Since I actively started cycling about 3 1/2 years ago (100 miles a week on an average), I noticed that my nails and hair are growing considerably faster than before. It's not like I have been keeping a journal about it, but I have noticed the change.
What I know has changed is the increase in my calorie intake and yet I have lost some weight. I guess what happens is that digestive system and everything else in the body accelerates because of the activity, so it would make sense that nails and hair growth accelerate as well.
Anyone else notice this change as opposed to before you started?