servo-motor as a precisely controlled tendon hammer. The system uses a LabVIEW-based program to both control electrical or mechanical stimuli and record and measure the resulting M and H waves. The hammer can deliver tendon taps with selected velocities, durations, frequencies and excursions. Preliminary results for both soleus and flexor carpi radialis muscles show that impact velocity is an important variable in eliciting tendon reflexes. As expected, the tendon reflex amplitude was also found to be dependent on excursion depth, but not as significantly as hammer velocity. Other stimulus paradigms are also presently being investigated.