Shoulder training

Geschatte leestijd: 13 minuten

Training shoulders can be done in different ways. Here we discuss the anatomy and functions of the shoulder joint. With that knowledge, we describe and compare possible shoulder exercises.

Check the following link for all shoulder exercises

Training Shoulders

You can train shoulders more effectively and safely by having more insight. Insight into the anatomy and the functions of the various muscles/heads in the shoulder joint.

Naturally, you can also just get started with a list of shoulder exercises. You will see that you can choose from a very large number of exercises and variations thereof. Discussions are often held in the gym about which exercise or variation is the best. With a bit of luck, some context is provided such as: “If you want to get stronger, do this, if you want to get more muscular, do that”. Unfortunately, such nuances are often omitted and discussions are usually based on ‘bro science’.

For example, if someone asks you why you perform a dumbbell shoulder press standing up and not sitting down. Then it is useful if you can refer to research that has measured the difference. But it is also nice if you have basic knowledge of how muscle mass works so that you can explain a (measured or not measured) difference.

Shoulder Muscles

The shoulder region consists of several muscles involved in arm movement. When training, most attention is focused on the deltoid. This is the large shoulder muscle responsible for many of the larger movements of the upper arm.

In addition, there are smaller muscles that mainly stabilize the shoulder joint. A somewhat experienced athlete knows how to train the (front, back, and side of the) deltoid. Specifically training the underlying stabilizing muscles is often a lot less known.

Stabilizing Muscles and Injuries

Training these stabilizing muscles is especially important for injury prevention and recovery from injuries. Shoulder injuries are relatively common among athletes. Especially athletes who make a lot of movements above shoulder level benefit from this (volleyball, baseball, tennis, etc.). If you are just starting out with strength training, then the normal shoulder exercises aimed at the deltoid (initially) are sufficient. However, if you also engage in sports such as those described above fanatically, then it is advisable to do exercises for the underlying stabilizing muscles to prevent shoulder injuries.

Even if you have been training for a while and the deltoid is well developed, you are at risk of injuries due to the difference in strength between the deltoid and the underlying muscles. So it becomes important to train these as well.

To understand all this, unfortunately, you cannot avoid anatomy. So first a small lesson on the anatomy of the shoulder. I will not mention all the points of origin and insertion. These are freely translated: Starting point and endpoint of the muscle. In other words, the two body parts connected by the muscle. I will mainly focus on the functions and key points.

Function and Muscles in the Shoulders

There are a total of 7 muscle groups that form the shoulder joint. These connect the shoulder blade (scapula) to the upper arm bone (humerus). In the image above you see the shoulder joint from the back. The trapezius is not shown so you can see the muscles underneath it. For the same reason, you only see the front half of the deltoid. The back half is ‘cut off’.

Deltoideus

Of these muscles, as mentioned, the deltoid, the large shoulder muscle, is trained the most. This is an important motor behind movements with the upper arm. Moreover, this muscle partly determines the appearance of the shoulder. ‘Broad shoulders’ are the result of a long collarbone and/or a thick deltoid. You cannot train those collarbones. But you can train the muscle that lies on the end.

Next to this text is a depiction of the deltoid, named after the Greek capital letter delta (Δ). The main functions of the deltoids are flexion, extension, horizontal abduction, and rotation of the upper arm. In other words: moving the upper arms forward, backward, sideways, and rotating them in and out.

In addition, the deltoids prevent the upper arms from slipping out of the joint when lifting weight.

Shoulder Heads

As you can see, the deltoid can pull the upper arm from various directions. Some of the fibers pull more from the front. Their starting point (origin) is at the end of the collarbone. This is also called the front ‘head’, or simply ‘front shoulder’. Because they pull from the front to the upper arm, their function is mainly to lift the arm forward. They also help with lifting sideways.

The so-called ‘middle head’ of the shoulders has its origin in the acromion (‘shoulder roof’). This is why these fibers are especially good at lifting the arm sideways.

