Why Does CrossFit Work?
Creating Imperative & Driving Adaptation
The Human body as we know it today has evolved over the last 10,000 years to become the most impressive and complicated biological system ever studied. It is because of the complicated nature of the human body and the biological uniqueness of individuals that there is no simple solution for fitness that fits every single person. There are however several fundamental concepts in biology that holds a universal truth for us all, that allows our bodies to change. Adaptation occurs when the human body is faced with a new stress that causes the body to change the way it behaves in order to deal with that stress. For instance, when a person moves to a colder climate, over time the enzymes and hormones in that person’s body change to allow that person to acclimate, this is an adaptation. Adaptations in the human body take many forms, from increasing Erythropoietin (the hormone that controls red blood cell production) at high altitudes so that it can transport more oxygen when the air is at lower pressures, to provoking forms of neovascularization such as angiogenesis and vasculogenesis (the formation of new blood vessels) and even arteriogenesis (the increase in lumen diameter of existing vessels) occurs in response to exercise to help handle the increased oxygen and nutrient demands of the muscles. The examples are nearly endless!
While the Human body has an amazing capacity for change its preferred state is one that allows the body to spend more energy on daily maintenance and up-keep, this state is referred to homeostasis. For change to take place whether it is the amount of red blood cells circulating through our body, or to shed pounds of fat, or to build big lean muscles, the human body needs to be given a reason to change. This reason we refer to as an imperative. In biological systems change is driven out of necessity for survival. If there is no risk of survival, there is no imperative to adapt. Our bodies would rather spend its resources on preparing for a shortage of energy (storing fat) than it would on building muscle that it has no need for, and might never use, which in turn it would then have to maintain and take care of. This is why people lose muscle if they stop training, the body would rather spend its energy on systems that it uses everyday, than on maintaining muscle that it does not use.
Creating a physiological imperative for change in a biological system such as our bodies is what allows us to build muscle, burn fat, and have a stronger immune system! Exercise performed at a high enough intensity is viewed by our bodies as a stress. This stress is interpreted as a threat to the survival of the biological system, so in response the body adapts. After a bout of high intensity exercise our body experiences a period of increased metabolic activity, our body burns calories for hours and hours after we are done working out repairing muscles, building new pathways for blood to flow, and converting and storing nutrients for future endeavors. The body also increases production of white blood cells (boosting the immune system) in response to the stress, preparing to fight for its perceived incipient survival. It does this in preparation for encountering future stresses of the same magnitude. This preparation performed by our bodies during the recovery days following the high intensity workout means that the next time you go to workout your body will be a little faster and a little stronger. However, if all you do is expose your body to the same stress day-in and day-out, after the initial adaptions our body no longer needs to make any more changes, as it no longer views the stress as a threat to its survival. This is why you see many people who take up running initially exhibit results but after a short time their physiological transformation hits a metaphorical wall. The athlete is left with a choice, go further or go faster, both of which usually do not yield the same results as those that were initially exhibited when they first started running. CrossFit offers a paradigm shifting solution to this dilemma, by always changing the stress exerted on and by the athlete their body must continually adapt. Not just changing the distance or the speed, but by changing the actual movements, the durations of the workouts, the loads moved during the workouts, and distance those loads are needed to be move. Constantly changing these parameters allows us to achieve an unparalleled level of success in creating imperative and driving adaptation.