The electromyographic activity of the trapezius and serratus anterior muscles was studied in 24 male volunteers during pull-over exercises. In 54.2% of the cases, the activity of the trapezius varied from weak to strong. In the remaining cases, as well as in pull-overs done with the arms bent, this muscle was inactive. Thus, the trapezius acts preferentially in pull-overs, but its variable levels of activity do not justify its inclusion in programs of physical conditioning. The serratus anterior had levels of activity which varied from weak to very strong in pull-over exercises. In pull-overs with bent arms, this muscle showed very strong activity in almost half of the cases, thus justifying its inclusion in basic exercises in programs for physical conditioning. When conditioning the serratus anterior muscle using pull-over exercises with bent arms, the execution should not exceed the half way point of the return movement.