I’ve now had plenty of time to reflect on Ironman Texas. I’ll be honest with you. In the first few days after the race, I was in complete shock. In what I had intended on being the best race of my life, I performed the worst. I had a decent swim and a good first three hours on the bike. But in the final hour on the bike I pushed a wattage that I would normally push on my “easy” days. And then I ran a marathon at slower than I normally do my “active recovery” runs. To train so hard for something and then perform so far from what was expected, was a difficult pill to swallow.
What made it even more difficult was that I was in the best shape of my life going into the race. In the months leading into the race, I had exceeded all of my best pool times, all of my best bike wattages, and did many workouts on the run that were comparable to the best workouts I’ve done since starting to train for triathlon. I was having an experience very similar to the experience I had after St. George 70.3 in 2014 where I was beaten by 10 minutes i.e. “how the heck am I going to make up that much time?” But, as they say, time heals all wounds. Eventually I started to get my wits about me and I began applying the same process I’ve used to make all of my improvements: critical analysis.
The first thing that should be noted is what I said above, that “I had a decent swim and a good first three hours on the bike.” That totals about four hours of racing. That just so happens to be about how long it takes me to complete a half-Ironman. Thus, it seems possible that something began to play a factor in this race, that doesn’t play nearly as much of a factor in a 70.3. By about five hours of racing in Texas, I was beginning to feel woozy and dizzy, something I have never experienced in a 70.3.
Was it the swim? I didn’t have a swim at Ironman Florida. But I’ve swam 4 kilometers many times in practice and then done hard bikes and runs after, that looked nothing like the final four hours in Texas. It’s possible that the swim took a little out of me, but not enough to account for such a massive performance deficit on the run.
Was it the bike wattage or pacing? I’ve pushed the power output I pushed in Texas on many occasions in practice, for the duration I pushed it in Texas, and then ran significantly better off of it. At Ironman Florida, I pushed 13w more than I pushed in Texas and then ran a 2:44 marathon off of it, with the first half of the marathon in 1:17. I’ve also pushed the power WAY more sporadically in 70.3s and ran significantly better off of it. The effort on the bike could have played a role, but if it had, it was difficult to ascertain why my run performance in Florida was so much different.
Was it my nutrition? On the bike, I consumed approximately 400 calories per hour. According to many scientists, that is pretty close to the maximum amount of carbohydrate that the gut can absorb per hour during exercise. So if nutrition was the reason, there wasn’t much I could do about it. Though, I have experienced “bonking” on several occasions, and the way I felt in Texas was nothing like any “bonk” I had experienced before.
The only major difference between Ironman Florida and Ironman Texas was the heat. According to my Garmin, the average temperature on the bike in Florida was 13C (or 55.4F) with a maximum temperature of 20C (68F). According to my Garmin, the average temperature on the bike in Texas was 24C (75F), with a maximum of 30C (86F). But that doesn’t tell the whole story. I looked up the historical weather data for Panama City Beach on November 1st 2014, and the average humidity level that day was 50. The average humidity in The Woodlands on May 16th 2015 was 82.
Based on this data I started to think that the major reason for my performance was that I was not properly acclimatized to the conditions. The conditions were rather extreme, but my training room is always warm and humid. Not HOT and humid, but WARM and humid. It was difficult to believe that the way I felt on the marathon in Texas was purely a byproduct of having not acclimated to the heat.
My final suspicion was that the performance had something to do with an electrolyte imbalance. This was a topic that I had absolutely no knowledge of. I had no idea what sort of effect an electrolyte imbalance would have on my performance, but off a google search of some scholarly articles it seemed like this could have played a major role.
So, this past Wednesday, I went to the Gatorade Performance Centre in Guelph and had a sweat test done. Long story short, I cycled in a “heat chamber” for 90 minutes at my Ironman race wattage and then ran 60 minutes on the treadmill, also in the heat chamber, at my intended Ironman run pace. The average temperature in the heat chamber was about 28C (82F) and the average humidity was around 70. In other words, very similar conditions to both Ironman Texas and to Kona.
Mark Linesman, the scientist who was conducting the test, said to me “I bet you’re sweating at around 2 liters per hour. You’d have to be based on how much power you’re pushing.” At this time I had a huge fan blowing in my face. I didn’t feel hot at all. There was barely any moisture on my skin, and almost no sweat on the floor. I thought to myself, “yeah right. This is dumb. I’ve got this huge fan blowing in my face cooling me down. This is nothing like it was in Texas. I’m not even sweating. I’m going to get nothing out of this test.”
