Perception vs Reality: the Temperature Disconnect

Editor’s note: Robbie Britton is an ultra-endurance coach and runner, the British 24-hour record holder (277 km/172 miles), and a manager for the Hour 7 ultra-distance running team. Robbie is also part of our CORE Coaches community and wrote this brilliant piece about how he uses the CORE sensor as an athlete and a coach.

People look back wistfully to the era of hardmen on bicycles who didn’t know how long each stage was. Or runners who simply toed the start-line, to find out who had “the most heart”.

But nowadays we have data on top of data and some believe that athletes don’t have to think for themselves anymore. Come race day, athletes at all levels still need to have a strong understanding of their abilities and limitations, not least because any technology can have a day off (such as my heart rate monitor battery dying in the warmup to a key race).

Data isn’t just about control of an athlete’s effort though, but education and learning around it as well.

As a coach it can be key to encourage athletes to use and learn from their wearable technology, but not become reliant upon it for success. Raw data is valuable but only if athlete and coach can interpret and use the information for their own individual context and situation.

CORE learnings for athlete education

It was on a 1st January training ride, often a day of great revelations, that one key use for the CORE sensor become apparent for me as a coach and an athlete. The session was 3 x 15 minutes uphill, the company was young local cyclist Giacomo Cerutti and it was a pretty chilly day.

We used three different hills for the efforts, and each involved a bit more climbing and then some descending after the intervals. Wearing the CORE sensor, linked to my computer, it was fun to watch my temperature climbing in each of the intervals, but it was what happened in between that was of most interest. Whilst the hard effort had stopped and it felt as though we were starting to cool down, my body had other ideas. The high point at 39.3° C/102.7° F was actually when I was feeling a bit cooler and my skin had started to cool down in the cold weather.

Then came the descents, which actually felt quite cold, but the CORE sensor only recorded a slight drop and then we were going up again. On the next effort, once again, the peak of 39+ degrees (102.2° F) came after the effort had finished.

Perception versus reality

Reducing the work rate didn’t cool me down; it didn’t even stop overheating. In low environmental temperatures, an easier effort uphill still kept the core temp rising. The next lesson was the disconnect between skin temperature and our perception of how hot we are, and the reality of what was going on within.

As athletes in a race, we rely on our perception of effort, body temperature, and fatigue to gauge our own race effort. This can be impacted by factors such as sleep deprivation, environmental conditions, and how our competitors around us look and feel too.

Our perception is a skill that can be worked on in training and this is where devices such as the CORE sensor can come in handy. Building your knowledge and experience around what you’re feeling and what’s actually happening can make a big difference in those key moments in a race.

Validating theory in the lab

This experience as an athlete then led to changes in how I coach. The two main lessons that had been taken from using the CORE sensor in training, both indoors and out, were as follows:

  1. The disconnect between how hot we feel and how hot we are
  2. The impact short, harder efforts or surges have on our core temperature

Working with a top US trail athlete it was two important lessons we wanted to work on in the build-up to the Western States Endurance Run, one of the marquee 100 mile trail races in the world. One of the cruxes of Western States is the heat. The canyons, as you drop down from altitude to closer to sea level in California can get a little toasty.

At Liverpool John Moores University, working with Senior Lecturer Dr. Jamie Pugh, the plan was to replicate elements of the Western States course and environmental conditions, whilst monitoring core temperature, running economy and heart rate to see what happens over the course of 4-5 hours of running.

The hypothesis was that the higher effort climbs would have an accumulative impact on core temperature, and therefore heart rate, cardiac drift and running economy as the run continues. We were looking for the critical power we could sustain on climbs and the impact of going over that level and how that felt for the athlete.

The athlete made a greater connection between effort level, effort stability during a race and core temperature that could be brought into practice in training and come race day. Now the CORE sensor will help us put these lab findings into practice on the trails.

What can an athlete do in the field?

Now we understand that using a university environmental chamber to do a 4-hour run might not be accessible, nor desirable, for many athletes reading this, but the lessons remain the same. In the field, using a CORE sensor, you can start to experiment with the impact prolonged exercise, effort and harder surges can have on your core body temperature and how this feels.

Recognising and starting to understand the signs that your core temperature is rising will help athletes pace on race day. If you’re waiting for your watch to tell you you’re too hot then it’s likely too late, especially if you’re only racing for 2-3 hours.

Practicing in the field, across different workouts and longer runs and rides, in different environments will start to educate an athlete on not only how their body reacts to temperatures, but also practice cooling techniques and how impactful they can be too.

Combine this with looking at cardiac drift over longer efforts and any endurance athlete can start to dial in the most sustainable race efforts for the big day. Then you just have to worry about your snacks, but that is another article all together.