Effects of intermittent tendon pressure on alpha motoneuron excitability

The purpose of this study was to test the effectiveness of intermittent tendon pressure on the depression of alpha motoneuron excitability. The excitability changes of the motoneurons were assessed by measuring changes in H-reflex amplitudes before, during, and after intermittent tendon pressure application. Twenty-six of 28 subjects with no known neurological deficit displayed an immediate decrease in H-reflex amplitudes during tendon pressure (X = 73% of control values), which reached a maximum depression (45% of controls) within 20 to 30 seconds of application. The analysis of variance revealed significant differences (p less than .05), and post-hoc t tests indicated that these differences were between control values (prepressure and postpressure) and those values obtained at times 0, 5, 10, 20, and 30 seconds of pressure application. These results suggest that a maintained reduction in muscle tone might be induced through intermittent tendon pressure. Because we found no carry-over effects after pressure application, the usefulness of this technique is limited to the time during which the stimulus is presented.