Tendinitis (tendinopathy)

A tendon is the tough cord that ties a muscle to a bone. Every bit of force the muscle produces travels through it, which is why tendons hurt in people who run a lot, lift a lot or work long hours with their hands — and in people who suddenly go back to activity after a long break. The word "tendinitis" implies inflammation, and for decades the treatment followed from that: rest, ice, anti-inflammatories. We now know that something rather different is usually going on, and that it responds to the very thing people used to be told to avoid.

Why "-itis" is not quite the right word

When a tendon spends months under a load it has not had time to adapt to, the tissue reorganises: collagen fibres lose their tidy parallel arrangement, more water and more small blood vessels appear between them, the tendon thickens and copes less well with stretch. In long-standing cases there is almost none of the classic inflammation with inflammatory cells pouring in. That is why doctors increasingly say tendinopathy — an overload remodelling of the tendon.

The difference is not in the label but in what follows from it. Calming inflammation with rest makes sense. Remodelled tissue is not rebuilt by rest: a tendon responds only to load, and without load it carries on getting weaker. Everything below follows from that.

The usual sites are the Achilles tendon, the patellar tendon, the rotator cuff tendons of the shoulder, the tendons at the outer and inner bony points of the elbow, the thumb tendons at the wrist and the gluteal tendons on the outside of the hip. If the pain sits strictly on the outside of the elbow and appears when you grip something, that is lateral epicondylitis, or tennis elbow, which has its own page — though everything said here about loading and timescales applies to it too.

How a painful tendon behaves

Tendon pain is recognised by its timing rather than its severity.

• It hurts at the start of activity and eases after a few minutes of movement — the tendon "warms up".
• The real reckoning comes later: a few hours afterwards, or the next morning. That reaction is what tells you whether the load was manageable or too much.
• In the morning the tendon is stiff, the first steps or first movements are awkward, and it loosens off over ten or fifteen minutes.
• Tenderness is pinpoint: your finger lands on exactly one spot on the tendon or where it attaches to bone.
• The tendon may feel thicker than on the healthy side, and moving it sometimes produces a faint creaking, which means the sheath around it is irritated.

Joint pain behaves differently: it is diffuse, it gets worse on moving the joint in any direction, and the whole joint often swells. Tendon pain is tied to one particular action — pushing off, lifting, gripping.

Signs that mean seeing a doctor today

Overload pain builds over weeks. Anything that happens in an instant is a different story.

Sudden severe pain, a feeling of being struck on the back of the leg, or a snap or pop during a movement raises the suspicion of a ruptured tendon. It is especially telling if, straight afterwards:

• you cannot stand on tiptoe on that leg or push off when walking — that is how an Achilles rupture behaves;
• the arm stops lifting out to the side or overhead after a jerk or a fall;
• a bulge of muscle appears in the arm that was not there before;
• a finger or hand loses one particular movement suddenly and completely.

Achilles rupture is often missed in the first few days: the person can still walk with a limp and assumes they have pulled something. The earlier it is diagnosed, the wider the choice of treatment, so that story needs to be seen the same day.

Separately: if the area over a tendon is red, hot and swollen and a temperature comes with it, that may be infection and needs urgent assessment. If you cannot put weight on the leg, if swelling is growing fast, or if numbness appears, call an ambulance (in Spain, Italy, Portugal, Poland and Ukraine the single European number 112 is in use).

Medicines that damage tendons

Fluoroquinolone antibiotics — ciprofloxacin, levofloxacin, ofloxacin, moxifloxacin — raise the risk of tendon inflammation and rupture, most often of the Achilles. This is a rare but well-documented complication. It can begin in the first days of the course or show up several weeks after it has finished, sometimes on both sides at once. The risk is higher in older people, in those also taking corticosteroids, and in transplant recipients.

The practical point is straightforward: if a tendon starts to hurt during, or soon after, one of these antibiotics, stop loading that leg or arm and contact a doctor. Do not "wait and see": it is loading an altered tendon that leads to rupture. The doctor will decide whether to switch the antibiotic. Stopping it on your own, without agreeing how the infection will be treated instead, is not a good idea.

Corticosteroids taken by mouth long term, and repeated steroid injections into a tendon itself, act in the same direction. Less often, tendon pain is caused by drugs that lower oestrogen levels and, on some evidence, by statins. If the pain started soon after a new medicine, mention it: the timing is a useful clue.

When it is not overload

There is a pattern in which the thing to look for is not a training error but a disease.

