Hydration – A Comprehensive Guide
As a trainer and fitness fanatic you know first-hand the importance of good hydration and fluid and electrolyte balance. But do your clients?
Hydration is essential—for healthy bodies, athletic performance, energy, digesting food, functioning joints, and so much more.
Dehydration occurs when the amount of water you take in is less than the amount of water your body is losing. Your fluid balance is out of whack.
Make sure you know everything about hydration, dehydration, strategies for hydrating before, during, and after events, and what can happen when fluids are out of balance, so that you can educate your clients, help them perform better, and keep them safe.
The Importance of Fluid Balance and Hydration
Water performs several important functions in the body:
- Water dissolves and transports minerals, vitamins, proteins, and other important substances throughout the body.
- Water speeds up the breakdown of food and absorption of nutrients.
- Water lubricates our eyes, joints, spinal cord, and other areas of the body.
- Water regulates body temperature.
- Water helps catalyze chemical reactions in the body.
To perform optimally and to be healthy we need to have fluid balance. This means that the amount of water you consume needs to equal the water you lose during the day. How do we lose water? By sweating and through the skin, when eliminating waste, and when exhaling during breathing.
And how do we take in more fluids? The only way to get water in is to consume it, although this is not restricted to drinking water. All beverages you consume provide water, as do foods you eat. Just be sure to stick to eating a balanced diet and skip sugary drinks. Focus on foods that have more water than others, like fruits, vegetables, and cooked grains and beans. Fatty foods provide less water.
What is Dehydration?
Maintaining good, steady hydration means you shouldn’t feel thirsty, ever. If you get thirsty you are already dehydrated, having lost between one and two percent of your body weight in fluids. And if you’re in the middle of an athletic performance, you can’t recover that hydration quickly enough. Your performance is already suffering.
Dehydration is the loss of water and electrolytes—mineral salts like sodium, calcium, and potassium—from the body to the degree that it impairs body functions. The best way to combat dehydration is to avoid it. Being proactive and staying hydrated is important.
What Does Dehydration Feel Like?
Thirst is a sign of dehydration, but there are other clues that you have lost your fluid balance. The early signs of dehydration include:
- Thirst and dry mouth
- Darker urine
- Flushing of the skin
- Elevated body temperature
- Increased breathing rate
- Elevated pulse
Dehydration Impacts Performance
During a workout or athletic event, dehydration can lead to decreased performance. You’ll start to feel fatigued and like everything requires more effort than usual. Dehydration triggers muscle cramps, nausea, and headaches. You will lose some muscular endurance and strength and your overall performance will decrease.
The Dangers of Dehydration
There are also some very serious potential consequences of dehydration. It can become severe if you don’t stop to rehydrate. Dehydration can lead to:
- Kidney failure.
- Heat exhaustion.
Dehydration can literally be fatal. The risks are greatest during intense physical activity, especially in the heat. For this reason, hydration is a serious matter.
Determining Hydration Needs
If your client is not engaging in exercise on any particular day, two liters of water plus water from a healthy diet—this includes several servings of fruits and vegetables—is adequate for hydration. This basic formula can be scaled up for larger people and those exercising and sweating a lot, and down for smaller individuals. To be more specific, there are two basic calculations for determining fluid needs:
- Metabolic rate. You need to consume 80 to 110 milliliters of water for every 100 kilocalories of metabolic rate. For example, if your BMR is 2,000, you should be drinking 1.6 to 2.2 liters of water per day as a baseline.
- Body weight. A slightly easier way to estimate water needs is by weight. Consume 30 to 40 milliliters of water for every kilogram of weight. If you weight 50 kilograms (110 pounds), for instance, you need at least 1.5 to 2 liters of water per day.
It’s also important to consider factors that change basic fluid needs. You need to up these baseline fluid intake amounts in the following situations:
- When temperatures are high, you sweat more and need more fluids to replenish lost water.
- More intense and longer workouts also increase sweat output.
- Exercising during warm weather conditions requires that you increase fluid intake even more.
Achieving a fluid balance is all about taking in enough water to match your individual weight or metabolic rate, with respect to your activity level and environmental conditions on a given day. On any day that you are not working out or participating in an athletic event, the baseline amount of water should be adequate. For training and exercising, however, you may need more specific strategies to make sure you don’t get out of balance.
How to Hydrate before and During Exercise
When working out, a good general rule is to drink 500 milliliters (about two cups) a half an hour in advance and to get in 250 milliliters of fluid every 15 minutes during the activity. The idea is to get pre-hydrated so you start exercise in a state of having extra fluid and a good electrolyte balance. Drinking during the workout helps maintain hydration and prevent dehydration.
