ELECTROLYTES AND REHYDRATION

As advances in electrolyte and sports medicine continue, athletes are more cognizant than ever about their diet, nutrition and hydration practices. This is vital particularly since athletes depend on performance for livelihood. Electrolytes are often the center stage of discussions related to sports nutrition – on podcasts as well as on the field.

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Electrolyte Powders & Rehydration

Unfortunately, different electrolytes are often clumped together as a group in discussions, but they are significantly complex in what they do, how they transport within the body and how they are regulated. A change in absorption, transportation or excretion can rapidly change their levels and dramatically affect performance. Electrolyte powders that are comprised of a potent mix of a few vital minerals are often used by athletes to rehydrate themselves. Below, we discuss some fundamentals about electrolytes and guidelines for athletes to meaningfully incorporate them in their rehydration practices.

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WHAT ARE ELECTROLYTES?

By definition, electrolytes are molecules that are electrically charged and function largely due to their charged status. The quantity or abundance of the electrical charge, their overall levels in the body (loss or gain from diet) and the person’s activity status – all of these alter electrolyte levels within the body. These electrolytes are constantly in a state of transport – from the gut where they are absorbed into the bloodstream, then to distinct cells where they initiate their actions; from their storage in various tissues and then through the filtering units or kidneys which ultimately regulate their excretion (if the condition so desires). The kidney serves as a last “controller switch” for maintaining electrolyte levels within the bloodstream. If the electrolyte levels are low (due to a loss from diarrhea), the kidneys reduce their excretion in the urine to keep the levels maintained within the body. If the electrolytes consumed (through diet) are more than the body needs, the extra load is excreted in the urine. Thus, the kidneys adapt and alter their response based on the dietary intake of electrolytes as well as their overall tissue stores. By doing this, the electrolyte levels are always maintained within a defined range in the body. Below, we summarize the principal electrolytes and their functions within the human body:

Sodium

THE MOST ABUNDANT ELECTROLYTE IN THE BLOOD

Sodium is freely distributed in the extra-cellular fluid and is vital in exerting the function of almost all the cells within the body. Combined with potassium, which mainly resides within the cells, movement of sodium inside the cell leads to an electrical change which causes muscle fibers (or cells) to contract as a unit. Sodium maintains the osmolality (or thickness) of the blood and maintains blood flow to the organs. Sodium can be lost in significant amounts through the sweat glands during workouts, particularly in warm weather conditions. Replacement of sodium is vital in recovery and sodium chloride as an additive to the hydration mix has shown to prevent cramps in certain individuals.

Chloride

BALANCES THE POSITIVELY CHARGED ELECTROLYTES

Chloride is the negatively charged electrolyte that often circulates bound to sodium in the blood. Chloride levels are not monitored regularly in the clinic unless they are accompanied by a state of acid build-up (acidosis) that may signify an underlying kidney disease. This electrolyte balances the positively charged electrolytes (e.g., sodium) to maintain an electrolyte neutral status of the blood, preventing large changes in either direction.

Potassium

INITIATES AND MAINTAINS CONTRACTION

Potassium is an electrolyte that resides mainly inside the cells. A specialized channel along the cell surface allows sodium to be kicked out and potassium to be drawn in so that an electrical gradient is maintained. Thus, sodium and potassium are significantly co-involved in making sure that muscles can work after a stimulus. Potassium losses are significant in gastrointestinal illnesses that lead to vomiting and diarrhea. Potassium allows muscles to initiate and maintain contraction. Loss of potassium leads to significant muscle weakness and correction of potassium stores using an electrolyte supplement has shown to improve muscle function in those who are deficient in it.

bicarbonate

UNCOVERS THE ACID-BASE STATUS

When measured in the blood, bicarbonate typically uncovers the acid-base status of an individual. A drop in bicarbonate levels in the blood could signify more acid build-up. Similarly, a rise in bicarbonate can be due to dehydration and fluid losses, a state called contraction alkalosis. Changes in bicarbonate generally indicate an alteration in how the body handles the acid-base balance.

calcium

MAINTAINS HEART CONTRACTILITY, RHYTHM AND BLOOD PRESSURE

An electrolyte predominantly stored in bones, calcium makes up for the “bony architecture” in mammals. The bones serve as a warehouse for calcium, which is available for use based on specific needs. For example, if the blood calcium drops, a hormone can be released from specialized glands called parathyroids, which resorb the bone and move the calcium back into the blood. Calcium circulates in a free form (ionized) as well as in a protein-bound state. The free calcium is available to elicit function. Calcium is required for muscle contraction, maintenance of heart contractility, rhythm, and blood pressure (among others) and is commonly used as an electrolyte supplement in the carbonate form. Small amounts of calcium (up to 100 mg per serving) in an electrolyte powder is unlikely to be a meaningful supplement that can change athletic performance. Additionally, calcium deficiency is rare in athletes and is mainly seen in individuals as they age. Electrolyte powders typically do not contain calcium for this reason.

