The elaborateness of VO2max testing is to some people a luxurious non-necessity reserved only for people with western European accents or for those who love to impress with the latest in technological revolution. That was indeed the case… back in 1971. Now, with modern methods of Vo2 (that’s short for “volume of consumed oxygen) max testing, it’s quite simple to keep regular tabs on your current oxygen consuming capabilities. However, the question remains in the back of the heads of many-a-skeptic as to how participating in this type of test is beneficial to their athletic proficiency. For one, the maximal amount of oxygen carried/consumed by the working muscle is the true limitation to overall aerobic capacity and is regarded as the “standard” by which all endurance athletes are compared. While it is important to know where one’s limits truly lie, the Vo2max is merely a physiological reference point that is optimistically a second-rate determinant of endurance capacity and of little consequence during a season-long training structure. The hidden elements of the information gleaned from a Vo2max test provides the real physiological foundation for addressing athletic need in a particular area. This is the type of information can only be elucidated from Vo2max protocols, and is the basis for what adds or subtracts from your efficiency as an endurance athlete.
First off all, and without getting into too much unnecessary detail, the basic crux of the argument surrounding endurance training is the availability of oxygen as exercise intensities increase. Understanding how to maximize an athlete’s oxygen consuming (notice I did NOT say oxygen “carrying”) capacity is really the Holy Grail of endurance training. With an increase in oxygen consumption, you see cascades of positive events which all serve to increase the fuel economy of an athlete. Utilization of fats, in lieu of carbohydrate (CHO) is one of the most advantageous effects of an increase in oxygen consumption because it allows the athlete to successfully limit the amount of endogenous carbohydrate (muscle glycogen) used during low to moderate intensity exercise. Because fats need nearly 30% more oxygen to be converted into energy, only athletes who possess the proper cellular machinery to consume suitable amounts of oxygen to power fat oxidation see the benefits therein. Of course, this ability is trainable but ONLY if stress is applied to the zones that will elicit the greatest increase in aerobic capacity. This zone is commonly referenced as the “Aerobic Target”. The AeT, for short, is the intensity zone in which the athlete shows the greatest dependence on fatty acids during exercise. Because the individual metabolisms of endurance athletes are inescapably different, any basic standardized formula used to predict this range based on a age-estimated max heart rate is a complete waste of time- and can often be detrimental by providing justification to train at intensities that are much to great to elicit an aerobic response. The only method of determining this zone is by use of devices that measure and compare levels of carbon dioxide and oxygen within expired breaths (i.e. participation in a Vo2max test).
Secondly, and in the same vane as increasing fat oxidation via training according to one’s own metabolism, is the elucidation of the anaerobic threshold (AT). There have been many field tests proposed and many attempts at isolating this metric without expiratory data, but research has clearly stated that because of the uniquity of each endurance athlete, without capturing expelled carbon dioxide, elucidation of AT becomes a metabolic snipe hunt. Before continuing, in would be prudent to further clarify what AT is as there is some degree of confusion about the point at which the AT is reached and the results of such action. When an athlete increases his/her intensity past the point where sufficient oxygen is present to continue the breakdown of CHO to meet the necessary energy demand, the muscles begin converting CHO to energy without the presence of oxygen. This point, and resulting metabolic switch, is called the anaerobic threshold (or lactate threshold). Most athletes fear the point at which they go anaerobic due to the resulting buildup of lactic acid. While this is the case, and something to heed, the effects of long-term (low-level) anaerobic respiration, such as that which is encountered in marathons and long-course triathlon, are much more global. When anaerobic, muscles are producing energy at an accelerated rate thus satisfying the energy demand, however each molecule of CHO produces 18x less energy via anaerobic metabolism when compared to aerobic metabolism. Thus it is easy to see from an energy accounting standpoint, that long-term exposure to exercise intensities at and above AT puts a substantial strain on muscle glycogen levels. Thus, knowing exactly where this metabolic change takes place is essential to rationing and supplementation of carbohydrates if exposure to intensities in excess of AT is necessary for extended periods.
While understanding of this biochemical ballet is crucial to training efficacy, the real advantage of Vo2max testing becomes evident when you begin to globally examine what limits your overall physiology in your endurance pursuits. Athletes who make the common mistake of engaging in training structures that are much to intense are subject to reduced aerobic efficiencies, CHO dependence, exercise induced hypoglycemia, and low Vo2maxs. It is always a shocking discovery for any athlete to be confronted with the fact that their training has actually led to a systematic weakening of their aerobic metabolism. In other words, because they were unaware that the majority of their training was done in excess of their AT, there has been little no stimuli or justification for the body to increase it’s oxygen consuming abilities. Therefore, to counteract this, the athlete would need to spend more time in zones beneath the AT so that proper stress is placed on the aerobic system to become stronger and more efficient. Without identification of this issue, and due to the fact that the athlete was completely unaware that the AT was constantly reached, there would be little improvement in overall aerobic proficiency. Additionally, because the data from a Vo2max test will provide a detailed outline of which macromolecule (fat or CHO) is being used most readily and to what extent, it is possible to determine, to the calorie, how many grams of CHO are necessary to continue fueling at a given intensity as to avoid complete muscle glycogen deficit.
As should now be clear, the uses of Vo2max/metabolic data reach far beyond exposition of just Vo2max alone. They provide the framework for isolating and improving upon any metabolic limitation whether at low or high intensity. Secondly, Vo2max/metabolic data allows for a non-biased, individual assessment of training and diet effectiveness. Therefore it is possible to determine if further attention to your limitations is necessary before moving into a different period of training instead of blindly adhering to traditional season-long non-individualized periodization plans.