Water and Sodium Levels During Exercise – Can You Drink Too Much Water?

People who are exercising vigorously and/or in hot environmental conditions may lose as much as three liters of water and 3.5 grams of sodium per hour. Many people now drink large amounts of water to avoid dehydration and an increase in core body temperature while exercising, but sometimes this approach may do more harm than good.

Can a person drink too much water while exercising vigorously? What are the risks for developing and symptoms of exercise-associated hyponatremia (EAH)? How can people treat this potentially serious imbalance? Learn more about how to stay safe during rigorous and extended exercise.

Vigorous Exercise Can Lead to Sodium Loss - Photo by Dontworry at Wikimedia Commons

How Much Water Should You Drink During Exercise?

Recommendations for re-hydration during exercise have changed many times over the years. Early recommendations ranged from discouraging any intake of fluids during exercise to drinking as much as possible. Much of the current research is leaning toward a common sense approach in which people who are exercising should drink when thirsty to prevent dehydration, adjusting fluid intake for variables such as environmental temperatures, clothing, and the intensity of the workout.

Water has been hailed as a great choice of beverage, particularly for those who are attempting to decrease calories and lose or maintain weight. Many people are turning to water as a beverage of choice – bottled water sales tallies second only to soft drinks in the United States. WebMD offers an informative quiz on water that people may find very helpful.

Some studies have indicated that athletes may be more likely to drink an increased amount of fluids if they have added flavorings. The FDA now requires manufacturers of flavored water, water beverages with added electrolytes and/or nutrients, and similar water-containing beverages to list ingredients on the labels and to produce these beverages under sanitary conditions with quality control processes in place. Some sources indicate that people who are exercising may benefit from drinking some fluids with electrolytes added, but more research is needed in this area.

Over the years, previous endurance limits have been pushed, with many athletes going greater distances and attempting harder forms of exercise than ever before. Some folks are pushing their own limits by making fitness commitments to increase their activity drastically, and some careers place people in hot areas while exerting much energy over extended periods of time.

Although a more active lifestyle has the potential to improve one's overall fitness level, extremes in exercise combined with large amounts of water intake can be dangerous and even deadly if a person's sodium level drops to unsafe levels.

Causes of Hyponatremia Related to Exercise - Photo by Kencf0618 at Wikimedia Commons

What Causes Low Sodium Levels During Exercise?

Many folks know that exercise can cause blood sugar levels to drop, particularly in someone who has diabetes; however, exercise, particularly if the exercise is rigorous, can also change electrolyte levels. Electrolytes are minerals in the blood that carry an electrical charge. Examples of electrolytes in the body include sodium, potassium, magnesium, and calcium. Electrolytes in the blood can affect acid/base balance, fluid status, muscle functions, and many other vital body processes.

Serum sodium, the level of sodium in the blood, is an electrolyte that can be affected by exercise, water replacement, potassium levels, and several other factors. Normal ranges for serum sodium is 135 to 145 milliequivalents per liter (mEq/L). Table salt is sodium chloride, and many people are trying to lower dietary sodium with good reason. According to the CDC, many Americans eat a diet much higher than the upper limits of  2,300 mg/day; the recommended limit for sodium is 1,500 mg/day for those with hypertension or high risk for complications related to a diet high in salt.

Although too much salt can cause many long-term health problems such as high blood pressure, a sudden drop in serum sodium, called hyponatremia, can quickly become a medical emergency in the short term. Sodium levels can decrease via sweating when a person exercises vigorously or continuously over a long time, but the drop in levels appears to be more related to drinking large amounts of water, the body's inability to excrete the excess water by urinating, or a combination of those factors.

Exercise-associated hyponatremia (EAH) may also be called:

• Fluid overload
• Water intoxication
• Exertional hyponatremia
• Exercise-induced hyponatremia

Risks for Exercise-Associated Hyponatremia - Photo by U.S. Army at Wikimedia Commons

Who is at Risk for Exercise-Associated Hyponatremia?

Most people who drink water or sports drinks while exercising do not experience unusually low sodium levels, but others may experience moderate or even severe drops in serum sodium. Several people tend to be more likely to develop a dangerous drop in sodium levels associated with exercise, including:

• Women (perhaps due to size, an increased likelihood to heed recommendations to drink more fluids, or genetic factors)
• People who have smaller bodies and lower body weight
• Folks participating in continuous exercise over an extended period of time
• Those exercising in warm environments, particularly if the person is not acclimated to the warmer temperatures (although some athletes may experience hyponatremia while exercising in cooler environments as well)
• Those who drink large amounts of water before and/or during exercise (some have experienced hyponatremia when hydrating with fluids with added electrolytes)
• Slower athletes (probably due to added time exercising in order to finish the course and perhaps the intake of additional fluids during that time)
• Those with certain pre-existing health conditions such as people who are not able to excrete fluids efficiently or those who excrete higher than normal amounts of sodium in sweat, such as someone who is a carrier of the cystic fibrosis gene
• People taking certain medications that decrease sodium levels

Symptoms of Water Intoxication - Photo by Ceccomaster at Wikimedia Commons

What are the Symptoms of Exercise-induced Water Intoxication?

