Deltoids Anatomical Training Guide

Deltoids Anatomical Training Guide by Thats_Justice


Similar to the triceps, there are 3 heads to the deltoids; the anterior, the middle, and the posterior.


The deltoids play a big role in the movement of the upper arm. When all heads of the deltoid contract at the same time, this muscle serves to abduct the arm. Another lesser known function of the deltoids as a whole is to prevent the dislocation of the humerus (upper arm) when someone lifts heavy loads. Have you ever performed heavy shrugs, deadlifts, or farmer’s walks, and noticed that your delts look huge while you’re doing them? It’s because they’re working hard to make sure that the weight you’re lifting doesn’t rip your arm out of your socket. But each head of the deltoid also serves an individual purpose.

Anterior Deltoid

Lateral Deltoid

  • Primarily used to abduct shoulder when the arm is internally rotated

Posterior Deltoid


Due to their numerous functions, deltoids are involved in almost every upper body workout, and many lower body workouts as well (ex. deadlift). Since they are used so often, they are very easy to injure. It is very important to make sure you warm up and get blood flowing in your deltoids before you begin your workout so you can prevent injuries. Bryce Lewis demonstrates a great upper body warm up here (I usually do the warm up from 1:00 – 2:33).

To maximize deltoid development, it is important to train each individual head optimally. A typical deltoid workout for myself includes one exercise for each part of the muscle.


This head of the deltoid is used very often in pressing movements. This includes bench press, and other chest movements that move in a similar plane. Due to this, many people, myself included, do not think that isolation work (front raises) for the anterior deltoid is necessary for the average gym goer (if you are a bodybuilder, I wouldn’t neglect isolation work for any muscle). These are my favourite exercises for the anterior deltoid:

Standing military press is a great way to develop both deltoid mass and strength. One of the biggest benefits of the military press, in my opinion, is its carry over to bench press strength. Whenever my military press weight increases, so does my bench press. The same can’t be said for my dumbbell press.
I like training my pressing movements in both high and low rep ranges. I often start with heavier weights and stick around 6-8 reps, and then move to 8-12 reps towards the end of my pressing.


When training the deltoids through isolation work, most of my time is spent on the lateral head. Training this part of the deltoid is what will give them that round look from the front, and will make them “pop”. This head is not worked during pressing movements to the extent that the anterior head is, so it’s important to use isolation exercise to target it.

Although lateral dumbbell raises are a very common exercise, I often see people performing them incorrectly. Remember that the function of the lateral deltoid is to raise the arm, when it is internally rotated. Many people forget this, and perform raises with an externally rotated arm. This video by Ian McCarthy is a great demonstration on how to perform them correctly. The same rule with internal rotation also applies to cable raises.

For raises, it is very important to use light weight and perform these in a higher rep range (10+).


This is often the most neglected part of deltoid training. Many people believe that back training alone will target this muscle efficiently, but in order to fully develop the deltoid, and make sure that they are visible when people look at you from behind, you must work this head with isolation exercises. Neglecting posterior deltoid work can be detrimental to your shoulder health as well. Most people engage in so much pressing work, and often underwork pulling movements, leading to muscular imbalances.

I prefer doing rear delt flys on the machine because I can control the movement throughout the entire range of motion, and can really feel a contraction in them. Face pulls are an extremely beneficial exercise for your rear deltoids and overall shoulder health.


  • Deltoids have three heads: posterior, anterior, lateral
  • Overall function is to abduct the arm, but each head has a specific function
  • Anterior deltoid abducts the shoulder when the arm is externally rotated
  • Lateral deltoid abducts shoulder when the arm is internally rotated
  • Posterior deltoid extends the shoulder
  • Always warm up thoroughly
  • Isolation isn’t necessary for anterior head unless you are a bodybuilder
  • Use presses for anterior head, and isolation exercises for lateral and posterior head

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