What is V02 max?
V02 max is the volume (V) of oxygen (02) the body can absorb and utilise in one minute whilst working at maximal capacity (max). It is measured in ml/kg/min and is a good indicator of overall cardiopulmonary fitness.
Why is V02max important to endurance runners?
If you think of your muscles like a car engine, your muscles need fuel (fats, carbs) to power them and a steady supply of oxygen to ‘burn’ the fuel and provide energy. Oxygen plays a key role in facilitating aerobic metabolism, which burns fuel to provide energy to working muscles during endurance efforts. If there is an insufficient oxygen supply within the muscles, your body will start producing energy via other means (anaerobic glycolysis). This is not a sustainable means of energy production and will result in bi-products such as lactic acid accumulating in the blood, impacting performance. Consequently, a high V02 max is desirable as it will provide more oxygen to your working muscles, which increases the duration you can run before being inhibited by these bi-products.
There are many physiological factors which influence your ability to uptake oxygen. Whilst these factors are largely genetically predetermined, through endurance training the following adaptations can occur:
Increased cardiac hypertrophy – your heart grows bigger and stronger and is able to contract more forcefully, therefore pumping more oxygenated blood around the body per beat (i.e. increased stroke volume)
Decreased resting heart rate – as your heart can pump more blood per beat your heart beats less at rest to meet oxygen demands
Increased haemoglobin in blood - oxygen carrying red blood cells
Increased capillary density in lungs and muscles – increased rate of oxygen diffusion through alveoli (air sacks) of your lungs into the blood stream and from the blood stream into the muscle
Increased number of slow twitch muscle fibres – These types of fibres have a higher concentration of myoglobin (stores 02 in muscles) and mitochondria (facilitates aerobic energy)
All these variables combined, influence how efficient your body is at extracting oxygen from the blood, therefore affecting your running economy. You might be thinking this measure is biased as a taller/larger person will naturally have a larger heart, lungs and greater blood volume and thus be able to uptake more oxygen at max. Whilst this is true, we control for this by measuring V02max relative to body weight, height, age and gender.
Measuring V02 max provides endurance runners with individualised baseline data which gives an indication of current running performance and efficiency. Results of the V02 max assessment, including relative heart rate data, training zones, and V02max score, can inform training to help increase V02 max. Through training you can improve on the physiological factors highlighted above. Retesting 3-6 months later can assess the effectiveness of your training regime, as well as determine your new and improved training zones.
How is the test performed?
The V02 max test can be performed on a treadmill or stationary bike. Prior to the test commencing you must ensure you are wearing comfortable exercise clothes, are well hydrated and haven’t consumed any coffee or alcohol. You will be fitted with a heart rate monitor around your chest and face mask for gas analysis.
Our treadmill test follows the Modified Bruce Protocol which is set up in 3 minute stages, beginning at a warm up pace and gradually increasing in intensity, by increasing incline and speed. The test will end when you can no longer sustain running at the current intensity. This typically corresponds closely with your maximum heart rate and maximum RPE (rate of perceived exertion) value.
At the end of the test we have obtained a V02 max score which is derived from measuring the amount of oxygen inhaled into the body versus the amount being exhaled in 1 minute whilst at maximal effort. This number affectively tell us how efficient your body is at extracting the oxygen.
What do the values mean?
The formula for calculating V02 is as follows: V02 max = Q (CaO2 – CV02)
At first this might look complicated but if we break it down the equation is relatively simple.
Q = Cardiac output (How much blood is being pumped in 1 minute)
Ca02 = Concentration of arterial oxygen (How much oxygen has entered the blood via the lungs in one minute)
CV02 = Concentration of venus oxygen (How much oxygen is in the blood after being consumed by the muscles in one minute)
In simpler terms, we calculate how much oxygen has been consumed by the muscles and multiply this by the amount of blood being pumped around the body in 1 minute whilst working at maximum effort. Taking age, gender and weight into account, this will tell us how many mL of oxygen per Kg of body weight we can utilise in 1 min(mL/Kg/min). We can then compare our results to normative data to gain an idea of our current fitness levels in relation to the general population.
Using this table, a 25 year old male with a V02 max score of 50 mL/Kg/Min could conclude that their fitness level is excellent in comparison to the general population.
How to use V02 max to inform your training
If we know your V02 max score and heart rate training zones we can begin to train smarter and focus your training on improving the physiological factors which drive performance. Following your test, you will receive a detailed report outlining your results, training zones, and suggested training.
Example V02max results
Improving your V02 max through endurance style running is a crucial first step and enhances many of the physiological markers for an economical runner such as increased capillarisation, increased mitochondrial density and stronger connective tissues. However, studies have also shown that the most effective way to train to simply enhance your V02 max is through high intensity interval training (HIIT). This style of training aims to get an athlete into 90-100% of their heart rate max, for a short duration. For example, a runner might run 10 rounds of 1 minute at their V02 max pace (90-100% HR max) and then slow down to a light jog (50% HR max) for 1 minute. By keeping the intervals short and rest long we ensure that lactic acid is not accumulating in the blood, which allows the athlete to continually train in that high intensity zone without fatigue playing a role.
The red circles in the above graph demonstrate how we are able to accumulate time spent in the V02 max zone, through high intensity bouts with equal rest time. Once the body has adapted to the current training regime, we are ready to progress the training intensity. We can either alter the time spent in the training zone (e.g. 2 minutes work with 2 minutes rest) or increase the number of sets (e.g. from 10 rounds at 1 min to 15 rounds at 1 min).
It is important to note, that high intensity interval training is only recommended once you have established a strong endurance base, to ensure your muscles, and connective tissues are strong enough to handle speed running. If you’re itching to get into it straight away though, there are other options to increase V02 max without the high demand of speed work.
In a 2019 study Menz, et.al., explored whether functional HIIT (body weight squats, push-ups, burpees, etc) is as effective as traditional running HIIT when it comes to improving V02 max. Interestingly, they found that classic running HIIT and functional HIIT both improve V02 max and affect muscular endurance to the same extent despite a lower cardiovascular strain in the functional protocol. This tells us that as long as we keep high intensity with the same work to rest ratio, we can vary the mode of training and still achieve similar results. This is particularly important for newer runners or those who avoid speed intervals and sprints due to susceptibility to injury.
Following a few months of progressive interval training, re-testing V02 max, will assess the effectiveness of your training program.
How do I get tested
To organise a test, you can book here.
About the Author
Brendan Todd is a sport and exercise scientist and strength and conditioning coach at Sydney Performance Lab & North Shore Running & Outdoor Fitness. He is a football player and avid sports fan with a passion for using science to improve athletic performance. Outside of work you’ll find him on the sports field, behind a guitar/drum kit or out exploring Sydney’s pubs/restaurant scene.
Bassett, D., & Howley, E. (2000). Limiting factors for maximum oxygen uptake and determinants of endurance performance. Medicine and science in sports and exercise, 32 1, 70-84 .
Hasan, Muhamad. (2020). The Effect of Circuit Weight Training on V02Max. 10.2991/ahsr.k.200214.090.
Menz, V., Marterer, N., Amin, S. B., Faulhaber, M., Hansen, A. B., & Lawley, J. S. (2019). Functional Vs. Running Low-Volume High-Intensity Interval Training: Effects on V02max and Muscular Endurance. Journal of sports science & medicine, 18(3), 497–504.