Muscle Study: The Deltoids

In each muscle study, we’ll take a look at a muscle group, and examine what its purpose is in the body. Then using that information, we’ll take a look at a few ways to exercise the muscle and close with a sample workout that should effectively work the muscle. There may be some biological / technical jargon in this, but I’ll do my best to explain in plain English the terminology we’re throwing around as we go along!

The deltoid is the topmost muscle on the arm. It sits atop the shoulder and is a single rounded, triangular shaped muscle. It has three origins – the end of the clavicle (collarbone), the acrimion of the scapula (a bony protrusion on the shoulder blade) and the spine of the scapula (A bony plate connecting to the acrimion of the scapula). Each origin forms what we more commonly refer to as the front, side and rear deltoid (or “delt”) muscle. The bands of muscle from each origin merge together and insert on the deltoid tuberosity of the humerous (a slight bulge in the bone of the upper arm, located about two thirds of the way up the bone from the elbow).

So What Does This Muscle Do?

The deltoid has four primary functions:

  • Pulling the arm across the body – upper arm to collarbone.
  • Moving the arm forward or upward – as in punching or throwing a ball underhand
  • Moving the arm away from the body – reaching out to the side
  • Reaching backwards

So How Do We Best Work This Muscle?

By understanding how the muscle interacts with the body, we can begin to examine the best ways to engage it in exercise for maximum effect. Breaking down the way the muscle moves the arm, we know that minimizing flexion of the elbow as the arm moves cross body will work the front of the deltoid – however, this also engages a much larger muscle group – the pectorals; better to raise the arm in front of the body from the hip to the shoulder. Moving the arm upward, away from the body will work the side of the deltoid, and moving the arm backward – behind the plane of the body will work the rear of the muscle.

The shoulder is a complicated joint, so it’s best to be very careful when exercising it to avoid injury. Stick to light weight to avoid overtaxing the joint – rotator cuff tears can be very serious injuries! Remember, the arm is basically a lever, and the shoulder is the fulcrum, so weight has a multiplier effect on this muscle. Let’s take a look at three different exercises we can do to target the muscle fully, examine why they work, and how to properly perform them to best effect.

The 3-Step Cable Front Raise

This is a great exercise for the front deltoid that can be performed with either a cable machine, resistance band or dumbbell. Select a weight that is difficult, but not too heavy (see above about avoiding injury!)

When performing the exercise, your shoulders should be back and down (pinching the shoulder blades together slightly) and staggered with the working arm slightly closer to the weight stack if performing with a cable machine. The back should remain straight, and the chest should be “up” – no rounded shoulders.

1Start with your feet slightly wider than shoulder width. Knees should be slightly bent and the back facing the weight stack. If performing with a resistance band, it should be secured at floor level, behind the body. If using a dumbbell, it should be at your side, palm facing the wall behind you. Inhale prior to initiating the raise.

2Raise the arm up and out away from the body, palm facing the floor until the arm is parallel to the floor at the same height as the shoulder. The arm should remain straight throughout this movement, with no to very little bend in the elbow. at the end of the movement, the palm holding the cable / band / weight should be facing the floor. Pause for a 1 second mental count while squeezing the muscle.

3Exhale and slowly return the arm to the side over a mental count of 3 or 4 maintaining the same straight arm, palm facing the floor, and ultimately the back wall as the arm returns to the starting position. Rest for a mental count of 1 or 2 and repeat the movement until failure (the point at which you cannot perform another movement, or you cannot perform another movement without sacrificing form).

The 3-Step Seated Dumbbell Shoulder Press

The shoulder press targets the middle deltoid and can be performed with either a barbell or set of dumbbells. There are many variations of this exercise to target the various “heads” of the deltoids, but we’re performing ours seated at a 90 degree angle.

1Start seated on a bench or chair. Your shoulders should be back and relaxed, and your upper body should be upright (not leaning forward or back). Look straight ahead (not down) and flex your core to stabilize your spine. Hold a dumbbell in each hand slightly above shoulder level with the palms facing forward. Inhale prior to initiating the press.

2Exhale and focus the gaze straight ahead, and keep your spine straight as you press the weights upward and overhead over a slow mental 3 to 4 count until almost touching. Squeeze the shoulders to initiate and control the movement, and again squeeze them at the top of the movement for a 1 second count.

3Inhale as you slowly return the weights to the original starting position over a mental 2 to 3 count, focusing on keeping the spine straight and the core engaged to control the movement.

The 3-Step Seated Bent Over Dumbbell Lateral Raise

My favorite exercise for the rear delts is the face pull, but since one of the goals of this series is to provide exercises that don’t necessarily require heavy gym equipment, we’ll go with the seated bent over dumbbell lateral raise. As with the other shoulder exercises, go light, stay safe.

1 Start seated on the edge of a bench or chair. The shoulders should be back and relaxed, and your upper body should be upright and straight. Both feet should be planted on the floor with a 90 degree bend at the knee – and unlike the image above, the feet should be together. Lean forward at the waist until the chest / stomach make contact with the tops of your thighs. The hands should now be hanging behind your calves with the palms facing each other holding dumbells. The arms should be in a fixed position with a slight bend in the elbows.

2Holding that position, the arms should raise out and to the sides over a mental 2 or 3 count until about parallel with the floor. Inhale during the movement and hold the weight for a 1 – 2 second count at the top of the movement, squeezing the muscle. At the top of the movement, the shoulder blades should be slightly pinching together.

3Slowly return the weights to the starting position along the same path over a 1-2 count. don’t let the weights touch at the bottom. Rest for a 1-2 second mental count before repeating the movement to failure.

Stretch That Thing!

Strengthening the muscle isn’t good enough. You want a functional, strong, lean muscle that not only looks good, but that you can rely on. If you don’t stretch your muscles, you’ll begin developing range of motion issues that you don’t want. My rule of thumb – any time you work a muscle, you should also stretch the muscle. A few stretches you could perform after a delt workout might be:

Cross Body Shoulder Stretch
Child’s Pose

Wrap Up

There are many reasons to exercise this muscle group, ranging from functionality to simply aesthetic reasons. Hopefully this article sheds some light on the complexity of this popular muscle group, and increases your knowledge of how it’s used by your body. I’d love to hear your thoughts on ideas how you might be able to train it to work even harder.

Know someone who might like this article? Please share it with them, or via your social media network, it helps the blog out, and you never know who you might be responsible for motivating to live a healthier lifestyle!

Resources
innerbody – Deltoid Muscle

Muscle & Performance – 10 best shoulder exercises

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