Continuing the “no stone unturned” theme for Race Across the West Preparation, I headed to the Porsche Human Performance Centre yesterday for the first of a number of sessions in their heat chamber. The Mojave desert in June is going to hot. Very hot. Many of the riders who don’t finish RAW or RAAM come unstuck due to complications from dehydration and heat stress. Sometimes riders who are struggling can recover with some time in an air-conditioned RV and an IV drip, but for others it ends in a DNF and for the worst cases, a trip to hospital.
My rationale for the heat chamber is simple – forewarned is forearmed. I need to understand how a) how my body is going to react to the heat and b) how my mind is going to react. I need to know how to keep my core temperature at a level that allows me to make progress without going into the “red zone”, how to hydrate to ensure I’ve got the right fluid/ salt balance and how to control a very hot chimp. Several sessions in the heat chamber will allow the chimp to get used to the heat mentally as well as test strategies for hydration and cooling in a controlled environment. It will also help my body to gradually adapt to the heat which along with a week in California before the start of the race will enable me to be able to perform better at a higher core temperature. This is particularly important in the early part of the race where as well as the heat, there is also a lot of climbing to contend with so I will have to work harder.
The purpose of yesterday’s session was to introduce me to the heat chamber and establish some benchmarks that we can use for future sessions. The set-up at the Porsche HPC is excellent and both Jack and Russell gave me a lot of information about the process as well as examples of how other athletes use it, most notably racing drivers or runners doing the Marathon des Sables.
After the obligatory questionnaire, I was weighed and had my urine osmolality checked to ensure I was hydrated. It was then into the chamber at a toasty 33-34 degrees and on to the Wattbike. The aim was to complete an hour at a steady pace, i.e. in my Zone 1. Every 5 minutes my heart rate, power, temperature and RPE (Rate of Perceived Exertion) were measured. I acclimatised for 10minutes with some easy but warm spinning and then worked up to a steady Zone 1 pace. I had been warned that my heart rate and RPE would be higher than I would expect for my power output and sure enough, my heart rate climbed quickly to 150BPM at a wattage where it would normally be 120BPM. The legs felt fine, but everything was just that little bit harder. My temperature gradually climbed as expected. The cut-off limit for body temperature for the sessions is 39.5 as this means that your core temperature is already over 40 degrees, so at this point the HPC guys will open the doors and/ or take you out of the chamber until you’ve cooled down to a safe level. The idea is to get your temperature as close as you can to this level and sustain it for as long as possible.
After 40minutes, everything just suddenly seemed hotter. On talking to Jack and Russell afterwards, this is generally the time at which it starts to bite. I was literally watching the sweat dripping off me, sipping my (rather lukewarm) drinks and willing the next 5 minutes to pass for the tiny draft of cool air that came in as Russell opened the door to come and do my measurements. Talking was a great distraction but also required just that little bit more effort. There’s no breeze in there and the thought of anything cold or cooling became a fixation.
At the 50minute point my temperature was 39.4 so we took my wattage down by 20W so that I could finish the session. Apparently making it through the hour on the first session is a good thing so I was pleased with that.
After the ride I was weighed again along with my drinks and we calculated my sweat rate (1L/ hour). I had followed the hydration strategy from the Precision Hydration guys after my sweat test. This meant pre-loading with a higher concentration of electrolytes to start, then drinking to thirst – for me this was 750ml of electrolytes and 450ml of water. This meant that drinking to thirst did enable me to consume enough fluids to match my losses and we now have an idea of how much sweat I will be losing. Weight loss/ gain will be a useful measure of hydration during the race itself.
All–in-all, the session was a success and gave me a lot of confidence that the heat is something that we can manage. Over the next few sessions I will look to work harder and get my core temperature up higher earlier, then test ways of getting it down again, ranging from cold drinks, to ice vests and “misting” with cold water sprays. Many thanks to Jack and to Russell for their time.