Most runners already know they're a "head-case," but now there's science to prove it! You know that feeling towards the end of a race when it seems as if you're about to die and you can no longer control your legs?(Sometimes for me, that's before the race even starts.) That feeling could be all in your head. To be more specific, in your brain. A relatively new idea proposed by Dr. Timothy Noakes theorizes that the brain sometimes acts like a big brother during prolonged strenuous exercise. When "Big Brother" senses the body's normal operating system (homoeostasis) is getting out of whack, it's main priority is to protect his little brother—the heart—so Big Brother slows everything down by fatiguing the muscles. Noakes called this process The Central Governor Model. Kind of like a governor that's but on a school bus engine to keep it from going over a certain speed.
For decades most scientists, trainers, coaches, and runners have believed that the Cardiovascular/Anaerobic/Catastrophe Model was responsible for the fatigue. British physiologist and Nobel Prize winner Archibald Vivian Hill (he went by A.V.; wouldn't you?) proposed this model back in the 1920's. Basically he believed that a lack of oxygen to the muscles, a build up in blood acidity at your muscle cells, or both occurring at the same time was responsible for the fatigue.
Since Noakes proposed his new theory, more and more scientists, coaches, and runners have begun to question the original thinking. Basically it all comes down to fatigue. We know the symptoms, but what's causing them?" Is it a lack of oxygen to the muscles or is the brain constantly monitoring the body and acting as a governor by purposefully fatiguing the muscles when it fears the heart is in danger. The two main questions being asked are:
- If a lack of oxygen to muscles is the cause of the fatigue, then why isn't the heart starved of oxygen? It's a muscle too. If the heart were starved of oxygen, then the runner would experience heart pains.
- If the fatigue is purely caused by a physical problem (not enough oxygen getting to the muscles), then how do you explain runners who (even though they have to slow down) continue at a relatively good pace? Some runners can even pick up the pace when they near the finish.
If Noakes' model holds true and the fatigue is caused by the brain sensing a disturbance in homoeostasis, then a runner can tell the brain to "stop it!" More technically, the runner can recognize what's happening to him/her and make a conscious effort to override his/her subconscious. I didn't know what I was doing at the time, but when I ran the Baltimore Marathon in 2004, I think I did this exact thing to avoid bonking. At about mile 21, I started to get very fatigued. I was well hydrated, and had been taking gels regularly, and I hadn't gone out too fast like I usually do, so I was baffled as to why I was feeling fatigued. I remembered reading somewhere that if you feel fatigued, you should try speeding up because it will use different muscles allowing your fatigued muscles to recoup. So, I purposefully told myself to speed up and as a result, the fatigue dissipated and I ended with a good time and actually felt good after the race. I'm not sure that was The Central Governor Model in action, but it sure does sound like it.
So, the next time you feel fatigued during a race, tell your brain to "Stop it!" Of course the runner beside you may think your a nut case, but it'll be worth it.
Now, keep in mind that Noakes' model doesn't explain every case of fatigue. Sometimes fatigue may be a result of such things as increased levels of potassium which can hinder muscle contraction. And if you haven't pre-race-carb-loaded and you don't continue to refill your glycogen supplies during a marathon (especially if you're running more than two hours) then Hill's original theory could very well be the cause.
If you want to read more about Noake's Central Governor Model and more about the brain and running, check out the following books:
"Now revised, expanded and updated, Lore of Running gives you incomparable detail on physiology, training, racing, injuries, world-class athletes, and races. Author Tim Noakes blends the expertise of a physician and research scientist with the passion of a dedicated runner to answer the most pressing questions for those who are serious about the sport... Lore of Running is not only the biggest and best running publication on the planet. It's the one book every runner should own."—Amazon
"Based on new research in exercise physiology, author and running expert Matt Fitzgerald introduces a first-of-its-kind training strategy that he's named "Brain Training." Runners of all ages, backgrounds, and skill levels can learn to maximize their performance by supplying the brain with the right feedback. Based on Fitzgerald's eight-point brain training system, this book will help runners resist running fatigue, use cross-training as brain training, master the art of pacing, learn to run "in the zone", outsmart injuries, fuel the brain for maximum performance, and more."—Amazon