Bilateral deficit (BLD) is a phenomenon where the force generated from simultaneous bilateral limb contractions is less than the sum force generated by separate right and left limb contractions. There have been many BLD studies, but the measures of force generation have predominantly been with isometric and isokinetic contractions. There are, however, no dynamic upper body isotonic unilateral weight lifting studies on acute power output. The purpose of this study was to determine acute power output between bilateral and unilateral weight lifting under the conditions of traditional and circuit weight lifting. Seventeen male BYU rugby players (age = 21.8 ± 2.1 years; mass = 93.5 ± 12.5 kg; height = 181.9 ± 5.0 cm) participated in the study. Each subject participated in 4 randomized weight lifting testing sessions separated by at least 48 h. Each weight lifting protocol included 6 dumbbell lifts (bench press, bent over row, overhead press, bicep curls, front raise, and bent over raise) performed as explosively as possible for 5 sets of 5 repetitions at 40–50% of 1RM. GymAware [GYM] units measured power output for the right and left arms. Peak and mean power (of all lifts combined) was greatest in the unilateral traditional weight lifting (UTWL) group compared to all other groups (p < .0001 for each comparison). No significant differences in overall peak and mean power (all lifts combined) existed between the other 3 groups. UTWL peak and mean power outputs were significantly highest for all lifts. UTWL and bilateral traditional weight lifting (BTWL) generated the second or third highest peak power outputs for all lifts, but they were not statistically different from each other except for the bent over raise. Bilateral circuit weight lifting (BCWL) generated the lowest peak power output in all lifts, but was not statistically different from the third lowest peak power output except for the bent over raise. Our study determined that dynamic upper body isotonic unilateral movements generate significantly greater power output than dynamic upper body isotonic bilateral movements using free weights. It was also concluded that traditional weight lifting protocols generated greater power output than circuit weight lifting protocols.