One for the endocrinologists!
Every year around mid September I start to suffer from depression, and self medicate with hypericum which works, but takes a few days to kick in. When I'm feeling more positive (usually no more than ten days off) I'll get back out on my bike, but find that all my speed and leg strength have gone, but my base is more or less intact. So my average will drop from around 18mph (upper level 2) to around 16.5mph on my usual 60 mile loop. Now, this doesn't happen during the summer even if I have to take off a similar amount of time. I'm guessing that there must be a drop off in hormone levels along with the amount of effective serotonin knocking about in the brain. Anybody?