Shoulder pain: understanding causes and rehabilitation exercises

The shoulder: freedom of movement comes at a price

The shoulder is the most mobile joint in the human body. It allows you to raise your arm overhead, rotate it in almost every direction, reach behind your back, throw, push, and pull. This exceptional range of motion comes with a trade-off: stability. Unlike the hip, where the head of the femur sits deep within the pelvis, the head of the humerus rests on a shallow joint surface. It is like a golf ball sitting on a tee.

This design makes the shoulder heavily reliant on its muscular and ligamentous structures to stay in place. When those structures are weakened by overload, trauma, or simply the passage of time, pain sets in. It can strike suddenly after an awkward movement, or creep in gradually, first at night, then during everyday activities.

Understanding the causes of your pain is the first step towards effective rehabilitation. This guide reviews the most common conditions and then presents an exercise programme suited to each stage of recovery.

Shoulder anatomy: the structures at play

The shoulder consists of three joints working together. The glenohumeral joint connects the arm to the trunk. The acromioclavicular joint links the collarbone to the shoulder blade. The sternoclavicular joint connects the collarbone to the breastbone. On top of these, the gliding space between the shoulder blade and the ribcage, sometimes referred to as the "false" scapulothoracic joint, plays a vital role.

The rotator cuff is a group of four muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) whose tendons form a kind of hood over the head of the humerus. These muscles handle arm rotation and, more importantly, the dynamic centering of the humeral head within the joint socket. When the cuff works properly, the humeral head stays centred during every movement. When it malfunctions, the head migrates upward and compresses the tendons against the acromion, the bony roof of the shoulder.

The most common causes of shoulder pain

Rotator cuff tendinopathy

This is the most frequent cause of shoulder pain in adults. The supraspinatus tendon is most often involved. Pain appears when raising the arm, particularly between 60 and 120 degrees (the so-called painful arc). It is often present at night, especially when sleeping on the affected shoulder. Movements such as putting on a jacket, reaching for an object overhead, or fastening a bra become difficult.

Tendinopathy most commonly results from a gradual overload. Repeated overhead movements (painting, DIY, swimming, volleyball) push the tendons beyond their capacity to adapt. The tendon becomes irritated, thickens, and loses its suppleness. Without management, it can partially tear and then fully rupture.

Subacromial impingement

Subacromial impingement, or impingement syndrome, occurs when the space between the acromion and the humeral head narrows. The rotator cuff tendons and the subacromial bursa get pinched every time the arm is raised. This narrowing can have a bony cause (a hooked acromion shape) or a muscular one (an imbalance between the muscles that depress and those that elevate the humeral head).

Treatment relies first and foremost on rehabilitation. Strengthening the humeral head depressors and rebalancing scapular mechanics restores the space the tendons need to glide freely. Surgery (acromioplasty) is considered only after the failure of a well-conducted rehabilitation programme lasting at least 3 to 6 months.

Adhesive capsulitis (frozen shoulder)

Adhesive capsulitis is characterised by a progressive, global loss of shoulder mobility. The joint capsule, a fibrous envelope surrounding the joint, becomes inflamed, thickens, and contracts. The arm no longer goes up. External rotation disappears. Reaching behind the back becomes nearly impossible.

Capsulitis typically evolves through three stages. The inflammatory stage (2 to 9 months) is dominated by pain, often severe. The stiffness stage (4 to 12 months) sees pain decrease while mobility remains very limited. The recovery stage (5 to 24 months) brings a gradual return of range. Total duration varies considerably from person to person. Diabetes, thyroid conditions, and a history of trauma are recognised risk factors.

Instability and dislocations

In young, active individuals, shoulder pain is often linked to instability. After a first dislocation (the humeral head comes out of the joint socket), the stabilising structures (labrum, glenohumeral ligaments) are damaged. The risk of recurrence is high, especially before age 25. Rehabilitation in this case aims to compensate for the instability through targeted muscle strengthening.

Exercise programme for shoulder rehabilitation

This programme is intended for people dealing with rotator cuff tendinopathy, subacromial impingement, or those in the recovery phase of capsulitis. It follows a three-stage progression: relieve, strengthen, reintegrate. Adapt the intensity to your pain level. The golden rule: pain during an exercise should not exceed 3 out of 10.

Phase 1: relief and mobility (weeks 1 and 2)

Codman pendulum. Lean your torso forward, one hand resting on a table for support. Let the painful arm hang freely. Make small circles with the arm using the momentum of your body. 1 minute in each direction. This exercise mobilises the joint without actively engaging the tendons. The traction from the weight of the arm decompresses the subacromial space.

Passive external rotation. Lying on your back, elbow bent at 90 degrees, a stick held in both hands. Use the healthy arm to gently push the hand on the affected side outward. Go until you feel a moderate stretch. Hold for 10 seconds. Return. 10 repetitions. This movement recovers external rotation, often the first range of motion lost in shoulder conditions.

Passive elevation. Same lying position, stick held with both hands. Raise the arms overhead, guiding the movement with the healthy arm. The affected arm stays passive. Go as high as pain allows. Lower slowly. 10 repetitions. Practise this exercise twice a day.

