Set Muscle

For about three weeks my left knee has a dull ache, but only on the concentric coming out of the hole. No pain going down, no pain walking. Right knee is fine. Before I throw money at a physio, what worked for people who had the one-sided version of this?

One-sided almost always traces back to something asymmetrical. Check your stance - is one foot turned out more than the other? Film yourself from the front. Nine times out of ten the painful side is caving in or you're shifting your weight onto it coming up.

That's interesting, I do feel like I shift slightly left at the bottom. Hadn't connected it to the knee.

The weight shift is your answer then. Your left leg is doing more than its share on the way up. Single-leg work to balance it out - split squats, and actually pause and own the bottom position so you stop dumping to one side.

Before anything else, how's your warmup? Cold knees on a heavy first work set used to give me that exact ache. I added five minutes on the bike and a couple of bodyweight sets and it mostly went away.

Warmup is honestly minimal, I do one or two ramp sets and get into it. Could be that simple.

Try fixing the easy stuff first before assuming it's structural. Bike to get blood in, a few air squats, leg swings, then ramp in smaller jumps. If the ache is gone with a proper warmup you've found it for free.

Also look at your shoes. I got a nagging knee thing that turned out to be squatting in soft running shoes - my foot was rolling in under load. Switched to a flat hard sole and it cleared up in a week.

I do squat in running shoes actually. Didn't think the sole mattered that much.

Massively. A compressible heel lets your knee travel all over the place. Flat shoes or even just socks for a session and see if it feels more stable.