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Electrolyte Replenishment - Why It’s So Important and How to Do It Right

By Steve Born

Steve Born

Steve's decade-plus of involvement in the sports nutrition industry, as well as nearly 15 years of independent research in nutritional fueling and supplementation, has given him unmatched familiarity with the myriad product choices available to athletes.

Updated 03/2010

Electrolytes are analogous to the motor oil in your car - they don’t make the engine run, but they’re absolutely necessary to keep everything running smoothly. Proper functioning of the digestive, nervous, cardiac, and muscular systems depends on adequate electrolyte levels.

Muscle cramps, though there are many theories as to why it happens, usually involves improper hydration and/or improper electrolyte replenishment. No one wants to cramp, of course, but remember, cramping is a place far down the road of electrolyte depletion. Cramping is your body’s painful way of saying “Hey! I’m on empty! Re-supply me now or I’m going to stop!” It’s like the oil light on the dash; you never want it to get that low.

That’s precisely why, just as you shouldn’t wait until you bonk before you re-fuel, or dehydrated before you replenish fluids, you shouldn’t wait for cramps to remind you to take electrolytes.

In this article we’ll look closely at this vital, but often neglected and misunderstood, aspect of fueling. We’ll tell you why salt tablets don’t work, and why Endurolytes is unquestionably the finest electrolyte formula you can use.

Proper fueling during exercise requires more than replenishing calories and fluids; it involves consistent and adequate electrolyte support as well. Electrolyte needs vary much more than either caloric or hydration needs, so you will have to experiment quite a bit in training until you have this aspect of your fueling tailored to your specific requirements under various conditions.

What are electrolytes? Why do I need them?

Electrolytes are chemicals that form electrically charged particles (ions) in body fluids. These ions carry the electrical energy necessary for many functions, including muscle contractions and transmission of nerve impulses. Many bodily functions depend on electrolytes; optimal performance requires a consistent and adequate supply of these important nutrients.

Many athletes neglect consistent electrolyte replenishment because they’ve “never had cramping problems.” Even if you’ve been fortunate enough to have never suffered the painful, debilitating effects of cramping, you still need to provide your body with a consistent and adequate supply of electrolytes. Why? Because the goal in replenishing electrolytes is not so much to prevent cramping, but to maintain specific bodily functions at optimal levels. Cramping is your body’s way of letting you know that regarding electrolytes, it’s “on empty.” When you’ve reached that point, your performance has been severely compromised for some time. Remember, you want your body to perform smoothly, without interruption or compromise, so just as you shouldn’t wait until you’re dehydrated or bonking before you replenish fluids or calories, you never want to wait until you’re cramping before replenishing electrolytes. Consistent replenishment of electrolytes is just as important as the fuel you consume and the water you drink during exercise.

Can't I just use salt tablets?

Salt tablets are an unacceptable choice for electrolyte replenishment for two reasons:

They provide only two of the electrolytes your body requires - sodium and chloride.
They can oversupply sodium, thereby overwhelming the body’s complex mechanism for regulating sodium.

Each of these issues is important, and we’ll discuss both of them. Right now, let’s focus primarily on the second one.

Far too many athletes have suffered needlessly with swollen hands and feet from water retention due to ingestion of salt tablets or electrolyte products too high in sodium during prolonged exercise in the heat. The body has very effective mechanisms to regulate and re-circulate sodium from body stores. Excess sodium consumption interferes with or neutralizes these complex mechanisms. Sweat generates large sodium losses, which is monitored closely through hormonal receptors throughout the body. However, rapid sodium replacement neutralizes the system, allowing water intake to dilute the sodium content. High sodium electrolyte supplementation contravenes the natural physiological control of serum electrolytes, and once the body detects an increase in sodium from exogenous sources (i.e., food, salt tablets, or products too high in sodium), the hormone aldosterone signals the kidneys to stop filtering and re-circulating sodium. Instead, the kidneys will excrete sodium; another hormone, vasopressin, will predominate and cause fluid retention.

While taking large amounts of sodium may temporarily resolve a sodium deficiency, doing so substantially increases the risk of a number of problems, including increased fluid storage and thus swelling, or edema, in the distal extremities, elevated blood pressure, and increased rate of sodium excretion. All of these inhibit performance. If you’ve ever finished a workout or race with swollen hands, wrists, feet, or ankles, or if you have experienced puffiness under your eyes and around your cheeks, chances are your sodium/salt intake was too high.