The ‘rear head’ of the shoulders has its origin in the shoulder blade. This means it pulls more from behind on the upper arm. In addition to helping the other heads lift the arms sideways, the rear head also works with the large back muscle to pull the shoulders backward.

This division into three heads is sufficient in practice to effectively and specifically train the shoulders. However, it is good to know that the deltoid can actually be divided into 7 different muscle fiber groups. This is based on the separate nerves that control them (three in the front head, one in the middle head, and three in the rear head).

Rotator Cuff

Then there are the muscles of the so-called rotator cuff.

The rotator cuff consists of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis.

These muscles are not specifically aimed at moving the upper arm. But they mainly serve to stabilize the shoulder joint. Because the shoulder joint is very mobile, but therefore also relatively unstable, these muscles are very important. Without these muscles, the upper arm would always be partially out of the socket.

The subscapularis lies at the front of the shoulder blade and prevents the upper arm from slipping forward out of the socket. The supraspinatus, infraspinatus, and teres minor mainly prevent the upper arm from slipping backward out of the socket.

The rotator cuff also assists the deltoid with lifting the arm sideways. The muscle belly of the deltoid is relatively small compared to the strength with which the arm can be lifted sideways. The rotator cuff helps the deltoid here.

When performing shoulder exercises, it is important to work these muscles well and evenly to prevent injuries. If you are just starting out, it is not necessary to specifically train these muscles. This is especially important for athletes who make a lot of overhead movements (throwing, smashing, serving, etc.). These people run a relatively high risk of shoulder injuries.

For a more detailed explanation of the functioning of these muscles, check the following link shoulder exercises

Summary

Training the shoulders can be done in many different ways. With this in mind, it is important to have an understanding of the anatomy and functions of the shoulder joint. The deltoid muscle, consisting of three heads, is the main muscle targeted in shoulder exercises. However, it’s also crucial to train the stabilizing muscles, such as the rotator cuff, to prevent injuries and ensure balanced strength development.

Whether you’re a beginner or an experienced athlete, incorporating a variety of shoulder exercises that target different muscle groups will help you achieve optimal results and reduce the risk of injury.

For more information and a comprehensive list of shoulder exercises, check out the link provided.

Safer full can

This was also the conclusion drawn by researchers from Florida. They also indicate that the Full can and Empty can equally load the supraspinatus and due to the risk of injuries, it is better to choose the Full can [6]. However, in contrast to the Japanese, they mention that the full can also loads the infraspinatus more.

Research from the U.S. also observed a difference in the effect on the supraspinatus by the empty can and the full can. They also found that the full can loads the supraspinatus more (5).

So, two studies demonstrating that the full can is better for the infraspinatus and a third study that points to the empty can for this, but only sees a small difference. Considering also the risk of injuries, the full can is therefore recommended.

In addition, research from Colorado has shown that the push-up plus is a very good exercise for both the supraspinatus and the infraspinatus. This was evident when they examined which exercises were best for the subscapularis [7]. This is a variation of the push-up where the arms remain straight. Only the shoulders are pushed forward and pulled back.

Exercises for the subscapularis

There has long been confusion about the function of the subscapularis (literally: “Under the shoulder blade”). This may have been caused by the fact that it was seen as a muscle that receives one control from the nervous system and therefore works as one muscle without distinction in function per part of the muscle [7]. However, it has now been shown that the subscapularis is controlled in different ways by the nervous system [8,9] and activated [10]. This was visible, among other things, because the top of the subscapularis is much more active in movements above shoulder level such as throwing than the bottom of the same muscle [11].

