I guess this is the hamstring thing. Warning signs came after the failed 10K experiment. Perhaps too quick in too cold with too few clothes on. I had to take a few days off and the week ended with just 50K total.
Yesterday a nice 13.6K in Jaala, the classic route Ruokoniementie there and back in 55 mins. That means c. 4.00/km – however, I had to watch for the right one. I really hope this will be it. Tomorrow there will be another hard one in Sjundå. I think I’ll go.