Sports Performance, VO2Max

What we learnt from 750 fitness tests (2): Power, Endurance and VO2Max

[In Part 1 of this analysis of over 750 fitness tests conducted on Revvo, we looked at how metrics of overall fitness (VO2Max, Recovery) correlated with activity, weight and other demographic indicators.]

In this second part, we’re taking a deep dive into some of the performance metrics we collect on Revvo, to better understand how they correlate with each other.

MAX POWER (ANAEROBIC CAPACITY)

Max power is the maximum cycling output, measured in watts that an individual can produce on average over 30 seconds (called a Wingate protocol) and is considered one of the best ways to measure anaerobic capacity / output. I think of this as “sprint power”.

Revvo measures max power by guiding the individual step by step through a ~15 minute fitness test where the target increases progressively until the person reaches exhaustion. (Click here to see how the test works).

Max power was pretty well distributed across the 750+ tests and centered around 300-400w – with men producing on average ~100 watts more than women. Gender differences in max power persisted even after correcting for weight (men produced 5.1 watts / kg on average versus women who produced 4.4 watts/kg) and might reflect underlying differences in fitness levels and body composition.

 

 

This slideshow requires JavaScript.

VO2Max and Max Power

VO2Max had a strong positive correlation with max power – both in absolute terms and particularly when adjusted for weight (max power in watts / body weight in kg). Higher aerobic capacity could therefore create a strong foundation to help maximize anaerobic output.

 

This slideshow requires JavaScript.

Its also well established that high intensity (anaerobic) interval training is very effective at improving VO2Max. Tabata et al studied the effects of moderate intensity endurance and higher intensity interval training on both VO2Max and anaerobic capacity. The study found that high intensity interval training increased both metrics significantly, whereas moderate intensity endurance training only increased VO2Max (to a lesser degree).

So while VO2Max could improve without increase in anaerobic capacity, it seems likely to improve more when anaerobic capacity is also simultaneously targeted/increased.

Weight and Max Power

Does body weight make a difference to your max power output? Other things being equal, the heavier you are the more power you should be able to produce on a cycle due to sheer gravitational effect. And that’s what the data shows – max power in absolute terms increases with body weight.

 

This slideshow requires JavaScript.

However, max power per unit of body weight declines with increase in weight — i.e. heavier you are, less the power produced per unit of your body weight. And max power / kg is a better indicator of performance on the road, particularly when going uphill.

Recovery and Max Power

Could your state of recovery affect your max power output? Turns out it does – doubling your recovery (e.g. from ~5%, which is low to about 10%, which is good), increases max power by around 0.25w/kg – which can make all the difference in a competitive sprint.

Max Power X Recovery

THRESHOLD (ENDURANCE)

Revvo detects the lactate threshold by analyzing the heart rate response to different levels of stress as the individual progresses through an intermittent ramped cycling test.

Lactic acid is produced as a by-product when muscles use glucose as fuel, creating the familiar sensation of “burn”The lactate threshold is the highest intensity at which you can tolerate the amount of lactic acid being produced and can therefore sustain. As a result, the threshold has a ~90% correlation with endurance performance.

Web graphics 3 ThresholdAt intensities above the threshold, there is excess lactic acid produced, slowing you down when you cannot tolerate the “burn” anymore.

Screen Shot 2017-10-27 at 2.17.31 PM

Based on the threshold watts per kilo of body weight, cyclists are typically classified into the following 9 categories. Where Pro are typically national champions and elite are world class.

 

 

The distribution of the Revvo sample is below — with a good spread from Cat 3 (experienced cyclists) to novices.

Threshold Distribution

Threshold and VO2Max

How does VO2Max impact the lactate threshold — in theory the two are semi-independent. High VO2Max is a necessary but not sufficient condition for endurance performance.

And the results confirm that — there is a positive but weak correlation between VO2Max and threshold in absolute terms. The correlation does strengthen when we consider threshold watts / kg but this is still not as high as that between VO2Max and Max Power.

 

This slideshow requires JavaScript.

The implication from a training perspective is to focus on the factor that is relatively weak — improving that will deliver the biggest bang for your effort. And to polarize training (mid of high intensity interval training and moderate intensity endurance training) so that is able to target these two systems more directly and effectively.

Threshold and Weight

The relationship between threshold and weight is very similar to that between max power and body weight. In absolute terms threshold output increases with body weight but threshold watts/kg declines fairly significantly as weight increases. A 25lb. increase in body weight is the equivalent of dropping one category in terms of threshold output.

 

This slideshow requires JavaScript.

Threshold and Recovery

Low recovery clearly dampens threshold output, very similar in magnitude to the effect on max power.

Threshold X Recovery (2).png

MAX POWER AND THRESHOLD

Cycling is a sport that requires both endurance and power (to take on hills) – elite cyclists need to develop both capabilities. So not a surprise that there is a pretty high correlation between the two.

Threshold X Max Power

SUMMARY

Traditionally, studies on performance metrics have been conducted largely amongst population of well trained athletes and as such its hard to see much divergence in these metrics across populations that have been training for long periods of time.

The Revvo sample on the other hand reflects a much broader range of individuals and therefore we are able to see how these metrics perform in less trained individuals / closer to their natural state.