The researchers from Colorado mentioned above used EMG to determine the extent to which seven different exercises activate the two parts of the subscapularis. They did this to find out which exercises would be best suited for the prevention and rehabilitation of injuries to this muscle [7]. The seven exercises they did were:

The different tested exercises:

1. Dynamic Hug: This is horizontal adduction, or in other words: Flyes as they are normally done for the chest muscles.
2. Forward punch: Like a punch: This is the same as bench pressing with dumbbells with a narrow neutral grip (thumbs up).
3. Diagonal: Diagonal adduction with endorotation. The arm starts stretched at shoulder height and is brought to the belly with an inward rotation, stretched.
4. Push-up plus: Like a push-up, but without bending the arms at the elbow. Only the shoulder blades are pushed forward and pulled back. If you look this up on Google, you get all sorts of pictures of ladies in push-up bras. Very annoying of course.
5. Internal rotation low: Endorotation. Turning the hand inward. This was done from three positions. In internal rotation low, this was at 0 degrees abduction (arms beside the body)
6. Internal rotation high: Endorotation from 90 degrees abduction (arms like wings and then thumbs down),
7. Internal rotation mid: Endorotation from 70 degrees abduction (arm slightly below shoulder level).

The results

In the table, you can see the results, where it is also interesting to see how much the other muscles were loaded. Because bands were used, the concentric phase (for example, during the push in the forward punch) is expressed as increasing force (increasing force), because the further the band is stretched, the more resistance it gives. The way back is then logically expressed as decreasing force. This is different from dumbbells, where gravity provides the resistance and the whole movement can remain the same depending on the angle trained.

In the overview, only the muscles are listed that showed more than a 20% increase in activity compared to the maximum voluntary contraction (MVC). What this exactly means and how it was measured is a long story. What is important here is which exercise showed the greatest activity for the subscapularis.

From the overview, it is clear that during the push-up plus, both the upper and lower parts of the subscapularis are most activated (respectively 121% and 46%). Especially for the upper part, the difference with other exercises is very large. For the lower part, the difference with some other exercises is much smaller. Because the upper subscapularis shows a greater activity in all movements than the lower part, the upper part is the most important to train for the prevention or rehabilitation of injuries.

As indicated above, this research also shows that the push-up plus is very suitable for training the supraspinatus and infraspinatus.

Exercises for the teres minor

In the study from Colorado, unfortunately, the activity of the teres minor was not measured. However, this was done in the Japanese study where the effect of the three exercises Empty can, Full can, and horizontal abduction were measured. Of these three, the “can exercises” hardly had any effect on the teres minor. Horizontal abduction (performed in a supinated position, with thumbs up!) had a fairly large effect on the teres minor (Table 3).

Researchers from the U.S. had subjects perform seven different exercises often used as rehabilitative exercises for the shoulder external rotators [12]. In other words, exercises aimed at the muscles that rotate the arm outward in relation to the torso. This also includes the teres minor (see overview of functions per muscle at the top of the article).

In the overview below, you can see the effect of the different exercises on the activity of the teres minor. Also here expressed as a percentage of the maximum voluntary isometric contraction (MVIC). From their results, it appears that especially the side-lying external rotation had the greatest effect.

In this exercise, you lie on your side with the elbow against the side and the forearm extended forward (see image->) and you raise the fist until it points to the ceiling and back again. The upper arm remains parallel to the torso during this movement. This exercise also had the greatest effect on the infraspinatus (of the tested exercises at least).

They also saw, like the Japanese, that horizontal abduction with external rotation (as fig. 2: Lying or bent forward, but then with thumbs facing up) strongly activates the teres minor (exercise no. 5 in the image above). However, from the overview, it appears that there are several exercises besides side-lying external rotation that better target the teres minor. These are all focused on active external rotation where the upper arm rotates outward during the exercise (and does not remain rotated outward like with horizontal abduction).

So, multiple exercises are suitable for the teres minor. These are especially the exercises where the arm must rotate outward. The side-lying variant has the greatest effect.

When to train the rotator cuff muscles and how intensively?

