Why pain comes back after physio, and how graded loading helps

Six weeks of physio and the knee finally settled. Then came a Saturday on your knees in the vegetable bed, weeding until the light went, and by Sunday night the ache was back.

It is tempting to call that a relapse, or to decide the treatment was a waste of money. Usually it wasn’t. The first round calmed the symptoms. What it didn’t change, because six weeks is rarely long enough, was how much everyday load the knee could handle. Physiotherapists work on that gap with graded loading, a planned and gradual increase in the work a joint or tendon is asked to do.

About a third of people who get over an episode of low back pain have another within a year. That figure comes from a 2017 review by da Silva and colleagues ^[1], and there is little reason to think knees and shoulders do much better.

Ask what changed between discharge and the flare-up. The answer is often dull. Rest or hands-on treatment settled the pain, while the strength and endurance around the area stayed roughly where they were. The home exercises stopped the same week the pain did (almost everyone does this). Then something asked more of the area than it was ready for. Moving house will do it. So will the first fortnight of a new running program.

Sleep plays a bigger part than most people expect. A run of bad nights can make the same knee more sensitive to the same load.

Then there’s the worry that a flare-up means fresh damage. It usually doesn’t. When the International Association for the Study of Pain rewrote its definition in 2020, it said plainly that pain can occur without actual tissue damage ^[2]. A sore knee after a day in the garden is more often a sensitive joint meeting a load it hasn’t seen for a while.

Start with whatever the painful area tolerates now, not what it managed five years ago. Then add to it in planned steps over weeks. Load can mean weight, repetitions, distance or simply time on your feet.

Your physio will usually choose a starting point that causes little or no lasting rise in pain. From there, progress follows a rule: perhaps one extra set or a little more weight each week, provided the previous week went well. Bad weeks get a rule as well. After a flare-up you cut the program back. You don’t abandon it.

The exercises should look like the life you want back. For a keen gardener that might be step-ups and slow squats to a low stool, since getting down to the ground and up again is the real test.

Pain doesn’t automatically mean stop. In a 2007 trial with Achilles tendon pain, Silbernagel’s group let patients keep running and jumping as long as pain stayed at 5 or below out of 10 and had settled by the next morning ^[3]. They did as well as the group told to rest from those activities. With your physio’s agreement, the same 5-out-of-10 check works for a sore knee.

A few days of rest after an acute injury is sensible. Weeks of it, for pain that has hung around for months, is another matter. You lose strength and tolerance, so the next jump in activity is more likely to hurt.

None of this is quick. Think in months. Most programs go wrong at the starting point: set it too high and the program brings on the flare-ups it was meant to prevent. A physio who starts you low and builds slowly is doing you a favour, even if the first fortnight feels pointless.

For osteoarthritis the evidence is about as clear as it gets in this field. The American College of Rheumatology and the Arthritis Foundation strongly recommended exercise for knee and hip osteoarthritis in their 2019 guideline ^[4]. NICE in the UK says much the same in its 2022 guideline (NG226), which calls for therapeutic exercise tailored to the person ^[5].

The fear people bring into the clinic is that a sore knee will wear out faster if they use it. Bricca and colleagues went looking for that harm in 2019 and didn’t find it: no evidence that exercise damaged knee cartilage, whether people already had osteoarthritis or were at risk of it ^[6].

Expect some discomfort during or after. If it’s gone within 24 hours, the load was probably about right. If it hasn’t:

• Swap walking for cycling or a session in the pool, which may load the knee less.
• Split the work up. Two 20-minute stints in the garden with a cuppa in between are easier on a knee than one long morning.

A joint that turns hot and swollen needs a prompt visit to your GP. So does one that starts locking or giving way.

Most people leave physio with a printed sheet of sets and reps. What it almost never says is why the program is built that way. That reasoning is often what keeps someone going in month three, when the knee feels fine and the sheet is somewhere under the fruit bowl.

A handful of clinics write the reasoning down for their patients. The free Pivotal Motion physio article library, published with the Newmarket, Brisbane clinic Pivotal Motion Physiotherapy, has a piece titled “Osteoarthritis: Should I Exercise If My Joints Hurt?”. It takes the same question as the section above, but from a treating clinic rather than a guideline panel, so it deals with what patients actually ask in the room.

Scale the program down rather than stopping it. Drop the step-ups to one set and keep the walks short. If the knee settles within a couple of days, build back up from there.

If it keeps getting worse over several days, book a review with your physio. A week on the couch usually leaves you starting from a lower level than before.

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