Rehydrating after Workouts
Even with good efforts to stave off dehydration during a workout or sporting event you are likely to have lost a lot of fluids and electrolytes. The purpose of hydration post-workout is to rehydrate and to assist recovery. Without proper rehydration at this point you risk becoming dehydrated and delaying recovery.
Fluid Intake after Being Dehydrated – Rapid Rehydration
If you do get excessively dehydrated after an activity, you need to take steps to get rehydrated as quickly as possible. It’s not difficult to get to this state, especially when you misjudge the weather conditions or when the event or workout is tougher than you anticipated and fluids aren’t top of mind during the activity. To rehydrate rapidly, take in up to 1.5 liters of fluid per hour. This is as much as the body can absorb, so drinking more than that will not be useful. Some situations in which it is important to rehydrate at this rate include:
- In between events during a long tournament.
- After an intense workout in hot conditions.
- After intentionally dehydrating for a body sport weigh-in.
Protein Intake for Hydration
The latest sports science research indicates that getting some protein during and after a workout is a beneficial part of rehydrating. Protein helps enhance recovery, muscle protein synthesis, glycogen synthesis, and immune function. It also reduces muscle soreness. As a good general rule, add 15 grams of protein to 600 milliliters of fluid that you use during and after exercise.
Check out this post about busting protein myths to learn more about how much protein you really need.
Sports Drinks vs. Water – The Importance of Electrolytes
For most people who are not exercising intensely, water and a healthy diet are adequate for maintaining good hydration. For athletes, on the other hand, and for your clients if they’re pushing hard on a race day or during a heavy training session, water doesn’t quite cut it.
Electrolytes are the minerals in our bodily fluids that conduct electrical signals and assist in a lot of other important functions. As with fluid balance, you need to maintain a balance between electrolytes in and electrolytes out. When you sweat a lot, you lose water as well as electrolytes, so in any situation in which you are training, performing, or just working out, you need to include electrolytes in fluid intake.
A good sports drink likely provides what you need for electrolytes during training and events, but generally you should aim for six to eight percent electrolytes in a fluid for the best results.
Carbohydrates are important too. In your sports drink or homemade fluid mix, be sure to include 30 to 40 grams of carbs in 500 milliliters of water, a six to eight percent solution. Carbohydrates help with absorption of water and electrolytes, improve endurance during activities, decrease the body’s stress response, decrease inflammation after working out, and improve glycogen synthesis.
Share this ISSA infographic with your clients to help them better understand the importance of sodium in the diet.
The Risks of Over-Hydration
Athletes are at risk of going overboard on hydration before and during events. Even the most experienced athletes are vulnerable. In a study from Europe, researchers found that ten percent of the over 1,000 competitors in the Ironman European Championships had hyponatremia.1
If you drink too much, especially plain water without electrolytes, before and even during or after a sporting event, you can end up with hyponatremia—low concentrations of sodium in body fluids. In other words you dilute blood and other fluids until the levels of electrolytes are dangerously low.
Just like dehydration, hyponatremia can become severe and even be fatal. Early signs of the condition include:
- Nausea and vomiting
- Gastrointestinal distress
- Swelling in the hands and feet
- Confusion and restlessness
Ultimately, hyponatremia can cause brain cells to increase water content causing cerebral edema, excessive fluid and swelling in the brain. This condition is fatal if not addressed. It’s unlikely that in the normal course of trying to hydrate for physical activities that you will develop severe hyponatremia, but it is something to be aware of and to avoid.
Manipulating Hydration for Performance
If you have ever participated in or been involved in training for body sports like bodybuilding or fitness figure competitions, you know that athletes will intentionally manipulate their hydration levels. For an example of how and why an athlete might do this, consider weight class athletes. They drop 10 to 15 pounds of fluid weight about a week before an event weigh-in and then quickly rehydrate to get the weight back in time for the actual event.
Through specific hydration steps you can actually train your body to excrete a lot of fluid over several days. Fitness figure competitors may also do this in order to lose fluid to make their muscles stand out during the competition.
Manipulating hydration and the balance of fluids and electrolytes can be risky, so never try it without input from someone more experienced, and discourage your clients from doing it unless you have the expertise to help them do it safely.
Hydration is so important, not just for athletic performance but just for being well overall. Take this information and use it to lead your clients to a better understanding of why they need to consider fluid balance and how to do it right.
To learn more about nutrition for athletes, check out the ISSA’s Sports Nutrition Certification course.
Click HERE to download this handout and share with your clients!
1. Danz, M., Pottgen, K., Tonjes, P.M., Hinkelbein, J., Braunecker, S. (2016) Hyponatremia among Triathletes in the Ironman European Championship. N. Engl. J. Med. 374 (10) 997-998
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