Part 2a of 2: What's happening to me!?!? What happens to your body during a marathon, ultramarathon, Ironman, or other race distances of silly proportions.

Hello again, seekers of knowledge! This is the second portion of a multi-part post, so allow me to recap:

  • training and racing for events that require an outfit change and/or multiple snacks is silly and excessive
  • I love silly and excessive things. The purpose of this post it to inform you so that you can do those silly things better. The purpose is not to judge you.
  • Training for these silly +/- excessive races allows your body to adapt in some very significant ways, including: an increase in blood volume, a general decrease in heart rate, and an increased efficiency of oxygen use.
  • Nervousness and excitement on race day cues certain body systems to start working overtime. In turn, this prepares your body for the upcoming shenanigans it is about to experience. So your pre-race GI issues and sweat armpits are normal and even beneficial. Rejoice!
  • While racing, your body uses glucose to fuel your every effort. It can use glucose efficiently if enough oxygen is present, or inefficiently if oxygen is in short supply. Long story short, don't go out like a fool in the first mile.
  • If you are confused, please refer to part 1 of 2 which contains more detailed information and many witty comments. 

Enough recap! Let us proceed. Imaging that you are now in the very-long homestretch of your very-long race. You have been Doing Work for the last few hours. Your fancy new Garmin is telling you that you are moving at the same speed, but it feels ten billion times harder than it did before. You have stuck to your plan and kept a reasonable pace, but you are sucking wind like Fatty McGee. You know that you have consumed adequate nutrition but you are getting T-I-R-E-D. What's the deal? Why is your body failing you? 

There are many theories as to why we eventually fatigue during endurance exercise. The most notable include:

1. Cardiac Drift. Cardiac drift describes how heart rate may increase after a certain amount of time even though pace, intensity, and all other factors have stayed the same. In layman's terms, it is a seemingly random increase in heart rate during steady exercise. Cardiac drift can occur for a few reasons, but is most often attributed to an increase in core body temperature and/or dehydration. 

Your blood is made up predominately of water (90%, in fact). If you are racing on a hot day, don't consume adequate electrolytes to prevent water loss, are a heavy sweater, or even just sweat a little but for a really long time...there will be a substantial decrease in the amount of water in your blood. This means that your blood gets thicker and that the total volume of blood in your body becomes less. As a result, your heart has to beat harder in order to circulate the same amount of blood throughout your body EVEN THOUGH you have not increased your pace or effort. Bummer. 

But what if you have been drinking water and popping nuun like crazy? And maybe it's not even that hot of a day? Exercising for a silly +/- excessive duration will inevitably increase your body's core temperature. A sustained increase in your core temperature will have the same results described above- a general loss of water, thicker blood, lower blood volume, and a heart which compensates by beating faster and faster. 

So what can you do? Train hard, train often, be prepared, and know to expect a little cardiac drift during your race!

2. Central Nervous System Fatigue. If you have personally experienced central fatigue, you know that THAT $H!T is REAL! There is an element of exhaustion that cannot be explained by muscle failure alone. It is possible to exercise for so long that you actually have neurochemical changes in the brain and central nervous system. Most notably, excessively prolonged exercise reduces our levels of dopamine and increases our level of serotonin. Isn't that kind of scary and awesome?

Dopamine plays a huge role in regulating how alert and motivated we feel, in addition to how coordinate we are. So a reduction in dopamine literally makes exercise seem less fun. Do you absolutely love running, but have told yourself mid-race that you HATE it and will never ever run again as soon as you cross the finish line? I have. Too many times to count. 

Serotonin on the other hand, does the opposite. An increase in serotonin makes us sleepy and makes physical exertion seem harder. An increase in serotonin is like

Whereas low dopamine levels during a race is just all

I can't even right now. 

Our bodies are so intelligently designed, it amazes me every time I think about it. 

3. Mental Fatigue. Do I really even need to explain this one? Regardless of the neurochemical effects discussed above, sometimes you just have "it" and sometimes you don't. Training your mind is an entire area of athletics that sounds hippy-dippy but has real, researched based implications in sports performance. In the words of Rudyard Kipling:

"If you can force your heart and nerve and sinew
To serve your turn long after they are gone,
And so hold on when there is nothing in you
Except the Will which says to them: 'Hold on!'

So alright tough girl and guy, you've crushed the race and the sickeningly long final stretch. You can, for once, physically see the finish line. You start to forget about the 8 toenails that you are pretty sure you are going to lose. And the inner-thigh rub that will without a doubt burn like a fire-ant sting in the shower tonight. In fact, you are suddenly feeling so freaking good that you think you may try to bring it in a little. You start to wonder if you can pass that jerk who has been swapping places with you for the last 20+ miles...

Most people assume that THE KICK is just something that comes out of mental fortitude. To some extend, it does. Obviously, you have to make the mental decision to change gears and then commit to the level of discomfort which will inevitably ensue. Yet have you ever stopped to really consider the scientific basis of THE KICK? As a huge anatomy and physiology dork, I have. I raced cross country and track in college and I was constantly losing places at the end of a race. My coaches placed me in the "bad kick" category. My parents referred to my kick in hushed, sympathetic tones.However, deep inside me I knew that I had finishing speed and that I was somehow cheating myself out a proper race finish. So I looked into it.

Let's go back to glucose use and oxygen. Remember that in the presence of sufficient oxygen, glucose can be broken down efficiently for an extended period of time. While performing THE KICK, oxygen is not the main concern. Your main concern is crushing the soul of that person in front of you and/or eeking under that time goal you set for yourself. In a true kick, not just a slight bump in pace, you are giving it all you've got at that moment. Your body still needs fuel to make your muscles work, but it doesn't have enough oxygen. So what does it do? It converts glucose inefficiently, but the best way it can, through a process called anaerobic respiration. This is like spending all of the money in your bank account as fast as you can. You will have a lot of money to spend really quickly, but the fun will only last for a limited time before you are bankrupt. 

Anaerobic respiration can occur for 10-30 seconds max before your body becomes bankrupt in fuel. After that, you are toast. My problem in college is that I kicked 60, 90, 120 seconds away from the finish line. I looked like a complete idiot, passing girls up with gusto only to fade as the monkey, piano, and 600-pound lady jumped on my back. You cannot outrun science. Your full kick will last you 30 seconds or less, so time it appropriately! I didn't make this up. Dr. Wikipedia agrees. Check it out HERE

What happens to your immune system once you cross the finish line? How can your heart change with repetitive ultra-endurance training? What the heck DOMS really and why does it hurt so bad to just sit on the toilet post-race?

Reading this post may turn into an ultra-endurance activity itself, so join me for the final kick in part 2b, "DOMS, and Why isn't there an elevator to floor one?" 

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