Example from Cape Epic Day 4. 89F average temperature with a power/hr of 1.29

Example of a May mountain bike ride. 61F average temperature with a power/hr of 1.36 

**CORE Sensor and Heat Training Case Study**

After racing and training for over 30 years, I don’t expect to see much improvement at my age. In fact, I anticipate the opposite. I had signed up for my third Absa Cape Epic, which was scheduled to take place in March 2025. The Absa Cape Epic is held in South Africa, at the end of their summer, and requires us from colder climates to train throughout the winter in frigid conditions. It had been ten years since I last raced there, but recalling numerous details about the event prompted me to create a checklist of things that would aid me during the race.

First and foremost, achieving a high level of fitness is crucial. While this may seem obvious for an 8-day race, training in a cold environment—often indoors—can be mentally challenging and adds an extra layer of difficulty. Illness can hinder performance, so being fit increases the chances of finishing despite adversity. Additionally, I needed to ensure my equipment was well-prepared, as cycling technology has changed significantly in the past decade. I now had a much more computerized bike with electronic shifting and suspension, which necessitated further planning. I needed to consider how many power banks I might require for instance and, since I had been using waxed chains for years, I also had to determine how many pre-waxed chains to bring and test their durability against the frequent power washings that the race involves.

This planning was standard, and I was well aware of it. However, by the fall of 2024, as I began to prepare for serious training, I wanted to be ready for the variable conditions of the inland Western Cape. I aimed to test a training method that had gained popularity, particularly among professional cyclists: heat stress training. After doing some research, I made two key decisions: first, I would focus on active heat training rather than passive routines like using a sauna; second, I would commit to at least two sessions per week and remain consistent. This led me to the CORE sensor, which would help me monitor my efforts accurately. After reviewing the training protocols, I designed a recovery-type ride that would keep my core temperature aligned with their recommended heat zone.

I began heat training about five months ahead of the event. While this was more time than necessary solely for heat adaptations, I became curious about the potential physiological benefits. Given the harsh winter weather, I ended up riding indoors more often, which allowed for a controlled environment and measurable performance indicators. Initially, I eased into heat training by riding without a fan for two weeks while wearing a long-sleeve base layer. Those first two weeks were difficult, particularly the first ride, which felt oppressively hot. However, I eventually adapted to the absence of a fan and the extra layer of clothing. Over the subsequent four weeks, I gradually added more layers until I was wearing two top layers and a winter hat. By the final two months, I was fully dressed in thermal gear—excluding shoe covers and gloves—for rides without a fan. To my amazement, I managed these sessions comfortably, despite sweating excessively, which indicated my body was adapting well to the heat.

On some weeks, I was able to fit in three of these sessions, but I maintained a minimum of two per week. Most of these rides lasted between 60 and 80 minutes, with a ramp-up to Zone 2 until I reached the designated heat zone, followed by maintaining or slightly reducing exertion to stay in that zone for 40 to 60 minutes. I chose to use thermal gear I already owned instead of a Tyvek suit, which is often recommended. My protocol and frequency closely aligned with CORE's guidelines.

Now, for the results and some intriguing details. I felt very acclimated to riding fully dressed without a fan indoors. However, I was surprised to see power increases. I added about 12 watts to my 20-minute power compared to what I had recorded over the past few years. So, just before I left for the trip, I was already experiencing an improvement in power output. Since my training habits hadn't changed, the only factor I could attribute this improvement to was heat training. I couldn't determine if the gains resulted from better heat management during efforts, a change in blood values, or both, as I didn’t have records of my blood values before and after months of heat training. Nonetheless, it was thrilling to witness any improvement at my age. As I prepared for my trip to South Africa and reviewed my data, I couldn't help but reflect on how far I had come despite the ongoing winter conditions.

Upon arriving in Cape Town and getting in a couple of rides before the race, I didn’t initially notice much of a difference in my perception of temperatures. We experienced a few days in the 80s, and it felt like it was indeed in the 80s. I wasn't particularly suffering and otherwise felt comfortable, but it highlighted that heat training wouldn't make hot weather feel cool. In terms of power and heart rate, I didn't observe anything unusual; everything felt normal and noticeable increases heart rate were absent. I certainly wasn't struggling during exposed climbs on sunny days.

However, when the race started and I began to push myself, I felt similarly to how I typically do in mid-summer after becoming adapted to hot weather. As the race progressed and we moved into Paarl, a region known for its heat, we encountered some very hot days with temperatures even exceeding 100 degrees. This was when I truly noticed the impacts and benefits of my heat training. To my surprise, my heart rate was remarkably low, even while sustaining Zone 4 power output on the climbs. It was as if my heart rate was barely elevated above conditions at only 70 degrees. While it felt hot, I certainly didn’t feel like I was suffering.

In the end, I gathered valuable data that confirmed everything I had read about heat training. I can confidently recommend this type of training with CORE sensors to clients looking for performance improvement, especially those who have previously struggled in hot conditions. I believe it can be a game changer for anyone willing to commit to a regimented heat training plan leading up to their goals or in the spring to prepare for hot weather.