Ironman World Championships - Kailua-Kona, October 11th, 2014
On a day that many were calling the windiest and most difficult bike day in the last 15 years of the Ironman World Championship on the Big Island, Hawaii, SRM sponsored triathlete, Michael Weiss, posted a bike split of 04:33:35. In a stacked field that included all the best Ironman athletes on the planet, that was good enough for the 6th fastest time of the day and that even included a rear wheel puncture while riding at 60km/h just 15km into the ride which took Weiss approximately 5 minutes to repair without race support, damaged his speed/distance sensor and effectively killed his chances of catching the leading group right then and there. Thereafter Michael battled the swirling winds over the infamous lava fields entirely alone making for a long hard day in the saddle. Even so, he still managed an average of 294W (306W normalised power) for the duration and in so doing expended 4770 Kcals.
After completing the 3.86km (2.4 mile) ocean swim our strategy on the bike was to ride with as minimal fluctuation as possible in both power and cadence irrespective of wind or gradient. This would not only spare glycogen reserves for the run, but because the temperature in Kona rarely falls below 28C, this strategy would also help to keep core body temperature from rising uncontrollably. To this end Michi did a very good job but we can see that as the air temperature increased by 3-4C in the second half averaging close to 35C, Michi found it considerably more challenging to keep the watts up and indeed his cadence became less metronomic as he searched for ways to extract more power from his legs. In addition, although he was not wearing a heart rate belt, I am certain if he had been we would have seen an increased heart rate in the second half in spite of lower average power output due to the higher air temperature leading to an increased sweat rate, reduction in blood plasma, a decrease in cardiac output and increased heart rate to compensate – otherwise known as cardiac drift. It is also quite normal to see a decline in average power in the second half of an Ironman bike leg amongst those pros that possess a really strong run and is almost certainly a subconscious strategy to ready the legs for the physiologically demanding transition from hard cycling to fast running.
Zoning-In On Power
Typically I would expect an age group Ironman athlete who had done his homework to be able to maintain in the region of 70-75% of his Critical Power (threshold) for the duration of the bike leg. This means that Ironman cycling intensity is necessarily a zone 2 effort for most age groupers intending to run the marathon. In the pro ranks this can be as much as 75-80% of a considerably higher threshold number. Indeed, in Michi’s earlier season races he was able to average up to 82% of his threshold for the bike leg. This means that much of the ride will be at zone 3 intensity and even into zone 4 for short periods. In Hawaii this number was closer to 75% for Michi which, while still impressive, may also be a symptom of an 11 month race season which has included 4 x full Ironmans, 3 x 70.3 events, 1 x Olympic distance, 1 x Xterra triathlon and 1 x sprint distance, not to mention plenty of hard training in between! This highlights just how insightful power analysis can be when comparing files over the longer term and (coaches take note) should certainly inform future racing and training plans. While not necessarily being the end of Michi’s season just yet, this latest file may push us to clearly define the start date of his off season and well deserved period of rest and regeneration. Thankyou again to Michi for opening up his SRM files for us (and his competitors and their coaches!) to see and well done on yet another fine Ironman performance at the Worlds. Onward and upward!
On the marathon many of the top favorites succumbed to the heat, humidity, and pure exhaustion, Weiss endured the conditions and ran his way to 16th overall crossing the finish line in 8:38:27.
"I'm proud of my performance in this incredibly talented, world-class field of competitors." Michael shared after the finish. "A perfect day in Kona requires a bit of luck and that was not on my side today… One thing is already certain: I have some unfinished business here on Big Island and I'll be back again next year!"