The Shoulder: How it Works and Why it Hurts

What causes shoulder pain?

There are many reasons that the shoulder can hurt. Traumatic injury, arthritis, and inflammation are all extremely common causes for chronic discomfort in the shoulder joint. However, with the exception of traumatic injury, these types of discomfort are usually the result of a lifetime of repetitive shoulder strain combined with the gradually decreasing healing ability that is common with advancing age. Even injury can contribute to chronic pain if the recovery was not properly monitored and the structures healed in a compromised position. (This is one of the major reasons for splinting an injury – so that as it heals, everything ends up where it’s supposed to. Without a splint, the body will still heal, it will just do so in a way that ignores proper alignment and can continue to contribute to chronic pain and discomfort. The only way to rectify this situation is to recreate the injury and reset the structures properly, a less than ideal situation for most people.)

As with the other articles presented so far, the focus of this article will be on pain that results from the muscles and joints in the shoulder being out of balance. With the shoulder, this commonly results from one muscle group being overly tight and the opposing group being regularly overstretched.  Over time, this situation can contribute to weakness in the joint that can lead to arthritis, muscle strain, frozen shoulder, permanent postural changes, increased risk of dislocation, and mid-back pain. In fact, most people in their thirties have some degree of mid-back (or thoracic) discomfort that is linked directly to the shoulders being out of balance. Specifically a dull ache between the shoulder blades that is usually a dull ache, but which can sometimes incorporate a sharper pain.

What are parts of the body are involved in shoulder pain?

For the purposes of this article, use of the term shoulder is somewhat misleading. In medical terms, the shoulder is simply the ball-and-socket joint where the upper arm (the humerus) attaches to the trunk (at the outer edge of the clavicle, or collarbone, and the scapula, or shoulder blade).  If you include all of the muscles that attach to bones listed in the last sentence, this structure is more commonly referred to as the shoulder girdle. In layman’s terms, this means the upper half of the upper arm, the chest, the upper back, and some muscles that attach to the neck.

The most common area of pain when the shoulders are out of balance is in the mid-back, between the shoulder blades. This is the location of the rhomboid muscles, which are made of two muscles on each side that run between the spine and the shoulder blade. When engaged, they pull the shoulder blades closer to the spine and assist with many movements and posture. They are often overstretched as a result in too much strength being exerted by the next group of muscles.

The pectorals are another pair of muscles that work together. The pectoralis major covers the upper chest, running from the sternum (or breastbone) to the head of the humerus. The pectoralis minor runs from 3rd-5th ribs and connects to the front of the scapula.  These are often some of the most over-developed muscles in the human body, as every time the arms are used to do something in front of the body, they are engaged. This will be examined more in a future passage, but for now, there are a few additional muscle groups that need to be examined.

An equally over-engaged muscle is the trapezius muscle. When someone complains of pain in the top of their shoulder, this is often the offending structure.  This rather large muscle originates at the spine, running from the neck down to the midback, and connects to the back of the upper arm. It serves multiple functions in moving both the clavicle and the scapula, but for the purpose of this article, its most important function is elevating the shoulders (as can be seen when shrugging). It’s assisted in this task by a relatively smaller muscle called the levator scapulae. This small muscle starts at the neck and attaches to the upper and innermost aspect of the shoulder blade. These two muscles, since they work together, are often equally affected by muscle imbalances.

While there are numerous muscles involved in the rotation of the shoulder (a topic that will discussed more in the next section), there is one final muscle that needs to be touched on before posture is examined. The subscapularis muscle is one that is often ignored, even by professional bodyworkers. This muscle originates from the front of the scapula and attaches to the upper arm. Its position between the shoulder blade and the ribs is one of the reasons it is often ignored, as the only way to work on it is to either pull the shoulder blade away from the body or to go in through the armpit. In a case where this muscles has been tight for a long time, moving the shoulder blade might be too painful for the patient and for both patients and practitioners, working inside the armpit can be both an intense and uncomfortable experience. However, if the muscle is ignored completely, it can form adhesions that will literally attach the shoulder blade to the ribs. This can lower mobility, increase discomfort, slow recovery, disturb sleep, and even limit breathing. As such, even though it is a difficult muscle to work on one’s own, it is important to be aware of it.

What are the long-term complications from poor posture in the chest and upper back?

