The effect of loss of visual input on muscle power in resistance trained and untrained young men and women.

Visual impairment has been shown to reduce muscle power when compared with that in sighted individuals. The purpose of this study was to assess whether the loss of visual input affects lower limb muscle power production in sighted men and women who are resistance trained and untrained. Twenty-seven college-aged participants (19-23 years) performed a seated double-leg press with and without visual input (resulting from being blindfold) in 2 separate counterbalanced trials. Lower limb concentric power was calculated by measuring the distance and time a leg press footplate was displaced while lifting 60% of 1-repetition maximum as quickly as possible. Loss of visual input reduced power output by 22.8 W (-6.4%) in all participants (p < 0.01). When resistance training status was taken into account, resistance trained participants (n = 12, trained >2× per week) did not lose power output (4.4 W, -1.1%, p = 0.90), whereas untrained men and women (n = 15) had significantly less power when visual input was removed via blindfold (37.6 W, -11.7%, p < 0.01). Untrained women experienced the greatest decrease in power when blindfolded (39 W, -15.9%, p < 0.01). Muscle power decreases in the absence of vision, but a regular strength training program attenuates this occurrence in young men and women. In practical application, strength training interventions may be successful in protecting individuals from losses in muscle power when visual input is removed.