Heat Acclimatisation Training

Now that I live in Norway, I don’t have to worry so much about the summer heatwaves anymore. But I am planning on walking the four-day marches next year. That got me thinking, how am I going to prepare for the heat?

My group commander used to say ”You’re not hindered by the heat if you’re fit”. We all knew that this was a bit exaggerated, but there is some truth to it. So why does training and adaptation help us cope better with the heat?

”Your not hinderd by the heat if your fit”

Physical Fitness Enhances Heat Tolerance: Key Adaptations

Physical fitness enhances heat tolerance by improving the body’s efficiency in dissipating heat through increased sweat production, better cardiovascular function, and effective thermoregulation. These adaptations help maintain a stable core temperature and reduce heat-related stress during exercise.

1. Improved Cardiovascular Efficiency:
   • Increased cardiac output and stroke volume facilitate more efficient blood flow, aiding in heat dissipation.
2. Higher Sweat Rate and Increased Sweat Gland Sensitivity:
   • Enhanced ability to produce sweat more efficiently, promoting evaporative cooling and reducing core body temperature.
3. Increased Plasma Volume:
   • Expanded plasma volume helps maintain blood pressure and improve thermoregulation by transporting heat away from core organs.
4. Enhanced Thermoregulatory Control:
   • Better autonomic control of skin blood flow and sweating, allowing for more effective temperature regulation.
5. Lower Core Temperature:
   • Fit individuals tend to have a lower resting core temperature, which helps buffer against the rise in temperature during heat exposure.
6. Efficient Heat Acclimatization:
   • Faster and more effective acclimatization through repeated exposure, leading to physiological changes such as a reduced core temperature threshold for sweating and improved overall thermoregulatory responses.
7. Reduced Electrolyte Loss:
   • More efficient conservation of electrolytes in sweat, preventing imbalances that can impair performance and thermoregulation.
8. Improved Metabolic Efficiency:
   • Enhanced metabolic efficiency reduces heat production during exercise, decreasing the thermal load on the body.

Suaning for Enhancing Exercise Performance in Hot Temperatures

I’m already a big sauna fan, and I w as happy to learn that saunaing can be helpful when training for hot weather. Here are some findings from papers backing this up.

1. Post-Exercise Sauna Bathing Improves Exercise Performance: Three weeks of post-exercise sauna bathing significantly improved running performance, reducing peak rectal temperature, skin temperature, and heart rate, thereby enhancing exercise capacity in both hot and temperate conditions (Kirby et al., 2020).

2. Heat Acclimation via Sauna Use: A five-day heat acclimation protocol using a sauna or hot-water immersion led to beneficial adaptations, such as reduced core and skin temperatures and lower heart rates during exercise in hot conditions, proving effective for military personnel (Ashworth, Cotter, & Kilding, 2022).

3. Sauna and Physiological Adaptations:Regular sauna use improved arterial compliance, reduced blood pressure, and increased plasma volume, which are beneficial for cardiovascular health and performance during exercise in hot environments (Lee et al., 2018).

4. Neuromuscular Recovery: Infrared sauna sessions post-exercise improved recovery of neuromuscular performance and reduced muscle soreness after resistance training, which can enhance overall athletic performance (Ahokas et al., 2022).

5. Endurance Enhancement: Post-exercise sauna bathing increased run time to exhaustion by 32%, which corresponds to a significant improvement in endurance performance. This enhancement was correlated with increases in plasma and total blood volume (Scoon et al., 2007).

Heat Acclimation Plan Leading Up to Race Day

Experts say that it takes about 14 days to fully adapt to the heat. But if you have a longer timeframe with access to a sauna, a better suggestion is to do a longer adaptation program. This way, less strain is put on the body in the time close to the event. The program below is from the Trainright blog which focuses on ultra running. But I suppose it applies just as well for an event like the four-day marches.

1. Two Phases: Start by acclimating about six weeks before your event. Then, do a second round of acclimation in the final week before the event.
2. Maintenance Sessions: Between these two phases, do shorter heat sessions every three to four days. This helps keep your body used to the heat and makes the final acclimation more effective.

These maintenance sessions help prevent the ~2.5% daily loss of heat acclimation. Plus, repeated exposure to heat has a cumulative effect, making your body even better at handling the heat (Périard et al., 2021).