What is VO2max again?
The amount of oxygen(milliliters) you can use in one minute per kilo of body weight is the individuals VO2max or the highest rate of oxygen consumption attainable during maximal or exhaustive exercise(2). An athlete who is fit will have higher a VO2max than an untrained athlete at higher exercise intensities (3). As an athlete increases their exercise intensity their oxygen consumption increases until it reaches its maximum capacity. It is this point where VO2max is reached, however it is important to note that the exercise intensity can still increase however without further oxygen uptake (3). It is important to note that VO2max on its own is an inappropriate predictor of athletic performance (2,3) however it does provide a indication of athletic potential where lactate threshold will provide a better indication of athletic performance relative to the individuals ability (2).
Factors affecting VO2max
Genetic endowment contributes largely to ones VO2max due to the body’s ability to either utilize available oxygen or deliver oxygen to active tissues.
Utilization Theory
Maintains that VO2max is determined by the body’s ability to utilize the available oxygen. In effect, VO2max is limited by a lack of sufficient oxidative enzymes within the cell’s mitochondria (2).
Presentation Theory
Maintains that it’s the ability of the body’s cardio-vascular system to deliver oxygen to active tissues that is the key determinant, VO2max depends on increased blood volume, maximal cardiac output and better perfusion of blood into the muscles (2).
While both theories have their role in determining VO2max it is concluded that oxygen supply is the major influence in determining endurance performance as only weak relationships exist between oxidative enzymes and increase in VO2max (2).
Age
VO2max decreases with age, at an average rate of decline of 1% every year after age 25 and is typically attributed due to the effects of aging on the cardio-vascular system (2).
Intensive training during younger years does not offset this process, actually elite athletes have shown a more rapid decline (1.5% per year) once their careers are finished (2). This is not all doom and gloom, conversely master athletes show only minor loss (0.5-0.6% per year) while maintaining the same relative intensity of training (2).
Interval Length/Rate of Recovery and VO2max
vVO2max is the velocity at VO2max. When work intervals are conducted below vVO2max the total load on the cardio-vascular system can be directly related to the length of the work interval (1). On a study of work intervals over 30 seconds, 1 minute, 2 minutes, 3 minutes all carried out at moderately high but not high vVO2max intensities it was found that the shortest intervals produced sub maximal load on the circulatory and respiratory systems as well as low lactate levels (1). From this we must suggest intervals lower than vVO2max are more appropriate as the lactate production and elimination should be trained for longer endurance events and maximum speed at vVO2max is not as necessary as for a 5 kilometer runner.
In using the longer intervals VO2max will be attained in the first interval and subsequent recovery intervals will need less time to depress oxygen usage. Why? When moving at less than 90% vVO2max but above 90% of vVO2max it takes roughly two minutes.
From a practical point of view one should decrease work intervals during the session instead of increasing recovery interval as this will decrease average oxygen consumption rates and mean levels of lactate production effects which are counter productive in terms of VO2max and lactate threshold (1).
If VO2max or lactate threshold are unimportant and you only want to improve running economy the recovery to work ratio should be high(1) e.g. a 400m runner with little need for lactate threshold and aerobic capacity would have short work intervals and long recovery intervals to increase economy and speed.
Importance of vVO2max and Interval Progression
Long intervals can produce problems as they may display a false positive. Athletes with high vVO2 will be able to run quickly at VO2max, hence is fairly efficient making vVO2max a good indicator of performance (1). For example an athlete with excellent economy (running speed) may have a poor VO2max and is unable to reach high speeds at VO2max (1), a vital attribute for racing.
French researcher Veronique Billat has suggested the best way to convert interval training into performance increases is utilize vVO2max efforts in training to improve vVO2max, VO2max and lactate threshold and economy (1). While this training may cause lactate threshold to remain consistent the velocity at lactate threshold will increase due to improvements of vVO2max, furthermore training at vVO2max increases strength and power, strength boosts economy as when muscle fibers are stronger fewer are recruited to move at similar paces (1).
Ofcourse for the majority of athletes performing 3 minute intervals at vVO2max is not attainable from the get go; they need to build up to such an intensive session.
Billat suggests the use of 30 seconds at 100% vVO2max followed by 30 seconds at 50% of vVO2max. Interestingly even when the 30-30 is performed till exhaustion (when vVO2max cannot be sustained for 30 seconds) it is still less taxing than 5 x 3minutes at vVO2max (1). This 30-30 session can then progress to a 60-60 at which point one can begin training the classic 5 x 3 minutes at vVO2max.
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