Can Lance Win in Kona?
How the top performers of IronMan events are able to run the final marathon leg in 2h40min after having pedaled "in the wind" for 180km at 40km/h is a "METABOLIC PRODIGY" not easy to explain.
Even if we consider the swimming leg (about 50min), the bike part alone means an effort of 4h30min, which, for the corresponding intensity translates to a consumption of approximately 700g of CHO and 175g of fats (Med Sci Sports Exerc 1998, 30:1744-1750; Plugers Arch 1998, 436211-219).
Since the maximum amount of glycogen that can be stored in the muscles for an athlete of 70 kg is around 700-800g, it is difficult to explain how an athlete can run for 42 km at 16 km/h with glycogen stores almost totally depleted by the previous cycling performance.
Running at this speed requires an oxygen consumption of 53ml/kg/min, which corresponds to 70% of the average VO2max value of elite athletes (VO2max = 75ml/kg/min): impossible to hold this intensity of effort without a significant contribution of CHO as fuel.
In order to be able to realize such performance at the end of an IronMan, the triathlete must have a lipid power (see article 53x12.com) definitely higher than other elite athletes, with values up to 1.20 g/min, so he/she can use a high % of fats in the bike leg, saving the glycogen essential for the running.
Lance Armstrong has recently completed a 70.3 (half Ironman in Panama) in 3h50'55": after a good swimming leg, he rode the undulating 90 km at 41.5 km/h and ran the 21.1 km at 16.4 km/h.
The first part of the running leg was done a bit too fast (around 18 km/h), thus compromising the final phases of the race (the last 6.3 km were done at 14.8 km/h): a wrong distribution of the intensity of effort probably cost him the victory in this event, which in any case resulted in an excellent 2nd place just 42" behind the winner, Olympic medalist Bevan Docherty from New Zealand.
Now, a 70.3 is a very different thing from a full IronMan, but knowing the athlete well, I can hazard a few calculations.
Pedaling at 40 km/h, on a flat course, with a time trial bike, Lance produces a power of 250w (personal observations): this intensity is relatively low for his aerobic engine, representing around 50% of his VO2max.
It takes 4h30min to ride the whole 180 km at 40 km/h; at an average power of 250W, this corresponds to a consumption of 900Kcal/h, equal to 4050Kcal for the cycling effort.
Assuming Armstrong at such low intensity (for him) utilizes 40% carbohydrate and 60% fats as fuel (with an RER = 0.82 approximately), in the bike leg he will consume 405g of CHO (1.50g/min) and 270g of fats (1.00g/min).
Running the marathon in 2h40min corresponds to a consumption of 1100Kcal/h, for a total of 2975 Kcal: if Lance will be able to use 50% carbohydrate and 50% fat (RER = 0.85 approx.), in the running leg he will consume 372g of CHO (2.32g/min) and 165g of lipids (1.03g/min).
It would probably be more convenient for Lance to ride the bike part at 41 km/h (260-265w), completing the 180 km course in about 4h23min, and set the running part at a more cautious pace (around 15 km/h), a speed best suited to his physical characteristics.
In order for Lance to succeed in the challenge, he will have to:
- get his organism used to burning fats as fuel (through diet and training)
- saturate his glycogen stores before the race (cargo-loading)
- improve his efficiency in running at the race pace (reduce the energetic cost/km)
- decrease his body to around 70 kg
- distribute the race pace as best as possible, also in relation with the outdoor temperature
If his 40 years of age will allow him to recover the hard necessary training and avoid any injury, he may as well make it...