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19 May 2026Summer’s not even here yet, and many areas have already experienced warmer-than-usual temperatures. Fresno’s March weather was far hotter than normal, so you can only imagine what summer’s heat and humidity will be like.
When you’re an athlete, training in summer’s heat is difficult. Not only are you at risk of heat-related illnesses, but the heat itself also affects your body, making every workout challenging. Here’s how you can safely train this summer.
Physiology and Its Burden on Summer Training
When athletes train through Fresno’s dry, hot summers, a problem occurs. You’re battling the workout your joints and muscles endure, and the basics of your body’s physiology. Baseline metrics are thrown out the window because your body is coping with the heat, but the air is just as warm, so body heat cannot dissipate. That can lead to heat stress.
What Is Heat Stress?
Heat stress occurs when your muscles generate metabolic heat during a workout. As that heat moves to the skin, it is transferred to the outdoor air. When it’s hot outside, there’s nowhere for the heat to go. That leads to:
- Cutaneous Vasodilation – To cool the warm blood, blood vessels at the skin’s surface expand to carry heat away from the muscles.
- Sweating – The body secretes sweat to cool the skin through evaporative cooling. If it’s also humid out, high humidity keeps the sweat from evaporating.
As blood tries to circulate faster to dissipate heat, your core temperature rises. This can trigger cardiovascular drift.
The Mechanics of Cardiovascular Drift
Cardiovascular drift occurs when your blood flow to the skin increases, moving blood plasma to the skin slightly faster than normal. The extra work increases your heart rate.
You may start feeling your heartbeat with every move. Your body may start to feel more fatigued. Even if it’s been half the time that you usually work out, your mind starts thinking you’ve overdone it, and it can cause you to lose momentum.
If you keep going, you’re going to have to deal with increased cardiac output. Your summer workouts need to adjust to hotter temperatures using the Rate of Perceived Exertion, which also accounts for your breathing rate, sweat, and muscle fatigue.
What Are the Best Proactive Defensive Measures?
When you’re working out in hot summer weather, you need to take steps to train effectively without risking your life. Being proactive with your workouts is key and involves these areas.
1. Heat Acclimatization
Your body needs to be able to train while dissipating heat and maintaining performance levels in hotter temperatures. Working with a sports and orthopedics specialist on heat acclimatization improves your performance in heat.
Typically, a two-week program helps your body:
- Expand the plasma volume by as much a s 15%, which helps with cooling and muscle performance.
- Getting your body to start sweating at a lower core temperature helps with evaporative cooling before you get too hot.
- Improving your body’s absorption rate of the electrolyte beverages you drink.
As your body starts to make these critical changes, you lower the strain on your heart and body when you’re working out on a hot day. It’s done by gradually increasing the time spent exercising in a hotter temperature. Generally, that schedule involves a 20% exposure on the first day, with maximum increases of 20% thereafter.
2. Hydration and Electrolytes
Water isn’t always enough to replenish the liquids you lose when sweating. Your sweat is salty because you’re losing minerals like sodium, too. To ensure you don’t cause an electrolyte imbalance within your body, you must carefully hydrate to replenish both water and the minerals you lose.
The sweat your body releases to help cool your core temperature is mostly water, but it also contains amino acids, ammonia, electrolytes like sodium, and urea. You need to replenish the water and the electrolytes. Do this in three stages (Tri-Phasic Hydration Framework).
- Pre-hydration (2 to 4 hours before a game, practice, or workout)
- In-Workout Hydration (Every 15 to 20 minutes)
- Post-Workout Recovery (Within 2 to 4 hours of stopping the workout)
Knowing how much to drink depends on your individualized sweat rate. Strip off all clothing and record your weight. Work out for an hour and keep track of your fluid intake and urine output. Once the hour is up, get back on the scale after stripping down. Run those numbers through this formula:
(Pre-workout weight – Post-workout weight) + (Fluid intake – Urine Output). The result is how much fluid you lost and need to replace.
Modify Your Workouts in Summer Temperatures
Your workouts have to take the weather into account. Modify them to match the temperature.
1. Use the Wet Bulb Globe Temperature
As you work out in the heat, you do have to adjust to the outdoor temperature and humidity. While the Standard Heat Index provides some information, the Wet Bulb Globe Temperature (WBGT) is the best source to rely on as it accounts for air temperature, humidity, radiant solar heat, and wind speed.
If the WBGT is over 86ºF, consider training indoors or stopping frequently to take breaks in the shade and have more electrolyte beverages.
2. Shift Focus to the Rate of Perceived Exertion (RPE) and Heart Rate Zones
Another factor to consider is that your heart rate will be higher in the heat due to cardiovascular drift. Instead of aiming for your usual heart rate zones, use the Rate of Perceived Exertion (RPE). You have to slow down.
3. Fabrics as a Pre-Cooling Strategy
Finally, work out safely using fabrics designed to keep you cooler. Cotton can trap the heat against your skin. Moisture-wicking fabrics help with evaporative cooling. You could also consider wearing an ice vest or dampening shirts to help lower your core temperature.
Worst Case: How to Treat Heat-Related Illnesses
Even if you’re proactive about training in the summer, heat-related illnesses can still occur. Knowing the early warning signs and when to seek medical care is essential.
1. Dehydration
As you exercise in summer’s heat, you sweat. If you’re not replacing the salt and water you lose, your body mass declines from fluid loss, which negatively affects your brain, heart, and other organs.
You need to make sure you’re replenishing what you lose through sweat. If you’re excessively thirsty, you’re already dehydrated. Don’t wait until you’re “dying of thirst” to replenish your fluids. Monitoring the color of your urine is one way to determine if dehydration is a problem. Urine should be pale yellow.
2. Heat Cramps
Heat cramps are painful muscle spasms that occur when your body loses fluids and sodium through sweating. Your muscles become fatigued, and it’s time to stop, get to shade, and drink a beverage that replenishes your electrolytes.
3. Heat Exhaustion
Heat exhaustion builds upon heat cramps and dehydration. Your core temperature is increasing, but it’s not over 104ºF yet. Signs include:
- Cool, clammy skin
- Dizziness
- Excessive sweating
- Fatigue
- Headache
- Muscle cramps
- Nausea
- Rapid/weak pulse
If you reach this stage, you need to stop, lie down, elevate your legs, and sip an electrolyte beverage. Don’t continue the workout. If you’re not feeling better after an hour, get medical care.
4. Exertion Heat Stroke (EHS)
Once the temperature exceeds 104ºF, it’s a medical emergency. Signs of EHS include:
- Central nervous system dysfunction (unusual behavior or emotions)
- Collapse
- Diarrhea
- Disorientation
- Dry mouth
- Headache
- Muscle cramps
- Nausea
- Profuse sweating
- Rapid pulse and breathing
- Weakness
Someone must call 911 and get you to the emergency department. Heat stroke isn’t something to ignore. The core body temperature must be lowered under medical guidance, and IV hydration is often necessary.
The Importance of Working With a Sports & Orthopedics Specialist
The risk to your health is great if you dive into training or games without preparing for summer’s heat. Working out in heat and humidity takes a greater toll on your body than you might think. That’s why it’s important to work with an expert in sports and orthopedics.
Premium Sports & Orthopedics offers specialized training programs that blend the fitness and muscle training you need while also accounting for water loss and potential dehydration. Talk to us about our targeted programs, like EMS training for muscle strength and IV drip therapy, that ensure your body gets an energy and immunity boost before an intense workout or game.
