With the heat ramping up, it’s easy to overlook electrolytes' role in the body's fluid balance, muscle function, and nerve signaling. We know we must fuel our muscles with glucose and repair them with protein and amino acids. Yet, we often forget about electrolytes (sodium and potassium) even as we sweat them out.

Understanding how and when to replenish electrolytes is vital to thriving in the heat. You need electrolytes, whether heading outside for cardio, traveling to a breathtaking hiking destination, or planning summer recreational fun.

Let’s break down electrolytes' role in our bodies, their impact on performance, and the best sources to obtain them. With proper hydration, preparedness for the heat, and electrolyte balance, get ready to maximize your outdoor summer plans!

Role in the Body

Electrolytes are minerals dissolved in fluid that carry a positive electrical charge (Lewis). Sodium is one of the electrolytes consumed from food and exits the body via sweat and urine. The kidneys regulate the amount of sodium that the body retains or expels. 

Sodium, the most abundant electrolyte in our body and our diet is vital to the body’s functioning, and we would not survive without it. Sodium plays a role in (Veniamakis):

• Maintaining blood pressure and volume

• Organ perfusion

• Stimulation of muscle and nerve cells

• Balancing fluids and intravascular osmotic pressure

• Thirst stimulus and urine production

Several other electrolytes play similar roles in our organs, nerves, and muscles:

• Potassium

• Calcium

• Magnesium

• Chloride

• Bicarbonate

• Phosphorus

Impact on Performance

Given their significance in human physiology, electrolytes play just as significant a role in performance. Proper electrolyte balance during activity will ensure no adverse performance effects and lower the risk of heat-related illnesses (Armstrong). Maintaining normal sodium levels in the body will also prevent hyponatremia (low serum sodium concentration). 

Electrolytes are unlikely to matter in resistance training sessions because the duration is usually under 2 hours, with most closer to 1 hour. Endurance events are the types of activity for which electrolyte levels and replenishment should be considered. 

In endurance events, minor performance declines may occur at a loss of 2-3% of body weight via sweat loss, with obvious declines occurring at or above 4% loss (Armstrong). 

Electrolyte Planning

All types of electrolytes can be sufficiently attained through foods. Most people don’t need to try harder to get more sodium and chloride because it is a common additive (table salt) that makes food taste better. Foods with high amounts of electrolytes include:

Potassium: Avocados, bananas, potatoes, spinach, legumes, and squash

Calcium: Dairy products, seeds, fish, lentils, leafy greens

Magnesium: Nuts, seeds, legumes, grains, corn, dark chocolate, papaya

Chloride: Table salt, processed meats and foods

Phosphorus: Diary, poultry, legumes, eggs, tofu

If a workout or activity takes less than two hours, or one hour if hot and humid, then electrolytes can easily be restored through normal dietary intake. However, if the length of the activity exceeds this limit, it is crucial to replenish sodium since it is lost the most through sweat. The fastest, most efficient way is through an electrolyte supplement or drink. This way, it can be absorbed rapidly, rather than waiting for food to be digested while exercising. 

If exercising for more than two hours, the recommendation is to consume 300-600 mg/hour of sodium (Vitale). 

Potassium replacement post-exercise, on the other hand, does not help in the rehydration process (Vitale).

Sources

1. Veniamakis E, Kaplanis G, Voulgaris P, Nikolaidis PT. Effects of Sodium Intake on Health and Performance in Endurance and Ultra-Endurance Sports. Int J Environ Res Public Health. 2022 Mar 19;19(6):3651. doi: 10.3390/ijerph19063651. PMID: 35329337; PMCID: PMC8955583.

2. https://www.msdmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/overview-of-sodium-s-role-in-the-body

3. Vitale K, Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019 Jun 7;11(6):1289. doi: 10.3390/nu11061289. PMID: 31181616; PMCID: PMC6628334.

4. Armstrong LE. Rehydration during Endurance Exercise: Challenges, Research, Options, Methods. Nutrients. 2021 Mar 9;13(3):887. doi: 10.3390/nu13030887. PMID: 33803421; PMCID: PMC8001428.