The shoulder is made up of three bones; The Scapula (otherwise known as the shoulder blade), The Clavicle (or collarbone), and The Humerus (or the upper arm). They are held together by the Glenohumeral Joint (or shoulder joint).
The main muscles in the shoulder are the Deltoid muscle and Rotator Cuff, though some people include The Trapezius muscle and other muscles as well.
The Deltoid is one muscle with three heads, these are sometimes mistaken as three separate muscles but in actuality it is one muscle made up of three different fibre types (or heads). These are:
- The Anterior Deltoid
- The Middle Deltoid
- The Posterior Deltoid
Recently it has been discovered that there are as many as 7 different sets of fibres , but the three mentioned are the ones we will be concentrating on.
The Rotator Cuff Muscles are a group of muscles that stabilise the shoulder, these muscles are:
- The Supraspinatus Muscle
- The Infraspinatus Muscle
- The Teres Minor Muscle
- The Subscapularis Muscle
Training these muscles alone could be the best change you make to your shoulder program, but we still have one more muscle to check out. This is the Trapezius muscle, often thought of as exclusively an upper back muscle, the Trapezius extends from one shoulder to the other at its widest point.
One of its prime roles is to retract and medially rotate the Scapulae. So whilst it is not wrong to call the Trapezius an upper back muscle, it also has a very important role as a shoulder muscle.
Now that you know what the shoulder consists of we can go into how to make the most out of training shoulders by avoiding the following mistakes.
Mistake #1. Training Chest and Shoulders together
Now, there is nothing wrong with training chest and shoulders together as part of a full body workout.
In fact, not performing a full body workout could be one of the mistakes that you are making, as this will allow you to train the muscles more often throughout the week which leads to increased strength .
But training one or two muscles together such as back and biceps is a bodybuilding staple. In this case, putting chest and shoulders in the same workout is a pretty big mistake.
This is because the most common chest exercises; Bench Press, Dips, Press Ups are also Anterior (front) Deltoid exercises.
As a result you are now training the front deltoid for all of the chest exercises and then expecting to train the front deltoid for all of the shoulder exercises; Front Raises, Shoulder Press, Military Press etc …
This will 1) Over-train the Front Deltoid creating an imbalance of the Deltoid group 2) Prevent yourself from maximising your shoulder workout as your muscles will already be fatigued from the chest exercises.
Mistake #2. Ignoring the Middle and Posterior Delts
This was touched upon in the last point, but the middle and posterior delts are just as important for a healthy and strong shoulder as the anterior delts.
Building bigger middle deltoids isn't just good for shoulder health, they are also a good ‘mirror muscle‘ in that they can make your shoulders wider which will in turn improve your shoulder to waist ratio.
But the rear delts are the most important muscle to concentrate on, poorly worked rear delts can lead to rotator cuff injuries, and bad posture.
Rear delts don't need to be trained in isolation, they can be worked while performing most rowing movements, particularly the bent over row or single arm row. Adding rear delts to a back workout, or the pull day for a push/pull program can really help you fit them into your program.
Mistake #3. Performing the Upright Row badly
The Upright row has become the least popular exercise with physiotherapists because it is so often performed incorrectly.
When most people perform the Upright Row, they tend to place their hands very close together in the middle of the bar when they should actually space their hands out wider.
Another big mistake is raising the elbows above shoulder height. Schoenfeld et al (2015) demonstrated that modifying the exercise so that the elbows do not pass shoulder height could prevent any rotator cuff injuries from occurring .
Mistake #4. Arching the Back during Shoulder Press
This could be put another way, don't use more weight than you are comfortable lifting.
The reason is that during a shoulder press (particularly the military press) if the weight is too heavy the lifter will subconsciously arch their back so that they can almost turn the movement into a bench press. By arching your back you are recruiting your upper pectorals to help you lift.
This will cause havoc in your Erector Spinae muscle group, and will eventually lead to injury.
It also leaves you with a pretty poor shoulder workout as you are now taking away the emphasis of the front and middle delts, and placing it on your pectorals.
Lower the weight and make sure that you are fully upright when performing this exercise.
 Brown, J., Wickham, J., McAndrew, D., Huang, X. 2007. Muscles within muscles: Coordination of 19 muscle segments within three shoulder muscles during isometric motor tasks. Journal of Electromyography & Kinesiology 17: 57-73
 Schoenfeld, B., Ratamess, N., Peterson, M., Contreras, B., Tiryaki-Sonmez, R. 2015. Influence on Resistance Training Frequency on Muscular Adaptations in Well-Trained Men. The Journal of Strength & Conditioning Research 29(7): 1821-1829
 Schoenfeld, B., Morey, K., Haimes, J. 2011. The Upright Row: Implications for Preventing Subacromial Impingement. Strength & Conditioning Journal 33(5): 25-28