VO2max / What is VO2max?
The VO2max or maximal oxygen uptake is a key physiological measure of cardiovascular fitness. Higher values of VO2max indicate greater levels of aerobic fitness and can help to explain differences in performance between individuals. A high VO2max is important for success in endurance sports like running, cycling, triathlon, duathlon and cross country skiing.
So what does VO2max actually mean? VO2max tells us the maximum amount of oxygen that we are able to absorb, transport and use during exercise. Normally, this is expressed per kilogram of bodyweight, although it can also be expressed as the total amount of oxygen consumed.
VO2max is influenced by a number of factors including:
- The ability of the lungs to absorb large amounts of oxygen;
- The ability of our heart and blood system (blood, blood vessels – arteries, veins, capillaries) to efficiently transport and distribute oxygen around the body to the working muscles;
- The ability of the working muscles to absorb and use large amounts of oxygen – this is dependent on factors like the proportion of slow twitch muscle fibres, the amount of mitochondria, aerobic enzymes and capillaries.
Why is VO2max important?
A high VO2max is an important predictor of endurance exercise performance.
So, why is a high VO2max important? An athlete with a higher VO2max has a greater ability to absorb, transport and use oxygen during exercise. In this way an athlete with a high VO2max will have an efficient cardiovascular system that can absorb and transport large amounts of oxygen around their body. They will have muscle fibres that can efficiently uptake oxygen from the blood. And, the ability to work at high intensities ‘aerobically’ for sustained periods of time.
Taken together, this means that an athlete with a high VO2max has the potential to work at higher intensities, or work rates, before the demand for oxygen exceeds the supply.
Not surprisingly VO2max is considered to be the best indicator of cardiovascular fitness and has been shown to be a key determinant of endurance exercise performance (Conley and Krahenbuhl, 1980; Morgan et al., 1989; Jacobs et al., 2011). Interestingly, a high VO2max may be more important for older athletes, where research suggests that it may be a better predictor of endurance performance capacity than the lactate threshold (Marcell et al., 2003; Wiswell et al., 2000).
The importance of a high VO2max has been questioned by some researchers and coaches. However, the majority of elite endurance athletes tend to record very high VO2max values (Noakes, 1991; Daniels and Daniels, 1992). Despite this it is important to note that there are a number of other factors that contribute to endurance exercise performance – exercise economy/efficiency, sustainable %VO2max, Lactate threshold and the velocity at VO2max (vVO2max) or the power at VO2max. As such an athlete with a higher VO2max will not necessarily beat an athlete with a lower VO2max.
In essence a high VO2max gives an athlete the potential to reach an elite level, but their performance will also be dependent on other factors (Conley and Krahenbuhl, 1980; Morgan et al., 1989; Fallowfield and Wilkinson, 1999).
VO2max and recovery from exercise
A further advantage of a high VO2max is improved recovery from both exercising at high intensity and larger training volumes.
Why is improved recovery important for success in endurance sport? An efficient cardiovascular system allows an athlete to maximise their potential, by increasing their rate of recovery after exercise. This is likely due to an improved capacity to transport blood, oxygen and key nutrients.
An improved recovery is important due to the physiological demands of the large training volumes and intensities utilised during endurance training.
In this way athletes with a higher VO2max may be able to train harder, or at higher intensities, and cope with larger training volumes.
Being able to cope with and adapt to these volumes and intensities is key to long term success in any endurance sport.
The increased recoveries rate is supported by research, looking at the effects of interval training on excess post-exercise consumption (EPOC). The researchers found that those with greater cardiovascular fitness (i.e. higher VO2max) had a reduced magnitude of EPOC (Matsuo et al., 2012) – in other words they had a quicker return to resting metabolism than those with lower VO2max.
Absolute vs Relative VO2max
VO2max can be expressed in two ways:
Firstly, it can be expressed as an absolute value called absolute VO2max. When we talk about an absolute value we’re only considering the total amount of oxygen consumed and not relating this to body weight. This is expressed in litres of oxygen per minute. The highest absolute VO2 max values tend to be seen in sports such as rowing.
