The factors that determine VO2 max

Endurance exercise is a physiological challenge to the human body. Our ability to perform for a prolonged period of time is mostly dependent on four factors:

 

1. VO2max;
2. Cycling economy;
3. Maximal sustainable intensity (Threshold);
4. Muscle power.

 

In this article, we will provide a brief summary of the factors that determine VO2max.

VO2max


The most common variable associated with cardiorespiratory fitness is VO2max. This is the maximal rate at which oxygen can be absorbed and used by the body during exercise. There is a strong association with endurance performance and VO2max, with high values (> 70 ml/min/kg) seen in elite endurance athletes.

 

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In order for our muscles to use oxygen to generate force, the oxygen must first be delivered to and extracted by the working muscle. There are numerous processes involved in the delivery of oxygen to the working muscles, and each of these steps is potentially a limiting factor of an athlete’s VO2max.

 

1. Pulmonary diffusion capacity


Pulmonary diffusion is the process of moving oxygen from our lungs, which receive it from the external environment, and moving into the blood where it is then transported to the muscle. At sea level, the movement of oxygen from the lungs (external environment) to the blood, is not a limiting factor to oxygen consumption in healthy individuals.

 

2. Cardiac output


Cardiac output is a measure of the amount of blood leaving the heart per minute. Increases in exercise intensity will result in more muscle being recruited and this will, in turn, result in an increase in cardiac output to meet the demands. The heart is essentially a slave to the working muscles.

 

We typically see large differences in the VO2max values between trained and untrained athletes. The differences in maximal cardiac output between these two populations has been suggested as one of the main differences in VO2max. Endurance training results in an increase in plasma volume, the volume of the heart and the force of the heart’s contraction. All three of these will result in an increase in cardiac output.

 

3. Muscle’s capacity to extract oxygen


Increased cardiac output results in an increased blood flow within the body and as a result, an increase in oxygen delivery to the muscles. In order to make use of the increased oxygen delivery, the muscles must increase their capacity to extract the oxygen. Once the oxygen is extracted from the blood by the muscle, it is used in the mitochondria of the muscles to produce energy.

 

Endurance training results in an increase in the number of mitochondria in the muscles. The increase in mitochondria, means we have more power stations that can consume the oxygen and ultimately produce energy for the muscular work.

 

4. The blood’s capacity to transport oxygen


Increasing the oxygen carrying capacity of the blood is a target of both legal and illegal practices. Spending a prolonged period of time (~ 3 weeks) at a moderate altitude (2 000 – 2 500 m above sea level), is likely to result in an increased number of red blood cells. Increases in the oxygen carrying capacity of the blood will result in improved delivery of oxygen to the working muscles, and ultimately an improved performance.

 

If endurance performance was solely determined by VO2max, we would not need races to determine who the best cyclist in the World was. We could simply measure the VO2max of all the competitors and award the trophy to the cyclist with the highest value. Therefore, endurance performance is determined by more than just VO2max.

 




13 Comments

davidvh, May 17 2018 10:22

How accurate is the VO2max in the Garmin app?

Schnavel, May 17 2018 10:36

How accurate is the VO2max in the Garmin app?

Simply put - it's not

SciencetoSport, May 17 2018 10:41

Hi David

Thanks for your question.

Firstly, I am not sure which algorithm the Garmin app uses to predict VO2max, so I will address predicted values in general. 

Any predicted variable, whether it be maximal heart rate or VO2max, will have some error in the estimate.

The predicted value will be based on a study where, hopefully,  a large number of participants had their VO2max and, heart rate, power output or running speed measured. 

VO2max would then have been correlated to the other variables and the end result would be an equation that allows you to predict VO2max from one of the other variables. 

While this may work for some athletes and produce VO2max values similar to their actual measured values, it could be WAY out for other athletes.

We would always encourage athletes who want to know VO2max or any other variable such as maximal heart rate etc., to have the variable measured directly. 

Predicted variables could be inaccurate. 

I hope that adequately answers your question David.

Thanks for engaging and we hope you found the article interesting.

Headshot, May 17 2018 11:56

How does this information/science relates to cycling activities like enduro racing? Enduro requires extreme  levels of intensity down the hill coupled with lots of climbing over shorter distances. I usually do limited endurance i.e distance, coupled with sprints and high speeds downhill - i.e race simulation. What would work better? 

SciencetoSport, May 17 2018 12:27

Hi Headshot

VO2max or endurance capacity is probably a weak predictor of enduro or downhill performance. 

Repeated sprint ability (intermittent intensity) as well as skill level are likely stronger predictors. 

As mentioned below, there are periods of intense cycling (sprinting) on the way down, but you still need to get to the start of the next segment, so some endurance training is required so you aren't too tired when you start the next timed segment. 

I would recommend that you keep some low intensity (zone 2 or EASY) training in your programme, and include two - three (maximum) sessions a week where the focus is on intensity work. Start with longer intervals, but shorten them as you get closer to the event. Include session like 40:20s (40 seconds on 20 seconds off), which mimic the on/off nature of racing. 

Dr Mike Posthumus explains both periodisation and how to design a training programme in our Cycling Science course. 

You might be interested in having a look at the course overview here:

https://ssisaed.com/...=cyclingscience

How does this information/science relates to cycling activities like enduro racing? Enduro requires extreme  levels of intensity down the hill coupled with lots of climbing over shorter distances. I usually do limited endurance i.e distance, coupled with sprints and high speeds downhill - i.e race simulation. What would work better? 

davidvh, May 17 2018 01:34

Hi David

Thanks for your question.

