Infraspinatus Pain: Where It Sits, How It Feels, What Helps

Infraspinatus pain is an ache from a muscle most people have never heard of, even though they use it every time they reach behind themselves. The infraspinatus is one of the four rotator cuff muscles, the set of small muscles that hold the ball of the arm bone in its shallow socket and steer how it turns. This one covers most of the back of the shoulder blade, below the bony ridge you can feel across the top. Its tendon fastens onto the back of the ball of the arm bone. Its main job is turning the arm outward, and it helps keep the ball centred while the arm lifts. Its neighbour above the ridge, the supraspinatus, has a different job and a different pain pattern, covered in our guide to supraspinatus muscle pain.

How infraspinatus pain usually feels

Most people describe a deep, dull ache over the back of the shoulder blade, or behind and to the outside of the shoulder. It is tender when pressed. The odd thing about this muscle is where else it can be felt. A sore infraspinatus often sends pain to the front of the shoulder, deep in the joint, and down the outer arm, sometimes as far as the hand. This is referred pain: pain felt some distance from its source.

The ache builds with reaching behind: a back pocket, a seat belt, the rear seat of the car. Lying on that side presses on it. Lying on the other side lets the arm drop forward and pulls on it for hours, so many people with infraspinatus muscle pain cannot settle on either side at night. Turning the arm outward against a load, like a backhand with a racket, can feel weak as well as sore. Usually that is the muscle holding back from the ache rather than true weakness.

The everyday triggers behind a sore back of the shoulder

It is rarely one dramatic moment. More often it is a change in dose: the same movement repeated more than usual, or a position held far longer than the muscle expects.

The desk is the one I hear about most. With the mouse arm held forward and turned slightly in, the infraspinatus sits lengthened and quietly working for hours. Sleep is the second. A side sleeper spends a third of the night either pressing on this muscle or hanging the arm forward off it. Overhead work does it too: a weekend painting a ceiling asks the cuff to steady the arm in the air far longer than it is used to. And any sudden season of throwing, swimming, or racket sport loads the outward turn hard after months of not asking for it.

Our Feldypedia entry on frozen shoulder explains how a shoulder that guards for months can begin to stiffen, which is a different story from a muscle that is simply overworked.

Why the shoulder blade and ribs matter so much here

In lessons I notice the same thing over and over. The infraspinatus is anchored to the shoulder blade, and the blade is meant to glide across the back of the ribs. When you reach behind you, a good share of that movement belongs to the blade sliding toward the spine and the ribs turning a little. If the blade is parked and the ribcage held still, the whole turn falls to the small muscles at the back of the shoulder.

A Feldenkrais® lesson approaches this from the other end. Rather than stretching or pressing the sore spot, it invites the parts around it to take up their share. In one Awareness Through Movement® lesson you lie on your side with the top arm resting forward. You turn the hand slowly, palm up and palm down, and follow how far the turning travels: forearm, elbow, upper arm, and at last the ball of the arm bone rolling in its socket. Then the chest and ribs join the turn. When they do, the infraspinatus is no longer working against a fixed background, and many people notice the back of the shoulder feels quieter by the end of the lesson.

What tends to help infraspinatus pain

Ease the dose for two or three weeks. Put the things you reach for in front of you rather than behind. Bring the mouse in close so the upper arm can hang by your side. If you sleep on the other side, hug a pillow so the sore arm rests on it instead of dropping forward. None of this loads the sore muscle, and none of it asks you to stretch it.

Small turns, inside comfort. Sit with the elbow bent and resting at your side. Turn the forearm outward a little way, then back, as if opening and closing a small door. Stay well inside the easy range and repeat a dozen times, several times a day. Is the tenth turn smoother than the first?

Let the ribs turn with you. Next time you reach into the rear seat, let the chest and ribs turn toward the thing first, and let the arm follow. The reach becomes shorter for the shoulder.

For a guided version, our frozen shoulder stretches lesson works in this supported, unhurried way, frozen or not. Our gentle exercises for rotator cuff pain add hanging and swinging movements that ask almost nothing of the cuff. Feldy offers the Feldenkrais Method® as short daily audio lessons, mostly lying down.

Clinical care has its own place beside all this. A physiotherapist can measure the strength of the outward turn, check the tendon, and set graded loading once the ache has settled. Yoga and Pilates use a different mechanism altogether: held shapes and counted repetitions that build range and strength.

Sore muscle, rotator cuff tear, or nerve: telling them apart

Several quite different things can ache at the back of the shoulder. This page cannot tell you which one you have, but the patterns differ, and knowing them helps when you describe things to a clinician.

A sore infraspinatus aches with use and with lying on it, is tender over the back of the blade, and the arm still works. If a friend gently lifts the arm for you, it usually goes further than when you lift it yourself, because what stops you is the ache and not the joint.

A rotator cuff tear more often announces itself. The arm goes suddenly weak after a fall, a wrench, or a heavy pull, and turning it outward or lifting it becomes hard. Tears can also develop slowly and quietly, and some cause no pain at all, so a tear on a scan is not always the source of the ache. Real weakness, not just holding back from pain, is the sign to have checked.

Nerve pain is sharper, burning, or electric. It runs in a line down the arm to particular fingers, brings pins and needles or numbness, and shifts with the position of your neck more than with what the arm is doing. Usually the nerve is being irritated in the neck, and our guide to a pinched nerve in the shoulder explains that pattern. One nerve, the suprascapular nerve, supplies the infraspinatus itself. When it is squeezed, the muscle can thin without much pain, leaving a slight hollow at the back of the blade.

