Stand completely straight with a dumbbell in each hand (palms facing your body). While holding your upper arm still, curl the weight upwards until the biceps are fully contracted with the dumbbell at shoulder level. Once the dumbbell reaches shoulder level, hold the peak contraction briefly before lowering the weight under control to the starting position. Repeat for the desired number of repetitions. When performing this exercise ensure that the torso remains stationary and that the palms are facing inwards (with no twisting) throughout the course of the entire motion. This exercise can be performed either one arm at a time or both arms at the same time.