While a person can live with poor shoulder girdle posture a lot more comfortably than, say, someone dealing with low back strain, it presents a number of problems that can greatly impact a person’s quality of life. The pain and discomfort related to muscle imbalance is the most obvious symptom, but there are other, less obvious problems that can affect a person’s day-to-day life in surprising ways.

One of the major reasons why proper chest posture is so important has to do with what major autonomic functions occur in the upper chest. Specifically, respiration (or as the general public calls it, breathing).  Most people in this country already do a lousy job of breathing – they don’t breathe deeply on a regular basis, they hold their breath, they engage the wrong muscles when they are doing it – these are just a few examples. A proper breathing technique is what is commonly referred to as a belly breathing. Watch a sleeping infant. When they take a breath, their chest expands a little, but most of the movement is in the abdomen.  Now compare that with an adult who doesn’t breath properly. In the case of the adult, the belly rarely shifts while the chest often expands a little while the shoulders elevate. This form of breathing is less efficient, robbing the body of the oxygen it needs. Worsening this situation is compression of the chest caused by overly tight muscles, which further restricts the ability of the lungs to expand and contract properly.

Why this becomes increasingly important is due to the body’s reaction to oxygen deprivation. The body uses oxygen for a number of chemical reactions that take place in the body. When there is a lack of it, the body has to work harder to accomplish normal daily activities. The first result of this deprivation is therefore fatigue. The individual feels more tired because his or her body is having to do more with less.  Sleep apnea is a common disorder directly linked to this, though in that case, the problem is related to breathing difficulties while sleeping, but the symptoms are usually very similar to postural-related breathing difficulties.

Like sleep apnea, one of the common side effects of poor respiration is weight gain. This is because our body uses oxygen as fuel as much as it does food. When the oxygen levels in the body are decreased, it will try to make up for the discrepancy by increasing caloric intake. However, this is a less efficient method, so overall, there will still be fatigue, both physical and mental, from the lack of nutrients and as an added side effect, the body will enter ‘starvation mode’. This is an unofficial nickname for when the body has become convinced that it has entered a time of scarcity and will make burning calories harder in order to conserve resources. Adding to that, the lack of oxygen will also impede caloric consumption as it serves as the fuel needed to ‘burn’ the stored fat.  Insufficient respiration also creates a problem due to it not only being about bring fresh air in, but in also pushing used air out.

A common waste product of the human body, carbon dioxide, is primarily exuded from the body during respiration. When this builds up in the system, it creates increased inflammation and discomfort, as well as slowing healing.  As it builds in the body, more problems will start to appear. Chronic sweating is a common sign of oxygen deprivation as sweat is one of the other ways the body can rid itself of excessive CO2. Over time this can contribute to dehydration, weakening other toxin eliminating systems in the body. These increased toxins will further worsen inflammation and will start creating dysfunctions in the body’s healing ability, which increases the instances of auto-immune problems and cancerous growths over the course of a lifetime.

A less terrifying but still distressing side effect of muscle imbalance in the shoulder joint is a condition referred to as thoracic outlet syndrome (or TOS). This condition is characterized by symptoms very similar to carpal tunnel syndrome, in that numbness and tingling in the hands is often the first sign that the condition exists. The primary difference between the two is that carpal tunnel syndrome is caused by the circulation being blocked at the wrist, while in TOS the blockage occurs in the shoulder. It’s not uncommon for someone to have carpal tunnel surgery, get no relief from his or her symptoms, and have it ultimately revealed that the problem is that muscles in the shoulder are cutting off the flow of blood. This can be especially distressing as it most commonly effects people who do a lot of work with their hands (which will be addressed in the “What specifically causes problems” section further down.)

Before comparing bad versus good shoulder posture, one last issue of chronic muscle tension needs to be addressed.  When a muscle is tight for an extended period of time, the body will assume that there is an injury in that area and will attempt to immobilize the injury. It does this by forming an adhesion between the muscle and the connective tissue. An adhesion is basically a specialized form of scar tissue which prevents the muscle and connective tissue from moving freely. When injured, this splinting can help support the body during healing, but unlike the splint that the hospital puts on, this immobilization remains after the injury has healed. For most people, outside help is required in clearing out an adhesion (acupuncture, massage, and rolfing are all commonly used to accomplish this). This can become a lifelong issue when the adhesions hold the individual in an unhealthy posture, as he or she will have a much more difficult time in getting the muscles to relax on their own.

So what does healthy shoulder posture look like? 

