ABSTRACT: Visual impairment has been shown to reduce muscle power when compared to sighted individuals. The purpose of this study was to assess whether loss of visual input affects lower limb muscle power production in sighted men and women who are resistance trained and untrained. Twenty-seven college-age participants (19-23 yrs) performed a seated double leg press with and without visual input (due to blindfold) in two 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 1RM as quickly as possible. Loss of visual input reduced power output by 22.8 watts (-6.4%) in all participants (p<.01). When resistance training status was taken into account, resistance trained participants (n=12, trained >2 x's per week) did not lose power output (4.4 watts, -1.1%, p=.90) while untrained men and women (n=15) had significantly less power when visual input was removed via blindfold (37.6 watts, -11.7%, p<.01). Untrained women experienced the greatest decrease in power when blindfolded (39 watts, -15.9%, p<.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 protects individuals from losses in muscle power when visual input is removed.