• Several tendons hurt at once in different places — both heels, a shoulder and a knee — particularly in someone young who is not doing heavy training.
• Heel pain comes together with morning back pain and stiffness that lasts more than half an hour and eases with movement rather than rest. That combination is typical of the spondyloarthritides, and it is very often written off as "heel spurs" and "wear and tear".
• There is also psoriasis, inflammatory bowel disease, repeated inflammation inside the eye, or close relatives with similar back and joint problems.
• Swelling and pain arrived as an attack, over a day, with marked redness: gout can behave like that, and it does not affect only joints.

One more rare but valuable finding: firm, painless thickening of both Achilles tendons in a young person can be cholesterol deposits from familial hypercholesterolaemia. That is a reason to check a lipid profile rather than book a massage, and a reason to test relatives too.

In all of these, blood tests and an examination are more use than another set of exercises.

The treatment is load, not rest

The central idea of the modern approach is that a tendon is treated with gradually increasing load. Complete rest for weeks makes things worse: the muscle weakens, the tendon loses its capacity to hold force, and the pain returns as soon as normal life resumes.

What that looks like in practice:

• Remove the peaks, not the movement. Jumping, downhill running, sprints and holding heavy tools at arm's length go for the time being — whatever produces pain the next day. Walking, cycling, swimming and strength work for other muscle groups stay.
• Start with isometrics. Holding a static muscle contraction without movement for several tens of seconds is tolerated even when pain is bad, and often quietens it for a few hours.
• Move on to slow strength work. The backbone of the programme is slow-tempo exercise with emphasis on the lowering, eccentric phase: for the Achilles, for instance, lowering slowly from a raised heel. Slow means a count of three or four, not "one-two".
• Add weight steadily. The load has to increase: without progression the tissue does not remodel.
• Use the next-morning rule. Moderate pain during the exercise is acceptable, but if the next morning is clearly worse than the day before, the load comes down next time.

The programme is best built with a physiotherapist or a rehabilitation doctor: every tendon has its own mechanics, and exercises picked up online often turn out to be the wrong ones.

How long it takes, and why people stop halfway

This is worth knowing in advance: improvement is measured in weeks and months. The first shift is usually somewhere between the sixth and twelfth week, and full recovery often takes six months to a year. Expecting a result in a fortnight is the surest way to decide that "it isn't working".

The commonest reason for failure is stopping halfway. People drop the exercises as soon as the pain goes, but pain settles long before the tendon has finished rebuilding, and a month or two later it is all back. So the programme carries on for a while after the symptoms have gone, and only then is it gradually wound down.

To avoid judging progress by how one particular day felt, it helps to test yourself the same way every two or three weeks: how many heel raises you manage before it hurts, how long you can carry the shopping, how the tendon feels the morning after an ordinary day. That marker shows the slow forward movement in a stretch of time when, day to day, nothing seems to change. Going back to sport is staged in the same way — volume first, then speed and jumping, rather than everything at once on the first free weekend.

Injections, machines and surgery

Steroid injections, honestly. An injection of corticosteroid next to a tendon really does take the pain away quickly, sometimes within a couple of days, and for some weeks. But compared with an exercise programme, at six to twelve months the people who were injected do worse: more recurrences, and the tendon is no better. On top of that, injections should not be repeated into the same tendon: they weaken the tissue and increase the risk of rupture. It is particularly risky to be injected and go straight back to full load, because pain is the only signal a tendon has, and it has just been switched off.

Painkillers and anti-inflammatories, by mouth or as a gel, make sense as a short course so that you can exercise and sleep. They do not treat the problem and do not replace the exercises.

Shockwave therapy helps in some stubborn tendinopathies, but alongside exercise rather than instead of it. Platelet-rich plasma injections are widely offered and, so far, without convincing evidence of benefit. Surgery is considered rarely, usually after a properly built loading programme has been followed honestly for many months without success.

One further note about scans. Ultrasound and MRI show altered tendons in a great many people who feel nothing at all, and the reverse also happens. Decisions are therefore made on the history and examination, and imaging is mainly needed where a rupture or another disease is suspected.

Online consultation

A remote appointment is useful in three situations. First, working out what this actually is: the doctor will ask how the pain relates to activity, what you did the day before and how it behaves in the morning, and will separate an overload tendinopathy from a rupture, an infection or an inflammatory disease that needs blood tests. Second, building and running the loading programme: which exercises, at what weight and tempo, how to tell that you have overdone it, when to progress and when to return to sport or to your usual work. This is exactly the stage at which people give up, and brief regular contact with a doctor helps more here than any procedure. Third, going through the offers you are unsure about: whether an injection is worth it, what to expect from shockwave therapy, whether a scan is needed. A separate reason to get in touch without delay is tendon pain while taking a fluoroquinolone antibiotic.

This material is for information only and does not replace medical advice.