Pain reaching behind your back — doing up a bra, getting a wallet from a back pocket — is a very common shoulder complaint, and one of the more common reasons people worry something is torn.
The short version
- Pain with this movement is often seen in rotator-cuff-related shoulder pain, but other shoulder problems can feel similar.
- Reaching behind places the shoulder near the end of its range, which can feel painful when the area is sensitive or irritated.
- Pain doesn't automatically mean a tendon is badly damaged — tendons generally respond well to being strengthened.
- Many people start to improve over 6 to 12 weeks, although full recovery can take longer.
Why it happens
Reaching behind your back asks a lot of your shoulder in one go. Your arm has to turn inwards and go backwards at the same time. This movement places the shoulder near the end of its range and can feel painful when the area is sensitive or irritated. If something in there is already irritated, this is often the first movement that tells you about it.
The usual culprit is the rotator cuff — a set of four muscles and their tendons that sit around the shoulder and hold the ball steady in the socket while your arm moves. NHS musculoskeletal services call this "rotator cuff related shoulder pain," and they describe exactly this pattern: pain that's worse reaching up overhead or putting your hand behind your back. It's most common between the ages of about 35 and 75.
Why does the cuff get irritated in the first place? Often it's simple: the shoulder was asked to do more than it was used to — a weekend of painting, a new gym programme, carrying something heavy and awkward. Sometimes it builds slowly with no obvious trigger at all. In many cases, the pain starts after the shoulder has done more than it is used to. Pain does not automatically mean that a tendon is badly damaged, and tendons generally respond well to being strengthened.
One other pattern worth knowing: if your shoulder is stiff in every direction — you can't reach behind you, but you also can't reach up or out to the side, and someone else moving your arm for you doesn't help — that's a different picture, and worth having looked at rather than working through on your own.
⚠️ When to see a doctor in person
Get medical help the same day if the shoulder is hot, swollen and red and you feel feverish or unwell, if you can't lift your arm at all after a fall or accident, or if the shoulder looks a strange shape after an injury.
- The arm is clearly weak rather than just sore
- Numbness or pins and needles down the arm
- A new lump or swelling, unexplained weight loss, or night sweats
- No improvement after around 12 weeks of sensible exercise
- Severe or worsening pain, or pain repeatedly disturbing sleep or daily activities
- New symptoms after a significant injury, even if the arm can still move
- A history of cancer, recent infection, or major immune suppression with unexplained, persistent pain
Starter exercises
These three are the set recommended in NHS shoulder self-management guides. They're low load, need almost nothing, and are meant to be done regularly rather than hard.
Hands on a wall, thumbs towards you, cloth under each hand. Push gently and slide hands up as far as comfortable, then back down. Rest a minute between rounds.
Hands a little wider than shoulders, elbows below shoulder height. Lower your chest towards the wall keeping your body straight, then push back.
Elbow resting on a rolled towel at shoulder height. Loose fist, rotate your forearm so your hand points upward, then return and relax.
On pain during these: a small increase in pain while exercising is fine, as long as it settles within about 30 minutes and isn't worse the next day. If it is worse the next day, do fewer reps and build back up.
Progression note
Give it time before you judge it. It may take 6 weeks before you notice a change, and 6 to 12 weeks to feel a real difference. Progress by adding a little weight or a few more reps, not by pushing into pain. It's also sensible to temporarily cut back on the things that flare it most — repeated overhead work and repeated reaching behind — while you build strength, rather than avoiding them forever. Get it assessed sooner if it is severe or getting worse; otherwise, seek advice if there is little or no improvement after 6 to 12 weeks.
The bottom line
Pain with this movement is often manageable with gradual exercise and does not automatically mean serious damage. Gradual strengthening is the first-line approach and it works for a good proportion of people, but it's a two-to-three-month job, not a two-week one. Get it checked if the arm is genuinely weak, numb, or the shoulder is hot and swollen.