EFFECT OF MANUAL THERAPY TECHNIQUES ON THE STRETCH REFLEX IN NORMAL HUMAN QUADRICEPS

The effect of four manual therapy techniques on the quadriceps stretch reflex amplitude (elicited by mechanical vibration) was studied in a randomized, controlled trial in 120 (20 in each of six groups) healthy human subjects aged 18-64 years. Passive and active techniques were s tudied; each under static and dynamic conditions. The passive procedur es were massage (static) and knee oscillation (dynamic) for 5 min. Act ive techniques involved eight repetitions of isometric quadriceps cont ractions (static) and leg extension (dynamic). The two static techniqu es had no effect on the stretch reflex amplitude. Both dynamic techniq ues caused a reduction (active by 25%, p < 0.00001 and passive 12%, p < 0.05). Only the active, dynamic technique caused a greater change th an in the control group (p < 0.005). The effect lasted for less than 1 min. These data question the ability of such techniques to make clini cally valid changes in motoneuron excitability. Further studies are re quired on those with neuromuscular pathology, who may respond differen tly to normal subjects.