Analysis of anterior, middle and posterior deltoid activation during single and multijoint exercises

Although comparison between multi and single joint exercises has been conducted, there is insufficient evidence that these exercises could lead to different muscle activations. The aim of this study was to compare deltoid muscle activation during multi and single joint exercises.

Twelve male participants (23.4±1.6 years) with at least one year of strength training experience were assessed performing inclined lat pull-down, reverse peck deck and seated row exercises. Surface electromyography was used to measure activation of anterior, middle and posterior portions of deltoid muscle during each exercise. Deltoid activation was recorded during maximum voluntary isometric contraction (MVIC) and during dynamic isoinertial exercises of ten maximum repetitions for inclined lateral pull-down, reverse peck deck and seated row.

There was no difference in activation of the anterior portion of deltoid muscle for any of the three exercises (P=0.08). The middle portion presented greater activation during the reverse peck deck (P=0.03) and during the seated row (P=0.03) compared to the inclined lat pull-down. For the posterior portion of deltoid muscle there was greater activation during the reverse peck deck (P=0.001) compared to the seated row and to the inclined lat pull-down.

Results indicate that reverse peck deck and seated row should be more appropriate for recruitment of the middle portion of the deltoid muscle than the inclined lat pull-down. Differently, the reverse peck deck should be primarily used rather than the seated row and the lat pull-down for recruitment of the posterior portion of the deltoid muscle.