A frozen shoulder is different again. Frozen shoulder is the everyday name for adhesive capsulitis, where the capsule around the joint itself thickens and tightens. StatPearls puts it at up to 5 in every 100 people and lists the outward turn of the arm as the direction that tightens before any other (StatPearls, 2023). Because the infraspinatus is the outward turner, an early frozen shoulder can pass for a sore muscle. The difference is that a frozen shoulder stops at the same point even when someone else lifts the arm for you.

Clear signs to get the back of the shoulder assessed

Some things should be looked at before you try anything here. The arm went weak suddenly, especially when lifting or turning it outward. The pain began with a fall, a wrench, or a heavy pull. There is numbness, pins and needles, or a hand that has become clumsy. The shoulder is steadily losing its outward turn. A hollow has appeared over the back of the blade. Pain grows through the night and leaves you no position to settle in. Arm pain that arrives with pressure in the chest, breathlessness, or sweating is an emergency.

Beyond those, infraspinatus pain that has not shifted after three or four weeks of lighter use deserves a proper look. A clinician can tell a sore muscle from a tear, a nerve, or a tightening joint quite quickly.

Find where to start

If one shoulder has grumbled for weeks while the other has stayed quiet, that difference deserves some curiosity, and it usually lives in how the blade and ribs move rather than in the muscle alone. The Feldy program for a sore or stiff shoulder is built around learning to feel that difference.

Curious which approach might suit a sore shoulder blade? Try the 60-second Movement Match quiz, it asks three quick things and names one method worth trying first.

Common Questions about infraspinatus pain (FAQ)

Is gentle movement a sensible idea with infraspinatus pain, and who should hold back?

For the everyday sore muscle pattern, yes. Small turns of the arm inside a comfortable range ask very little of the muscle and tend to quiet the guarding around it. Hold back and get assessed first if the arm went weak suddenly, if the pain began with a fall or a hard pull, if there is numbness or tingling in the arm, or if the shoulder has been steadily losing its outward turn.

What tends to keep infraspinatus muscle pain going?

Repeating the one movement that spikes it, many times a day, without noticing. The usual suspects are reaching into the rear seat, sleeping on the sore side, and hours with the mouse arm held forward and turned slightly in. Hard stretching of the tender spot, and pressing on it with a ball for long spells, tend to stir it up rather than settle it. Ease the dose of those for two or three weeks before judging.

How can I tell infraspinatus pain from a rotator cuff tear?

You cannot be certain at home, but the pattern gives clues. A sore muscle aches with use and with lying on it, is tender when you press the back of the blade, and the arm still works. A tear more often follows a fall or a heavy pull, brings sudden weakness when you turn the arm outward or lift it, and sometimes a pop at the moment it happened. Tears can also develop slowly and quietly, so weakness that creeps in over months deserves a look too.

Is pain behind the shoulder blade coming from a nerve or from the muscle?

Muscle pain tends to be a dull, deep ache that changes with how you use or lie on the arm. Nerve pain is more often sharp, burning, or electric, travels in a line down the arm to particular fingers, and may bring pins and needles or numbness. It often shifts when you move your neck rather than your arm. If yours sounds like the second picture, the neck is the more likely source and a clinician can check it.

How often is it worth trying the small experiments on this page?

Whenever the chance comes up, and it comes up many times a day. Reaching for a seat belt, a back pocket, or a top shelf each gives you a chance to notice whether the shoulder blade and ribs are taking part. None of them needs a mat or a set number. One short lying down lesson a day, of the kind Feldy offers, is enough for the noticing side of things.

How many weeks does infraspinatus pain usually take to quieten?

A muscle that has been overworked often feels noticeably better within one to three weeks once the provoking movements ease and it is moved gently and often. A tendon that has been irritated for months is slower, and improvement is usually counted in months rather than days. If three or four weeks of lighter use have changed nothing at all, book a review rather than waiting longer.

What is the best infraspinatus pain relief for someone who works at a desk all day?

Change the position the muscle is held in, rather than adding a stretch in the evening. Bring the mouse close so the upper arm can hang by your side, let the elbow rest, and let the palm sit flat instead of turned inward. Stand and let the arm swing for a minute every half hour. At night, if you lie on the other side, hug a pillow so the sore arm does not drop forward and pull on the muscle for hours.

How is this different from rotator cuff strengthening with a band?

Band work loads the outward turn on purpose, in sets, to build the tendon's capacity over weeks. That has good evidence for a tendon that has been irritated for months, and it is best begun once the sharp ache has settled. The experiments here do a different job. They lower how much of each reach lands on the infraspinatus by getting the blade and ribs to share it. One adds capacity, the other takes away demand, and the two fit together well.

Which signs mean the back of the shoulder should be looked at promptly?

Sudden weakness lifting the arm or turning it outward, especially after a fall, a wrench, or a heavy pull. Numbness, pins and needles, or a hand that feels clumsy. A shoulder that has grown steadily stiffer, so that turning the arm out is harder each week. A hollow appearing over the back of the blade. Arm pain that comes with chest pressure, breathlessness, or sweating needs emergency care. Otherwise, a few weeks of easing off with no change at all is the cue to book an assessment.