Firstly, I am not sure which algorithm the Garmin app uses to predict VO2max, so I will address predicted values in general. 

Any predicted variable, whether it be maximal heart rate or VO2max, will have some error in the estimate.

The predicted value will be based on a study where, hopefully,  a large number of participants had their VO2max and, heart rate, power output or running speed measured. 

VO2max would then have been correlated to the other variables and the end result would be an equation that allows you to predict VO2max from one of the other variables. 

While this may work for some athletes and produce VO2max values similar to their actual measured values, it could be WAY out for other athletes.

We would always encourage athletes who want to know VO2max or any other variable such as maximal heart rate etc., to have the variable measured directly. 

Predicted variables could be inaccurate. 

I hope that adequately answers your question David.

Thanks for engaging and we hope you found the article interesting.!

 

Thanks for the response!

Robbie Stewart, May 17 2018 02:52

So I'm curios. My HR when I ride / train on spin bike is generally high. Ave HR always hovers around 148 - 154 bpm for spin sessions, and around 166 - 168 for riding sessions. I ride a mix of trails and cross country terrain on MTB, but can generally outlast my boet on any given ride. He on the other hand maintains a low HR average, and says no matter how hard he tries, he finds it excessively difficult to breach +- 124 bpm Ave HR, and when we ride together, I out-climb him by quite some margin on most days. I mostly end up waiting for him at the tops, whereby he catches up but looks much more worse for ware and needs extended recovery time. One caveat is he smokes, but I am 6 years his senior at 41.

I am guessing that the VO2 (and the effect of cigarettes) uptake has a lot to do with this outcome?

milky4130, May 17 2018 03:37

How accurate is the VO2max in the Garmin app?

For me personally a test I did in the lab back in 2015 vs. what Garmin predicted for me a few weeks ago, was not that far off. My level of fitness this year has been the best in years therefore for me I can use it as an estimator of where I am currently. Luckily we don't use the Garmin value for anything except to indicate our level fitness at any given point in time.

milky4130, May 17 2018 03:41

@S2S points 2 & 3 makes mention of "Endurance Training" with reference to this article what is the definition of "Endurance Training", lots of 65%-75% Zone riding or will it be Zone 2+ some Zone 4 + Zone 5 intervals as well?

SciencetoSport, May 17 2018 04:06

So I'm curios. My HR when I ride / train on spin bike is generally high. Ave HR always hovers around 148 - 154 bpm for spin sessions, and around 166 - 168 for riding sessions. I ride a mix of trails and cross country terrain on MTB, but can generally outlast my boet on any given ride. He on the other hand maintains a low HR average, and says no matter how hard he tries, he finds it excessively difficult to breach +- 124 bpm Ave HR, and when we ride together, I out-climb him by quite some margin on most days. I mostly end up waiting for him at the tops, whereby he catches up but looks much more worse for ware and needs extended recovery time. One caveat is he smokes, but I am 6 years his senior at 41.

I am guessing that the VO2 (and the effect of cigarettes) uptake has a lot to do with this outcome?

Hi Robbie

Thanks for the question. It is important to remember that each individual cyclist is unique and therefore training intensity prescription should also be unique. For example, Cyclist A (25 years) has a maximum heart rate of around 174 beats per minute while Cyclist B (32 years) has a maximum of around 199 beats per minute. The age-old formula of 220 – age to determine maximum heart rate, is not relevant to either of these individuals. A revised equation of 206.9 – (0.7 x age) improved the accuracy of the maximal heart rate prediction, but the most accurate determinant of maximal heart rate is still performance testing. These days many devices provide you with a predicted maximum heart rate, and training zones based on this predicted maximum. Once again, these training zones may provide you with a guideline for training intensity, but they can be greatly improved upon via performance testing.

Researchers at Western State Colorado University recently investigated whether training according to percentages of heart rate reserve (HRR) was as effective as training according the individualised training zones determined from performance test data. The group who trained according to individualised training zones showed greater and more uniform improvements in VO2max compared to the group which trained based on percentages of HRR. If you are interested in reading more, the full article can be found here: https://www.ncbi.nlm...odel a superior

 

Make sure that you only track your heart rate, because someone else's heart rate value, will provide no input on your own intensity. 

 

Smoking can reduce the pulmonary diffusion capacity (see point 1 above). So I would expect to see a reduced VO2max in someones who smokes compared to someone who doesn't. 

SciencetoSport, May 17 2018 04:09

@S2S points 2 & 3 makes mention of "Endurance Training" with reference to this article what is the definition of "Endurance Training", lots of 65%-75% Zone riding or will it be Zone 2+ some Zone 4 + Zone 5 intervals as well?

Hi Malcolm

Thanks for the question. 

'Endurance training' refers to both low-intensity and high-intensity training. We realise it is a bit broad, but both low and high-intensity training will result in increase cardiac output and the number, size and function of mitochondria. 

I hope that answers your question. 

milky4130, May 17 2018 04:12

Hi Malcolm

Thanks for the question. 

'Endurance training' refers to both low-intensity and high-intensity training. We realise it is a bit broad, but both low and high-intensity training will result in increase cardiac output and the number, size and function of mitochondria. 

I hope that answers your question. 

It does thanks, all the terminologies can sometimes be overwhelming & bit confusing, so just wanted to be sure.

milky4130, May 17 2018 10:12