We can also express VO2max in relation to bodyweight. This is called relative VO2max. Here we divide the absolute VO2 max value by body weight in kilograms. This tells us the amount of oxygen consumed in millilitres per kilogram of body weight per minute. This is considered a more useful measure since it tells us how much oxygen is consumed per kilogram of body mass. The highest relative VO2 max values tend to be seen in sports like cross country skiing, cycling and running.
VO2max and Body weight
Whilst the absolute value can be useful in non weight baring sports like rowing, it is less useful in sports like running, cycling or cross country skiing. Here the relative VO2max value tends is more useful.
So, why is the relative VO2max value important? This relative value explain differences in performance between two athletes with the same absolute value. If we consider two athletes with the same absolute VO2max (in this example 4 litres per minute). If one of the athlete is lighter, then there will be a greater distribution of oxygen per kilogram of body mass. So more oxygen will be available per kg of body’s. In our example if one athlete is 70kg and one 80kg, then their relative VO2max values would be ~57ml/kg/min (70kg athlete) and 50ml/kg/min (80kg athlete).
As such changes in bodyweight can significantly affect VO2max values – a reduction in bodyweight (e.g. reduced body fat) would normally result in an increased VO2max. Whereas increased bodyweight (whether that be increased body fat or muscle) would result in a reduced VO2max. This is one of the reasons why most successful endurance athletes tend to have fairly low body weights. The exception to this being in non weight baring endurance sports like rowing.
Most elite athletes undergo VO2max testing in order to monitor fitness levels and for determining VO2max training zones. This would normally be done using an incremental exercise test in which speed or power is increased in incremental stages until either oxygen consumption plateaus or the athlete fails to complete a work stage.
There are also a number of field based tests that can be used as an estimate of VO2max – these are discussed later in this article.
Although the measurement of VO2max can be useful for athletes it is primarily a measure of cardiovascular fitness. Many coaches and sports scientists view the measurement of the lactate threshold to be of greater importance for both training prescription and assessment of race fitness.
What’s a normal VO2max Value
VO2max values can vary greatly between individuals with untrained individuals typically have a VO2max in the range of 25-45ml/kg/min. Following a period of intensive aerobic training this can increase significantly by approximately 10-25% (Gormley et al., 2008; Green et al., 1995; Smith and O’Donnell, 1984; Pollock 1973;).
The level of increase can vary greatly between individuals with some individuals showing only small increase whilst others show much larger increases. This variation in response is believed to be primarily due to genetic factors, in which some individuals have a genetic advantage. This allows them to gain greater benefit from aerobic training than others. Essentially they have a greater level of adaptation.
Elite endurance athletes typically record much higher VO2max values than those recorded for untrained or even trained individuals. Typically elite endurance athletes may have a VO2max in the region of 60-85ml/kg/min – 60-75ml/kg/min in women and 70-85ml/kg/min in men – with some athletes recording values of greater than 90ml/kg/min.
Most of the improvements in VO2max appear to occur fairly early on in training. And, in the case of well trained endurance athletes there appears to be little subsequent increases in VO2max following increased training intensity or volume.
Research in cross country skiers found that there was no significant change in VO2max across a training season, even though there were significant changes in both volume and intensity across the season (Losnegard et al., 2012). In fact, improvements in performance of well-trained endurance athletes tend to be more associated with an increased ability to race at higher percentages of VO2max, improved lactate threshold profile and exercise economy (Jones, 2006).
In one case study (Jones, 2006) the previous women’s Marathon record holder significantly improved her running performance despite her VO2max remaining fairly constant (~70ml/kg/min) between 1992 and 2003. Interestingly her VO2max remained fairly constant despite her training volume increasing from approximately 25-30miles/week to 120-160 miles/week over the course of the case study.
