Training in the Heat: What Every Runner Needs to Know Before Summer Miles Ramp Up
If you run through the summer in the Midwest, you already know the struggle. One day feels manageable, and the next feels like you are breathing through a wet towel before sunrise. Here in Indianapolis and across the Midwest, summer running is not just about temperature. Humidity changes everything.
Paces slow down. Heart rates climb. Recovery takes longer. Easy runs suddenly feel hard.
But heat training is not something to fear. In fact, it can actually improve your body’s efficiency and help prepare you for stronger performances later in the year. The key is learning how to adapt safely while recognizing when heat becomes dangerous.
This takes me back to the days at Soot Yord Palung (Extreme Power Gym) back in my Muay Thai days. Surprisingly, I actually have fond memories of showing up in the Southern California gym in July to find all the doors closed and space heaters running on full! It hits different when you show up in a sauna suit (with full sweatsuit under). Brings a whole new meaning to sweatsuit, but anyone who has done this knows how important that training was. Anyway… Back to running.
Why Running in the Heat Feels So Much Harder
Your body is constantly working to maintain a safe internal temperature. During cooler months, it can direct more energy toward performance. In hot and humid weather, your body shifts resources toward cooling itself instead.
That means:
- Higher heart rate at the same pace
- Faster dehydration
- Increased fatigue
- Slower recovery
- More stress on the cardiovascular system
Humidity makes this even worse because sweat cannot evaporate efficiently. Sweat only cools you if it evaporates from the skin. In high humidity, the air is already saturated with moisture, so your body struggles to release heat.
This is why a 75-degree morning in the Midwest can feel significantly harder than an 85-degree dry-climate run out west.
Heat Acclimation: Your Body Can Adapt
The good news is that the human body is incredibly adaptable.
With consistent exposure over time, your body begins making adjustments that improve its ability to handle heat. This process is called heat acclimation.
Most runners begin adapting within 7–14 days of regular heat exposure.
Some of the benefits include:
- Earlier and more efficient sweating
- Lower heart rate during runs
- Improved blood plasma volume
- Better cooling efficiency
- Reduced perceived effort
At first, your runs may feel frustratingly slow. That is normal. One of the biggest mistakes runners make is trying to force spring paces into summer conditions. Summer training often requires checking the ego and adjusting effort levels.
Your fitness is not disappearing. Your body is simply working harder.
Stop Chasing Pace in the Heat
This is one of the most important mindset shifts for summer training.
When temperatures and humidity rise, effort matters more than pace.
A run that would normally feel easy at 8:30 pace may now feel easy at 9:15 pace. That does not mean you are getting slower. It means conditions changed.
Trying to “win” against the weather often leads to overtraining, dehydration, poor recovery, or injury.
Instead:
- Run by effort or heart rate
- Slow down early before overheating
- Accept slower paces on humid days
- Focus on consistency instead of pace perfection
Ironically, runners who respect the heat often come into fall racing season stronger than runners who constantly fight it.
Tips for Running Safely in Hot Weather
Run Earlier When Possible
Even a small temperature difference matters. Early mornings are usually safer and less humid than afternoon runs.
Hydrate Before You Feel Thirsty
If you wait until you feel thirsty, you are already behind.
Hydration also is not just about water. Long runs and hard workouts in the heat may require electrolytes, especially if you are a heavy sweater.
Signs you may need more electrolytes include:
- Muscle cramping
- Headaches
- Salt stains on clothing
- Dizziness
- Unusual fatigue
Dress for Heat
Wear lightweight, moisture-wicking clothing. Dark cotton shirts are basically portable saunas in July.
A hat and sunglasses can also help reduce direct sun exposure.
Adjust Workouts
Not every workout should stay the same during summer.
Sometimes the smartest decision is:
- Shortening intervals
- Increasing recovery time
- Moving a workout indoors
- Converting a hard day into an easy day
Good training is about adapting, not blindly following a schedule.
Heat Exhaustion vs. Heat Stroke: Know the Difference
Every runner should understand the warning signs of heat-related illness.
Heat Exhaustion
This is serious and should not be ignored.
Symptoms may include:
- Heavy sweating
- Dizziness
- Weakness
- Nausea
- Chills or goosebumps despite heat
- Headache
- Elevated heart rate
- Fatigue
- Confusion or trouble concentrating
If this happens:
- Stop running immediately
- Move to shade or air conditioning
- Hydrate with fluids and electrolytes
- Cool the body with cold towels or water
Do not try to “push through” heat exhaustion.
Heat Stroke
Heat stroke is a medical emergency.
Symptoms may include:
- Confusion
- Disorientation
- Loss of coordination
- Collapse
- Very high body temperature
- Lack of sweating despite heat
- Loss of consciousness
Call emergency services immediately if heat stroke is suspected.
Humidity Changes the Equation
Many runners only look at temperature before a run, but dew point and humidity often matter more.
A high dew point means the air is holding a large amount of moisture, making it difficult for sweat to evaporate.
General rule:
Dew point under 60°F: manageable
60–65°F: uncomfortable
65–70°F: difficult
Above 70°F: very stressful for endurance running
This is why some Midwest summer runs feel brutal even when temperatures are not extreme.
Summer Running Can Still Be Very Productive
Summer training is not wasted training. Running in heat builds mental resilience, improves efficiency, and often strengthens aerobic fitness. Many runners are surprised how strong they feel once cooler fall temperatures arrive. The goal is not to prove toughness every day. The goal is to train consistently, recover properly, and arrive healthy for the races and goals that matter most.
The runners who succeed in summer are usually not the ones forcing peak performances in July heat. They are the runners who adapt intelligently, respect the conditions, stay consistent, and take care of themselves.
Train hard. Run proud. Let’s Go!!