A-36 Free Communication/Poster - Bone, Bone Mineral Density, and Connective Tissue

Abstract

A common intervention for knee pain is the use of a brace. Studies have focused on how knee braces affect the braced limb; but few have examined the effects on the contralateral limb. PURPOSE: This study will examine the bilateral electromyography (EMG) of lower limb muscles while wearing a unilateral wraparound, hinged, prophylactic knee brace during a drop landing task. METHODS: Eleven healthy females (age 21.6 ±1.6 years) performed five drop landings from a 30 cm box while wearing a knee brace on their dominant (right) leg - intervention condition (IC), and five landings with no brace- control condition (CC). EMG was recorded for bilateral Rectus Femoris (RF), Medial Hamstrings (MH) and Gluteus Medius (GM). The right leg was braced and the left leg was un-braced during the IC. Maximal Voluntary Contractions (MVC) were recorded for all muscles prior to testing and peak activity during the drop landing (%MVC) was recorded. Muscle activations were compared across conditions (IC vs. CC) and across leg (Right - Braced vs. Left - Unbraced). RESULTS: In the CC, the MH was activated to a higher level in the left than in the right limb (Table 1). There were no differences in all other comparisons (Table 1). CONCLUSION: A hinged prophylactic knee brace does not change EMG activity levels in the lower extremity muscles during a drop landing in healthy females. Prior research has shown that wearing a brace does change the joint biomechanics during landing in the braced and un-braced legs compared to a control condition. Changes in mechanical demand with no change in muscle activation could potentially increase the risk for injury when wearing a prophylactic knee brace as a preventative measure. Further study is needed on pathological populations that wear knee braces.Table 1: Peak muscle activations (% MVC) of lower extremity musculature during a drop landing.