Wednesday, February 3, 2016

What does it take to qualify?: A physiologist's perspective

OK, so back to my normal milieu this week …..

Questions and emails on my ‘what does it take to finish an Ironman’ post seemed to indicate that you all liked the format but, for you, finishing isn’t going to cut it. You want to qualify! :-)

Today’s pic is of one of the top Age Groupers I coach, Shawn Burke, busting out a 9:23 qualifying time in Ironman Florida. Being able to work with Shawn and a number of other top age group athletes ‘up close and personal’ over multiple seasons, I’ve been able to witness first hand ‘what it takes’.

I’ve written a previous post on what it takes from a general work/commitment perspective to reach the very top of your age group. Despite the heat received, I stand by the message:

- Multiple years of physical training, amounting to several thousand hours of work.

Perhaps the message would be a little more moderate than what I outlined for a Kona slot, but the way things are going at the pointy end of the field, Kona qualifier and top AG are rapidly becoming one and the same. In fact, based on last year, most flat course qualifying males under 50 were in the 9:30’s!

But is work enough?

Gordo wrote a great blog this week on personal excellence. His conclusion that “protocol does not matter UNLESS it is supported by a habit of personal excellence” is worth a re-read. Or, put another way, you need to set up your life (& your program) to enable you to ‘do’ before worrying about ‘what you do’.

Based on the Kona qualifiers that I have worked with, some 20hr training weeks are almost a pre-requisite. Also based on the athletes that I have worked with (excepting those with freakish recovery abilities), 20hr weeks are going to be VERY hard to string together on much more than a ‘standard’ 40hr work week. Add in the constraints of a young family and you can see that for many, VO2max or FTP is NOT the #1 limiter.

That said, while a 20hr week load (and the life conditions to absorb said load) may be bordering on a pre-requisite for a Kona slot, it is not sufficient in and of itself. Put another way, just because you set up your life so that you’re able to string together the requisite load doesn’t guarantee that this load will give you all of the fitness abilities necessary to race at the very front of your age-group and secure a Kona slot. I can guarantee this from personal experience!

There is somewhat of a ‘bottle neck’ effect that kicks in around the 10hr Ironman mark. A lot of very serious folks getting their consistent 2-a-days in and all shooting for a limited number of slots. Under these conditions, only the smart survive. In these conditions, work is not enough, it is focused work that counts.

‘Focused work’, to me, means work targeted towards a specific objective. This necessitates that we define what physiological objectives are ‘mission critical’ to fast Ironman racing. By defining them we can assess whether you have that base covered as an athlete, and if not, the best way to rectify that shortcoming.


In my last blog piece I outlined the key endurance adaptation of glycogen supercompensation, in which with repeated bouts of glycogen depleting exercise, the body’s energy stores can double. Maybe somewhat surprisingly, this adaptation seems to have a ceiling that can be reached pretty quickly by novice or prospective Kona qualifier alike, i.e. both have ~3000-3500 cals to work with.

The major difference between the novice and the Konee when it comes to long duration fueling comes from the energy contribution from fat. Based on our lab testing, athletes who qualify for Hawaii are typically generating >33% of their energy needs from fat (~300kcal/hr). This is an important adaptation and one that can be limiting for a lot of athletes with V8 power but lousy fuel economy. By generating 5kcal/min from fat, a 10hr Ironman gets an additional 2800 calories of work done over the course of a 9.5hr Ironman. Add in ~2400 cals of worth of energy from exogenous carbs (gels, sports drink etc) and we’re up to ~8500 cals worth of energy to play with. So how much fitness do we need to get 8500 cals of work done over 9.5hrs?


8500 cals of energy output over 9.5hrs is equivalent to ~230W of power on the bike. Now, as outlined above, we want this 230W to occur within the zone of max fat oxidation (~60-65% VO2max) This infers that the athlete has a VO2max of ~5L/min at an economy of 75W/L.

These numbers also pre-suppose that a 230W output will ‘get the job done’ and get the athlete from A-B in ~9.5hrs. Based on my calcs, probably true for a 75kg athlete with decent position over a well paced flat course. Much bigger or any less aero, and the athlete will need more power.

So, in relative terms we’re talking about a VO2max in the neighborhood of 65ml/kg, equivalent to 5K speed of ~17:30 and a CP5 of ~400W. It goes without saying, that this represents a very high level of aerobic fitness: 1 in 200 fitness for a young male, 1 in 10,000 fitness for a 40-49 yo guy based on the Cooper Institute’s data!

It is also worthwhile remembering that this level of fitness is not sufficient if not paired with appropriate race specific endurance. If it is paired with a high level of fat oxidation and an AeT of >60% of VO2max, the athlete will be in a good spot for their Kona assault.

If the athlete has a particularly strong fitness base, i.e. an AeT at a higher % of max and a fat oxidation profile that continues over a broader range, they may ‘get by’ with marginally less VO2 ‘top end’. However, there are limits to the % of VO2 that any athlete can hold for a given duration and in the interests of long term development, shooting for this balanced mix of ingredients is the athletes best bet towards achieving their potential in the sport.

Setting these fitness pre-requisites in place before putting the final race specific endurance block in place represents a strategy of ‘reverse periodization’. I’ll talk a little more about this in a future blog. Until then…..

Train Smart,


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