From the perspective of an amateur endurance athlete in particular, it seems very likely that different individuals (even with similar performance levels) may have very different physiological make-ups. And understanding the underlying physiological make-up would allow you to customize the training program — so you’re targeting the area of greatest personal opportunity for improvement.

Advertisements
VO2Max

What We Learnt from 750 Fitness Tests!

TL;DR

Weight is a very poor proxy for fitness (even though culturally we think fitness = “being in shape”). Increasing activity improves fitness but does not lead to lower weight. Fitness declines with age, but this is not a given. Improving recovery is an ‘easy’ win for everyone.

THE FULL ANALYSIS

Revvo is the first exercise bike to measure an individual’s fitness profile : Aerobic Fitness/VO2Max, Recovery and Endurance/Threshold. And right from the earliest test, we’ve captured information on the individual’s demographics and current weight, activity levels (mainly because it was required pre-screening information).

1. Test Fitness

While we’re definitely not the first to aim to understand how these different variables correlate, the fact that we are measuring a wider range of variables on the same individuals with a pretty high degree of accuracy and consistency should hopefully provide some additional insight. Details on the test methodology can be found here: Revvo: Science.

1. We tested people across a wide range of fitness levels

While our sample is not a fully representative one (we do not have many at the lowest and highest ends of the fitness spectrum), it does represent a broad spectrum of fitness levels – both in terms of VO2Max and Recovery.

VO2MaxRecovery

Interestingly, Recovery is skewed lower than the VO2Max results and this is something that we’ve anecdotally observed in quite a few “fit” individuals. Recovery is partly an indicator of lifestyle – stress, lack of sleep will show up here. So if you’re looking to enhance performance or general wellness, check your heart rate recovery status — sleeping better and reducing stress might give you immediate results.

2. If you’re already fit, focus on recovery

In fact this opportunity to improve Recovery becomes more obvious when you cross-analyze VO2Max and Recovery data. In general, there is a positive correlation between the two i.e. higher the VO2Max, higher the expected Recovery. However this is a weak correlation as you’ll see from the plot.

Vo2Max Vs. Recovery.png

I’ve often seen people with relatively poor VO2Max scores who’re doing fine from a health perspective since their heart rate recovery is good and also fit people with poor recovery that indicates underlying health issues (perhaps genetics the culprit here rather than lifestyle). Fit people also often have poor recovery due to excessive training loads i.e. if you ran an ultra-marathon over the weekend, it will take a few days for recovery to return to normal levels.

3. You could be fat & fit or thin & unfit

We often conflate weight and fitness – but these are two semi-independent variables. We’re seeing lots of people who are relatively heavy but score pretty well on VO2Max (despite the fact that weight is the denominator in VO2Max calculations). And on the other hand many who have perfect BMI but with suffer from aerobic fitness.

VO2Max Vs. Weight.png

Above 250lbs however, its rare to find someone who’s really fit. But below 200lbs there’s a huge variation in fitness levels – if we only analyzed that population there would be very little correlation between fitness and body weight. So just because some looks thin doesn’t mean they are fit and vice versa.

Recovery versus body weight shows the exact same pattern.

Recovery Vs. Weight

4. Being active improves fitness, but doesn’t impact body weight

We’ve now seen a ton of data confirming that activity, on its own, doesn’t seem to make much difference to body weight. And our analysis supports that conclusion.

There’s practically zero correlation between how active people say they are and how much they weigh and a slight negative correlation when you contrast BMI vs. Activity. Yet we keep telling people that they should exercise more to lose weight, setting them up for failure!

Body Weight Vs. Activity

BMI Vs. Activity Level

Why does increasing activity levels not help with weight loss? Vox did a fantastic summary of the available evidence in this video and article.

The real benefit of activity is an improvement in fitness – and this is what our analysis reveals as well. Higher activity levels correlate pretty well with higher levels of fitness.

And aerobic fitness (VO2Max), as I’ve explained before, is not just an indicator of athletic potential but also the single best overall indicator of health. The primary purpose of exercise is to improve the functioning of your heart and muscle. Weight loss, if it happens, is a spin-off benefit.

Therefore if you want to assess if exercise is yielding results, track your fitness level, not your body weight.

VO2Max Vs. Activity

This is not of course not a perfect correlation as different types of activities have different effects: walking for an hour will not improve VO2Max as much as 10 minutes of high intensity interval training. And genetics also effects how well activity translates into an improvement. Which is why, even for people at the same level of activity, there is such a wide variation in fitness levels.

The correlation between Recovery and Activity is not as strong – and this makes sense. Lifestyle factors (sleep, stress etc.) often have a bigger effect on improving Recovery than increasing activity per se. And of course being too active can negatively impact Recovery. Recovery is intrinsically a more complex variable.

Recovery Vs. Activity

5. Fitness can – but need not – decline with age

At a general population level, VO2Max is reckoned to decline ~1% per year as we age and our analyses confirms the broad trend. However within that trend, there is huge variation: we’ve seen so many young people who are less fit than their grandparents and so many older individuals who’s fitness level has been an inspiration to me personally.

So your fitness is in your hands (or legs!).

VO2Max Vs. Age

Recovery seems to be even less correlated with declining age.

Recovery Vs. Age