First, here’s a few examples of poor shoulder posture.  Remember that shy kid in high school, the one who was always hugging a textbook to his or her chest, and even when he or she was seated, his or her chest would be drawn forward? How about the older woman who is permanently hunched over, maybe even to the point where she has developed a hump on her upper back?  Or the overly-muscled football player who walks like an ape because he can’t straighten his arms and whose shoulders are so high up that he doesn’t have a neck? These are all examples of how muscle development can have a marked impact on how the body develops, and with the shoulder especially, these postural imbalances are often maintained and even worsened simply by not being reversed.

The only other ball and socket joint in the body is in the hip, which often has just as many problems with alignment as the shoulder. The major difference between them, however, is that the hip is weight-bearing joint, so if there is any issue, it will make itself apparent every time the person stands or sits. The shoulder, in contrast, only bears weight when working out, so people who are less athletically-inclined are often unaware of any shoulder issue until it reaches the point where it interferes with day-to-day life.  By the time the shoulder has degraded to this point, however, the amount of work required to bring it back to health is much greater. One reason that greater work is required is because when using these muscles, people tend to hold them in the same position for extended periods of time. If the shoulder is seriously compromised, pain sets in fairly quickly, but in a healthy individual, it’s not uncommon for an unhealthy posture to be held for hours, worsening any postural ailments simply by day-to-day activities.

In an individual with good shoulder posture, if viewed from the side, the shoulders should form a straight vertical line with the ears, shoulders, hips, wrists, knees, and ankles all on the same vertical plane. Viewed from the front, the clavicle should be perpendicular to the neck and the shoulders, elbows, and wrists should form a straight line, with the thumbs pointed directly forward. In the back, the shoulder blades should rest flat against the ribs and should be about two-finger widths away from the spine.  Each aspect of this postural inventory can reveal muscle imbalances, which will now be examined a little closer.

In a person with over-developed pectoral muscles, the shoulders and chest will be drawn forward and the hands will often be inwardly rotated (where the thumbs point more towards the body than straight forward). If the trapezius and levator scapulae muscles are too tight, then the shoulders will be elevated and the two clavicles will form a shape reminiscent of a “V”, with the bottom of the shape made up of the sternum.  Usually both of these situations will exist simultaneously, as it is easier for the body to keep the shoulders elevated if they are being pulled forward while the elevation of the shoulders makes it easier to close the chest.

So what specifically causes muscle problems for the shoulder?

There are three major activities that are the most common causes for poor shoulder girdle posture – working, driving, and exercising. It’s not that the activities themselves are inherently harmful, but that people are doing them far too long without a break and with too much intensity. Each one will be examined individually, but as a group, these activities damage the shoulder in the same way.  They all encourage development of muscles which further reinforce the negative posture while simultaneously being stressful enough that the muscles are strained even more so than they would be otherwise.

Working is one of those things that most people just have to do, but think about the type of employment most people have nowadays. Most jobs require the person to stay in one spot for extended periods of time with the only part of his or her body that moves is the arms and hands, usually in a seated or standing position. And often that work takes place directly in front of the body, so the arms are often being brought in front of them more than they are being moved away from the midline. This applies to everything from working at a computer, drawing, food preparation, and a whole host of other activities. Worsening this is that work in often stressful, which increases muscle tension, reinforcing problems that are already occurring. This also increases the tension in the trapezius muscles, as a common reaction to stress is to hunch the shoulders.  To further increase the damage, these jobs are often done for hours at a time, often with little to no breaks. This increases the body’s misconception that the work posture is the natural one.

Driving affects the body similarly, in that the initial posture is often drawn inwards, which engages the pectoral muscles as well the muscles that draw the body inward. Combine this with the stress of driving and the long amount of time spent behind the wheel, and a situation is created where the natural posture is gradually replaced with a less healthy one.  Professional truck drivers often suffer a number of chronic musculoskeletal problems for this exact reason.

Exercise is another contributor to poor posture in the shoulders, but for a different reason. When executed properly, a good chest and arm routine will reinforce proper posture, but most members of the general public do not receive a comprehensive fitness education, and as a result, often worsen the problems they are trying to avoid. Push-ups are a great example of this. Most kids learn how to do a push-up at a fairly early age, but watch as they perform the motion. A proper push-up starts with the arms extended and when the body is lowered down, the shoulder blades should smoothly move together. When a kid does them, the child will often push past the point to where the arms are straight and will keep going to the edge of their range of motion. This hyper-flexion of the chest overly strengthens the pecs while simultaneously over-stretches the muscles in the back. Putting too much emphasis on the strength of one muscle group while hyper-mobilizing the opposing group is often a major contributor in ongoing postural issues.

