Sweating and Dehydration: What Every Athlete Needs to Know

Sweating and Dehydration: What Every Athlete Needs to Know

Stepping up to the Challenge!

Last year, I found a great deal at a local spin studio: $100 for unlimited spin classes. My friend and I immediately signed up and challenged ourselves to back-to-back spin classes from 6am-8am, 5 days a week. Crazy or not enough? As an athlete, finding new ways to push yourself is half the fun of an intense workout. Finding out what your body is capable of is empowering and feeling stronger every week is the reason why many people get addicted to working out. With willing and able bodies and minds, the spin challenge of 2012 began!

It was exciting and challenging to get myself out of bed at 5:30 am and hop on a spin bike and, as the weeks went on, I continued to feel stronger. When you increase your exercise, you become very in tune with what your body needs. Week three, I started getting afternoon headaches and realized I was not properly hydrated. My friend was aggressive and would sweat buckets. By the end of the spin class, his bike would be swimming over a pool of sweat! I didn't sweat nearly as much and therefore, thought I didn't need as much water. Wow, was I wrong!

Sweat and Sweat Rate

Sweating is a cooling process the body undergoes to protect cells and dissipate heat created by exercise. Did you know your muscles can generate 20 times more heat when they're working hard versus when they're at rest? The body combats this heat by releasing water, sodium, chloride and modest amounts of potassium (the components of sweat) to cool off. To understand how to effectively replace fluids to prevent dehydration, it is important to determine your sweat rate.

How do we do that?

  1. Weigh yourself in the nude before and after an hour-long workout.
  2. For every pound lost, drink 13-16 oz of fluid.
  3. Aim to drink this amount during each hour of exercise.
  4. One gulp is roughly 1 oz of fluid.


Remaining hydrated while exercising is crucial. If you wait until the feelings of thirst hit, you could already be dehydrated. When you feel thirsty, your body has lost significant amounts of fluid, causing sodium levels in the blood to become more concentrated, signaling thirst. According to the Sports Nutrition Guidebook, by the time your brain signals thirst, you may have already lost 1 percent of your body weight, about 1.5 pounds of sweat for a 150 pound person. This 1 percent loss corresponds with the need for your heart to beat an additional three to five times per minute. Dehydration is defined as a 2% loss of your body weight, which puts additional strain on the heart during exertion.

Common symptoms of dehydration can include headache, nausea, brain fog, difficulty with exercise, lethargy, fatigue, dry / sticky mouth, thirst, constipation, dizziness, lightheadedness and dry skin. Stay hydrated!

Importance of Fluids

Water is important, but, as mentioned earlier, sweat is made up of more than just water. Staying hydrated means replacing lost electrolytes and nutrients. Most people get an average of 20-30% of fluid just from the foods they eat and most foods contain vital electrolytes and nutrients. If you're engaging in endurance exercise for over 1 hour, you may need electrolyte-enhanced fluids and additional nutrients. A pound of sweat contains about 80-100 mg of potassium and 400-700 mg of sodium.

Quick Tips to Assess Hydration Status

• Check the color of your urine; it should be clear. If it is dark yellow, this means you need more water.

• Check out this awesome urine color chart.

• Check your weight after going to the bathroom in the morning (including a bowel movement). If your goal is not to lose weight, this number should stay consistent or increase. If you are noticing a decrease, you may be dehydrated.

Fluid and Nutrient Timing

Setting goals with fluid and nutrient intake will help prevent dehydration and keep your body moving! There is nothing worse than wanting to workout, but being physiologically limited due to dehydration. Ensure adequate fluids and nutrients are consumed prior, during and after a workout.

Before a Workout

• Drink 2-3 ml per pound of body weight at least 4 hours before a workout

• 1 ml = .03 fluid ounces

• Including a drink with a small amount of sodium, or eating a small salty snack before a workout, can help your body retain some of the fluid you drink.

During a Workout

• Always aim to sip water throughout a workout.

• If exercising longer than 3 hours, it’s important to know your sweat rate and replete fluids and nutrients as needed.

• Ideal fluid to drink per 8 ounces (1 cup) should contain 110-170 mg of sodium, 20-50 mg of potassium, 12-24 g of carbohydrates

• Can be consumed via coconut water, pretzels, bananas.

• If exercising for more than 1 hour, aim for an additional 120-240 calories of carbohydrates to help with your workout.

After a Workout

• Drinking 50% more fluid that what you lost in sweat will prevent dehydration.

• Sip on water throughout the rest of the day.

• If you will be working out again within 12 hours, make sure you eat something containing sodium or sprinkle small amounts of salt on your meal.

• It can take your body 24-48 hours to replace sweat losses.

Fluid Options

With all this information, it can be confusing to single out your best options for hydration. Below are some of the best choices to make to fuel your body during a workout.

  • Orange Juice - Carbohydrates are a crucial form of energy our body uses during a workout. Not only does OJ contain carbohydrates, but it also has high levels of Vitamin C, potassium and folate. A fresh, peeled orange is also a great option.
  • Coconut water - Filled with electrolytes, coconut water is like a natural form of Gatorade. I would choose this if you were on the go and needed to grab a quick drink. To make it even more effect, sprinkle in a little pinch of salt. After an intense workout, the added sodium will help replenish what was lost in your sweat.
  • Green Tea - With its high antioxidant levels and moderate amounts of caffeine, this can be a great way to hydrate, stay healthy and get a little extra boost from the caffeine. If you are sensitive to caffeine or are avoiding it within your diet, don’t go for this option. However, if you are an avid coffee drinker or trying to wean yourself from caffeine, green tea is a great alternative.
  • Water - It doesn’t get better than your old friend, water. The best way to get adequate water is to filter regular tap water into a reusable container. I recommend a BPA free vessel or a glass bottle. It is often easy to grab bottled water, but the implications on the environment are huge. Be conscious of waste that is created and opt for reusable containers.

Listen to Your Body

Taking the time to understand your sweat rate, staying adequately hydrated and listening to your body can help you become a stronger athlete. While remaining hydrated, it is important to remember that you can overdo it with fluids. Over-hydration, or hyponatremia, results when fluid is consumed above the level the body can process. Hydrate responsibly and listen to your body. With these tips, you are on your way to becoming a stronger and healthier athlete!

Registered Dietitian, Certified Specialist in Sports Dietetics

No Avatar

Thank you for your comment! It is pending approval and should be posted shortly.