The Effect of Shaving Body Hair on Plantar Flexion Torque in Humans

1660

Board #150 May 30 2:00 PM - 3:30 PM

Cutaneous feedback has been shown to have an effect on the motoneuron pool. Some forms of cutaneous stimulation have been shown to increase the excitability of the motoneuron pool while other forms of stimulation have been shown to decrease the excitability of the motoneuron pool. The ability to manipulate motoneuron excitability by adjusting cutaneous input has important implications in both rehabilitative and athletic settings. Currently, there are not any known studies that have looked at the effect of shaving body hair on motoneuron excitability.

PURPOSE: The purpose of this study is to determine if altered sensory input, resulting from shaving one's body hair, changes motor output.

METHODS: Six male college students were used for this study. The subjects underwent two rounds of testing: one before and one after the treatment. In each round of testing, the subjects began by doing maximal voluntary contractions (MVC). Next, H-reflex and M-wave recruitment curves were done on all subjects at rest. Subsequently, the magnitude of recurrent inhibition (RI) was measured in the soleus at rest and during a submaximal muscle contraction. After the first round of testing, the subjects' legs were shaved from ankles to knees. The second round of testing consisted of the same procedures as the first round of testing.

RESULTS: A one-sample T-test displayed a significant increase (9.6%) in torque production during an MVC from pre-treatment to post-treatment (p<0.05). A two-way repeated measures ANO VA and three-way repeated measures ANO VA were used to examine differences in H/M ratio and recurrent inhibition from pre- to post-treatment, respectively. There was no significant difference in H/M ratio of the soleus. Recurrent inhibition decreased from 71.6% to 49.2%. However, this was not a significant difference.

CONCLUSION: Although not significant, there was a 22.4% decrease in recurrent inhibition. It is possible that this decrease in recurrent inhibition is related to the increase in torque production. Additional research is necessary to determine the mechanism responsible for the increase in torque production.