Don't know what is happening but I have been finding my runs really difficult for about 4 weeks now. I seem unable to tackle even the slightest uphill, not out of breath or anything but my lower back aches. My pace has is awful. I used to take 63 mins to do 10k. Today I was 71 mins for 8.3km.
Its not the weather as it has been going on for a while .
I am running a 5k in 2 weeks and dreading how slow I will be.