After some recent chat on a club ride about training and VO2max, I thought I’d outline some key factors to help you understand more about your performance as a cyclist or runner. There's an increasing trend to find the magic interval session, and these are usually based around VO2max training. I'm not disputing that 6-8 weeks of VO2max intervals will give you a decent fitness boost, but it will plateau pretty quickly. There is more to training than simply doing the high intensity work.
So, your ability to run or ride fast will come down to 4 things.
1 - Maximum Oxygen Uptake (VO2max)
2 - Anaerobic Threshold
3 - Economy
4 - Fatigue Resistance
Maximal Oxygen Uptake (VO2max):
VO2max is the maximum amount of oxygen you can bring in and use in the working muscles. It’s measured as an absolute value in L/min, taller people generally have higher L/min readings as they have bigger heart and lungs (usually, but not always). This is why we often see VO2max values often normalised to body mass and expressed as ml/kg/min. It’s the test that Mark Cavendish famously didn’t meet the standard for the British cycling academy. Some examples include Paula Radcliffe who was around 70 ml/kg/min, Chris Froome was 88.2 ml/kg/min, Greg LeMond 92 ml/kg/min and Rob Watson....52.6 ml/kg/min. In my defence, I’d spent the 5 weeks prior to that test laid up with a virus (not Covid) so I’d hope it’s a bit better than that normally! Your VO2max sets the ceiling for the amount of oxygen you can bring in and utilise. Increasing it will help performance, but it’s not everything.
Anaerobic Threshold:
This is the percentage of VO2max that can be sustained during performance, its closely associated with an increase in lactate accumulation within your blood to around 4 mmol/L (fig 1). There are several definitions on what ‘threshold’ is, it can be called functional threshold power, maximum lactate steady state, critical power, or any other number of terms, which in practical use outside a lab mean the same thing. I’ll call it anaerobic threshold for now.
Fig 1
What it aims to identify is a maximum speed or power you can sustain for an extended duration of time with a relatively stable blood lactate level. This is usually more than 40minutes, but it’s often defined as 1 hour. Nobody really knows why we use 1 hour, it’s an arbitrary time as your power/speed won’t fall off a cliff at 61minutes. This can differ between individuals, for example 2 athletes could both have VO2max of 60 ml/kg/min. Athlete A’s lactate threshold occurs at 70% of their VO2max, Athlete B’s occurs at 80% of their VO2max, meaning athlete B would more likely be faster.
One point to consider is that there is no such thing as a steady state, no matter what intensity you exercise at, it will eventually become unsustainable.
Economy:
Economy is defined as the amount of oxygen required to move at a specific speed or power. A good economy means you will use less oxygen at that given workload, which is of huge benefit as you are using a lower % of your VO2max to produce the energy to keep moving. Better economy means you can create your energy via the virtually limitless sources of fats and oxygen, saving glycogen stores (which are limited) for higher intensity effort later in your race.
Fatigue Resistance:
This is your ability to maintain performance levels for the duration of your event. It’s hard to measure as there is no standardised test because, by definition, it is event specific.
For cycling, one way to assess this could be to test power output in 2 separate occasions, 1 in a fresh state and 1 after a defined amount of work, distance or time has been completed. The difference between these tests will identify how your power drops after a given workload.
For example, a cyclist using a power meter would complete a 20min power test in a fresh state, achieving a 300w average. 2-3 days later they complete a 20min power test after a set amount of work, 2000 kilojoules is an often-used number (roughly 4 hours of easy riding). They achieve an average 270w for 20minutes in the second test. The 30w deficit will give you the starting point, the closer you can get to the result from the fresh test, the better your fatigue resistance is. The benefit of improved fatigue resistance is that races are not won in a fresh state, the decisive moments are usually at the end when everyone is tired and the rider who is able to resist that tiredness (fatigue) produces the best performance. We all know that rider or runner who is great on the first hill but is nowhere to be seen towards the end of the session.
I believe it comes down to the key training principle of specificity in your training, making sure you’re training for the performance you need to produce.
Putting it all together:
Paula Radcliffe provides an excellent case study of how these 4 pillars interact to progress an athlete's performance. Radcliffe broke the world record for the marathon in October 2002 and April 2003, the latter a record stood until 2019. Find the link to the study by Andy Jones in the references at the bottom of the page.
VO2max - This is pretty consistent throughout her career between 67 and 71 ml/kg/min (fig 2), with only 1 year showing a significant bump (2001) to 75 ml/kg/min. But, if VO2max is so important why didn’t she break the world record in 2001? This is where it gets a little more complex because a high VO2max tends to reduce economy and vice-versa, it appears you can’t have both due to the way energy is created in the muscle cell.
Fig 2
Economy - The next 2 graphs are where it becomes clear why her performance improved over her career. In fig 3, she was instructed to run at 16kph and the oxygen she needed to do this was measured. As you can see, she required less oxygen year-on-year to run at the same speed, her body became better at creating energy to run at this speed.
Fig 3
Speed at VO2max - Fig 4 shows the running speed she was able to attain at VO2max and how this increased steadily over her career. For example, if you’re doing a ramp protocol on the bike or treadmill it means you’re breathing at the same rate and taking in just as much oxygen as previous years but you’re going faster/producing more power. This improvement is partly due because of increased economy, using the oxygen more efficiently to produce energy. Anaerobic threshold also increased steadily over the 12 year period from 14–15 kph in 1992–1994 to 17.5–18.5kph in 2000–2003.
Fig 4
I’d like to think that you have 100 tokens to spend on your training activities. You could spend 25 tokens working on economy, 25 on lactate threshold, 25 on fatigue resistance and 25 tokens working on top-end (VO2max) which should result in you being well prepared in all areas. Depending on your event or the time of year, you may spread these tokens differently. For example, if you race 45minute criteriums, economy is less important so you may choose to spend more tokens on VO2max work and less tokens on building economy through low intensity aerobic work. But, if you are an marathon-runner or ultra-distance cyclist you should spend more tokens towards becoming more economical with your energy. In practice it’s not quite as simple as that but it provides a good guideline to focus your training activities towards your goal.
In summary, VO2max is important and someone with a VO2max of 52.6 ml/kg/min is unlikely to become an Olympic champion runner. There seems to be a big focus on VO2max intervals in modern training, they are more interesting than long duration low intensity sessions and are less time consuming. They may give you a short bump in performance, but if you’re looking for long term adaptations from your training you need to look at improving anaerobic threshold, economy and fatigue resistance too.
How I can help you:
Strength Coaching - https://www.rwperformance.net/winterperformancepackages
Cycle Coaching - https://www.rwperformance.net/cyclingcoaching
References: