Hypothyroid drives out magnessium
in muscle tissue allowing lactic acid to set
in longer than it should leaving muscles in a constant burn state. The ATP muscle rebuilding process is then severely slowed or even stopped, that is why you can be sore for days on without muscle recovery. Deep muscle knots then form cutting of new blood flow, along with possible tendinitis, bursitis ect.
I can only imagine that the race is a annual event, so there is always next year.