Effect of using of brace in three different knee flexion angles on running economy and lower limb muscular co-contraction in individuals with genu varus

Genu varus deformity is associated with changes of lower limb muscle co-contraction and running economy. This study was done to evaluate the effect of using of brace in three different knee flexion angles on running economy and lower limb muscular co-contraction in individuals with genu varus.

This quasi-experimental study was done on active soccer male students including 15 healthy subjects (average age of 22.86±1.55 years) and 15 subjects with genu varus (average age of 22.13±1.80 years). The amount of electrical activity of the muscles (tibialis anterior, medial gastrocnemius, vastus medialis, vastus lateralis, rectus femoris, biceps femoris, semi-tendinosus) were recorded by electromyography system during four conditions of with and without using knee brace. After that, directed and general co-contraction was computed during running. The angles of brace were 15, 30, and 60 degrees. The values of VO2 max were recorded using of gas analyzer system to compute running economy.

The ratio of respiratory exchange was significantly more in the genu varus group than healthy group (P<0.05). However, the acute effect of brace was not significant on running economy and ratio of respiratory exchange. The main effect of brace was significant for general co-contraction of knee joint during the loading phase (P<0.05). Paired wise comparison revealed significant greater general knee co-contraction during brace conditions (P<0.05). However, the general knee co-contraction during loading phase reduced while using brace 15 degree. The main effect of “brace” for ankle joint general co-contraction during the push-off phase was significant (P<0.05). Paired wise comparison revealed significant greater general ankle co-contraction during brace conditions at push-off phase (P<0.05).

Knee brace did not change running economy. However, the using of brace 15 degree improved general knee joint co-contraction during loading phase.