Why am I suddenly getting tendonitis?

Sudden is rarely sudden: the tendon's lag and the twelve-week look-back

Why am I suddenly getting tendonitis is a question that contains its own misunderstanding in the word suddenly, and the honest page begins by correcting it, because the correction is also the diagnosis in most cases. Tendonitis, more accurately tendinopathy since the condition is a failed adaptation of the tendon's matrix rather than a simple inflammation, is almost never sudden in its cause even when it is sudden in its pain, and the reason is a mismatch in timescales between the two tissues that share every lift. Muscle adapts to a new load in weeks: strength rises within a fortnight through the nervous system and the fibres thicken within a month or two, so that a lifter who adds volume or a runner who adds miles feels stronger quickly and is encouraged. Tendon adapts to the same load over months: its cells are sparse, its blood supply is poor, its collagen turns over slowly and its stiffness and cross-sectional area change on a timescale of many months to years, so that the tendon is still carrying last season's capacity while the muscle pulling on it has already moved to this season's. The gap between the two is the window in which tendinopathy develops, and it opens six to twelve weeks after the load change, which is why the pain feels sudden and unprovoked: the thing that provoked it happened in a different month. The look-back is therefore the first tool, and it is a list of questions about the three months before the pain began. Did a new programme, a new coach or a new sport start? Did weekly volume jump, in sets, in miles or in hours, by more than the gentle increases a tendon tolerates? Did a new exercise or a new range arrive, deeper squats, a new grip, a hill route, a jumping drill? Did a job change bring new hands, new stairs, a new keyboard or a new tool? Did new shoes, a new bike fit or a new racket arrive? Did body weight rise, so that every step and every bodyweight movement loads the tendon more? Did training resume after a lay-off, an illness or a holiday at the old numbers, with the muscle remembering them and the tendon having lost them? One of these is found in most cases, and finding it does two things: it explains the pain, and it tells the reader that the fix is a load problem, treated by reducing the provoking load, rebuilding tendon capacity through progressive heavy slow loading with isometric holds for pain, and reintroducing the change at a rate the tendon can follow, which is months rather than weeks. Age sharpens the whole picture, because tendon's adaptation slows further from the forties and the window opens wider, so a change that a twenty-five-year-old's tendon absorbed is the one a forty-five-year-old's reports.

When the look-back finds nothing: the one-site rule, the systemic list, and the honest capsule

When the look-back finds nothing, or when the tendonitis has arrived in two places at once, the honest page applies a rule that every clinician uses and few shelf pages mention, the one-site rule. Tendon pain at a single site, the patellar tendon or the Achilles or one elbow, following a load change, is a load problem and is treated as one. Tendon pain at two or more sites at the same time, both Achilles tendons, an elbow and a shoulder, several fingers, or tendon pain at one site with no load change anywhere in the look-back, or tendon pain arriving at an unusual age or with other symptoms, points at a systemic driver, something in the body rather than in the training, and is a doctor's assessment before it is anyone's programme. The systemic list is specific and worth reading slowly, because several items are things a reader has recently started. A fluoroquinolone antibiotic course in the preceding weeks to months carries a documented tendon warning, most often at the Achilles and with risk higher in older adults and alongside corticosteroids, and a tendon that becomes painful after such a course is a reason to tell the prescriber. A statin started in the last months is associated with tendon symptoms in some people, as it is with muscle symptoms, and is a conversation with the prescriber rather than a reason to stop it alone. The menopause transition changes tendon, as it changes other collagen tissues, and tendinopathy arriving in several sites in the late forties and fifties is common enough that it is a recognised pattern. Raised blood sugar, including undiagnosed diabetes, stiffens and weakens tendon through glycation and is associated with tendinopathy at multiple sites; raised cholesterol is similarly associated. Inflammatory arthritis and gout both inflame the tendon sheaths and attachments and present as tendon pain, often with swelling, warmth, morning stiffness lasting an hour or more, and pain at rest or at night, which are not load patterns and are the signs that most clearly separate a systemic cause from a training one. None of this is a reason for alarm and all of it is a reason for a doctor rather than a physiotherapist as the first call when the one-site rule points that way, because the systemic drivers are mostly treatable and the tendon pain settles when they are. Collagen appears in neither answer, and the honest page says why: a collagen shortfall is not a cause of tendonitis in a fed adult, since the tendon's cells make collagen from an amino acid pool that any ordinary diet fills, and the one collagen trial in tendinopathy, 2.5g a day beside six months of calf strengthening in the Achilles, is an adjunct beside the loading that treats the load problem and has nothing to say about the systemic list. The worked example is stated on its true terms: two capsules, 1200mg hydrolysed type 1 marine collagen with 12mg vitamin C at 15% of its reference value plus zinc, 120 for £16.99 at 28p a day, lab tested and UK made, below the 2.5 to 15g research band, carrying vitamin C's collagen formation sentence for cartilage and bones and no tendon claim. Why am I suddenly getting tendonitis: because of something you changed three months ago, or, if you changed nothing and it is in two places, because of something a doctor should look for.

What to check on the label