# Hydration & Heat: What Summer Athletes Miss
It's 85°F and humid on the practice field behind Bernardsville High School. Your legs feel heavy by the second quarter. Your focus drifts. You blame fatigue, but the real culprit started two hours earlier—before you even stepped outside.
Over the past several summers, our team at Advanced Health & Physical Therapy Solutions has worked with local athletes dealing with preventable heat-related performance drops and injuries. We've noticed a pattern: most athletes drink something, but almost none are drinking the right thing at the right time. It's a gap that costs performance and sometimes leads to serious overuse injuries or heat illness.
Let's talk about what actually works.
The Timing Problem: Hydration Isn't Just During Practice
We often hear athletes say, "I drank a full water bottle during practice, and I still felt terrible." The problem is they waited until they were thirsty—or worse, until they were already dehydrated.
Thirst is a late indicator. By the time you feel it, your body is already operating below optimal hydration. For summer sports in New Jersey's heat and humidity, hydration needs to start before you practice or compete.
Our recommendation: Start drinking 2–3 hours before activity. Have 16–20 ounces of fluid with electrolytes and a small amount of carbohydrate (more on that in a moment). Then, 15–20 minutes before you start, another 8–10 ounces. This primes your system so you're not chasing hydration during the most demanding moments.
During activity, drink smaller amounts frequently—roughly 4–8 ounces every 15–20 minutes if it's under an hour, or 6–8 ounces every 20 minutes if you're going longer. The goal is to prevent dehydration, not to "catch up" once you're already behind.
Water Alone Isn't Enough (Here's Why)
This is where we see a major disconnect. Many young athletes—and some parents—assume plain water is all they need. But here's what happens in your body during summer heat and exertion:
You're losing sweat, which contains water and electrolytes (sodium and potassium, mainly). As you drink plain water, it dilutes your remaining electrolytes. Your body senses this imbalance and actually makes you thirstier and reduces the amount of fluid your stomach will absorb. You drink more, absorb less, and feel worse.
Worse, if you're sweating heavily and only replacing with plain water, you can develop hyponatremia (low blood sodium)—a serious condition that mimics heat exhaustion but requires completely different treatment.
For exercise lasting longer than 60 minutes in heat, or for intense activity in any temperature, use a sports drink with:
- Sodium: 200–300 mg per 8-oz serving
- Carbohydrate: 6–8% solution (roughly 6–8 grams per 100 mL)
- Potassium: 30–200 mg per serving
This combination actually enhances fluid absorption in your gut and helps maintain performance. We've worked with soccer players, lacrosse athletes, and runners who were surprised how much better they felt once they switched from plain water to a proper electrolyte drink.
Individual Sweat Rate: Know Your Baseline
Here's a detail that separates athletes who stay healthy from those who struggle: knowing your sweat rate.
Not everyone sweats the same amount. A 140-pound tennis player won't sweat like a 200-pound football lineman, even in the same conditions. Genetics, fitness level, acclimatization, and individual physiology all matter.
To find yours, do a simple test: Weigh yourself before a practice session (minimal clothes). Drink a measured amount of fluid during practice. Weigh yourself after. Account for any urine output if possible. The difference tells you roughly how much you sweat.
Example: You lose 2 pounds during a 90-minute practice. That's roughly 32 ounces of sweat—so you'd want to aim for roughly 20–24 ounces of fluid during practice to stay ahead of it (you can't replace 100% and shouldn't; your stomach can't handle it).
Our athletes who do this simple test often realize they were chronically underfueling during summer workouts.
Heat Acclimatization Takes Time
One more crucial piece: your body adapts to heat, but it takes 10–14 days of gradual exposure. If you're jumping into summer intensity in mid-June after being indoors all spring, your sweat response and heat tolerance won't match what they'll be by late July.
Start with shorter, less intense sessions early in the summer. Gradually increase duration and intensity. This builds your body's ability to thermoregulate and reduces injury risk dramatically.
What We See in Our Clinic
We treat a lot of summer-related injuries that could have been prevented with better hydration habits: heat cramping leading to muscle strains, dehydration contributing to overuse injuries, and occasional heat illness. Many of these athletes are otherwise well-trained and motivated.
The gap wasn't effort—it was information.
Your Move
If you're training hard this summer in our New Jersey heat, take hydration seriously. Start early, use electrolytes for long or intense efforts, and know your sweat rate. Your performance will improve, and you'll stay healthier doing it.
If you're dealing with heat-related cramping, recurring muscle strains, or performance issues despite solid training, our team at Advanced Health & Physical Therapy Solutions would love to help. We work with athletes of all levels—high school through adult club sports—and we can assess whether hydration, movement patterns, or another factor is holding you back. Come see us in Bernardsville, and let's get you performing at your best this summer.