Having started training again in the recently improved weather, I've
been considering the pathways of endurance fitness. Cardio-vascular
improvements, and muscular strength are pretty obvious, but I got
around to considering mytochondria, which are pretty odd things, in
that they have their own independent DNA, and might even be considered
as a sort of parasite.
They are responsible for metabolising fuel for muscular effort, and
increase if you do a lot of endurance activity.
I was attracted by the closeness of the word to hypochondria. If there
was some metabolite that made you feel good, like endorphins, I could
use the term 'Mytochondriac' for someone obssessed with endurance
exercise. This obviously leads to some Googling. One article I found
What it says is that mytochondria in the brain increase (in lab rats)
due to endurance exercise. This means that the brain can support more
exercise without having to signal fatigue to stop muscles burning off
the fuel it needs. The idea of a physically-trained brain is
interesting, in that it might explain some of the growth in 'cycling
wisdom' needed in extreme rides. It's an appealing hypothesis, which
might explain some of the deeper appeal of long distances, especially
as the presence of greater brain hypochondria might be linked to a
desire to exercise more.
It also takes longer to grow mytochondria than to lose them, which is
one of the attractions of keeping your nose to the treadmill.