The effect of two intensities of massage on H-reflex amplitude.

The purposes of this study were (1) to investigate the effectiveness of two different levels of massage on the depression of spinal motoneuron excitability (as demonstrated by peak-to-peak H-reflex amplitude changes), (2) to investigate the presence of any gender effects in relation to massage, and (3) to describe a method used to quantify the amount of pressure exerted during two different intensities of massage. Two levels of massage were quantified and defined as light massage (LM) and deep massage (DM). These levels of massage corresponded to pressures of 1.25 and 2.50 kPa (5 and 10 in H2O), respectively. The therapist, before beginning the investigation, was trained to deliver these pressures. Ten peak-to-peak H-reflex recordings were elicited from the triceps surae muscle of each of 20 neurologically healthy subjects (10 male, 10 female) (mean age = 22.6 years) during five control and the two massage conditions. Each condition was 3 minutes in duration. Significant differences were found among the resulting means. The peak-to-peak H-reflex amplitudes recorded during the DM condition were reduced in comparison with those recorded during the LM condition. The peak-to-peak H-reflex amplitudes during both massage conditions were reduced in comparison with those recorded during the control conditions. These changes were noted against a stable M-response. This suggests that the mechanism involved in the observed inhibitory response is pressure sensitive, with DM bringing about a greater inhibitory response than did LM. No differential effects attributable to gender differences were found. These results will serve to define massage characteristics in an ongoing study investigating the effect of massage in persons with a spinal cord injury.