The truth is that the human body needs only a minute amount of sodium to function normally. We require a mere 250 mg of sodium each day, athletes maybe 500 mg, which is easily supplied by natural, unprocessed foods. However, the average American consumes approximately 6000 to 8000 mg per day, well above the upper end recommended dose of 2300-2400 mg/day.* The average athlete stores at least 8000 mg of dietary sodium in tissues and has these stores available during exercise. In other words, you already have a vast reservoir of sodium available in your body from your diet, ready to serve you during exercise. In addition, your body has a highly complex and efficient way of monitoring and re-circulating sodium back into the blood, which it does to maintain homeostasis. You do need to replenish sodium during exercise, but you must do so with amounts that cooperate with, and do not override, these complex body mechanisms.

* In 2009, data from the U.S. Centers for Disease Control and Prevention provided additional scientific evidence that the majority of Americans over the age of twenty should limit the amount of sodium (salt) they consume daily to 1,500 milligrams (mg) to prevent and reduce high blood pressure.

High sodium health consequences

Not only are high sodium diets bad for your health, but those who consume high amounts of sodium in their diet are guaranteed greater sodium loss rates and require greater sodium intakes during exercise. Sodium, as you probably know, drives thirst, and thirst drives drinking until excess results& definitely not a performance-enhancing scenario. Over the course of several years, we’ve repeatedly observed the following characteristics in endurance athletes who reported symptoms of severe sodium imbalance during or immediately following races/workouts:

Dietary sodium intake above 6000 mg/day.
Fluid consumption in excess of 30 oz/hr (approx 890 ml/hr).
Food consumption in excess of 300 cal/hr.
Failure to acclimatize to hyperthermic (hot weather) conditions, including at least one workout of 60% or greater of the event distance.

You can diminish performance-inhibiting problems of excess sodium consumption by:

Reducing your dietary intake of sodium to 2300 mg/day or lower. This not only aids performance, it’s a substantially healthier dietary procedure. Dr. Bill Misner writes, “Limiting sodium is recommended since research supports that chronic consumption of more than 2300 milligrams per day may contribute to congestive heart failure (CHF), hypertension, muscle stiffness, edema, irritability, osteoarthritis, osteoporosis, pre-menstrual syndrome (PMS), liver disorders, ulcers, and cataracts.”

Limit your fluid intake during exercise to 20-25 oz/hr (590-740 ml/hr). Refer to the article Hydration-What You Need To Know for more information on this topic.

Consume an appropriate amount of calories during exercise. For most athletes this is an intake of 240-280/hour. Refer to the article Proper Caloric Intake During Endurance Exercise for more information on this topic.

Train two to three weeks in the same heat or humidity as the event.

Bottom line: Salty foods and/or salt tablets will not cut it when it comes to electrolyte replenishment. Instead, adopt a low-sodium approach that emphasizes a balance of essential minerals that cooperatively enhance the body's natural hormone and enzyme actions. You want a product that will provide comprehensive electrolyte support without compromising internal regulation.

Don't I need to replace what I sweat out?

It’s easy to formulate a product that matches one of the many perspiration analysis studies and then sell it on the basis that athletes simply need to replace what they lose. Some products do just that. Unfortunately, there’s a problem with this because individual sweat-loss differences vary greatly, and the human body does not and cannot efficiently replace what it expends during exercise at any intensity above a walking pace. Electrolytes lost are not replaced by electrolytes consumed.

The body is able to replace, at best, only about one-third of what it loses during exercise; this is true for fluids, calories, and electrolytes. If you try to replace all the fluids at once, you may end up with dilutional hyponatremia (overly diluted blood sodium levels) or water intoxication. If you attempt to replace all the fuel you expend, your stomach will back up in total rebellion, and refueling will grind to a halt. And if you try to replace in equal amounts all the electrolytes you lose, a number of hormonal triggers may create all sorts of problems such as gastric distress, edema, muscle spasms, and cramping.

As emphasized in the Less is Best - The right way to fuel article, the key to successful fueling (fluids, calories, and electrolytes) is to NOT focus on what you lose, but rather on how much your body can effectively accept and absorb. Bill Misner, Ph.D., says, “Give it [your body] 30-40%, even though it cries aloud for 110%.” In regards to the amount of fluids you drink, calories you eat, and electrolytes you replenish, this is an absolutely vital principle to remember. The closer you adhere to it, the greater your opportunity for success.

Pre-loading sodium prior to a race? Bad idea!

Courtesy of an article written by a registered dietician, one practice now being considered and even adopted by many athletes is a recommendation to “& increase sodium in the diet by pre-loading three to four grams of sodium about 12 to 24 hours before the race.”