VO2max values of elite athletes
Elite Male Athletes VO2max Values
|Oskar Svendson||Cycling (Road & Time Trial Cyclist)||97.5/96.7|
|Espen Harald Bjerke||XC Skiing||96|
|Bjorn Daehlie||XC Skiing||96|
|Greg Lemond||Cycling (Road Cyclist)||92.5|
|Tore Rudd Hofstad||XC Skiing||92|
|Gunde Svan||XC Skiing||91|
|Matt Carpenter||Running (Ultra Marathon, Trail Runner)||90.2|
|Kilian Jornet||Running (Ultra Marathon, Trail, Sky Runner)||89.5|
|Miguel Indurain||Cycling (Road and Time Trial Cyclist)||88|
|Marius Bakken||Running (Track 3km-5km Runner)||87.4|
|John Ngugi||Running (Cross Country Runner)||85|
|Dave Bedford||Running (Track 5km-10km Runner)||85|
|Chris Froome||Cycling (Road and Time Trial Cyclist)||84.6|
|Sebastian Coe||Running (Track 800m-1500m Runner)||77|
Elite Female Athletes Recorded VO2max Values
|Joan Benoit||Running (Marathon Running)||78.6|
|Bente Skari||XC Skiing||76.6|
|Charlotte Kalla||XC Skiing||74|
|Grete Waitz||Running (Marathon Running)||73|
|Marit Bjoergen||XC Skiing||72|
|Ingrid Kristiansen||Running (Marathon Running)||71.2|
|Rosa Mota||Running (Marathon Running)||67.2|
Factors affecting VO2max
There are a number of factors that affect an individuals VO2max including: age, gender, genetics/physiology, altitude, bodytype/bodycomposition, training status, exercise type.
Age – Our VO2max is at it highest between the ages of 20-25. As we age our VO2max is known to decrease linearly with age. For most people VO2max decreases at a rate of approximately 0.5ml/kg/min per year. This decrease is due in part to the age related decline in maximum heart rate and stroke volume.
Training, particularly high intensity training, can help to delay the age related decrease in VO2 max. This is likely due to the way training can slow the age associated decline in maximum heart rate and help to maintain stroke volume.
Gender – Male athletes generally record slightly higher VO2max values (approximately 15-30% higher) than female athletes. The difference in VO2max between men and women is influenced by a number of factors including differences in %body fat, muscle mass, blood volume, and haemoglobin levels.
Genetics/physiology – genetics/physiology plays a significant role in VO2max with approximately 10-30% of the variability in VO2max being attributed to genetics.
Genetics appears to influence VO2max through a number of factors including: cardiac output – known to significantly influence VO2max (Poole and Richardson, 1997) , muscle fibre composition, body size, muscle mass, body fat %, mitochondrial density, aerobic enzyme levels, capillary density, lung capacity, viscosity of the blood and the concentration of red blood cells.
Genetics also influences how well we adapt to training. Some individuals show a greater level of training adaptation. Even if two athletes follow exactly the same training plan, there can be significant differences in how they adapt to this training. The differences in adaptation can be seen both in the short term and long term.
Altitude – Altitude can affect VO2max on two levels. Firstly, the decreased air pressure at altitude reduces the availability of oxygen which in turn decreases aerobic capacity. So when at altitude we see a decrease in aerobic capacity compared with when at sea level. The extent of the decrease in VO2max increases with increasing altitude.
There can be wide individual variation in the effect of altitude on VO2max with larger decreases typically being observed in athletes with a higher VO2max’s recorded at sea level.
A secondary effect of altitude, is that the adaptations that occur following sufficient exposure to altitude, can lead to increased aerobic capacity at sea level.
Bodytype/body composition – since VO2max is normally expressed relative to bodyweight any variation in bodyweight will affect VO2max. In this way, athlete’s with a large bodymass (even if its lean bodymass) tend to have lower relative VO2max than smaller athletes.
Body composition is also known to influence VO2max – an athlete with a higher % bodyfat will tend to have a lower VO2max than a similarly sized athlete with a lower % bodyfat.
Training status – training can significantly influence VO2max. The extent of any increase varies greatly between individuals but aerobic capacity can be increased by up to 20%, depending on current fitness, previous training history and your existing training regime.
