It's an unpleasant fact of life that most mass-participation
endurance events start at (and sometimes before) the crack of dawn. But
it's not equally unpleasant for everyone: the world is divided into
morning types ("larks"), evening types ("owls"), and those who don't
have a pronounced preference either way. What if you're a wonderful
endurance athlete, but you just hate getting up in the morning? Will
this make it less likely that you persist in the sport?
That's basically the question that a group of South African scientists from the University of Cape Town tackled in a recent study published in Chronobiology International.
They compared four groups of people: 125 cyclists, 120 runners, 287
Ironman triathletes, and 96 active but non-competitive controls. The
first test they did was to administer the "Horne-Ostberg
Morningness-Eveningness Questionnaire," which is used to distinguish
larks from owls.
Pretty big difference in the number of morning people in the athlete
groups compared to the control group. But this doesn't distinguish
between cause and effect: maybe years of pre-dawn rides have convinced
those cyclists that they really like getting up in the morning (because
if they didn't tell themselves that, they'd go crazy).
In this case, the "5 allele" is associated with shorter circadian
rhythms, which in turn translates to morning preference -- so people
born with morning preference are indeed (at least in this particular
sample of white South African men) more likely than the general
population to end up getting addicted to endurance sports, presumably
because of the time of day when most people train and compete.
So... who's going to found the first Evening Triathlon Association,
bringing endurance sports to the neglected owls of the world?