August 13, 2013
Free-Divers: The New Personal Trainers
For those of you who are unaware of the growing popularity of apnea training among endurance athletes, here is a brief summary of the status quo. For the past several years free-divers have been subjecting themselves to and surviving harsh stimuli that defy what many doctors have established as the “limits” of the human body. Conditioning the body to withstand these extremes, most notably hypoxia and water pressure, requires a very unique type of training.
Logic seems to dictate that any exercise regiment that allows athletes to achieve “superhuman feats” would probably improve general athletic performance. For these reasons, apnea training is going under the lens of the sport physiology world. Many professional free-divers such as Kirk Krack are becoming personal trainers for elite endurance athletes and Navy Seals.
So what is apnea training? How does/would it improve athletic performance?
Put simply apnea training is an exercise regiment designed to enable you to hold your breath longer. Though we are not experts in this field, the apnea training regiments of free-divers we have worked with can be broken down into exercises that target 4 different goals: 1) sympathetic nervous system control, 2) hypoxia tolerance, 3) hypercapnia (high C02) tolerance, 4) lung function improvement.
Underwater Altitude Training?
Though each of these four goals may also improve athletic performance, there are two (hypoxia tolerance and lung function) that are more likely to become the focus of further clinical investigation. In 2010 French scientists, Frédéric Lemaîtrea and his colleagues, published a paper called “Apnea: A new training method in sport?” In it, they compare the physiological adaptations attained from apnea training to those athletes seek from training at altitude. At first glance, their argument for apnea as an “altitude alternative” seems compelling. Apnea training can create a temporary spike in EPO production, which increases hematocrit…you know the story.
But how is apnea training different that altitude training “biologically?” Altitude training is hypoxic exposure, while apnea training is hypoxic-hypercapnic exposure. Scientific semantics….NO. Elevated C02 levels blunt the production of EPO that results from hypoxia. This is a very well documented effect that is explained by multiple mechanisms such as vasodilation, blood acidity, etc. So a given “hypoxic dose” from apnea training produces a smaller physiological improvement than an equal hypoxic dose from altitude. Combining this blunting effect of hypercapnia with the intermittent nature of apnea training, you do not have a very efficient method of raising red blood cell production.
Bring Out Your Inner Dolphin
There is another, more interesting difference between altitude training and apnea training. Apnea training invokes and strengthens what is called the Diving Response (DR). This response, possessed by all marine mammals, involves bradycardia (reduced heart rate), peripheral vasoconstriction, and, weirdly, splenic contraction. Why would holding your breath make your splene contract?
One of the functions of the human splene (though far more so in most mammals), is to be a red blood cell reserve in cases where a temporary increase in blood oxygen carrying capacity is needed. In trained free divers, the DR can spike hematocrit by as much as 7% (this effect lasts for about 10 minutes). For this reason, it has been purported that a few short breath holds before a race may provide an advantage in middle distance events.
Unfortunately, this is also likely a dead end for two reasons. The first is that the splene already contracts (though not fully during submaximal efforts) during exercise. So invoking the DR for performance may for the most part be a redundant measure. The second reason is that bradycardia and peripheral vasoconstriction contribute negatively towards athletic performance because they decrease oxygen flux to muscles. This is why swimming in cold water seems harder when you dunk your head in (seriously try it, cold water enhances diving reflex response).
For those who are interested, scientists are also suggesting that the diving response is evidence that we evolved from “aquatic apes.” This is a theory that many scientists once scoffed at, but is starting to yield some considerable merit. Here is a quick video done by Evolutionary Anthropologist, Elaine Morgan: http://www.ted.com/talks/elaine_morgan_says_we_evolved_from_aquatic_apes.html
There is one intriguing question that arises from these dead ends….Can you increase the size of your splene to enhance the volume of the red blood cell pool that is released into your blood stream during exercise? Horses and many other mammals store nearly half of the blood in their circulatory system in their splene while at rest. Increasing this red blood cell reserve could certainly enhance V02 max and aerobic power.
But is there any evidence that apnea training can make your splene grow? There are not studies linking this phenomenon to apnea training. It would require long term study on free-divers, of which there are little. However, there seems to be considerable variation in splene size among free-divers as well as a correlation between size and breath holding performance.
We will continue to post about this topic and cover how splenic hypertrophy and lung performance enhancement, may be an unexplored advantage for athletes. We will also cover how some aspects of apnea training may enhance altitude performance and tolerance.
This is a budding topic so keep tuning in and we will have some cool updates coming your way!