Started running in January, up to 20 km a week, and the outside of my right knee started aching around week six. I run in old cross-trainers that had already done maybe 600 km of gym work before I ever ran in them. Half the internet says get proper shoes and the other half says shoes don't matter, it's your training load. I've cut back to three runs a week and it has improved slightly.
Went through this exact thing last year. New shoes made day one feel great and changed nothing about the underlying problem, which was that I ran every single run at the same slightly-too-hard pace. Slowing down about a minute per km did more than any purchase.
The 300-500 mile replacement figure everyone quotes traces back to a midsole compression study from the mid-eighties, and it is a rough guide rather than a law. But 600 km of lateral gym movement plus running load is well past any version of it. Press your thumb into the midsole. If it doesn't push back, that's your answer.
Gym shoes also get compressed differently, sideways rather than through the heel and forefoot, so the wear pattern won't look like a worn-out running shoe even when it is one.
Just did the thumb test on both shoes. The right one has a visible dent that stays for a second. That is unsettling.
Terse version: buy shoes because the old ones are worn out, not because you're hoping they'll fix a knee. Fix the knee with load management and a professional.
One thing nobody has mentioned. Cross-trainers are usually much flatter than road running shoes, so if you've been running in something with almost no heel raise, that is a genuine change in how load goes through the calf and knee, entirely separate from cushioning.
@negative_split_nan · 3mo ago · 3 replies
Both camps are half right and they are arguing about different things. Shoe choice barely moves injury rates in the research, but a shoe with 600 km of gym use already in it has very little cushioning left, which is a separate problem from wrong shoe. You also went from zero to 20 km a week in six weeks, which is the more likely culprit by a distance.
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@curious_wren · 3mo ago
Laid out like that the timeline is embarrassing. I was adding about 4 km a week, every week, without a down week anywhere.
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@openkey_owen · 3mo ago
Outside-of-knee ache in a new runner ramping fast is a very common story and also not something anyone here can diagnose. One physio appointment beats three months of guessing on a forum.
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