This wouldn’t be such an issue if people worked out the opposing muscle to the equal degree, but as anyone who spent a lot of time in the gym can tell, most people will only work one half of a muscle group. Even those who spend as much time on the back as they do the front will still do those exercises with less intensity, and often these exercises are skipped if the person is pressed for time.  Part of the problem is that the exercises for these weaker muscles are left till the end of the workout. Proper training means spending more time on the weaker muscles, not the stronger ones, but the sad truth is that the weaker muscles are never the ones that make a person look buff in a tank top.

So why doesn’t resting help the shoulder feel better?

As mentioned previously, the shoulder is not a weight-bearing joint. In terms of recovery, this means that the only thing that will affect the way the shoulder functions is a conscious effort to make a change.  Otherwise, the established tension patterns will continue unabated and the discomfort and other symptoms won’t be reduced over the long term.

So what can be done do to prevent or reverse shoulder pain?

There are several small steps that can be taken immediately that will help reduce the strain on the shoulders and reduce any further damage to the joint and muscles. The first and most important is to take breaks. No activity should be attempted for more than hour without a break, even if it’s just some slight movement stretches. The biggest thing is to not hold the arms in the same position for an extended period of time if it can be at all helped.

Second, ergonomics. One of the major contributors to shoulder tension is a poorly designed work space. If the area where the work is being done is too high, then the shoulders will often unconsciously elevate to move them to the proper position. This increases the strain on both the traps and the levator scapulae muscles and will contribute to both pain and breathing difficulties.  Also, if the person is constantly bending their head downward to look at his or her workspace, this will increase strain on the shoulders as many of the muscles involved also connect to the neck and tension will spread from there into the shoulders.

Two examples of this are computers and driving. If the computer monitor is too low or too high, the neck and shoulders will often get strained by the constant downward or upward posture. Similarly, if the surface the keyboard and mouse are located on is too high, the shoulder elevation will cause problems over the long term. Driving has a similar pattern. If the steering wheel is to high, the shoulders will elevate to compensate. A simple adjustment to driving that most people can make that will help with chronic tension is to move the hands from the classic 10 and 2 position to a more neutral 9 and 3 position. If the thumbs are pointed toward the ceiling, then the shoulder is in a more balanced position.

The third step, and the most important one for lifelong shoulder health, is awareness. Once an individual is aware of his or her own poor posture developments, he or she can then work to try and keep bad habits from popping up.  And really, it’s the bad habits that have the biggest impact. Slinging a shoulder over one bag on a regular basis usually leads to that shoulder being more elevated. Using a mouse extensively will often create tension throughout that entire shoulder girdle. Even using the same arm to always carry a baby can create a lopsided shoulder posture. In each of the previous three examples, a mixture of taking breaks and awareness can keep a lot of those problems from popping up.

Fourth, if the weather is cold – dress appropriately. The body will naturally elevate the shoulders to protect the neck from cold, and if the shoulders are already tight, this will worsen any pre-existing tension.

Finally, proper stretching and exercise can have huge impacts on day-to-day shoulder discomfort. Even if they are insufficient to reverse the situation, a small amount of self-work on the shoulder can prevent further degradation of the joint.

The following section will present stretches first, arranged by muscle group, starting with the easiest and moving to the more advanced. Following that, some basic self-treatment exercises will be presented. When doing exercises, remember that these are presented from a rehab perspective – that means, in this case, pain is not something to work through, but should be a sign to take a break.

For ALL exercises listed below, remember to breathe! If you can’t breathe, your muscles will tense up.


The Doorway Pec Stretch
This is one of the easiest and most effective stretches for the chest. Find a doorway and place your toes so that they are level with the doorframe. Now rest the forearms against the door frame. Your elbows should be bent to about 90° and should be about level with your nipples (or 5th rib space). Now let gravity do the work as you fall forward, being supported mostly by your arms. If done correctly, you should feel a gentle stretch across the chest and front of the shoulders and your shoulder blades should be drawn together in the back.  Do this stretch for about 30 seconds at a time and whenever you feel it is necessary.

