A Physiological View Of What The Human Body Goes Through In An Ironman

  • By Matt Fitzgerald
  • Published Apr 5, 2013
  • Updated Apr 5, 2013 at 12:46 PM UTC


 The following story explains exactly what the body goes through over 140.6 miles of racing. This story originally appeared in the January/February, 2009 edition of Inside Triathlon magazine.

From the outside, swimming, cycling and running appear as movement. But from inside the triathlete’s body, swimming, cycling and running appear as an acceleration of time.

Blood gushes through veins and arteries like traffic through night highways in a time-lapse video. Within muscle cells, glucose and triglyceride molecules are tossed into the fiery furnace of mitochondria at a breakneck pace, as though someone has put a DVD of the process at rest on 4x fast forward. Armies of oxygen radicals punch holes in muscle cell membranes, causing a general deterioration that calls to mind those computer animations that show a person aging 20 years in 10 seconds.

Indeed, from an internal perspective, completing an Ironman is a bit like sitting on a sofa for 12 hours and aging two decades. In other words, the changes the body undergoes in 12 hours of extreme exertion are similar to some of those that occur in the body over the course of two decades of non-exertion, as a result of normal aging. Fortunately, though, those years are restored to you within a few weeks. Then it’s time to start thinking about tickling the reaper again.

Let’s take a more detailed look at how racing an Ironman affects various parts of your anatomy. There’s no particular lesson in this exercise, but it may give you a greater appreciation for the accomplishment of crossing an Ironman finish line.

Something “Wicked Hard” This Way Comes

Ironman begins to affect your body even before the starting horn—or cannon, in one notable event—sounds. Research has shown that the mere anticipation of exercise increases blood flow to the soon-to-be working muscles, as well as oxygen consumption and the release of hormones, including epinephrine (adrenaline), that prime the muscles for activity. This anticipatory response is mediated largely by a primitive part of the brain called the periaqueductal gray area, which is responsible for regulating the cardiorespiratory response to exercise.

That internal roiling you experience when you step out of your car at the event site on race morning, surrounded by your fellow competitors and the electric Ironman atmosphere, is essentially the same feeling your dog experiences when you show him the leash.

When the race begins, the biochemical state of every system in your body changes as each responds first to the challenge of swimming 2.4 miles, then to that of cycling 112 miles and finally to that of running 26.2 miles. Among the greatest physiological challenges are core body temperature regulation, dehydration, fuel supply and usage, muscle damage, nutrition absorption and processing and brain fatigue.

RELATED: Hawaii Ironman Tips From A Flying Dutchman

Next Page »Pages: 1 2 3 4

FILED UNDER: Features / InsideTri / Ironman / Training TAGS:

Sign up for our free e-newsletter, SBR Report!

Subscribe to the FREE Triathlete newsletter