Runner vs. Weather: Heat Acclimation
The first few days of hot humid weather are really challenging for runners. Everything feels bad. We’re sluggish; paces are slower but feel harder than normal.
But those first few days are usually the worst of it. Temps may not drop but our experience improves rather quickly. In fact our bodies begin to adapt to hot weather running within just a few days.
Physiological Changes
According to the Encyclopedia of Sports Medicine and Science, complete adaptation to heat can take up to two weeks, but within a 1-5 days our bodies will start to acclimate.
Increased production of plasma: “Plasma is the largest part of your blood. It makes up more than half (about 55%) of its overall content. Plasma carries water, salts and enzymes. The main role of plasma is to take nutrients, hormones, and proteins to the parts of the body that need it.“ (Rochester Medical Center)
We sweat more in hot and humid weather, but in just a few days our sweat will become less salty as our bodies retain more salt.
With the increased plasma and better retention of salts, our heart doesn’t have to work so hard to circulate blood to all parts of our body which means Heart Rate is also going down. Lower heart rate = lower perceived effort. Within a few days, running in the heat just doesn’t feel quite so hard anymore.
Embrace The Heat
Running in heat helps us become better at running in the heat. But did you know that running in heat also helps us become better at running in cool weather? Think of the heat as an added resistance, or handicap. Take it away and you’ll perform even better.
The trick is actually getting some doses of running in the heat safely. Most of us instinctively avoid the hottest part of the day, aiming to run in the morning and evening. This makes sense particularly for hard workouts when we want to set ourselves up for success. But don’t avoid heat like the plague, especially if you anticipate the possibility of heat and/or humidity for your goal race.
Strategically incorporate some hot running into your schedule, making sure you’ve also established a good recovery plan (For example: measure your hydration loss so you can ensure adequate rehydration, and plan how you will cool off quickly afterward.)
Poor Man’s Altitude Training (can we rephrase this to the more inclusive “poor runner’s altitude training?”)
Training at altitude (~5000-7000ft) is very common among elite and high level runners, and many of the world’s best endurance athletes were born and grew up in places of high altitude. The lower oxygen available in the air at altitude causes adaptations that improve running performance back at sea-level.
But many runners don’t have access or the means to travel to high altitude locations just for training! Studies have shown that running in hot weather (heat acclimatization) causes similar physiological responses as training at altitude (Training in Heat to Prepare for Altitude). Hot weather (or a treadmill in a hot room) is much easier to come by than an altitude training trip which is why heat and humidity have been dubbed the “poor” alternative to altitude training.
Nicole Sifuentes is a full-time Running Coach for adults of all ages and abilities. She is a former professional runner and 2-time Olympian, and Certified Strength and Conditioning Specialist. Read more about her services, and schedule your free coaching consultation.