Compared to the deltoids, the muscles of the rotator cuff are small muscles. They should therefore not be fatigued when you train the deltoids because this will affect the “real” shoulder training. You should therefore do these exercises after shoulder training or on a separate day (preferably not a day before or after shoulder training).

One exercise per muscle of only one set may be sufficient to ensure that these muscles do not become too weak compared to the other muscles that you train more often.

Because you mainly train these for strength and endurance, the number of repetitions per exercise can be relatively high. However, this is generally the case. The volume is very personal and depends on your goals and other sports. For example, as a pitcher for a baseball team, you are at greater risk of shoulder injuries and it is wise to do this at least once a week. As an average bodybuilder, once every two weeks may be sufficient to prevent many complaints.

Hand position for the posterior deltoid

The posterior deltoid is often trained with reverse flyes. This exercise can be trained in different ways. In addition to the seated, standing, or prone exercises with dumbbells, there are also specially designed machines for this exercise. With almost all of these machines and with all dumbbell exercises, you can also choose from three hand positions. You can choose a pronated grip (thumbs towards each other), a neutral grip (thumbs forward/up), or a supinated grip (thumbs pointing away from each other). The last method is the one the Japanese had their subjects do in their study.

In the Journal of Strength & Conditioning Research, the results of the different effects of the other two positions on the load on the posterior and lateral deltoid (‘Mean PD’ and ‘Mean MD’) and the infraspinatus (‘Mean IF’) were published this month.

Researchers had 19 trained students train on a reverse flyes machine with both grips and measured the load on the muscles using EMG. Half of the group first used a neutral grip and then the pronated grip, the other half did it the other way around (to prevent the order from influencing the results).

They set the machine to provide 75% of body weight as resistance and did as many repetitions as they could (to failure). The resistance doesn’t say much. How much resistance is provided depends on how this resistance is transferred to the person and not just on the weight hanging on it.

Bent-over reverse flyes with dumbbells of 75% of body weight is almost impossible for anyone (unless it is divided between both dumbbells), so this will not be the resistance actually exerted on the person. However, this doesn’t matter much because we are mainly looking at the different loads between the two hand positions. You may assume that if the load increases, it is still the same muscles that are being stressed, and one grip still has more effect than the other.

Their research showed that the neutral grip formed the greatest average and peak load for the posterior shoulder muscles and the infraspinatus, making it the best way to train them. Unfortunately, this was not compared to the other positions. Because a different method of measurement was used (EMG instead of MRI and relaxation time), I cannot compare them with each other).

More load on the shoulder muscles by squeezing

Swedish researchers looked at how grip strength affects the load during work and injuries. They had 9 people squeeze a dynamometer during various shoulder exercises to see if this increased muscle stress. The dynamometer indicates how hard it was squeezed, and instructions were given to exert 30% to 50% of maximum grip strength.

Especially during abduction between 60 and 120 degrees (90 degrees is when you spread your arms outwards from the torso like wings), the researchers saw increased activity in the supraspinatus and to a lesser extent in the infraspinatus. In the deltoids, the influence was generally smaller and greatest at an angle less than 90 degrees.

Conclusion

In practice, the deltoids often receive the most attention when training at the gym. These have the greatest impact on shoulder strength and appearance.

The deltoids can be functionally and visually divided into three parts/heads. The shoulder press is a popular exercise to train the entire deltoid. In reality, this exercise emphasizes the front head the most.

Training the rotator cuff muscles is important for the prevention and rehabilitation of injuries, especially when you practice sports that involve many movements above shoulder level. These muscles have different functions aimed at stabilizing the shoulder joint, supporting the deltoids, and rotating the arm.

The various muscles are best targeted with various exercises, although it remains difficult to determine which exercise is “the best” for each muscle due to the different methods used in the research. However, this is not very important. What matters is knowing which exercises effectively engage the respective muscles.