Despite this, highly trained elite athletes are unlikely to see further significant improvements in VO2max. Typically any further improvements in exercise performance come from improvements in the lactate threshold, % sustainable VO2max and improved exercise economy and the speed or power at which VO2 max occurs.
Exercise Type – the type of exercise is known to affect VO2max with greater values generally recorded in weight-baring exercises (e.g. running) than non-weight-baring exercises (e.g. swimming). Another factor here is that athletes tend to record higher VO2max values in sports they use in training. As an example you would expect to see a runner score higher during a running test, compared with if they underwent a cycling VO2max test.
An individual’s VO2max is tested using an incremental exercise test. During a VO2max test the speed, gradient or power (cycling) is increased in an incremental manner until oxygen uptake peaks. During the test oxygen uptake should increase linearly as the exercise intensity increases. Then at a certain point the increase in oxygen consumption should start to level off/plateau (see graph below). At this point oxygen consumption is at (or near) maximum, and will not increase further even if the exercise intensity is increased further.
In some cases there may not be a plateauing of oxygen consumption – in these cases VO2max will occur during the final stage that can be successfully completed during the test. The general criteria for achieving VO2Max is:
- Levelling off of VO2 with increased work rate <150 ml/min or <2.1 ml/kg/min
- Expiratory exchange ratio > 1.1
- Post exercise blood lactate of > 8 mM
- Rated perceived exertion (RPE) > 18 (Borg 6 – 20 scale)
- If a levelling off is not observed then VO2max is considered to have occurred if two or more of the above criteria occur.
The two graphs (below) demonstrate the plateauing of oxygen consumption with increasing speed or power output. In these examples oxygen consumption increases linearly until at a given speed (running) or power output (cycling) it begins to plateau.
VO2 max tests running
On the graph on the right you can see a typical VO2 response to increasing speed when running. In this example VO2max speed (vVO2max) would be close to 18.5kmh
VO2 max test cycling
When testing VO2 max with cyclist, power is used rather than speed. On the example on the right VO2max power would be around 300w.
Estimating VO2max using field based tests
There are a number of fitness tests that can be used to give an estimate of VO2max, these include:
The Cooper Test
The Cooper run test estimates VO2 max based on the distance covered during a 12 minute run. The formula for the cooper test is:
VO2max = (distance covered in 12 mins – 504.9) / 44.73
I found this test to be fairly accurate for myself:
My lab recorded VO2max = 81
My Cooper test VO2max estimate = (4020 – 504.9) / 44.73 = 78.6
The Cooper test is not accurate for everyone especially those with particularly good economy of motion. It is also far less accurate for those who participate in other sports such as swimming or cycling.
Ratio Between HRmax and HRrest
The ratio between HRmax and HRrest can be used to estimate VO2max (Uth et al., 2004). In this method you divide your maximum heart rate by your resting heart rate and multiply this by 15 to get an estimate of VO2max.
For me this tended to overestimate my VO2max predicting it to be 87ml/kg/min ([197/34]*15 = 86.9) however it is more applicable across multiple sports than the cooper test.
The Balke Test
The Balke Test was originally proposed by Bruno Balke (Balke, B. 1963) and involved running on a track for 15mins. VO2 max is then calculated by the following VO2max = 6.5 + 5*Laps completed.
This formula was then modified by Frank Horwill (Horwill F, 1991) so VO2max = (0.172*(distance in metres/15 – 133)) +33.3. This method tended to underestimate my VO2max predicting a value of around 68 (difference of 16.1%). This particular test appears to be better suited for people with good running economy (reduced oxygen consumption at given speeds) making it less likely to be accurate across other sports.
GPS Watch VO2max Estimate
A number of GPS watches now provide an estimation of VO2max.
This is based on either the relationship between heart rate and speed (running VO2max estimate), or heart rate and power (cycling VO2max estimate). These can be useful as a basic estimate of VO2max, although you often see variation in the VO2max estimate on a day to day basis.
VO2 max training
When we first start exercising, any form of aerobic fitness training can lead to significant improvements in our VO2 max. However, these adaptations quickly slow down. Although we can continue to see improvements, significant changes in VO2max our unlikely in well trained elite level athletes.
