Why 21s Are For Deltoids-Not Biceps

Learn how to properly apply 21s to build bigger shoulders!

- Curtis High

What are 21s?

21s are an old school exercise for the deltoids that allows all 3 heads (anterior, lateral & posterior) to work in isolation during a single exercise. The purpose of this article is to clear up exactly what 21s are and how to properly perform them.

The misconception

But first, let’s set the record straight…21s are not for the biceps!

This misconception is derived from the current trend of performing seven reps at the bottom, seven reps at the top and then seven reps for full range on bicep curling movements. The truth of the matter is that 21s only really give you an advantage on three headed muscle groups such as the deltoids. This is because you can work each head through the full range of movement as opposed to muscles performing half repetitions and not working efficiently.

The new trend

In recent years, 21s have been remodelled into a new training method. The creators of this trend have taken the original concept of lifting a weight three times for sets of seven repetitions and coupled it with the three ranges of movement performed during an exercise.