References

1. Adams GR, Duvoisin MR, Dudley GA: Magnetic resonance imaging and electromyography as indexes of muscle function. J Appl Physiol 73:1578–1583, 1992
2. Fisher MJ, Meyer RA, Adams GR, et al: Direct relationship between proton T2 and exercise intensity in skeletal muscle MR images. Invest Radiol 25: 480–485, 1990.
3. Fleckenstein JL, Watumull LD, McIntire DD, et al: Muscle proton T2 relaxation times and work during repetitive maximal voluntary exercise. J Appl Physiol 74: 2855–2859, 1993
4. Shellock FG, Fukunaga T, Mink JH, et al: Acute effects of exercise on MR imaging of skeletal muscle: Concentric vs eccentric actions. AJR Am J Roentgenol 156: 765–768, 1991
5. Yoshitsugu Takeda, Shinji Kashiwaguchi, Kenji Endo,Tetsuya Matsuura en Takahiro Sasa. The Most Effective Exercise for Strengthening the Supraspinatus Muscle. Evaluation by Magnetic Resonance Imaging. THE AMERICAN JOURNAL OF SPORTS MEDICINE, Vol. 30, No. 3
6. Escamilla RF, Yamashiro K, Paulos L, Andrews JR. Shoulder muscle activity and function in common shoulder rehabilitation exercises. Sports Med. 2009;39(8):663-85.
7. Michael J. Decker,† MS, John M. Tokish, MD, Henry B. Ellis, Michael R. Torry,‡ PhD en Richard J. Hawkins, MD. Subscapularis Muscle Activity during Selected Rehabilitation Exercises. THE AMERICAN JOURNAL OF SPORTS MEDICINE, Vol. 31, No. 1
8. Kato K: Innervation of the scapular muscles and its morphological significance in man. Anat Anz 168: 155–168, 1989
9. McCann PD, Cordasco FA, Ticker JB, et al: An anatomic study of the subscapular nerves: A guide for the electromyographic analysis of the subscapularis muscle. J Shoulder Elbow Surg 3: 94–99, 1994
10. Kadaba MP, Cole A, Wootten ME, et al: Intramuscular wire electromyography of the subscapularis. J Orthop Res 10: 394–397, 1992
11. DiGiovine NM, Jobe FW, Pink M, et al: An electromyographic analysis of the upper extremity in pitching. J Shoulder Elbow Surg 1: 15–25, 1992
12. Reinold MM, Wilk KE, Fleisig GS, Zheng N, Barrentine SW, Chmielewski T, Cody RC, Jameson GG, Andrews JR. Electromyographic analysis of the rotator cuff and deltoid musculature during common shoulder external rotation exercises. J Orthop Sports Phys Ther. 2004 Jul;34(7):385-94.
13. Schoenfeld et al. Effect of hand position on EMG activity of the posterior shoulder musculature during a horizontal abduction exercise Journal of Strength & Conditioning Research: POST ACCEPTANCE, 8 January 2013.
14. Swanik KA, Huxel Bliven K, Swanik CB. Rotator-cuff muscle-recruitment strategies during shoulder rehabilitation exercises. J Sport Rehabil. 2011 Nov;20(4):471-86.
15. Magee DJ. Orthopedic physical assessment. 2d ed. Philadelphia: Saunders, 1992.
16. Sporrong H. et al. Hand grip increases shoulder muscle activity, An EMG analysis with static hand contractions in 9 subjects. Acta Orthop Scand. 1996 Oct;67(5):485-90.
17. Saeterbakken AH, Fimland MS. Muscle activity of the core during bilateral, unilateral, seated and standing resistance exercise. Eur J Appl Physiol. 2012 May;112(5):1671-8. Epub 2011 Aug 30.
18. Saeterbakken AH, Fimland MS. Effects of body position and loading modality on muscle activity and strength in shoulder presses. J Strength Cond Res. 2012 Oct 23.
19. https://www.t-nation.com/training/inside-the-muscles-best-shoulders-and-trap-exercises