Magnesium

PARTICIPATES IN OVER 300 ENZYMATIC REACTIONS IN THE BODY

Recent studies have shown magnesium to be a vital mineral in muscle physiology. Magnesium participates in over 300 enzymatic reactions in the body; however, its use as an additive in an electrolyte drink is largely limited by the scarcity of clinical studies. Magnesium is absorbed from the gut and transported into the blood where it affects muscle function, cardiac rhythm, blood pressure, protein synthesis and inflammation. Magnesium is stored in bones and can be lost in states such as diarrhea. It is not easily found in diet and with the electrolyte-depleted soils due to packaging, less than half of Americans get enough magnesium through diet. Most electrolyte supplements do not contain sufficient magnesium to have an impact on performance. Magnesium deficiency can lead to muscle cramps, fatigue, soreness, sleeplessness, mood changes and abnormal heart rhythm. Conversely, magnesium supplements can prevent muscle cramps in certain individuals who are deficient in it, even if the deficiency is sub-clinical.

phosphorus

SOURCES ENERGY FOR ALL CELLULAR ACTIVITIES

The backbone of our cellular energy as ATP, phosphorus is involved in sourcing energy for all cellular activities. Just as calcium, phosphorus is also stored in the bones as well as muscles and is heavily regulated by the kidney and the vitamin D status of the individual. Low phosphorus levels are usually seen in kidney disease and after transplantation. This nutrient is easily available from dietary sources – hence, phosphorus is rarely used as an electrolyte additive for water unless specifically warranted in a clinical setting.

LOSS OF ELECTROLYTES: DEHYDRATION

Dehydration essentially means loss of water from the body, although, in reality, it is frequently used to designate a loss of electrolytes as well. Most symptoms of dehydration, such as fatigue, dizziness, headaches, weakness and cramps, result from a loss of both fluid and electrolytes.

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SODIUM

Sodium is the principal electrolyte lost in sweat, as the sweat glands have a sodium chloride channel. An individual almost always loses more water than sodium – light sweaters typically can lose about 300-500 mg of sodium for every liter of sweat. Heavy sweaters can lose from 1-2 grams per liter of sweat based on weather. Sweat rate and its composition is widely variable amongst individuals. Sodium deficits can range between 2-4 grams in a day based on the intensity and duration of the athletic activity. These changes in sodium and water are intricately linked to adapting mechanisms in the human body as well as stimulation of the thirst reflex that allows individuals to consume fluids. The best electrolyte powders used for hydration typically have an average of 300-500 mg of sodium chloride in their mix per serving. This ensures an adequate replacement of sodium lost in sweat while maintaining blood sodium levels within a normal range that in turn prevents the adverse effects of hyponatremia.

POTASSIUM & MAGNESIUM

Potassium and magnesium are not typically lost in sweat in heavy amounts but can be rapidly depleted with activity. Loss of potassium and magnesium is common in diseases of the GI tract leading to diarrhea and dehydration. Additionally, diuretic (water pill) usage can significantly reduce the stores of these two electrolytes which, can often result in muscle weakness and cramping. Certain occupations, such as firefighting, can expose individuals to unusual states of electrolyte depletion and dehydration. Magnesium has recently been recognized as a vital additive to hydration mix after certain studies showed an improvement in arm strength and muscle activity in some individuals with regular magnesium use. Magnesium status of the individual defines their potassium status as well. Magnesium deficiency leads to potassium loss in the urine. Thus, improvement in muscle cramps is unlikely to improve with potassium replacement alone unless magnesium is included in the electrolyte supplement.

CALCIUM & PHOSPHORUS

Calcium and phosphorus are not typically lost in sweat. Loss of these electrolytes is almost never physiological (or normal) and often happens in some underlying disease. Dehydration and water loss typically lead to a higher (not lower) level of calcium in the blood. These are also stored in large quantities within the bone matrix and can be available quickly to replete the blood levels under the stimulus of specific hormones.

rehydration with electrolyte powders

balancing water and electrolytes in your replacement fluids

The fundamental goals of rehydration are twofold

1) To prevent electrolyte and water loss and 2) to stay hydrated to minimize the ill effects.
The fastest and most convenient way to rehydrate, hence, is to use an electrolyte powder mix, such as MAGNAK®, that contains balanced electrolyte proportions of sodium, potassium and magnesium. As explained above, such a combination of these electrolytes is essential since these electrolytes are interdependent on each other for their actions. Such an electrolyte powder, when mixed with water, retains an osmolality slightly lower than that of the blood which helps its rapid transport via the gut. To rehydrate quickly, the electrolyte drink must be consumed during the ongoing fluid losses. A good practice is to rehydrate frequently, with 6-8 fl oz of electrolyte-rich isotonic fluid every 15-20 minutes during a high intensity work out. To prevent a dehydrated state, it is recommended to rehydrate simultaneously as fluid losses continue.

