Blood test? No, I just need some speedwork.
On Sunday I was chatting to a friend who is an ultra-runner, telling him how I have slowed down this year, and he was saying that he had also slowed down. He put this down to not doing speedwork: he had got into the habit of using Parkrun as his speedwork session, so hasn't done much since Parkrun stopped in March.
Anyway, I went back to my reps circuit that I haven't run since my injury last Autumn. I managed 6 reps (I usually do 8, sometimes more), and they were only about 5 seconds slower than usual (taking 2:10 - 2:20 each), so not too dreadful.