Most runners think about heat training one way: prep for a hot race. If you're heading somewhere with brutal conditions, you heat train beforehand so your body isn't shocked on race day. A new study on elite cyclists challenges that entire framing. Heat training didn't just prepare these athletes for heat. It made them more fit, period, in any environment.
ARTICLE BELOW:
The Research
Cycling research tends to run ahead of running research, so it's worth paying attention even though this study isn't about runners specifically. Forty-seven elite cyclists, both men and women, were split into a heat training group or a normal training group for 5 weeks. The heat group trained wearing extra layers, wool underlayers, a hat, heavier outer gear, to raise their body temperature during otherwise normal-intensity sessions. Everyone was then tested in cool, normal conditions afterward. The metrics researchers tracked, V̇O2max, lactate threshold, and power output, are the same ones we care about as runners.
What They Found
The research suggests these are the key takeaways
V̇O2max, lactate threshold, and power output all improved significantly more in the heat group than the control group, and this was tested in normal, cool conditions, not heat
Blood volume and hemoglobin mass increased meaningfully in the heat group, and this tracked closely with how much performance improved
Muscle fiber type and other cellular-level markers stayed unchanged. This isn't about becoming a different kind of athlete at the muscle level, it's about carrying more blood volume to do the job
Women and men saw comparable benefits. Most research in this space only studies men, so seeing both included, with similar results, matters
🟢 A well-designed, adequately sized study. But it's cycling, not running, so the exact numbers won't map perfectly, even though the underlying physiology (blood volume adaptation) isn't sport-specific.
What This Means For You
I'll be honest, this is a tough study to implement exactly as written. Five days a week, fifty minutes a session, for five weeks is a lot to ask of anyone juggling a normal life around their training.
I've experimented with a version of this myself. I've gone on my treadmill wearing a heat suit, hat, gloves, a wool layer, basically dressed for winter indoors, and moved at a manageable effort, not a hard workout, just accumulating volume in an added-stress environment. During one of my ultra training blocks, twice a week at thirty minutes was genuinely all I could manage. I'm not entirely sure how much was physiological and how much was placebo, but I felt like I was improving.
I've also had athletes use a passive version, jumping in the sauna for twenty to thirty minutes right after a run, a few times a week, specifically to prepare for races in a warmer climate than they'd been training in. They reported feeling like it helped too.
That gap between the study's protocol and what's realistic is the real question worth sitting with. What's the minimal effective dose here? Could passive heat exposure, sauna, a hot bath, supplement or partially substitute for the more demanding active version? The research doesn't answer that directly, but it's the practical question that matters most for actually using this.
🏆 How To Apply It
If you want to try active heat training, start smaller than the study protocol, two sessions a week at a manageable, easy effort is a realistic entry point, not five
Layer up for an easy run or treadmill session, extra clothing is the low-tech version of a heat chamber
Passive options (sauna post-run, a hot bath) are worth considering as a lower-barrier way to get some heat stress in, especially if you're prepping for a race somewhere warmer than you've been training
Don't treat this as a race-week tool only, the fitness gains here showed up in normal conditions, not just heat
This is best thought of as a supplement to your existing training, not a replacement for the basics
YOU NEED TO HYDRATE! MAKE SURE YOU’RE HYDRATING DURING THESE SESSIONS. THE STUDY DID 500ML OVER THE 50 MINUTES. I’D DO 500ML OVER 30 MINUTES. PLEASE BE SAFE!
-Keep running happy, healthy, and strong
Spencer
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