Deltoid Training and Anatomy for Dummies


  • 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

Deltoid Anatomy

Your deltoids are mode up the the anterior, lateral, and the posterior heads.

  • Your anterior begins on the front of your collarbone (the anterior surface of your clavicle)
  • The middle or lateral deltoid starts on your shoulder blades’ acromion and spine.
  • Your posterior deltoid begins at the your shoulder blades spine as well
  • All three heads connect at humerus on your upper arm

Deltoid Function

Your deltoids are responsible for the control and movement of your upper arm. Contracting all heads of the deltoid at once casuses your arm to abduct. The deltoids also support you when you lift heavy loads by supporting your humerus and stopping it from dislocating. This is why your deltoids might look giant when you are doing shrugs, because they are making sure your arm does not pop out of its socket. To break it down further, each head of the deltoid has a more precise purpose.

Anterior Deltoid

  • While your arm is externally rotated, the anteriod deltoid controls its movement. It allows your arm to flex at the shoulder and internally rotate.

Lateral Deltoid

  • The lateral deltoid is primarily used while your arm is internally rotated. It abducts your shoulder.

Posterior Deltoid

Deltoid Training

Because deltoids play a large variety of functions in different movements, they are involved in nearly all upper body workouts and even in some lower body workouts (eg: deadlift). Because of the frequency of use, they are easy to injure if you are not using proper form or you do not warm up enough and get your deltoids ready for your workout. Here is a great upper body warmup that will help to avoid some of the issues caused by not warming up.

Each head of your deltoid will need training so that your overall deltoid muscle is well developed. If you are doing a deltoid workout, it will help to focus on performing one exercise for each head.

Training Your Anterior Deltoid

The anterior head is used most often during your press exercises, such as bench press and other chest exercises. Because you are already working the anterior deltoid in compound movements, you probably are fine not using isolation exercises if you are a casual exerciser. Here are some great exercises that work out the anterior deltoid.

When doing press exercises, you may see some additional gains to your bench press weights, especially while doing standing military press. To achieve maximum gains, try to start heavy, doing 2 sets of 6 to 8 reps, and then shift to lighter weights and do 2 sets of 8 to 12 reps.

Training Your Lateral Deltoid

To make your deltoids get that “pop” and rounded look in front, you will want to perform some isolation work focused on training your lateral deltoids. Pressing movements do not workout this head of the deltoid nearly as much as the anterior head, making isolation key. Here are two exercises that will isolate and hit the lateral deltoid.

Because your lateral deltoids are responsible for raising your arms when it is internally rotated, you will want to maintain an internally rotated arm while doing your lateral dumbbell raises. If you do this exercises with an externally rotated arm, you will not exercise your lateral deltoid. Here is a useful video going over proper form.

For both exercises, you will want to go with a higher rep range (10 or more) and lower weights.

Training Your Posterior Deltoid

The posterior deltoid is commonly the most forgotten of the three heads of your deltoids. Although it is commonly thought that back exercises will hit this head, you will definitely need to train the posterior deltoid with isolating exercises if you wish to have a visible deltoid when looing at your back. If you do not train your posterior deltoid, you may have additional issues. Because we do lots of pressing exercises, and some of us are lacking when it comes to back exercises, you risk creating a lack of balance between your muscles. Here are two exercises that will isolate and hit your posterior deltoid.

For rear delt flys, you can go with either dumbbells or the machine. However, the machine will help to let you control your movement through the whole exercise. Not only are face pulls great for your posterior deltoid, but they also are great for maintaining your complete shoulder health.

Leave a Comment