Pain in the Infraspinatus Muscle: What Causes It and How to Fix It

Pain in the infraspinatus muscle is one of those shoulder complaints that is surprisingly common yet frequently misunderstood — and all too often misdiagnosed. It can feel like a deep, nagging ache at the back of the shoulder, or a sharp twinge that travels down the arm in ways that seem unrelated to the shoulder at all. Understanding exactly what this muscle does, what causes it to hurt, and how to address that pain effectively makes a meaningful difference to recovery time and quality of life.

What Is the Infraspinatus Muscle and What Does It Do?

Before exploring what causes problems, it helps to understand what this muscle actually is. The infraspinatus is a broad, triangular muscle that occupies most of the infraspinous fossa — the shallow depression on the posterior surface of the scapula (shoulder blade). It is one of the four muscles that make up the rotator cuff, alongside the supraspinatus, subscapularis, and teres minor.

Its primary function is external rotation of the shoulder — turning the arm outward away from the body. It also assists in stabilising the glenohumeral joint, which is the ball-and-socket joint at the top of the arm. Every time you reach behind your back, throw a ball, or lift your arm overhead, the infraspinatus is working.

Because of this, it is exposed to considerable repetitive strain. Desk workers who maintain poor posture, overhead athletes, painters, swimmers, and anyone who performs repetitive arm movements at work are all at elevated risk of developing infraspinatus problems over time.

What Causes Pain in the Infraspinatus Muscle?

This is the question that dominates UK search behaviour around this topic — and for good reason. The infraspinatus can become painful through several distinct mechanisms, and identifying the correct cause is essential for effective treatment.

1. Myofascial Trigger Points

By far the most frequent cause of infraspinatus pain is the development of myofascial trigger points — hyperirritable spots within the muscle fibres that produce both local tenderness and a characteristic pattern of referred pain. The infraspinatus is one of the most clinically significant trigger point muscles in the entire body, largely because its referral pattern is so misleading.

When trigger points develop in the infraspinatus, they typically refer pain to the front and outer aspect of the shoulder, down the upper arm, and sometimes into the forearm and the radial side of the hand (the thumb side). This pattern frequently mimics a rotator cuff tear or even a cervical disc problem, leading to misdiagnosis and unnecessarily prolonged suffering.

2. Rotator Cuff Tears

The infraspinatus tendon is one of the most commonly torn tendons in the rotator cuff, second only to the supraspinatus. Tears can be partial — involving only a portion of the tendon — or full-thickness, in which the tendon is completely severed. Partial tears often present with a dull, persistent ache that worsens with overhead activities and external rotation. Full tears typically cause significant weakness alongside the pain, and the arm may feel unable to rotate outward against even light resistance.

Age is a significant risk factor: rotator cuff degeneration becomes increasingly common after the age of 40, and many full-thickness tears in older adults are degenerative rather than traumatic in origin.

3. Overuse and Repetitive Strain

Sustained, repetitive use of the shoulder — particularly in overhead positions — places cumulative load on the infraspinatus. This is particularly relevant for swimmers (especially those who use freestyle and butterfly strokes), tennis and racquet sport players, manual workers, and anyone who spends extended periods with their arms elevated. Over time, this repetitive strain leads to micro-damage within the muscle and tendon that, without adequate recovery, progresses to chronic pain and inflammation.

4. Poor Posture and Muscle Imbalance

Rounded shoulders — now endemic in a culture of desk work and smartphone use — alter the biomechanics of the entire shoulder girdle. When the shoulders roll forward, the infraspinatus is placed in a chronically lengthened and weakened position, making it far more susceptible to strain and trigger point development. Strengthening the external rotators relative to the internal rotators is one of the most effective preventive strategies available. Our guide to posture correction exercises explores this in detail.

5. Suprascapular Nerve Entrapment

Less common but important to recognise, compression of the suprascapular nerve — which innervates both the supraspinatus and infraspinatus — can produce pain and progressive weakness in the infraspinatus region. This may occur at the suprascapular notch or, in the case of infraspinatus-specific involvement, at the spinoglenoid notch. Nerve entrapment tends to cause more pronounced atrophy (wasting) of the muscle over time and typically requires specialist investigation.

Recognising the Symptoms: Is It Really Your Infraspinatus?

One of the telling features of infraspinatus involvement is that the pain often feels like it originates in the front of the shoulder or down the arm — not in the back where the muscle actually sits. This referred pain pattern is what makes self-diagnosis so difficult and professional assessment so valuable.

Treatment Options for Infraspinatus Muscle Pain

The good news is that the majority of infraspinatus pain — particularly that which is trigger point or overuse related — responds well to conservative treatment. Here is how a structured approach typically looks, from initial management through to rehabilitation.

Rest and Activity Modification

In the acute phase, reducing or temporarily avoiding the movements and activities that aggravate the pain gives the tissue an opportunity to settle. This doesn’t mean complete immobilisation — gentle, pain-free movement is encouraged to maintain circulation and prevent stiffening — but high-load or overhead activities should be paused.

Physiotherapy and Manual Therapy

A qualified physiotherapist will assess the shoulder through a combination of orthopaedic tests, range-of-motion assessments, and muscle strength testing to identify the specific source of pain. Treatment typically includes trigger point release (either through manual pressure or dry needling), joint mobilisation, and a progressive strengthening programme focused on the rotator cuff and scapular stabilisers.

Research published in the Journal of Orthopaedic & Sports Physical Therapy consistently supports physiotherapy-led rotator cuff rehabilitation as the first-line treatment for non-traumatic infraspinatus pain, with outcomes comparable to surgical intervention for most partial tears and trigger point conditions.

Targeted Stretching

The cross-body stretch (drawing the affected arm across the chest) and the sleeper stretch (lying on the affected shoulder and gently pressing the forearm towards the floor) are two of the most evidence-backed stretches for infraspinatus mobility. Both should be performed gently and held for 30 seconds, repeated 3 times daily. Avoid aggressive stretching during the acute inflammatory phase.

Heat, Cold, and Supportive Self-Care

In the early days of acute pain, an ice pack applied for 15 minutes can help manage inflammation. Once the acute phase has passed (typically after 48–72 hours), heat becomes more beneficial — a warm bath, heat pad, or muscle soak can significantly reduce muscle tension and improve tissue pliability before stretching. For more on this approach, our article on muscle recovery and pain relief strategies covers the evidence in detail.

When Surgery Is Considered

Full-thickness rotator cuff tears — particularly in younger, active patients — may require surgical repair, typically performed arthroscopically. However, even in these cases, a period of physiotherapy is usually attempted first, and many people with full-thickness tears live without significant symptoms for years with appropriate strengthening and postural correction.

The Bottom Line on Infraspinatus Muscle Pain

Pain in the infraspinatus muscle is more common than most people realise — and more treatable than the sometimes alarming symptoms might suggest. Whether the cause is trigger points, overuse, or an early-stage rotator cuff problem, the vast majority of cases respond positively to a structured, evidence-based approach: activity modification, targeted physiotherapy, progressive strengthening, and sensible self-care in the interim.

The key is not to dismiss the pain as something that will simply pass, nor to catastrophise it as something irreparable. Understanding what’s happening in your body — and why — puts you in a far stronger position to make the right decisions about your recovery. And if in any doubt, a single session with a qualified physiotherapist is one of the most valuable investments you can make in your shoulder health.

For a broader look at natural pain management and muscle health strategies, explore our natural pain relief guide — a practical, science-backed resource for anyone navigating musculoskeletal discomfort.