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This is what happens when potassium levels are too low

potassium levels too low

Extreme fatigue, cramping, and constipation. This blog post explains why low potassium levels could be the cause of these unpleasant symptoms. 

Known as hypokalemia, low potassium levels can be detrimental to athletic performance.

Many parts of the body, ranging from the heart to the digestive system, rely on normal potassium levels to conduct nervous signals that prompt muscles to contract. Without enough potassium, this process is hampered, and a wide variety of negative symptoms results.

While this blog post focuses on what happens when you do not get enough potassium, if you would like to learn more about how the body uses potassium when adequate levels are present, please check out the following blog posts:

Continue reading to learn what happens when potassium levels are too low.

Muscular weakness, cramping or twitching

Potassium and sodium work together at the cellular level to assist with nerve functioning and the movement of glucose and other key nutrients in and out of the cell membrane. Additionally, both electrolytes are ions, meaning they contain electrical charges (thus the name “electrolytes”).

Potassium naturally accumulates inside the cells, and by building up a concentration of charged ions, a cell can become polarized. The nervous system uses this polarization to conduct impulses throughout the body, which prompt the muscles to contract or relax.

If a person experiences hypokalemia, this process is hampered, and sometimes, the body will overcompensate and send stronger-than-normal nervous impulses. When this happens, the muscles may not be able to relax, and cramping results. Additionally, low potassium levels slow down the process overall, resulting in fatigue or weakness.

Heart arrhythmia

Just like the muscles throughout the body need sufficient levels of potassium to work properly, the heart, which is also a muscle, is affected by hypokalemia.

During a heartbeat, sodium, calcium and potassium enter the heart’s cells in phases, causing the heart to contract and relax. These movements can be measured by an ECG, and a normal cycle looks like a string of peaks and valleys, recognizable to almost everyone:

heart rateAfter sodium and calcium enter the cell and cause a net positive charge, potassium rushes in and restores the electrical charge to negative. This process repeats itself over and over, throughout life. But without adequate levels of potassium, the cycle can be interrupted, and a person can experience heart arrhythmia (or the feeling that the heart is skipping a beat).


In addition to heartbeat, the digestive system is powered by proper muscular contraction and nervous system impulses. When the body does not maintain adequate levels of potassium, the digestive system is hampered as well. By slowing down the ability of muscles to contract, hypokalemia can cause constipation because the body cannot break down food in a timely manner, nor can it move waste through the intestines to be excreted.  

High blood pressure

In a normal state, potassium ions are more likely to reside inside cells and sodium ions are more likely to remain outside cells. The ratio of these ions must be balanced for normal functioning, and when levels are too high or too low, the body will compensate by moving water or ions in or out of cells to restore appropriate concentrations.

When sodium levels are too high, the body pulls water through the cell membrane and into the bloodstream to help remove excess sodium through the kidneys. Most people recognize that a common cause of high sodium levels is high sodium consumption, especially given that the average American adult consumes higher-than-recommended levels in his or her daily diet.

However, a more accurate description is the following: “A common cause of high sodium levels is high sodium consumption relative to potassium consumption.” In other words, another cause for high sodium levels is actually low potassium levels. In both situations, the body compensates by pulling water into the bloodstream, which raises blood volume. This increase in blood volume pushes against the blood vessel walls, resulting in high blood pressure.

To back up the idea that ratios of electrolytes matter more than absolute intake values, consider a 1997 study by the National Heart, Lung and Blood Institute, which found that volunteers who consumed 4,700 mg of potassium per day through a well-balanced diet that included lots of fruits and vegetables reduced their blood pressure in just two weeks. This study ultimately became the foundation for today’s DASH diet.

Who is at risk for hypokalemia?

While athletes who exercise for long periods of time without replacing electrolytes lost through sweat are at risk for hypokalemia, this condition is more likely to result from diuretics or from excess vomiting and/or diarrhea.

Diuretics interrupt the body’s natural fluid regulation system, and a side effect can be the release of too much potassium through urine. This problem can be compounded if a person consumes only water to replace the fluids lost, which will further alter the balance of water and electrolytes in the blood.

Hypokalemia is usually not caused by diet because potassium is found in an abundance of foods, including fruit, potatoes, beans and whole grains. Unless a person is consuming an extremely restricted diet, hypokalemia is much more likely to be caused by a problem within the body.

Long amounts of exercise can also cause hypokalemia, but only if an athlete does not take steps to replace the potassium lost through sweat. Because most electrolyte products contain some amount of potassium, this scenario is unlikely.

How can you alleviate symptoms of hypokalemia?

The most common way to alleviate symptoms of hypokalemia is to consume adequate levels of potassium. In situations of acute hypokalemia, such as the result of vomiting, diarrhea or intense exercise, potassium supplements may be necessary. In chronic situations, such as the result of a medical condition, dietary changes may help, but supplements may also be necessary, depending on the severity of the symptoms.

If you are an endurance athlete worried about hypokalemia, it is important to take steps to replace the potassium lost through sweat by consuming a source of balanced electrolytes, such as any one of the SaltStick products specifically designed for athletes, which are easily absorbed by the body.

As a reference, here’s how much potassium is contained in each serving of SaltStick products:

  • SaltStick Caps (1 Capsule) 63 mg
  • SaltStick Caps PLUS (1 Capsule) 53 mg
  • SaltStick Fastchews (2 Tablets) 30 mg
  • SaltStick Vitassium (2 Capsules) 100 mg


Disclaimer: Contact your physician before starting any exercise program or if you are taking any medication. Individuals with high blood pressure should also consult their physician prior to taking an electrolyte supplement. Overdose of electrolytes is possible, with symptoms such as vomiting and feeling ill, and care should be taken not to overdose on any electrolyte supplement.