When More Sweat Means Less Cooling

You’d think sweating more helps you cool down—but in high humidity, you sweat just as much and cool far less. The study found no difference in sweat rate across humidity levels, yet performance dropped by 16% in very high humidity. Why? The sweat didn’t evaporate—it dripped off uselessly.

Practical Recommendations for Cyclists:

1. Know the Danger Point:

• Absolute humidity over 2.5 kPa (e.g., 33°C & 50% RH) is the tipping point. Above this, evaporative cooling drops sharply, and performance declines begin.

2. Pace Smarter:

• In very high humidity, power output dropped from the start of the time trial. Cyclists naturally paced more conservatively to limit overheating. Plan your pacing strategy based on humidity—not just temperature.

3. Use Environmental Data, Not Just Air Temp:

• Monitor absolute humidity (or dew point) using a cycling computer or app. RH is misleading.

4. Pre-Race Strategy:

• Acclimate to humid heat with 7–14 days of training in similar conditions.
• Use pre-cooling methods: ice vests, cold drinks, cold showers before warmups.

5. Mid-Ride Strategy:

• Maintain hydration, but don’t over-drink just to cool off. You’ll likely lose aero advantage with more bottle grabs and won’t offset the lost sweat efficiency.
• If possible, increase airflow with faster riding or open roads. Even 30–44 km/h airflow didn’t improve cooling if sweat efficiency is already maxed, but it helps prevent early decline if you’re under threshold.

6. Plan Races Accordingly:

• Adjust your expectations and targets for hot-humid races. A 10–20 W drop in sustainable power may be purely environmental.

Takeaway:

Heat isn’t the only enemy—humidity quietly kills your cooling capacity. And when sweat doesn’t evaporate, your body still pays the price. Understand your environment like you understand your power zones.

Source:

Bright et al. (2025), Scandinavian Journal of Medicine & Science in Sports

https://doi.org/10.1111/sms.70...

On my mindChange Your Brain Every Day

I came across Change Your Brain Every Day by Dr Daniel Amen, and it’s surprisingly useful for understanding and disrupting negative thought loops—especially when energy or motivation dips.

The core idea? It’s not the thought that causes suffering, it’s the attachment to it.

Negative thoughts trigger chemical cascades that reinforce bad moods and behaviour. He introduces ANTs (Automatic Negative Thoughts) and shows how to counter them with accurate thinking, not blind positivity.

Ask yourself:

1. Is it true?

2. Can I absolutely know it’s true?

3. How do I feel with this thought?

4. How would I feel without it?

5. Is the opposite even more true?

This reframing technique rewires thought patterns—simple, but potentially game-changing.

Ref: Change Your Brain Every Day by Daniel G. Amen, MD.

Damian.