What is bothersome about this recommendation is that one would think that a registered dietician ought to be well versed on the health consequences of a high-sodium diet (which the overwhelming majority of Americans consume). Yet this particular person advocates additional sodium in the diet prior to a race. The question is: “Is this a safe and healthy practice?”

A number of references are provided in the article, apparently to solidify these recommendations:

1) Eichner, E.R. “Genetic and Other Determinants of Sweat Sodium.” Current Sports Medicine Reports 7.4 Supp 1(2008): 236-S40.

Comment: Our interpretation of Eichner’s statements/conclusions is that the more sodium in the pre-event diet, the more plasma aldosterone level is suppressed, resulting in a higher rate of sodium loss in sweat during the event. Our position is that suppression of aldosterone prior to events by increasing sodium intake is counterproductive to keeping natural body homeostatic controls in the healthy norm range, which means consuming a low sodium diet of under 2,300 mg daily.

Bottom line: More sodium in the diet equals more sodium lost during exercise.

2) Murray, R. and L. Kenney, “Sodium Balance and Exercise.” Current Sports Medicine Reports 7.4 Supp. 1 (2008): S1-S2.

Comment: Our position is that over 2,300 mg/day results in harmful consequences to health proportionate to predisposed individual sensitivity, while a large majority of human populations react negatively to >5,800 mg/day.

Bottom line: Keeping sodium intake levels between 1,500-2,300 mg/day will support sodium requirements without taxing the aldosterone pathway or the kidney organ’s role in homeostasis.

3) Stachenfeld, N.S. “Acute Effects of Sodium Ingestion on Thirst and Cardiovascular Function.” Current Sports Medicine Reports 7.4 Supp. 1(2008): S7-S13.

Comment: As alluded to earlier in this article, the human body is constructed to be sensitive to monitor homeostatic electrolyte balance, suggesting consistent intake of small amounts of fluid and electrolyte volume prevent severe deficits of fluid and electrolyte loss.

How the body controls serum sodium

Aldosterone is a hormone that controls the rate of sodium circulated in the human body. When sodium levels dip too low, via loss in perspiration or urine, aldosterone is released, stimulating the kidney tubule cells to increase re-absorption of sodium back into the blood. In basic terms, the body has a very complex and effective way of monitoring, recirculating, and thus conserving its stores of sodium.

High sodium intake will suppress serum aldosterone, whereas low sodium intake will elevate serum aldosterone. In other words, too much sodium—be it via diet and/or during exercise—will suppress and neutralize aldosterone’s sodium recirculation (and thus sparing) effects, causing more sodium to be lost. Conversely, a low-sodium diet and a more conservative sodium intake—in tandem with other depleting electrolytes—during a workout or race creates an environment where lower amounts of sodium are lost in sweat and urine.

This is also why “sweat rate” figures can be deceiving. You’ll find many a coach or researcher stating something to the effect of “I’ve seen athletes lose up to several grams of sodium during a one-hour training session.” That may very well be true for some athletes during such a short-duration bout of exercise, especially if it’s under a controlled environment (such as riding a stationary bike in a warm room with no circulating air). However, that doesn’t mean that those losses are sustainable hour after hour; again, the body’s built-in chemical messengers and hormones (namely aldosterone) help prevent those losses from continuing down the same path. Yes, the body does need sodium replenishment but it has to be an amount that works in cooperation with aldosterone’s “sodium recirculation/conservation” effects. A high-sodium diet and/or too-high sodium intake during a workout or race effectively negates aldosterone’s desired effects, which means greater sodium losses.

Bottom line: Instead of adopting a recommendation that more and more sodium be added to the already too-high and unhealthy amounts in the diet, athletes should focus more on lowering their daily sodium intake. It is almost virtually guaranteed that each and every one of us consumes far more sodium than we need on a daily basis, and the harmful effects of oversupplying the body with sodium above its daily needs is a real and present danger to compromise optimal health. Lowering your sodium intake in the diet— keeping it in the range of 2300 mg or less—is not only a more appropriate recommendation/protocol for general health purposes, it will also benefit athletic performance as well. Definitely do not pre-load sodium in the days leading up to a race.

So what is the answer? How should I replenish electrolytes?

Proper electrolyte replenishment during endurance exercise requires a gradual, consistent approach that incorporates all of the electrolytes in amounts that do not override normal body mechanisms. Remember, electrolyte intake needs to be below systemic detection, yet help alleviate systemic depression. This means that you need to consume enough to support body functions and prevent heat-related issues such as cramping without overwhelming your body; electrolyte intake must slip under the body’s “radar detection system” while still providing optimal support.

