Monday, 6 January 2014

Introducing the concept of "Aerobic Resilience"

I'm now into my forth year of running Ultra-marathons and this year will take my biggest challenge so far - running the West Highland Way Race that covers 95 miles from Glasgow to Fort William. Preparing for this race is both a physical and mental challenge for me, and having a rather analytical streak I'm drawn to try to understand how best to prepare for the challenge.  I did start writing a long reply on a friends blog about my thoughts so far, but it really deserved a blog post of my own, so I've put together my thoughts, a little rough and ready, but should help understand where I'm going.

A mass of advice, but a vacuum of scientific evidence and models

There is huge amount of material in books and our on the web about how different people prepare for marathons and ultra-marathons, really too much material to digest especially as advice can conflicts, and in particular ulra-marathons have almost no scientific studies that might help us understand what might best.  I love an intellectual challenge as much as a physical one so I've been trying to distil things down to key factors that we should be training for when training for marathon or ultra marathon distances race.

Understanding Patterns that emerge from analysing Ultramarathon race results

From my analysis of ultra marathon results I've seen the trend for faster runners to slow less through races and for them to be able to  sustain a greater proportion of their shorter races paces (for instance looking at ultra vs 10k pace.)   I will need to write this analysis up, but as this is quick post I'll leave this for a later series of posts.

There is also a great deal of noise to the data, so while there are overall trends there is huge individual variations.  I'm hoping to come up with a simple but viable model to explain these variations, at least accurate enough to inform how one should train and paces races to get the best performances.

Introducing the concept of Aerobic Resilience

My current model is to view basic "Aerobic" fitness as equating to a runners 10k or half marathon distances where pace is near is tad faster or around the anaerobic threshold, but still the vast majority of energy production is aerobic.  One then introduces a "Resilience" factor that determines how well we can maintain pace as we run further.   A very simplistic mathematically model one could use might be:

  Speed(distance) = MaxAerobicSpeed *  (ResilienceFactor)^Distance

When ResilienceFactor is nearer to 1.0 for the best endurance runners and lower for those who struggle to achieve their potential at marathon or further distances.

The term Aerobic Resilience probably best sums up what I'm trying to encapsulate with this model.

With training for short distance races like 10k and half marathons it's all about maximizing our aerobic fitness, and topping this off with a small contribution from our anaerobic metabolism.

For longer distances like the marathon and beyond the contribution from anaerobic metabolism is less than 2% so it's it's almost entirely a case of maximizing our aerobic fitness.  However, it's not just about aerobic fitness, muscle damage, dehydration and glycogen exhaustion all play a part.  These other factors all combine to give our Resilience on race day.

When training for races of marathon and longer we have to train to maximize the combination of our Aerobic fitness and our Resilience.  Ignore either and you will not make the best of your potential.

For me the key factors in Resilience are Mental Resilience, Structural Resilience and Metabolic Resilience, The ReslienceFactor is the product of these individual factors.

Mental Resilience

Mental Resilience covers out ability to stay focused and positive through a race, to keep on top of discomfort, to monitor all our physical and mental systems and know what to do when areas need more support i..e take a gel, take a drink, take a walking break, get back running.  The mental side also includes the macro level planning over the whole race and management of pace.  For trail races one often has to keep an eye on the weather and navigation, so being able to have a fully functioning brain throughout the race can be crucial to not making costly mistakes.  You can also borrow a bit of Mental Resilience from any support you might have or from other runners, either competitively or collaboratively.  Things outside your own personal body can also impact on your Mental Resilience, for instance getting over taken or seeing what you feel is cheating might impair you mood or judgement on how to manage your own body and race.

Structural Resilience

Structural Resilience covers the ability of our bones, ligaments, muscles, fascias, cartilage, nervous system, digestion and cardiovascular systems to work continuously handling the physical demands placed upon without breaking down.  All these factors are multiplied together, if any one part starts failing then our overall Structural Resilience is compromised, our running economy will diminish as well as put a large strain on our Mental Resilience as the discomfort levels mount.

Metabolic Resilience

Metabolic Resilience covers the ability of our body to metabolise carbohydrates, fats and proteins efficiently.  Our ability to digest carbohydrates, fats and proteins efficiently also plays a part in longer races.  A runner who has poor ability to metabolize fats will almost certainly have a relatively poor Metabolic Resilience so will likely hit the wall, and will be very dependent on consuming carbs during the race.  Runners with ability to maintain a good pace whilst metabolising primarily fats will have good Metabolic Resilience and will require less fuelling during races.

Ingesting too much food when working too hard causes gastric stress, so a poor Metabolic Resilience puts strain on our Structural Resilience and our Mental Resilience.  A runner with good Mental Resilience would not give in, but slow down till the gastric stress passed then push on when the body settled.  This is just one example of how each of the element of Resilience are interconnected connected.

How to maximize Aerobic Resilience?

A simple model of long distance performance like Aerobic Resilience is only useful if it helps inform how we should train and prepare to maximize our performance come race day.  This is a big topic in itself so I'll leave putting down my thoughts for another post or two.  If you feel that this model is useful, or has elements that I should include just let me know, I'd like to refine it over the coming weeks, months and years to help myself and others enjoy training and racing as much as possible.