Musculoskeletal · Patient education from the Pegasus Peak physiotherapy team.
Reviewed by the Pegasus Peak physiotherapy team — AHPRA-registered physiotherapists led by principal physiotherapist Kosta Logothetis. Last reviewed 2025-10-21.
Learn what the infraspinatus muscle does, why it’s prone to tendinopathy, and how evidence-based physio exercises help restore strength and shoulder function.
Anatomy and function of the infraspinatus, a key rotator cuff stabiliser of the shoulder.
When it comes to shoulder pain, few structures get as much attention in physio clinics as the infraspinatus muscle. This powerful yet often-overlooked rotator cuff muscle plays a critical role in shoulder stability and movement. But when it’s irritated or injured, it can make even simple activities, like reaching for your seatbelt surprisingly painful.
In this post, we’ll break down what the infraspinatus does, why it’s so prone to problems, and how evidence-based exercise and physio management can help you get it back in top shape.
The infraspinatus sits just below the bony ridge (spine) of the shoulder blade, nestled in the infraspinous fossa of the scapula. From there, it travels laterally to attach onto the posterior aspect of the humerus, specifically the greater tubercle.
Anatomically, it’s one of the four rotator cuff muscles, alongside the supraspinatus, subscapularis, and teres minor. Collectively, these muscles aren’t just “movers”; they’re the main stabilisers of the shoulder joint. Their job is to keep the head of the humerus tightly centered in the glenoid fossa during motion. Without them, shoulder movements would be sloppy and unstable.
While its primary action is external rotation of the shoulder (rotating the arm outward), the infraspinatus also contributes to dynamic joint stability. It’s active during abduction (raising the arm to the side), assisting the supraspinatus to prevent humeral head translation.
In short, whenever your shoulder rotates, lifts, or stabilizes under load—whether throwing a ball or holding a plank, the infraspinatus is quietly doing its job.
Given its central role, it’s no surprise that the infraspinatus tendon often falls victim to overuse. In physio practice, rotator cuff tendinopathy is among the most common causes of shoulder pain, particularly in people with physically demanding jobs or repetitive overhead activity.
When the infraspinatus tendon is overloaded, small microtears can occur, leading to a condition known as tendinopathy. The tendon becomes inflamed, degenerated, and hypersensitive. Because tendons have limited blood supply, healing is slow without targeted exercise intervention. According toFenwick et al., 2002, this poor vascularity is one of the key reasons tendons don’t repair effectively on their own.
Symptoms often include:
Tendinopathy can also coexist with subacromial bursitis, where inflammation spreads to the adjacent bursa, compounding the irritation.
Sometimes, a sudden overload, like lifting something awkwardly or catching a fall, can cause an acute strain in the muscle itself. This involves tearing of muscle fibers rather than the tendon.The good news? Muscles are well-vascularized, so they heal faster than tendons. Most mild to moderate strains recover in a few weeks with appropriate loading and gradual return to activity.
So, how do you fix an infraspinatus injury? The cornerstone of modern physio management is graded, progressive loading, particularly for tendinopathy.
In the early stages, it’s crucial to restore any lost shoulder movement. Gentle mobility drills or stick-assisted range exercises can help. As Page (2012) notes, frequent, low-intensity stretching is more effective for improving flexibility and tissue tolerance than occasional intense stretching.
Try this:
Once mobility improves, begin strengthening. The key is finding the optimal load, a resistance that causes fatigue at around 12–15 reps without sharp pain. If it hurts excessively, the load is too high; if there’s no challenge, it’s too low.
According toHa et al. (2013), the sidelying external rotation (wiper exercise) produces the greatest activation of the infraspinatus compared to other movements. It’s a fantastic way to specifically target the muscle while minimizing compensation from larger movers like the deltoid.
As strength returns, slowly increase resistance or the number of repetitions. Progression should be gradual, tendons adapt over weeks to months, not days. Consistency trumps intensity here. Stopping and starting too often, or pushing through significant pain, usually sets recovery back.
If the issue is more muscular, gentle loading can start earlier. Focus on controlled external rotation strengthening in the 8–12 rep range to rebuild capacity. Combine this with general shoulder stability work once symptoms settle.
Healing times vary depending on the severity and chronicity of the injury:
Rest alone rarely solves the issue. The right exercise dosage, helps stimulate collagen repair, restore load tolerance, and reduce sensitivity.
To keep your infraspinatus and other rotator cuff muscles healthy:
The infraspinatus muscle might be small, but it plays an outsized role in shoulder function and stability. Whether you’re an athlete, tradesperson, or office worker, keeping it strong and resilient is key to staying pain-free.
If you’re dealing with persistent shoulder discomfort, physio-guided rehab, not just rest, is your best bet. By combining evidence-based exercises, progressive loading, and patience, most people make a full recovery and return to their usual activities stronger than before.
References:
Fenwick, S. A., Hazleman, B. L., & Riley, G. P. (2002). The vasculature and its role in the damaged and healing tendon.Arthritis research,4(4), 252–260.https://doi.org/10.1186/ar416
Ha, S. M., Kwon, O. Y., Cynn, H. S., Lee, W. H., Kim, S. J., & Park, K. N. (2013). Selective activation of the infraspinatus muscle.Journal of athletic training,48(3), 346–352.https://doi.org/10.4085/1062-6050-48.2.18
Page P. (2012). Current concepts in muscle stretching for exercise and rehabilitation.International journal of sports physical therapy,7(1), 109–119.
Questions about the infraspinatus muscle – what it does and common problems? Our physiotherapists in Horningsea Park and Gregory Hills can assess and treat you — no referral needed.
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