Standing Lateralis Stretch
Stand with your feet about hips with apart and raise your hands over your head until your arms are mostly straight. Take the right wrist in your left hand and do a side bend slowly over to the left with your right hip jutting to the right. If done correctly, you should feel a stretch through the ribs and muscles in the right side. Reverse the directions to stretch the left side. Hold each side for about 5 to 10 seconds, switching once and repeat once or twice a day.

Morning Stretch
Stand with your feet hips distance apart (this one can also be done in the seated position once you have it down). Now raise your hands directly above your shoulders with the palms facing forward. Once the arms are fully extended, pull the arms down so that your elbows are bent and are alongside the body. You should feel the shoulder blades coming together as the arms come down. As you bring the arms down, come down slowly like you are moving through molasses. If you feel unsure about this stretch, perform it with your back against a wall so that your arms are in contact with the wall throughout the movement. Repeat as often as you feel you need to.

Reverse Huggers
Stand with the feet shoulder distance apart and extend your arms in front of you so that your hands are front of your shoulders. Now, keeping the arms straight and at level with the shoulders, draw the arms back like you are opening them for a hug. Pull them back as far as is comfortable and you should feel a stretch across the chest. Repeat this stretch 3-4 times throughout the day.

Shoulder Rolls
Simply roll the shoulders forward ten times and then backwards ten times. The big things to pay attention to are that you are moving throughout the full range of motion and that the shoulder blades are moving as well as the arms. You may hear some popping and cracking if your shoulders are tight, but in the absence of pain, you can ignore that.

These are a more complete shoulder rotation but should only be done one arm at a time. Start with your fingers pointed towards the floor and draw a full circle in the air with your arm as straight as you can. If you can’t create a complete loop, just do what you can and try to increase it a little more each time. After a few circles, reverse direction. Make sure to go in both directions with each arm.

Tricep Stretch
Stand with your feet shoulder distance apart and lift one arm like you are patting yourself on the back (the elbow should be directly above the shoulder). Now take the other arm and gently press back on the elbow of the first arm. You should feel a gentle stretch in the back of the arm. Hold for about 30 seconds and switch sides.

Behind the Back Stretch
Stand with your feet shoulder width apart and clasp your hands behind your back (the “at-ease” position). Now grasp your right wrist with your left hand and pull your right arm further behind your back. Now lean your head to the left side. You should feel a stretch in the front of the neck and shoulder on the right side. After 15-20 seconds, keep holding the stretch and rotate your head upwards. You should feel the stretch in a slightly different location in the right side of the neck. Hold again for 15-20 seconds and then rotate the head downward. Again the location where you feel the stretch should change. Hold again for 15-20 seconds, then bring your head back to initial stretch position, and slowly come out of the stretch. Switch sides and repeat. You should perform this stretch a few times a day depending how much tension there is.

Neck Rolls
One of the simplest stretches, simply rotate the head in a full circle several times in each direction. Go slowly and carefully and don’t push too hard. The most important aspect of this stretch is to keep the shoulders from rising up as you perform it. Do several circles in each direction and repeat throughout the day.

This is one of the best exercises for balancing out the strength differences between the front and back of the shoulders. If you have access to a gym, you can use the standard upright row machine, with a few caveats. First, make sure you are using a weight that you can move comfortably. If you are grunting and straining, it’s too much. These muscles tend to be weak, so especially when starting out, too little weight is preferable to too much.  Second, don’t hyper extend the chest. When lowering the weight, stop the movement when the arms are completely extended. If your chest moves forward, you’ve gone too far.

If you don’t have access to a gym, or if your gym doesn’t have the right equipment, there is still a variation you can do.  You can use free weights, resistance bands, or even jugs of water for this. Start by standing with your feet shoulder distance apart with the weights about a foot in front of your feet. Now bend through the hips (not the waist) until your upper body is perpendicular to the floor. Reach down and take the weights. Then, with your palms facing each other and your hands under your shoulders, bring your hands towards your shoulders. Your arms and shoulder blades should be the only parts moving during this exercise. Try to use a weight that allows for 15-20 repetitions and multiple sets. Finally, when you are finished, but before you straighten up, release the weights to avoid straining the low back.

So this has been an examination of the shoulder girdle, how it can get out of balance, and some things that can be done to reverse the situation. Hopefully it was educational and offers some simple solutions that can be applied to even the most hectic life. See you next time.