Many of the symptoms of exercise-associated hyponatremia result from fluid overload in the brain as brain cells tend to swell in an effort to compensate for the electrolyte imbalance. Unfortunately, many symptoms are non-specific and could be related to other exercise-related changes, such as a drop in blood sugar or dehydration.

Hallmark signs that the symptoms are more likely to be related to hyponatremia instead of other factors include:

1. The person has been drinking large amounts of fluids.
2. The person will typically experience weight gain during and/or at the conclusion of the athletic activity.
3. The person may become bloated or puffy around the ankles, fingers, and/or face. If the fluid settles in the lungs, pulmonary edema may result in which the person may experience coughing and shortness of breath that is worse if the person lies down.

Signs and symptoms of EAH are often related to swelling in the brain and may include:

• Fatigue and/or lethargy
• Stumbling or lack or coordination
• Muscle cramps, spasms, or weakness
• Nausea and/or vomiting
• Slurred speech
• Headache
• Changes in mental status
• Confusion or strange behavior
• Seizures
• Coma

Sodium levels do not necessarily correlate with the severity of symptoms with hyponatremia, but levels higher than 128 and below 135 mEq/L are less likely to result in swelling of the brain than levels below 128 mEq/L with resulting serious signs and symptoms. According to a 7/15/2005 Sports Medicine article, an athlete with a serum sodium level of 87 mEq/L survived while others with levels of 117 and 122 mEq/L died, indicating that the sodium level may not necessarily predict the outcome of this medical emergency. Symptoms also seem to be related to how quickly the sodium levels drop and tend to be more pronounced in those who are overhydrated rather than dehydrated.

Few people would have access to laboratory equipment used to measure serum sodium levels while exercising, so recognizing early signs and symptoms and seeking proper emergency care could be a life-saving measure for an athlete with dangerously low sodium levels. Symptoms of hyponatremia can progress quickly and have the potential to lead to serious symptoms, including death.

Treatment for Low Sodium - Photo by Danny Hayes U.S. Navy at Wikimedia Commons

How is Low Sodium Caused by Exercise Treated?

Prevention of hyponatremia can be quite complex. Most people participating in exercise do not exercise with such intensity or duration to necessitate preventive steps. Those who are at risk for EAH or who have experienced EAH in the past should speak with a qualified healthcare professional regarding an individualized preventive plan, which might include a variety of suggestions, such as:

• Exercising at a less intense level
• Exercising for shorter periods of time
• Decreasing the amount of fluids ingested before, during, and after exercise while being careful to avoid dehydration
• Drinking or eating electrolyte replacements specific to that person's needs

Because the symptoms of hyponatremia are often non-specific, many people mistakenly encourage an athlete with hyponatremia to drink more water. This only adds to the problem by adding to the fluid overload and dropping the serum sodium levels further.

Someone experiencing symptomatic exercise-associated hyponatremia should seek emergency medical care and avoid drinking additional fluids. Cases of symptomatic hyponatremia typically require in-hospital intervention with treatment focused on increasing the person's urine output in order to lower the serum sodium levels and decrease edema in the brain. Treatment usually includes administering intravenous fluids that have high high levels of sodium. One study mentioned the possibility of administering certain types of diuretics to correct EAH, but more research is needed to determine if this treatment would be ideal.

Drinking sports drinks and/or administering intravenous normal saline does not seem to adequately treat hyponatremia in athletes that are experiencing symptomatic fluid overload and may lead to continued hyponatremia and swelling in the brain. Some studies have demonstrated that fluids with added carbohydrates and electrolytes are associated with higher plasma levels of sodium when compared to distilled water, green tea, or flavored water during and after exercise.

Some studies have looked at having athletes participating in long-endurance exercise to drink or eat sodium replacement fluids that are higher than typical sports drinks, including pickle juice, dissolved bullion cubes, chicken noodle soup, or soup broth, but I could not find clear guidelines for administration of oral fluids with high volumes of salt. Oral replacement with a high sodium content might discourage some athletes to drink due to an unpleasant salty taste and could in turn lead to dehydration.

Water and Salt Levels During Exercise - Photo by Gabriel Martin U.S. Navy at Wikimedia Commons

Exercise and Low Salt Levels

I was prompted to research the topic of exercise-induced hyponatremia after a friend of mine experienced significant symptoms after exercising. She survived, thanks to the quick response of her husband and the great EMTs in the area, but a sudden drop in sodium levels can lead to serious health concerns and even death.

