If you've ever noticed that sweat sometimes burns your eyes, tastes salty or even feels gritty, then you know that it's not just water you're losing. Sodium, chloride and other minerals also get expelled.

That's why water alone isn't enough to maintain the right balance of fluids in your body during exercise, particularly endurance sports like running, according to Dr. Megan Arthur, a primary care sports medicine physician at Houston Methodist.

"When we say, 'staying hydrated,' what that really means is maintaining a good balance of fluids in the body to help support our normal physiologic functions," Dr. Arthur says. "That involves not just drinking water, but also balancing that intake with the appropriate amount of electrolytes so that your body can perform its proper functions."

Drinking too much water can dilute the concentration of electrolytes, potentially leading to symptoms such as headache, muscle cramps and even confusion. Too little water can lead to dehydration, which include symptoms like thirst, tiredness, dizziness and even the potential for heat exhaustion and heat stroke.

Therefore, the balance between the two substances "really is key," says Dr. Arthur.

So, what's the right balance, and how do you know if you're in need of one or the other? Dr. Arthur provides a primer on proper hydration — complete with general guidelines, varying factors, tips and more.

How much water should you be drinking when exercising?

While many online resources recommend six to eight cups of plain water or 11 to 15 cups of total fluids daily, Dr. Arthur says there really isn't a one-size-fits-all answer when it comes to how much water you should be drinking, especially as it pertains to exercise, when sweat can significantly change the amount of water loss you experience on a daily basis. However, if you're drinking more than one liter of only plain water per hour of exercise, then that's a bit too much, she says.

"For shorter exercises — less than an hour — I generally recommend about a half cup to a cup of water every 15 minutes based on your thirst and intensity of your workout," Dr. Arthur says. "For exercises longer than an hour, such as distance running, at that point you'll want to balance that water intake with electrolytes such as in a sports drink."

Besides salt, what exactly are electrolytes?

Salt, or sodium chloride, is perhaps the most well-known electrolyte. But electrolytes are any mineral that naturally carry a positive or negative electric charge, especially when dissolved in water, which includes that in our bodies and blood.

According to Dr. Arthur, these minerals — namely sodium, potassium, calcium, magnesium and chloride — are found in nearly every part of fluid and cell within the body and are crucial for helping our body regulate itself, including nerve function and muscle contractions.

How do you lose electrolytes?

Just like we lose water through urine, sweat and other bodily fluids (like vomiting and diarrhea), we also lose electrolytes by these same pathways. This loss becomes even greater during exercise or when it's hot outside as the body produces even more sweat to try and cool itself down.

"Especially in hotter and more humid environments like Houston, both dehydration and overhydration can occur when you're either not drinking enough fluids or if you're drinking too much plain water and not enough electrolytes," says Dr. Arthur. "You really want thirst to be your guide."

(Related: What Happens If You Eat Too Much Salt?)

5 tips for replenishing your electrolytes and staying properly hydrated

In addition to drinking water, Dr. Arthur shares five tips for refueling your electrolytes before, during and even after a race or exercise, in some cases.

1. Pre-hydrate before your event or race

Whether you're running a marathon or simply planning on biking around town for a few hours, drinking fluids from a few hours to a few days leading up to a race, event or a big exertion can help ensure your body is well hydrated beforehand, says Dr. Arthur.

"Generally about four hours before exercise, if you're slowly drinking about 12 to 20 ounces of fluids, that can be helpful for pre-hydrating," she says. "At the same time, you'll also want to consider taking electrolytes of some sort like a sports beverage."

2. Consider refueling after short exercises or cooler conditions

In instances where you're only exercising for a short amount of time or in cooler conditions where you're not sweating a lot, Dr. Arthur says you may not have to replenish your electrolytes until after the fact.

In other words, the less you sweat, the fewer electrolytes you tend to lose and need to replenish.

3. Refuel with sports drinks, electrolyte tablets or food

Electrolytes come in many different forms, not just your favorite flavored sports drink. Electrolyte tablets, some energy gels and even foods rich in those minerals like potassium and magnesium may all serve to replenish the minerals you lost to sweat in addition to your sports beverage of choice.

Bananas are a good option, but so is a breakfast or energy bar — just something that's quick to eat and easily digestible, Dr. Arthur says.

4. Avoid sugary drinks

If there's one thing you should watch out for, according to Dr. Arthur, it's sugary drinks.

"Beverages that are high in sugar can actually cause cramping, increase your desire to urinate during the competition and has no clear performance advantage," she says.

5. Pay attention to your body

"Always listen to your body," says Dr. Arthur. "Pay attention to signs of being dehydrated or overhydrated and adjust your fluid intake according to those."

Symptoms of dehydration may include:

• Feeling thirsty
• Muscle cramps
• Headache
• Dark or strong-smelling urine
• Feeling tired, dizzy or lightheaded
• Dry mouth

Symptoms of overhydration or hyponatremia may include:

• Muscle weakness or cramps
• Headache
• Nausea and vomiting
• Confusion
• Fatigue or lethargy

"If you feel like you're drinking too much, consider reducing your water intake," Dr. Arthur says. "However, if you experience symptoms like muscle cramps or feel like you're underperforming, then you may need more water or electrolytes."