For most workouts under 45 minutes, water is all you need. Once you push past that threshold, or you’re exercising at high intensity in the heat, a drink containing electrolytes and some carbohydrates will help you maintain performance and replace what you’re losing in sweat. The specifics depend on how long you’re working out, how hard, and how much you sweat.
Water Is Enough for Shorter Workouts
If your session is under 45 minutes, plain water handles the job. You’re sweating, but not long enough to deplete your sodium stores or burn through your carbohydrate reserves in a way that a drink needs to fix. A gym session with weights, a 30-minute run, a quick cycling class: water covers all of these.
There’s no single volume that works for everyone. Your sweat rate depends on your body size, fitness level, the temperature, and how hard you’re pushing. A good rule of thumb is to sip when you’re thirsty rather than forcing fluid on a schedule. Drinking more than about 800 milliliters (roughly 27 ounces) per hour is not recommended, as it can actually dilute your blood sodium to dangerous levels, a condition called hyponatremia.
When to Add Electrolytes and Carbs
Once a workout stretches beyond 45 minutes to an hour, your body starts losing meaningful amounts of sodium through sweat. Sodium concentration in sweat varies widely between people, ranging from about 230 mg to over 2,000 mg per liter. That’s a huge range, which is why some people finish a long run with white salt streaks on their shirt while others barely notice. Potassium losses are smaller and more consistent.
Sodium matters because it helps your muscles contract, your nerves fire, and your body hold onto the right amount of fluid. When levels drop too far, you can experience cramping, nausea, confusion, and in severe cases, dangerous swelling in the brain. A sports drink or electrolyte mix helps prevent this by replacing sodium as you go. Sodium-rich foods and fluids should be available during long efforts in hot conditions, though they won’t prevent problems if you’re overdrinking at the same time.
Carbohydrates in your drink serve a different purpose: fuel. Your muscles burn through stored glycogen during sustained effort, and sipping on carbs keeps your energy steady. Sports drinks typically contain a 6% to 8% carbohydrate concentration, which hits the sweet spot for comfortable absorption. Go much higher and the drink sits in your stomach longer, potentially causing bloating or nausea.
Types of Sports Drinks and How They Differ
Sports drinks fall into three categories based on their concentration relative to your blood:
- Hypotonic drinks have a lower concentration than your blood. They absorb into your bloodstream fastest, making them ideal when quick rehydration is the priority and you’re getting calories from food instead.
- Isotonic drinks match your blood’s concentration. They deliver a balance of fluid, electrolytes, and carbohydrates at a moderate absorption rate. Most mainstream sports drinks (Gatorade, Powerade) fall into this category.
- Hypertonic drinks have a higher concentration than your blood. They deliver more carbohydrates per sip but absorb slowly. Your body actually pulls water from your bloodstream into your gut to dilute these drinks before absorbing them, which can worsen dehydration during intense exercise. These are better suited for recovery or ultra-endurance events where calorie delivery matters more than speed of hydration.
For most people doing a standard workout, isotonic or hypotonic options are the practical choice. Save hypertonic drinks for specific situations where you need a heavy dose of energy and can tolerate slower absorption.
Coconut Water and Other Alternatives
Coconut water has gained popularity as a “natural” sports drink, and it does contain potassium and some sodium. But research comparing it head-to-head with traditional sports drinks tells a mixed story. A study from the University of Memphis tested coconut water against a standard carbohydrate-electrolyte sports drink in exercise-trained men after a 60-minute dehydrating treadmill session. Both rehydrated comparably, but subjects reported feeling more bloated and experienced greater stomach upset with coconut water.
The bigger issue is that coconut water is relatively low in sodium compared to what you lose in sweat, so it’s not a great standalone option for long or sweaty workouts. If you prefer it for taste, you may want to add a pinch of salt or pair it with salty snacks.
Other options people reach for include diluted fruit juice (which can work but often lacks sodium), electrolyte tablets dissolved in water (convenient and easy to customize), and milk-based drinks (better suited for recovery than mid-workout). Whatever you choose, the key factors are the same: adequate sodium, moderate carbohydrates if you’re going long, and a concentration your stomach can handle.
What About BCAAs and Protein Drinks?
Branched-chain amino acid (BCAA) supplements are marketed as intra-workout muscle protectors. Exercise does increase your body’s breakdown of these amino acids, and there’s evidence that supplementing with BCAAs before and after exercise can reduce muscle damage and support muscle repair. However, the practical benefit of sipping them during a workout specifically is less clear-cut. If you eat enough protein throughout the day, you’re likely already getting sufficient BCAAs from food. They won’t hurt mixed into a drink, but they’re not essential for most people’s mid-workout hydration.
Protein shakes are generally too heavy for mid-workout consumption. They slow gastric emptying and can cause stomach discomfort when you’re moving. Save those for after your session.
How to Calculate Your Personal Sweat Rate
The most useful thing you can do is figure out how much fluid you personally need. The CDC recommends a simple sweat rate test: weigh yourself before your workout (without clothes, ideally), exercise for a set time, track how much you drink during, then weigh yourself again afterward. The formula is straightforward.
Take your pre-exercise weight, subtract your post-exercise weight, add back the weight of any fluid you drank (1 liter of water weighs 1 kilogram, or about 16 ounces equals 1 pound), then divide by the number of hours you exercised. The result is your sweat rate per hour for that type of workout in those conditions.
If you lost weight, you need to drink more next time. If you gained weight, you drank too much. Run the test in different conditions (hot vs. cool, indoor vs. outdoor) because your sweat rate can change dramatically. This gives you a personalized target instead of guessing based on generic recommendations.
The Overdrinking Risk Most People Miss
The biggest hydration mistake during exercise isn’t drinking too little. It’s drinking too much. Exercise-associated hyponatremia happens when you take in so much fluid that your blood sodium drops below safe levels. The usual cause is overhydration with water or even sports drinks, both of which are hypotonic compared to the concentrated sodium in your blood.
This risk is highest during long endurance events like marathons and triathlons, especially among slower participants who have more time (and more aid stations) to drink. Certain medications, including common anti-inflammatory painkillers and some antidepressants, can increase the risk by affecting how your kidneys handle water. Symptoms range from nausea and headache to confusion and seizures in severe cases.
The best prevention strategy is simple: drink to thirst. Your body’s thirst mechanism is well-calibrated during exercise. Forcing yourself to drink on a rigid schedule, or chugging water “just in case,” is how problems start. No specific fluid volume has been shown to reliably prevent hyponatremia, so listening to your body remains the most evidence-backed approach.