Tuesday, January 20, 2015

Why Some People Run Fast

So I get lots of questions from people all the time about how to get better. The below is my understanding of the science and it seems to make sense to me. Sports scientists please take pity on a layman.


There are 3 main physiological drivers for athletic performance in races of 3k and longer and less than marathon (e.g. ignoring the peculiarities of MD performance and the lactic acid complexities and the whole fat-burning lipids / glycolitic stuff). The trick to getting yourself into great shape is by triggering the adaptations required in the right way. Each of these triggers can be improved by training as hard as possible but that's almost certainly likely to lead to injury.
  • Vo2 Max
  • Lactate Threshold
  • Running Economy (or aerobic efficiency)
Now these interact in different ways but essentially your "maximum" performance potential is set by your Vo2 max. Let's say yours for arguments sake is approximately 72 which wouldn't be an unreasonable figure for a ~30 minute 10k runner. You then run most distances at a percentage of your VO2 max. Let's say your lactate threshold (which governs 10 mile / half marathon performance) is right now about 80% which wouldn't be unreasonable. 

So when you do a 10 mile or HM race you'll be taking in approximately 58 millilitres of oxygen per kg per minute - on its own the amount of oxygen you take is a relatively good proxy of speed (hence why Jack Daniels uses the term VVo2 max / V-dot and directly correlates a VO2 figure with paces). Now let's say you're racing someone with a VO2 max of 80 (which would probably be a top class MD runner) but their lactate threshold occurs at 75% of their VO2 max. They would be running at 60 millilitres - generally we would roughly expect the two of you to be quite close in the race with him having a slight edge ignoring the psychological components, drafting etc. This is if we’ve locked the two of you in separate rooms with treadmills and no knowledge of the other performance.

The final element (and the key one) is running economy / efficiency or how your use of the oxygen translates to a running pace. Using 58 millilitres of oxygen per kg per minute you may be able to produce a 5:00mm performance. On the other hand your rival may be less efficient and require 60 in order to run at 5:00mm pace - now the two of you are dead even. 

The training we normally do is designed around improving these three factors (in different priorities at different times) whilst minimising the stress on your body.

VO2 Max

VO2 max is basically the maximum amount of oxygen you can take in - anything longer than about 6-8 minutes of exercise and the amount of oxygen you can take in is no longer the limiting factor. Below 6 minutes and you will be constantly running at maximum oxygen and so your body finds other ways to compensate (mostly by hugely increasing the amount of lacate in your blood stream causing you to rig up due to negative hydrogen ions apparently!)).

There are lots of ways to improve it but the most basic one is by running more mileage. Until you hit around 80 miles per week your VO2 max will continue to increase and you need to stay a while at that volume to maximise the gains. This makes a lot of sense to me - I (and lots of others) have seen big improvements over 1500-5k performance without doing any specific work at race pace but just by running a lot more. Put another way - if you take a sedentary individual and get them to run 80 miles per week they would run a significantly faster 1500m after a year than they would have done without any training!

The other way to improve VO2 max is by doing intervals at between 3k - 5k pace and these should be done with roughly equal recovery ( if you make the reps too long, too often or with too short recovery - you either compromise pace by the end of the session or you take yourself out of action for too long). You want to maximise your time at VO2 max which means generally intervals of 2-5 minutes (with 5 minutes being at 5k pace and 2 minutes at 3k pace). One point to note is that you gain nothing by running faster than your VO2 max which is why I generally try and limit the pace people run in these sessions - you can run them faster but running them faster doesn't help maximise your time at VO2 max.

Intervals whilst they can "super-boost" the VO2 max often have only a limited period of effectiveness with the benefits after 6 weeks being significantly decreased (unlike the mileage which takes much longer to take effect) and why they are often the staple of "six weeks to your new PB" schedules. 

On a side note - due to the nature of VO2 max (oxygen per kg of body weight per minute) I'm sure you can see that there's a variable there that can be substantially changed without necessarily any training. Weight. That's the main reason why you sometimes see people who look skeletal running fast for a short time period - this never works in the long term because they then can't improve any further as their bodies are totally incapable of taking the mileage and intervals they need to improve- often bone density is compromised. 

Lactate Threshold

Lactate threshold (or more specifically maximum lactate steady state) is the intensity where your body can manage to clear the lactate from your body being generated by the intensity. You can over time gradually increase the intensity that you can run at whilst clearing the lactate successfully and keeping your body in equilibrium. 

This is a highly trainable characteristic and there are a couple of different theories about how to train it - my view from what I've seen (and from the anecdotal evidence from the Kenyans) is that you can train it in two ways which we're covering both of - shorter runs where you run slightly faster than your lactate threshold and so you get your body used to clearing it from your system. These need to be kept nice and short because you want to get your body used to clearing the lactate levels - not flooding the body with them! Once you get more than about 20 minutes in at a slightly faster pace you are getting closer to a race effort. 

The other (and potentially more effective) form of training is where you run at just below your lactate threshold whilst not quite touching it - this gets your body used to running at the appropriate state (e.g. where you are clearing all the lactate) rather than it building up.

This is far more trainable over a long-term basis than VO2 max training and can be seriously improved until you're able to run at a significantly higher percentage of your VO2 max. You wouldn't necessarily be any "faster" but you would be running at a significantly higher effort level. My own experience of this is when I went sub 70 (and ran 31:38 for 10k) I wasn't necessarily that much better over 3k than I'd ever been before but I was able to maintain a very high intensity the whole way. 

Running Economy

This is the big one that is an incredibly wide term as to what it actually means... It's really at this stage more of a catch-all than an actually measurable "thing" like the two above and I think there will be other "new" factors modelling this in the future as it just seems so vague at the moment.

Loads of things can affect your efficiency - from the obvious like tight muscles to mitochondrial development after lots and lots of running. A couple of the key takeaways of things that have been shown to consistently improve running efficiency:-

  • Running lots of mileage (mostly due to the increased mitochondrial development and capillary beds)
  • Doing hill work - particularly short and sharp efforts called "Canova" Hills due to high muscle recruitment
  • Strides
  • Drills (mixed evidence)
  • Running at or close to your target pace
  • Long runs (particularly once the fast-twitch fibres have been exhausted (pure Lydiard).

There is also evidence around things like circuits and weights. I would mostly separate it into physiological (e.g. the mileage) and the neuromuscular benefits. 


What we need to do is to maximise performance by improving each of these factors (and at a later stage the glycolictic/ fat-burning marathon stuff). The way to do that isn't going to be through nailing sessions as hard as possible and running yourself into the ground but by knowing the drivers and hitting them without fatiguing yourself overly. 

Most training does not involve running for as hard or as fast as possible, running insanely quick 400m sessions or hitting your whole steady runs very fast on a daily basis -  all that will do is tire you out hindering your recovery and prevent you from achieving your best performances and focusing on getting the sessions right that matter. You will find it very difficult at times to not worry about whether you're actually improving as you won't necessarily have any clear evidence until race day - you just need to have faith. 

Patience and smart consistent training will see you make huge improvements and when you need to be "on" you will be ready to roll!




Dawn Broom said...

Enjoyed reading that Bryn!

Ed Rees said...

Thanks Bryn really useful post!

Bryn Running

Training diary and musings on running in general.