Staying hydrated and understanding electrolyte balance (by Julia Roe)

Well, it’s officially summertime.

Aka bring on the heat, humidity, and sweat. When you’re living (and training) in these environments it’s much easier to become dehydrated and lose the proper electrolyte balance. This article will detail how to stay hydrated during training and why electrolytes (and not water!) are important.

Adequate hydration is vital for homeostasis of cellular and metabolic processes, removal of waste products, proper kidney, GI and heart function, joint lubrication, thermoregulation, and optimal exercise performance. There is a higher chance of dehydration during periods of severe vomiting, diarrhea, laxative abuse, and possibly those with eating disorders. Dehydration also becomes a risk in hot and humid environments and during high intensity exercise because of increased sweat rates and heat production. Water loss through sweat is variable and can depend upon: Activity level, individual sweat rates, body weight, adaptation to heat, type of clothing worn, and your diet. Consuming hydrating or salty foods will impact your hydration status!

Why is it so important to stay hydrated? Even a loss of 2% of body weight (in sweat) can reduce performance and may cause muscle weakness/cramping, fatigue, altered thermoregulatory capabilities, increased perceived efforts and mood/cognitive changes. Dehydration can also cause upregulation of catabolic processes and result in decreased glycogen synthesis in muscle and liver, increased glycogenolysis and increased protein breakdown.

This is where electrolytes come into play.

It’s important to keep in mind with increased water loss through sweat there is also an increased loss of electrolytes. Sodium and chloride are the two main electrolytes lost in sweat followed by potassium, magnesium, and calcium, which are lost in smaller amounts. Sodium is the main electrolyte that needs to be replaced during and after high rates of sweat and fluid loss. This is because sodium aids in water retention and helps maintain fluid balance.

How do you know if you’re hydrated? 

You might assume that you could detect dehydration through thirst, but this isn’t always the case. Thirst is often suppressed during high intensity exercise. Thus, once thirst is detected, dehydration is likely already present and performance is affected. Even during periods of rehydration, thirst can disappear prior to adequate hydration levels. Thus, while participating in high intensity exercise, it may be beneficial to drink above thirst cues and consume an electrolyte enhanced beverage to help with fluid retention and replace electrolytes.

The easiest way to monitor hydration is through urine output and color. Optimal urine color is a pale yellow hue, clear urine is actually sub-optimal as it may indicate electrolytes have been flushed out. For a more precise estimation of hydration needs, it may be helpful for athletes in specific sports to weigh themselves before and after training sessions. Athletes can experiment weighing themselves after participating in various training intensities and weather conditions. This will help an athlete understand estimates of their sweat losses under different conditions, and how to hydrate accordingly.  It is recommended that weight loss should not exceed about 1–2% of body mass.

The mechanisms of dehydration and thirst (simplified)

So, what are electrolytes?

Electrolytes are important minerals that maintain fluid balance and are involved in muscle contraction and relaxation, nerve excitability, endocrine secretion, membrane permeability, neurological functions, acid-base balance and assist in controlling the movement of fluids between cells.

Let’s go through the main electrolytes

Sodium: Sodium is the most abundance extracellular ion. Sodium is responsible for ~1/2 of the osmotic pressure gradient that exists between cells, plays an important role in nerve/ muscle function, and blood pressure control. Sodium levels are controlled by the hormone aldosterone (made by the adrenal glands). Aldosterone causes the kidneys to hold on to water instead of producing urine.

Potassium: Potassium is the most abundant intracellular ion important for maintenance of blood volume, blood pressure and electrochemical gradients. Potassium is a part of the sodium potassium pump  (Na/K-ATPase) which maintains extracellular sodium and intracellular potassium.  The Na/K-ATPase creates an electrical gradient  necessary for the kidney filtration, regulation of electrolyte levels in  the blood, electrolyte absorption, and is involved in many other vital processes.

Chloride: Chloride is an abundant electrolyte that plays a key role in maintenance of body fluids, acid-base balance, electrical neutrality, and maintenance of osmotic pressure. Chloride is predominantly regulated by the GI tract and kidneys.

Calcium: Calcium is necessary for skeletal bone mineralization/bone strength, muscle contraction, nerve impulse transmission, release of neurotransmitters, and hormone secretion. Calcium is regulated by calcitonin and the parathyroid hormone.

Magnesium: Magnesium is a cofactor for >300 enzymes. It is essential for ATP production, contraction and relaxation of muscles, proper neurological functioning, helps maintain bone mineral density, blood pressure/ glucose regulation, and is involved in neurotransmitter release.

How to stay hydrated  

Sports drinks are a convenient way to stay hydrated and support optimal performance. Although sometimes sports drinks like Gatorade, Powerade, etc. have received a bad reputation due to the high sugar content, these drinks can be extremely helpful since they are specifically formulated with optimal electrolyte concentrations. Sports drinks contain carbohydrates which are likely necessary during long duration, high intensity exercise for optimal performance. Even if you opt for a sugar free sports drink, you can still get the electrolytes without the carbs!

Coconut water has become a popular ‘natural’ sports drink option as it is high in potassium. However, it is low in other electrolytes, namely sodium, so if you do choose coconut water, it’s likely helpful to supplement with additional sodium.

Lastly, Thermotabs are a great alternative we recommend for clients as they are easy to carry in your gym bag or to travel with and completely negate additional carbs if that does not fit your current goals or program. They are also the most cost effective electrolyte tabs we’ve found (versus other flavored ones, like Nuun).

Outside of sports drinks and/or electrolyte tabs, here are some hydrating and electrolyte rich foods you can eat throughout the day:

Hydrating foods with a high water content: Most fruits and vegetables including watermelon, cucumber, cantaloupe, spinach, lettuce, & more.

Foods high in sodium/chloride: Salted nuts/trail mix, pretzels, crackers and table salt (not recommended for those who are “salt sensitive” or do not tolerate salt well, have any blood pressure/cardiovascular conditions).

Foods high in potassium: Apricots, lentils, bananas, potatoes, dark leafy greens, and oranges.

Foods high in magnesium: Pumpkin seeds, almonds, cashews, peanut butter, spinach, whole grains, and beans.

Foods high in calcium: Milk, yogurt, almonds, sardines, and more.

Don’t let your training performance suffer this summer. Stay on top of your hydration and electrolyte balance and you’ll keep your performance and recovery in check!