I took a sweat test at Gatorade's elite sports lab. It revealed 3 hydration mistakes I was making.

"It's HOW hot in here?"

I'm no stranger to sweating. As a competitive roller derby athlete, I spend hours a week racing around the track and smashing into my friends (and rivals), often amid sweltering NYC summers.

But this time, I was locked in, literally harnessed to a giant industrial-looking cardio machine at the high-tech Gatorade Sports Science Institute as part of an exclusive battery of tests normally reserved for performance-maxxing professional athletes.

The 45-minute sweat test was my firsthand look at the Institute's cutting-edge environmental chamber. It can reach up to 104 degrees and 80% humidity to mimic real-life conditions for athletes who compete in hot weather, like those in the NFL or the US women's national soccer team.

I was working out at a mere 85 degrees and about 50% humidity, and pouring sweat, but the mild suffering was a privilege.

You can't pay to get a consultation at this lab. The Institute works only with Gatorade's partner athletes, including Caitlin Clark, Lionel Messi, and Venus Williams. The lab's researchers analyze everything from metabolic rate to muscle power and mental function so athletes can perform at their best.

I learned there that I was far from performing my best. Despite working out well over five hours a week for years, I was wrong about how to stay hydrated and fueled during exercise. My lab results showed I should be drinking more water,taking more electrolytes like sodium, and eating carbs than I thought to achieve peak performance.

And I'm not the only one — here's what I learned about fueling the right way.

I tested my hydration, body composition, and sweat rate

The Gatorade Sports Science Institute is about an hour by train from New York City, part of the sprawling PepsiCo campus in Valhalla, New York.

I got a quick rundown and tour from the Institute's director, Lindsay Baker, and senior principal scientist, Matthew Pahnke, both top researchers in exercise, hydration, and performance.

Then it was time for the tests. I started with an initial hydration assessment, otherwise known as peeing in a cup (a great icebreaker activity for meeting new people in a professional setting). My hydration level was determined by a simple color check, which confirmed I was well hydrated at the start of my visit.

From there, I quickly became even closer to the research team. I had to strip naked for a precise body weight measurement (thankfully behind a closed door). Then I donned a sports bra and compression shorts to step into the Bod Pod, a futuristic-looking capsule that measures body composition, the ratio of fat mass to lean mass, including muscle tissue.

All this information would help the research team assess how my body performs during exercise, including how much I sweat, to provide customized advice for how I should hydrate.

The grand finale of testing was a 45-minute cardio session in the environmental chamber, an imposing brick of a room with massive metal doors that allow scientists to precisely control what happens inside.

Before entering, I was outfitted with a heart rate monitor, a strip of gauze to capture my sweat for later testing, and a Gatorade sweat patch, a high-tech, single-use wearable that analyzes how much sweat I'm producing and what's in it.

Then it was time to sweat.

I was slightly dehydrated without realizing it

After years of training and competing in roller derby, I felt ready to take on the Gatorade sweat test.

I opted for a moderate jog during the required 45 minutes of continuous cardio, as researchers checked my heart rate and my subjective sense of how hard I was working. They also stood ready with bottles of Gatorade for when I asked for a drink.

This is where things went slightly awry.

By the end of the test, I was covered in sweat — about 34 ounces of it, according to the analysis. The problem was that I only drank about 6 ounces, not nearly enough to replace the fluid loss.

As a result, I lost 1.8 pounds, about 1.3% of my body weight, while sweating on the treadmill. I felt classic symptoms of dehydration, like a dry mouth and chapped lips.

Ideally, if I had been drinking enough water to replace what I'd lost through sweat, I shouldn't have lost much weight at all, said Tom Coughlin, a sports nutritionist not affiliated with Gatorade who works with pro teams and elite athletes. As it was, I was in the early stages of dehydration, a common issue for athletes.

"Above 2% loss of body weight, you're starting to get physiological impairments, and your body has to work harder to shuttle oxygen around the body," he told me.

For me, that meant it felt harder to keep up the same pace. If I was competing, I'd start to slow down physically and mentally, and have a tougher time making snap decisions or reacting quickly during gameplay.

Part of my problem, testing revealed, is that I'm a heavy sweater, something I've long suspected and now can't wait to share at parties.

My high sweat rate means I'll lose about 1.4 liters of fluid per hour of exercise, putting me at risk of dehydration for efforts longer than an hour. That's bad news, since my typical workouts, including roller derby practice, are often two hours long.

Time to invest in a bigger water bottle.

I'm salty — literally

Losing water wasn't my only sweat-related problem. I also learned that I have particularly salty sweat, losing a moderate level of sodium when I'm working out.

The saltiness of sweat can vary widely from person to person, ranging from a loss of between 500 mg and 1,500 mg per hour. I'm at about 900. If you can't test it in a lab or with a wearable, Coughlin said a good indicator that you're on the salty side is visible salt marks on your clothes after sweating, suggesting you should up your sodium intake.

Sodium is one of seven key electrolytes, alongside potassium and magnesium, which are essential for maintaining fluid balance, so your muscles and nerves can function properly.

Drinking too much plain water without replacing electrolytes can lead to a rare but serious health issue called hyponatremia, which can cause headaches, nausea, cramps, dizziness, or, in extreme cases, death.

While I wasn't in danger, I was still losing more electrolytes than I replaced with the few sips of Gatorade I had drunk during my run.

Coughlin said replacing my lost sodium could help prevent a dip in performance, which could compromise the bursts of speed and laser focus I need at practices and on game day. "Ideally, you want to maintain that balance you started out with," he said.

Adding a pinch of sea salt to a tall glass of water has long been part of my morning routine. I previously consulted sports dietitian Angie Ashe, and she approved, telling me that a little salt in my water or a homemade electrolyte drink could help improve my hydration as an athlete.

Now I just need more electrolytes during exercise — for a DIY sports drink recipe, Asche recommends a mix of sea salt, coconut water, orange juice, and lemon juice to top up sodium, potassium, and magnesium.

I could benefit from more carbs during a workout

The final missing piece in my personal recipe for workout success: sugar. Maligned as an ultra-processed additive, sugar from refined carbs can be a great fuel source for athletes who need quick energy and don't have resources to spare on digestion.

I had a measly 3 grams of carbs during my sweat test. For my moderate pace, I should have been consuming between 10 and 30 grams of carbs per hour, according to the researchers.

That's well within what Coughlin recommends, too.

During a higher intensity activity (like roller derby), I'll burn through more fuel, making it even more important to have some carbs on deck.

Endurance athletes can use between 60 grams of carbs per hour and a whopping 120 grams or more for athletes like elite marathoners, according to Coughlin.

That means I'll definitely be packing gummy bears for my next practice.

The takeaway

I didn't totally flunk my hydration test — I'd probably give myself a C — but there was plenty of room for improvement. I learned I should:

• Drink more water overall during exercise
• Don't drink plain water alone — mix in some electrolytes
• Add more carbs around a workout, especially for long, high-intensity sessions
• Start drinking (and fueling) before I feel tired and thirsty

If you often feel run-down during and after workouts, you might benefit from better hydration, too. Coughlin said it's a common issue during exercise, and the best approach is to be proactive before symptoms start.

"The majority of athletes are underfueling. I see that in my own practice," he said. "Anything over an hour, that's when you burn through, and energy starts to drop. But elite marathon runners don't wait for an hour; they're fueling every 20 minutes."

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