I don’t know if I’ve ever properly used the term “paradigm shift” in a sentence, but once I finished the test, I’m pretty sure I had a paradigm shift. After 2.5 hours of exercise, I had lost 3.9kg. I wanted this test to be as close to Texas as possible, so I used the EXACT same fueling and hydration strategy I used there. That’s not 3.9kg of sweat. The quantity of sweat would have been more as I consumed about 1.5L of water and Gatorade in that time. I was in a deficit of 3.9kg. That is 8.58 pounds. That is 5.3% of my body weight. And that was only after 2.5 hours of exercise!! At that point in the workout I was already having mental impairment and my perceived exertion was ramping up quickly.
It then dawned on me: I was severely dehydrated in Texas. It all started to make sense. During drug testing after the race, after 2 hours of sitting there pounding back water, coke and Gatorade, I was only able to pee 60mL. The minimum amount required is 90mL. Thus, I had to do a bunch of paperwork and then wait there even longer before I could produce the remaining 30mL. It took me a good 2.5 hours after the race to produce 90mL of pee, and I was trying to push it out with all my might. After that, I don’t remember peeing until late that evening.
It turns out, that under conditions very similar to Texas, at the power output I pushed on the bike, my sweat rate was at least 2L/hour. Keep in mind, it was sunny in Texas, which raises your skin temperature even more, a factor that was not accounted for in the laboratory. I also likely would have sweat in the water while swimming as the water temperature was 81 degrees. For argument’s sake, let’s say my sweat rate in the water was half of my sweat rate on the bike. That means by the end of the bike I had sweat about 9.36L. I consumed 6 bottles of fluid on the bike. Two of them were my own, each containing about 700mL. The other four were from aid stations, each about 700mL as well. It should be noted that when pouring a bottle into the cockpit hydration system, a great deal is spilt, so these numbers are likely even lower. Regardless, that’s about 4.2L consumed by the end of the bike. Meaning, coming off the bike, I was already in a deficit of about 5.16L. My weight that morning was about 165lbs. That means I had already lost about 6.8% of my body mass before starting the marathon.
There are countless studies on the negative effect of dehydration on performance. Here is an excerpt from Asker Jeukendrup and Michael Gleeson’s book Sport Nutrition that I thought was interesting as 7% dehydration was the most extreme of the conditions used in the study:
“A study investigated the capacity of eight subjects to perform treadmill walking (at 25% .VO2max with a target time of 140 minutes) in very hot, dry conditions (49° C [120° F], 20% relative humidity) when they were euhydrated and when they were dehydrated by a 3%, 5%, or 7% loss of body mass (Sawka, Young, Francescone, et al. 1985). All eight subjects were able to complete 140 minutes walking when euhydrated and 3% dehydrated. Seven subjects completed the walk when 5% dehydrated, but when dehydrated by 7%, six subjects stopped walking after an average of only 64 minutes. Thus, even for relatively low-intensity exercise, dehydration clearly increases the incidence of exhaustion from heat strain. Sawka et al. (1992) had subjects walk to exhaustion at 47% .VO2max in the same environmental conditions as their previous study. Subjects were euhydrated and dehydrated to a loss of 8% of each individual’s total-body water. Dehydration reduced exercise endurance time from 121 minutes to 55 minutes.”
Unfortunately, the race didn’t end there. I then had to run a marathon. We found in the sweat test that my sweat rate on the run and bike are very similar i.e. about 2L/hr. I was hydrating at an even more reduced rate on the run. In other words, I was becoming progressively more dehydrated at an even faster rate. It would not be difficult to imagine that by the end of the run I had lost 10% of my body mass. Here is an excerpt from a study by RJ Maughan published in The Journal of Clinical Nutrition called The Effect of Mild Dehydration on Wellness and on Exercise Performance:
“If the loss of water reaches 10–15% of body mass, about 20–30% of total body water, death is the likely outcome.”
I remember on the run actually beginning to fear the moment of passing out. I remember wondering what it would feel like to wake up and discover I was lying on the side of the road. It has been my life dream to push myself “through the door.” This race was definitely the closest I have ever come to pushing myself to my absolute physiological and biological limits. It was actually a bit scary. For a while after the race I feared doing another Ironman.
But it all makes a lot more sense now. I was ignorant of one of my biological limitations: The fact that my body is mainly composed of water. The fact that my body utilizes that fluid to cool itself and carry out cellular functions. And that that fluid needs to be replaced as it is lost. It might sound really dumb, but I honestly didn’t fully realize that just because I can’t see the sweat, that I’m not sweating. I have been exercising for years, in severely dehydrated states. It just took the most painful experience of my life to finally realize it. It has now come to my attention that I have become greatly desensitized to the effects of dehydration.
It’s hard to pin point the moral of the story here. I think the big one is that going into this race I really felt like I was starting to understand a great deal about exercise and triathlon. This experience and this new knowledge showed me that I am still very ignorant. It’s actually kind of fun because it has opened up a whole new realm of learning, experimentation and data analysis.
If you’ve made it this far. Thanks for reading! Don’t forget to hydrate!