Six years ago as a freshmen at the University of Miami I decided I to major in exercise physiology as a means to learn ways to improve upon my performance. Call me selfish, but as an 18 year old collegiate athlete who was absolutely infatuated with running, it seemed a logical area of study. To my surprise, exercise physiology was about a lot more than running a fast 10k. Fortunately however, with the exception of Biomechanics, I came to really enjoy some of my undergraduate classes. Coming to Wake Forest for my Master's degree, I hadn't the slightest idea what I would be doing. I did know however, that I didn't have a clue what I wanted to do for a job, and going to school for 2 more years and getting paid to do so sounded like a pretty sweet gig. So what did I do at Wake Forest? In a nutshell I learned more than I could have possibly imagined about:
1) myself
2) research
3) old people
Now I can assuredly say that my interest in exercise physiology far exceeds my desire to improve upon my performance. I find an overwhelming satisfaction in working with older adults, which is fortunate because its looking like Ill be doing so for four more years at Ball State. That being said, performance is still a great interest of mine. Please allow me to share with you a little theory that I have been investigating on my own time for the past couple of months.
Maybe not all of us have run a marathon or competed in a triathlon (but if you are reading this you probably have) but nearly every one of us knows how it feels to run out of steam when we are trying to physically exert ourselves. Think back to the mile run in elementary school. The PE teacher passes out Popsicle sticks and we run 6 times around the baseball field, throwing a stick into the bucket on each lap (in retrospect giving kids sticks and telling them to run as fast as they can is a really stupid idea). Four laps down and two to go and what happens? All of a sudden we just CANT move as fast anymore. Our lungs are burning and our legs feel like lead weights. Why does this happen?
In 1920, famed physiologist AV Hill came up with a model termed the cardiovascular/anaerobic model of fatigue explaining that human performance is limited by the amount of oxygen that our heart is able to provide to working muscles. In accordance, individuals with a higher VO2 max and lactate threshold, and a better running economy should outperform those with a lower oxygen capacity and an inferior running economy. To this day, the cardiovascular/anaerobic model remains the most widely accepted explanation of fatigue. That being said, the model is not without flaw, as it neglects one of the most important aspects of performance, the mind.
Recently building on the work of Hill, a prominent South African exercise physiologist by the name of Tim Noakes has adapted Hill's model to include the power of the mind in what is known as the Central Governor Theory. To do so, Noakes sought out an answer to the question, "Where does fatigue occur?" It is known that to produce a greater amount of force an increasing number of muscle fibers are recruited to produce that force. So is fatigue the result of muscle fibers being unable to sustain a contraction? Or does fatigue occur somewhere else in the body, possibly the mind? In a one-hour cycling time trial with 6 interspersed maximal sprints Noakes and colleagues observed a decrease in muscle activation and power during sprints 2-5. On sprint 6 however, a significant increase in muscle activation and power was seen. If the decline in muscle activation and power observed in sprints 2-5 was a product of fatigue, the increase on sprint 6 would not have been possible. However the cyclists were able to produce a greater amount of power on the 6th and final sprint than on any of the previous sprints. This can be attributed to the knowledge that it was the final sprint, and therefore the cyclists were mentally ready to full exert themselves on this final effort. This, supporting Noakes Central Governor Theory. According to the Central Governor Theory our mind acts as a barrier to protect our bodies from harm and injury and preserve homeostasis. Critics will question the great frequency at which overuse injuries are observed. While Noake's Central Governor Theory might not be perfect, it certainly has some pretty cool implications.
So what can we take away from this? How can we explain the universal acceptance of Hill's model of fatigue, which blatantly neglects what seems such an integral part of performance? It is of course easy to believe what we are told, it is harder to question, because that requires the use of ones mind. Personally, I take great solace in the Central Governor Theory. The next time you think or someone tells you "it CANT be done." Think twice, maybe it can.