However, the training methods used to improve VO2max are highly effective for improving endurance exercise performance. So, even if these may not lead to significant improvements in VO2max they should still form a key part of endurance training.
The current recommendations for maximising VO2max are:
Adequate Training volume – VO2max increases in response to increased training volume, however, training more than 6-7hours of aerobic training per week is not believed to result in further increases in VO2max but can lead to improvements in exercise economy and the sustainable %VO2max. It is important that an adequate amount of the training is performed at low/moderate intensity (approximately 50% of total training volume) and should be performed at approximately 70-80%HRmax.
Interval training – training at between 90 and 100% VO2max – often referred to as high intensity interval training – is believed to be one of the best training methods for placing the greatest physiological stress on aerobic energy systems. This type of training involves performing repeated intervals (e.g. 5*3minute intervals with 60-90seconds recovery) at speeds or intensities that correspond with 90-100% VO2max.
Altitude training/simulated altitude – altitude training has been popular amongst elite endurance athletes looking to enhance performance at sea level.
This is mainly due to the increased stimulation of red blood cell production following exposure to altitude. However, the benefits of living and training at altitude are controversial mainly due to the decrease training intensity at altitude.
Research suggests that a better approach is to either, live at altitude whilst training at sea-level, or, to utilise simulated altitude tents (Levine and Stray-Gundersen, 1997;Bonetti and Hopkins 2009) although it should be noted that there appears to be a minimum exposure of 12h/day required for stimulation of erythropoiesis (red blood cell production) at altitude (Millet et al., 2010).
Final thoughts on VO2max and training
VO2 max is clearly an important determinant of endurance exercise performance which appears to benefit both race performance and the ability to recover after training. However, most research suggests that VO2max does not significantly change in elite or highly-trained athletes and therefore coaches should consider the extent to which they are using training specifically to target further improvements in VO2 max.
Whilst there appears to be a clear benefit to including training at intensities around VO2max intensities (e.g. ~95-105 %VO2 max) it is not clear whether these are as useful for longer term development as lactate threshold or tempo training. Most research that has looked at the benefits of high intensity training has only used very short term interventions (typically using just 4 week interventions). However, we know that long term success is built over many years.
From my own experience VO2max interval training has led to improved performance at intensities close to VO2max but has not always led to improved endurance race performance, particularly in events of >30mins duration, and I have observed better long term progression through lactate threshold training and sub-maximal intervals (~90-95%VO2max) especially when utilising short active recoveries (~20-25% of the effort time). Despite this including VO2max training is beneficial, it just needs to be considered as part of the larger training picture. And, attention needs to be paid to the individual responses to this type of training.
- VO2max is the maximum amount of oxygen that can be absorbed, transported and utilised during a given physical activity. It is normally expressed relative to bodyweight (militres of oxygen per kilogram bodyweight [ml/kg/min]).
- Untrained individuals may have VO2max figures in the region of 25-40ml/kg/min whereas elite endurance athletes often have substantially higher VO2max’s in the range of 60-85ml/kg/min.
- Since VO2max is expressed relative to bodyweight any increase in bodyweight will negatively affect VO2max values.
- Your VO2max is influenced by a number of factors including age, gender, genetics, physiology, body-type/body-composition, training status, and exercise type.
- VO2max is normally established during a laboratory based incremental exercise test in which the speed/workrate is increased until the oxygen uptake peaks or there is a levelling off (plateau) in the oxygen uptake.
- A number of field tests (Cooper test, Balke test, ratio between HRmax and HRrest) have been established to provide an estimate of your VO2max although the accuracy of these tests has been questioned and they tend to produce varied results.
- VO2max can be significantly increased in the untrained or moderately trained – with the greatest improvements occuring with high intensity interval training – although the level of increase appears to be affected by genetic factors.
- Significant increases in VO2max appear to be unlikely in well trained or elite athletes.
- A high VO2max appears to enhance recovery rates after exercise.