Endurolytes and Endurolytes Powder are full-spectrum electrolyte products designed to fulfill the body’s electrolyte requirements, countering the effects of hyperthermia, optimizing specific bodily functions, and enhancing endurance performance, especially beyond the two-hour mark. The electrolyte profile of Endurolytes balances cations (positively charged ions) and anions (negatively charged ions) responsibly without emphasizing one electrolyte over others. This is a key thing to remember: When a balance of electrolytes of cations to anions are managed in the energy producing cell—assuming the cell has adequate fuel and fluid—such a cell will produce energy at a higher rate than one overdosed by a single cation mixed with an irrational list of anions. That’s a darn good reason to avoid going “salt only” or to use products—be they supplements or fuels—that contain high levels of sodium, especially at the expense of too-low amounts of other electrolytic minerals.

Additionally, we do not formulate Endurolytes and Endurolytes Powder to reflect the amounts of electrolyte loss in sweat because each person has a unique biological predisposition in terms of minerals lost via perspiration. Additionally, the differences in an athlete’s size and fitness, as well as the pace of exercise, and of course the humidity and heat, can mean up to a 1000% difference when one athlete’s sweat rate is compared to another’s. A “one size fits all” formula based merely on sweat rates cannot, and will not, adequately support your specific electrolyte requirements.

In the purest sense, the Endurolytes formula is not so much an electrolyte replacement product, but is better described as an “electrolyte stress support formula.” It helps the body perform better under the demands of exercise, especially in heat, by providing a full complement of minerals in the proper balance without interfering with normal body control systems. Endurolytes and Endurolytes Powder work with your body, not against it.

The Endurolytes formula

Endurolytes contains chelated minerals. Chelation is the process of bonding a mineral to another substance, ideally an amino acid, making the mineral more bioavailable. Chelated minerals are the form most often recommended because they provide greater absorption than their non-chelated counterparts. For example, magnesium is 87% absorbed when chelated, but only 16% when taken in an inorganic, non-chelated form. One nutritional scientist wrote, “Estimates of normal mineral absorption average 10%; however, absorption of chelated minerals may be as high as 60%.”

CALCIUM is the most abundant mineral in the human body (about 2.85 lbs/.8 kg in the average person). Normal heart rhythm, healthy nerve transmission, and strong muscle contractions require a constant blood calcium level. During exercise, calcium-dependent enzymes produce energy from fatty and amino acid conversion. Because fatty acids are such an important fuel during endurance exercise, providing 60-65% of your energy needs when exercise goes beyond two hours in length, having adequate calcium available to efficiently convert them into energy is crucial. When blood calcium runs low, the body extracts it from the bones, but this process can’t keep up with your exercise depletion rate. Serum calcium deficiency during endurance events may produce high blood pressure, muscle cramps, and weakness. Calcium intake at 150-300 mg/hr will optimally sustain the multiple physiological functions listed above.

MAGNESIUM should accompany calcium at a ratio of 1:2. When calcium flows into working muscle cells, the muscle contracts; when calcium leaves and magnesium replaces it, the muscle relaxes. Many enzymatic reactions necessary for fuel conversion to muscular energy occur in the presence of adequate magnesium. Deficiency of magnesium contributes to muscle cramps, tremors, sleep disturbances, and in some cases, convulsive disorders. We lose at least 100 mg/hr via sweat, in addition to what is depleted by muscle use. Supplementation of 75-150 mg/hr adequately replenishes magnesium without the laxative effect that larger doses can produce.

POTASSIUM is the chief cation (positively charged ion) within all muscle cells. It is necessary for maintaining the optimal concentration and balance of sodium. Potassium deficiency symptoms are nausea, vomiting, muscle weakness, muscle spasms, cramping, and rapid heart rate. 75-150 mg/hr is an adequate replenishment amount. Even though 100-200 mg are lost in sweat alone (not counting internal muscle and cell use), if we try to replace it all at once, optimal sodium balance is altered. In addition, too much potassium is hard on the stomach and can cause severe stomach distress.

SODIUM is the chief cation (positively charged ion) outside the cell. The average American carries 8000 mg of excess sodium in extracellular tissues. During endurance events, a minimum of three to four hours is necessary to deplete this mineral, which may result in symptoms of abnormal heartbeat, muscle twitching, and hypoventilation. However, if sodium is replaced at or near the same rate as depletion, it overrides the hormonal regulating mechanisms that enable the body to conserve electrolytes. Consumption of too much sodium will cause a variety of problems, the least of which is fluid retention. Therefore, we highly recommend a more moderate, body-cooperative replenishment of 120-240 mg/hr of sodium as sodium chloride.