powdered electrolyte mixes: a faster onset of action

Individual electrolyte supplements which comprise of salts of potassium or magnesium have been tried by some athletes to improve performance. However, electrolyte tablets, e.g. magnesium oxide, suffer from poor bioavailability and delayed onset of action due to a slower absorption, not to mention the inconvenience of taking these during athletic activities. Athletes typically have reported greater compliance with powdered electrolyte mixes due to the convenience and possibly, a faster onset of action. Thus, electrolyte powders packaged in stick packs offer the most convenient form of using a blend of vital electrolytes that can be altered to one’s taste and can be made fresh during each serving.

Sugar is vital in absorbing sodium

One of the common dogmas that athletes in the 90s lived by was to consume a lot of sugar during exercise. Electrolyte powders that are rich in sugar have a higher osmolality and sit in the gut too long. By principle of osmosis, the water moves from the blood stream and into the gut, defeating the purpose of rehydration. This frequently causes nausea and bloating, a common side effect experienced by athletes on the field. Thus, an electrolyte drink should be slightly hypotonic (but not just water) to absorb faster and rehydrate quickly. Sugar is vital in absorbing sodium through specialized channels in the gut and is also a source of immediate energy during a workout. Hence, sugar-free solutions that may be preferred by some individuals (e.g., diabetics) are not ideal for everyone for the purpose of hydration, as they do not get the maximal effect of sodium transport. In simple terms, some sugar is needed to help the salt. And it makes it taste better too; however, too much sugar is not only unnecessary but also unproductive for rehydration. This fundamental principle of salt and sugar mixed in water was first explored as a rehydration mix in the 1970s (as ORS – oral rehydration solution).

electrolyte drinks utilize a variety of vitamins in their formulas

Lastly, there are some electrolyte drinks that utilize a variety of vitamins in their formulas. Studies have looked at utilizing vitamin D and E in preventing muscle cramps in athletes. These have largely been inconclusive without any added benefit. Vitamin E has been shown to prevent muscle cramps in patients on hemodialysis, but not in the general population or in endurance athletes. Scientifically speaking, fat-soluble vitamins (A, D, E and K) are not lost in the sweat, indicating that addition of these is largely for marketing but is not supported by clinical data. Vitamin C, however, has been utilized for its anti-inflammatory properties and many athletes have utilized it after exercise to relieve muscle soreness. Vitamin C has additional roles in iron absorption and immune regulation and is highly water soluble, making it an attractive additive in the electrolyte powder mix.

So what should an ideal
electrolyte drink mix look like?

How to rehydrate effectively to prevent ill-effects of dehydration, particularly during those crazy endurance feats, remains the number one priority of most high-performing athletes. Clearly, some progress has been made in the electrolyte field over the last two decades and this has allowed people to truly push their limits. However, definitive guidelines are hard to prescribe, particularly since there are no good randomized clinical trials addressing the utility of electrolyte supplements for enhancement of athletic performance.

Below are some general recommendations based on recent scientific reviews, although more research is certainly required in the future:

WATER

Water is the base of any hydrating solution but avoid drinking pure water unless the activity is deemed to be light: water is hypotonic and in long endurance activities, drinking water alone can lead to hyponatremia (low blood sodium) that can be dangerous.

SODIUM

Use enough sodium per serving: most experts agree that a sodium serving of 300-500 mg/serving mixed in about 500 ml of water would make the cut.

MAGNESIUM & POTASSIUM

Use a magnesium-rich electrolyte drink mix such as MAGNAK® that can prevent muscle cramps and soreness, and improve fatigue. Optimally, the ratio of sodium, potassium and magnesium should be balanced. We recommend at least 300 mg of sodium, 150 mg of potassium and 100 mg of magnesium per serving of the electrolyte drink for optimal performance.

SUGAR

Some sugar is vital – both for energy and to absorb the sodium rapidly. So, try to avoid those sugar-free electrolyte mixes unless needed for medical reasons. After all, if you are working out, you will burn that sugar.

~~VITAMINS~~

Lose the additives: other vitamins (A, D, E, K) and other ingredients that (cannot be pronounced) are not shown to significantly impact athletic performance unless the individual is clinically deficient.

~~ARTIFICIAL INGREDIENTS~~

Leave the artificial ingredients behind – those are things of the past. There is no role of artificial dyes to enter a body that is being conditioned by training, discipline and exercise.

~~CAFFEINE~~

Caffeine has no role in an electrolyte powder. Your heart rate should accelerate from exercise and not from caffeine.

Read more about the science of MAGNAK® by following The Electrolyte Blog.