Exercise is arguably the most important, and most neglected, tool in our quest to live the longest and healthiest lives that we can, which is why we put so much emphasis on it at NiaHealth. How fit you are impacts all areas of your health from how likely you are to develop diabetes to your risk of many cancers. Our most important fitness metric is VO2 max, which has been shown to be particularly important for your heart health.  

VO2 max is literally the maximum amount of Oxygen that your body is able to use while you are exercising - but that is not a particularly useful definition so let’s unpack it.

Imagine you start jogging at a steady pace on a treadmill. After a few seconds you might notice that you are breathing a bit harder and your pulse has increased. Your body is responding to the exercise by sending more blood through the lungs where it picks up oxygen to take to your leg muscles. 

At this point your legs are hopefully feeling okay with no pain as this is a fairly easy pace. It’s not painful because your muscles are able to get all of the energy they need from ‘aerobic’ respiration. This is the energy producing process that most of our cells use all the time - and it requires oxygen.

Aerobic respiration is great because it gives the muscles lots of energy without producing harmful waste products. But what happens if we suddenly increase the incline and speed on the treadmill? 

You start breathing much harder, and your pulse rate goes up even further. Your body is trying to deliver more oxygen to your leg muscles which are now working much harder.

After a few more seconds of this unpleasant treatment your legs will start burning and you will feel like you are gasping for breath. At this point your heart and lungs have reach the limit of how much oxygen they can send to the muscles.

To keep going, the muscles have to switch to anaerobic respiration - which doesn’t require oxygen. This is much less efficient and importantly produces a waste product called lactic acid. That burning in your legs is lactic acid building up in the muscles as they struggle to keep up with the demands of the treadmill.

The point where your muscles have to switch from aerobic to anaerobic respiration occurs when you exceed your “VO2 max” - the maximum amount of Oxygen you can consume in a minute. Technically, it’s the rate at which your body can use up oxygen during a maximum effort which is why the units are milliliters of oxygen per kilogram of body weight per minute. 

VO2 max depends on lots of factors including how good your muscles are at taking up oxygen, and how well your blood can carry oxygen. But most importantly for heart health, it’s a key indicator of how well your heart can pump. Which is probably why it’s such a good predictor of mortality. 

Research comparing VO2 max levels in people of the same age has shown that if you are in the bottom 25% your risk of mortality in the next 10 years is 4 times higher than someone who is in the top 10% of people. This is 10 times the increased risk of dying that comes with smoking cigarettes.

This should be both scary and encouraging because VO2 max is one of the risk factors that we can make the most difference to by following a tailored exercise plan. In fact, raising VO2 max by just 1ml/kg/min can reduce your risk of dying in the next ten years by as much as 9%. 

If you want to find out more about VO2 max testing and how we use it have a look at our sample dashboard.

Key Resources 

• More details on VO2 max testing from the Cleveland Clinic (our testing partner): https://health.clevelandclinic.org/what-is-vo2-max-and-how-to-calculate-it

Key academic sources:

• Strasser, B. and Burtscher, M. (2018). Survival of the fittest VO sub 2 sub max a key predictor of longevity. Frontiers in Bioscience, 23(8), pp.1505–1516. doi:https://doi.org/10.2741/4657.
• Harber, M.P., Kaminsky, L.A., Arena, R., Blair, S.N., Franklin, B.A., Myers, J. and Ross, R. (2017). Impact of Cardiorespiratory Fitness on All-Cause and Disease-Specific Mortality: Advances Since 2009. Progress in Cardiovascular Diseases, 60(1), pp.11–20. doi:https://doi.org/10.1016/j.pcad.2017.03.001.

All the views expressed here are based on careful research conducted by the research team at Niahealth. However, in some places we have omitted certain details for the sake of clarity and simplicity. If you have any questions about our research or the content of this blog email our head of research Dr Robin Brown at : robin@niahealth.co