CHLORIDE is the relative anion (negatively charged ion) that accompanies sodium. This electrolyte is absolutely necessary in maintaining the osmotic tension in both blood and extracellular fluids. It’s a somewhat complicated process, but to put it in the simplest terms, think of osmotic tension as being the proper balance and consistency of body fluids and electrolytes. We believe 180-360 mg/hr of chloride (as sodium chloride) adequately replenishes chloride without overriding the function of the hormone aldosterone in regulating and conserving proper electrolyte levels.

Note: “salt” (commonly called “sodium”) refers to sodium chloride, which is 40% sodium and 60% chloride by weight. The recommended amounts given above for both electrolytes, sodium and chloride, when combined together equals 300-600 mg sodium chloride, our recommended hourly “salt” intake for the majority of athletes.

MANGANESE is included in Endurolytes as it is necessary in trace amounts for optimal muscle cell enzyme reactions for conversion of fatty acids and protein into energy. Again, fatty acids and protein are a crucial part of the endurance athlete’s fuel supply, so while manganese is not technically an electrolyte, its importance cannot be overstated. Research also shows that manganese deficiency plays a key role in blood sugar fluctuation, free radical build-up from intense exercise, and nerve function disorders, especially in older athletes. Taking 5-10 mg/hr will help resolve all of these issues, hence its inclusion in Endurolytes.

PYRIDOXINE HCL (vitamin B-6) is a coenzyme required in 60 enzymatic reactions involving metabolism of carbohydrates, fats, and protein. We include this water-soluble B vitamin in Endurolytes because of its active role in maintaining sodium-potassium balance.

L-TYROSINE is an amino acid added to protect thyroid and adrenal function. Blood plasma deficiency during extreme endurance events will lower thyroid and adrenal production, which hinders the proper rate of metabolism. Symptoms of l-tyrosine depletion first appear as depression, later anger, then despondency that degenerates into total despair. If any of these has ever happened to you during a long training session or race, it may be due to low thyroid and adrenal production; it can be easily avoided by the intake of supplemental l-tyrosine at 50-100 mg/hr.

GLYCINE is an amino acid added to Endurolytes Powder to help neutralize the naturally salty/bitter taste of the minerals.

Suggested amounts of Endurolytes to consider

Electrolyte expenditure, and thus replenishment, varies tremendously between athletes, and it can also vary considerably for one athlete during the course of an event. Sweat composition studies performed by Shephard, Noakes, Costill, Moody, and others, have shown in a variety of stress exercise forms that an acclimatized, fit athlete loses half of the electrolytes and fluids as an un-acclimatized, unfit athlete does. Event-specific training in both duration and intensity halve electrolyte and fluid requirements in an endurance event. Body weight, fitness level, weather conditions, acclimatization level, and biological predisposition all greatly affect electrolyte depletion and the need for replenishment. That's why the hourly Endurolytes dose can range from 1-6 capsules/hr. That being said, a good starting dose to consider is:

Lighter weight athletes: 1-2 capsules/hour
Medium weight athletes: 2-3 capsules/hour
Larger athletes: 4-6 capsules/hour

Remember though, these are only suggested starting doses and the amount you need may be different, and may vary from hour to hour.

What about HEED?

HEED is Hammer Nutrition’s complex carbohydrate powdered sports drink. One of the nice features of HEED is that it contains a complete and easily assimilated electrolyte profile, not just salt and potassium, which is all you get in most other sports drinks. Two scoops of HEED provides the electrolyte equivalent of approximately 1.25 Endurolytes capsules. Some athletes will find that with a scoop or two of HEED in their water bottle, they’re good for an hour or more. For other athletes, the electrolyte profile in HEED will provide an excellent base from which additional Endurolytes capsules can be consumed (or Endurolytes Powder can be added to the mix) to completely satisfy electrolyte needs.

Summary

Consistent replenishment of fluids and calories is essential to maintain energy levels during workouts and races. Providing constant replenishment of electrolytes is an equally important component of proper fueling. Getting your fluid and caloric needs dialed in and nailed down is fairly easy to accomplish, but fulfilling your electrolyte needs requires more attention because you have much more variability to account for. Using Endurolytes or Endurolytes Powder in your training will resolve that challenge. They contain the right minerals in the right balance, and because they are independent of your caloric and hydration sources, they provide you with the necessary dosage flexibility. Regardless of your size, sport, training intensity, fitness level, or the weather, you can fulfill your electrolytic mineral needs accurately and precisely hour after hour with Endurolytes or Endurolytes Powder.

The Hammer Nutrition website has several detailed articles on sodium and electrolyte replenishment. We especially recommend:

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