Pectoralis minor stretch. Standing in a doorway, forearms resting on the door frame, elbows at shoulder height. Step the torso forward until you feel the stretch across the front of the shoulders and chest. Hold for 30 seconds. Repeat 3 times. Shortening of the pectoralis minor, common in people who work at a desk, pulls the shoulder blade forward and reduces the subacromial space.

Phase 2: cuff and scapular strengthening (weeks 3 to 6)

External rotation with band. Elbow pinned to the body, bent at 90 degrees. Hold a light resistance band attached to a door handle. Rotate the forearm outward, keeping the elbow in contact with your ribs. Control the return over 3 seconds. 3 sets of 15 repetitions. This exercise targets the infraspinatus and teres minor, two rotator cuff muscles that centre the humeral head and counterbalance the upward force of the deltoid.

Internal rotation with band. Same position, but this time you pull the band towards your belly. 3 sets of 15 repetitions. This movement strengthens the subscapularis, the most powerful of the four rotator cuff muscles.

Scapular retraction (rowing). Seated or standing, a band held in both hands in front of you with arms extended. Pull the elbows back, squeezing the shoulder blades together. Hold for 3 seconds. Release. 3 sets of 12 repetitions. This action strengthens the rhomboids and the middle trapezius, two muscles that position the shoulder blade correctly. A well-positioned scapula provides a stable platform for arm movements.

Lateral raise in Y (scaption). Standing, arms at your sides, thumbs pointing up. Raise the arms at 45 degrees in front of you (between a front raise and a lateral raise) up to shoulder height. Lower slowly. 3 sets of 10 repetitions. Start with no weight. Add light dumbbells (0.5 to 1 kg) once the exercise is pain-free and controlled. Scaption loads the supraspinatus along an axis that minimises subacromial impingement.

Wall push-ups. Facing a wall, hands placed at shoulder height. Bend the elbows to bring the chest towards the wall. Push back. 3 sets of 12 repetitions. This movement strengthens the serratus anterior, a muscle that holds the shoulder blade flat against the ribcage. Its weakness causes scapular winging, visible when the arm is extended forward.

Phase 3: functional reintegration (weeks 7 and 8)

Full active elevation. Standing, raise the affected arm overhead in a controlled manner. Hold for 3 seconds at the top. Lower over 4 seconds. 3 sets of 10 repetitions. If the arm does not travel in a straight line or the shoulder hitches towards the ear, return to phase 2 exercises for an additional week.

Functional diagonals. Start with the arm at your side, hand on the opposite hip. Raise the arm diagonally to full extension overhead, thumb pointing back. Lower. 3 sets of 10 per arm. This movement reproduces everyday gestures (reaching for a seatbelt, putting an item on a high shelf) and integrates coordination between the shoulder, scapula, and trunk.

Weight-bearing proprioception. Plank position on the hands (or on the knees to reduce intensity). Hold for 20 seconds. Then, without moving the hips, lift one hand and touch the opposite shoulder. Alternate. 5 repetitions on each side. This exercise trains dynamic shoulder stability under load, a capacity essential for sporting activities and carrying tasks.

Common mistakes in shoulder rehabilitation

• Forcing range of motion. Aggressively stretching a painful shoulder worsens inflammation. Recovering range happens gradually, never through sharp pain.
• Neglecting the shoulder blade. Many programmes focus solely on the rotator cuff. Yet the position and movement of the scapula directly govern shoulder mechanics. Scapular work is essential.
• Using loads that are too heavy too soon. The rotator cuff tendons are small and thin. They cannot handle the same loads as the deltoid or pectorals. Start light and progress slowly.
• Performing behind-the-neck movements. Behind-the-neck pull-downs, behind-the-head military presses, and behind-the-back stretches with the arms raised overhead place the shoulder in a position of maximum impingement. Avoid them as long as pain persists.
• Giving up too early. Shoulder rehabilitation takes time. Tendinopathies rarely respond in less than 6 weeks. Capsulitis can last over a year. Perseverance is what separates those who recover from those who end up with chronic pain.

When is surgery justified?

The vast majority of shoulder pain resolves through rehabilitation alone. Surgery is considered in specific cases: a complete rotator cuff tendon rupture in an active individual, recurrent dislocations despite strengthening, or subacromial impingement resistant to 6 months of well-conducted rehabilitation. Even after a surgical procedure, rehabilitation remains the cornerstone of recovery. Surgery repairs the structure. Exercises restore the function.

Preventing recurrence over the long term

A healed shoulder is not an invincible one. To maintain the gains from rehabilitation and prevent pain from returning, a few habits are well worth adopting.

Maintain a rotator cuff and scapular stabiliser strengthening routine twice a week, even after symptoms have resolved. Watch your posture at the desk: shoulders back, screen at the right height, regular breaks. Warm up before any physical activity involving the arms. Avoid habitually sleeping on the sensitive shoulder.

If you play a sport with overhead movements (tennis, volleyball, swimming, CrossFit), include external rotation exercises in your warm-up and monitor your training volume. Overload remains the leading cause of relapse. The body needs to recover as much as it needs to work. Find that balance, and your shoulder will support you without protest in everything you take on.