After months of cold weather running, the summer heat and humidity feel like a shock to the system. When you are out running, they literally are. Your cardiovascular system works harder to pump enough blood to the skin to keep you cool. Faster rates of fluid loss can affect muscle function. Overheating can send a signal to your brain to shut down the run. Each year, no matter how many years you have been running, you need to adjust your training for running in heat and humidity as part of the acclimatization process.
Training adjustments to heat and humidity will vary widely based on the individual runner. Your current fitness, personal preference and tolerance for hot weather, and geographic location will all impact how much you need to adjust your training at the start of summer. High humidity also requires acclimation; if you live in a humid area, your training may require more adjustment than if you train in an arid region. There is a reason many elites train in Flagstaff, not the Midwest!
Some runners may barely need to adjust, especially if summer temperatures gradually increase. Others may need to allow longer to adjust, especially if the weather suddenly changes from 45-degree mornings to 70-degree mornings.
Temporarily adjusting your training will not harm your fall racing goals. If anything, a focus on long-term, sustainable growth will only benefit you in fall races – and beyond.
Treat the Heat and Humidity as a Training Stress
It is vital to understand heat and humidity as a type of training stress, just like mileage and intensity. Training does not take place within a vacuum. Heat and humidity make running objectively harder, particularly before you are acclimated for the season.
Too much stress hinders adaptation, increases injury risk, and multiples the likelihood of mental burnout. You do not want to increase multiple training stresses at the same time. Your long-term training will improve if you allow yourself time to adapt to the stress of the heat, before increasing mileage or intensity.
As you acclimate to summer weather, consider keeping other aspects of your training load the same. The first few weeks of summer may not be the ideal time to increase mileage or start a speed segment. You may even choose to slightly decrease volume or intensity as you acclimate.
Train for Time, Not Distance
Almost all runners will slow down during the acclimation period, if not during the entire summer. Any run will naturally take longer. If you are limited on time or tempted to push the effort to finish at your normal pace, consider running for time instead of distance. An hour easy run is an hour easy run, whether you run it at a 10:00 min/mile in 70-degree heat or a 9:00/mile in 40-degree temperatures.
When in Doubt, Run Easy
Many runners possess a tendency to go too hard, too often. When heat and humidity spike, this tendency becomes even more detrimental to adaptation. Running too hard too often when unacclimated to the heat will apply too much training stress. Too much stress hinders adaptation and creates a vicious cycle of subpar runs and performance plateaus.
An easy run is always beneficial, no matter what your goals are. Want to run faster? Easy runs will improve your running economy. Want to run farther? Easy runs build endurance. If you struggle with heat and humidity, just focus on easy mileage for a few weeks as you adapt.
If you struggle with controlling your effort in the heat and humidity, consider training with heart rate. Heat and humidity will spike your heart rate, so you will likely run much slower to maintain an aerobic heart rate zone – but in summer, easier is better.
Modify Your Quality Workouts
If you are well adapted to quality workouts such as tempo runs, intervals, and the like, you can likely continue them during summer. However, you may want to modify the format and scale the intensity as you acclimate. This post details exactly how to modify a speed workout for summer. Opt for shorter intervals and fartlek-style workouts, hill repeats, and leg speed development runs (such as these summer speed workouts). Take your focus completely off of pace, because your paces will be slower to reflect the higher energy demands of running hard in the heat. Effort is what matters!
Know When to Bail a Run
Extreme heat and humidity can be dangerous, especially if you are not acclimated. If you stop sweating, experience lightheadedness or dizziness, or your form noticeably deteriorates, stop running. Those extra miles have no training benefit at that point and the risk of heat stroke or hyponatremia is high.
How do you adjust to summer running?
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