Exercising regularly has many benefits for one's body and well-being. Many people assume that if drinking a little bit of water is good that drinking lots of water will be even more beneficial; however, that is not always true when replacing fluids lost during vigorous exercise. Most people who exercise will not experience hyponatremia, but those who are at risk or who have experienced EAH previously would benefit from consulting a healthcare professional for an individualized exercise and re-hydration plan to meet their special needs.

Find more of my articles at the Fit Tips 4 Life site map.

Sources (accessed on April 23, 2012 unless otherwise noted):

• Center for Disease Control and Prevention 02/23/2011 article "Water: Meeting Your Daily Fluid Needs"
• Journal of Athletic Training March/April 2009 article by Costas A. Anastasiou et. al. "Sodium Replacement and Plasma Sodium Drop During Exercise in the Heat When Fluid Intake Matches Fluid Loss" (accessed 04/24/2012)
• Journal of the American College of Nutrition 01/09/2006 article by Rick L. Sharp "Role of Sodium in Fluid Homeostatis with Exercise"
• MayoClinic July 14, 2011 article "Hyponatremia: Symptoms"
• National Institutes of Health 05/26/2010 article by David Zieve et. al. "Sodium in Diet"
• National Institutes of Health 09/20/2011 article by David C. Dugdale et. al. "Electrolytes"
• National Wildfire Coordinating Group 08/12/2005 safety bulletin "Appropriate Fluid Intake"
• Sports Medicine 07/15/2005 article by Louise B. Weschler "Exercise-Associated Hyponatremia: A Mathematical Review"
• U.S. Food and Drug Administration 04/13/2012 article "FDA Regulates the Safety of Bottled Water Beverages Including Flavored Water and Nutrient-Added Water Beverages"
• Wilderness Medical Society Spring 2001 article by Ian R. Rogers, MD, FACEM "Fluid and Electrolyte Balance and Endurance Exercise: What can we learn from recent research?"

Can a Group Exercise Class Cause Permanent Hearing Loss?

Hearing Loss and Exercise Classes - Photo by Heather Warick at Wikimedia Commons

Many people who might not have tried a group exercise, or aerobics, class in the past are now much more interested in working out in a group. Quite a few facilities have begun to offer aerobics classes that offer a sort of club feel or party atmosphere featuring fun and toning moves set to the beat of cultural or popular music. Other classes may have turned up the heat with workouts that promise to take people to the edge of their physical abilities, all to the tune of a hard-driving beat. Yet, all too often, the music levels in many group exercise classes are far above what is considered safe and is typically only exceeded by an instructor shouting in the microphone.

Although many of these classes are packed, some participants are steering clear. Health club members may look wistfully at the class but keep walking down the hall. They might be able to try the moves and enjoy the workout but aren't willing to put their hearing on the line. One lady made an insightful observation by saying, "A gym should care about my total physical health...and that includes my ears!"

How Loud is Too Loud in Aerobics Class? © Katrena

Sound Standards for Group Exercise Classes

According to the Environmental Protection Agency (EPA), hearing may be affected when a person is exposed to sounds greater than 85 decibels (dB) for more than 45 minutes, with an increased likelihood of hearing loss with habitual exposure. Sound levels at 91 db for any length of time are considered unsafe by many sources. Although certified group exercise instructors may be aware of sound standards, they may not realize that the noise level is unsafe in their classes. Other instructors may know that the music volume is too high but assume that participants want the louder volume.

Most gyms do not have audiometers for checking dB levels, so the assessment of whether or not the music volume is at a safe level often lies with group exercise instructors. Although some facilities might mark a certain setting for music levels on the sound system, individual instructors might ignore that safety directive. In addition, devices such as mp3 players have individual volume controls that can override the volume set on the sound system.

What are warning signs or red flags that the noise level is too high in an aerobics class? As a general rule of thumb, if you must shout to be heard by someone three feet away during class, the noise level is likely too high. The music volume is probably too high if one's ears hurt or ring (tinnitus) immediately after a class is over.

These loud volumes may also affect the instructor's hearing and the hearing of others who are in nearby areas of the facility. OSHA addresses noise levels for employees in which permissible noise exposure is 100 dB if exposed to the noise for two hours/workday. That maximum number decreases if the person is exposed to loud noises for longer periods of time.

Hearing loss due to prolonged exposure to loud noises is usually permanent. Prevention is a much better strategy than treating the problem after the fact, however options for adaptive devices such as various types of hearing aids are much more plentiful than in the past.

Protect Hearing in Group Exercise Class - Photo by photographer at Wikimedia Commons

Hearing Loss Prevalence and Symptoms

Although many assume that hearing loss only affects seniors, approximately six million people aged 18 to 44 have a hearing deficit in the United States. One million school-aged children also have hearing loss. The percentage of younger people with hearing deficits is rising, but many physicians may not routinely check for hearing loss at a regular physical. Hearing loss may not be readily apparent to the healthcare provider in a quiet setting in which only two people are carrying on a conversation. Hearing loss tends to be more apparent in group settings with background noise.

Unfortunately, sensorineural hearing loss due to sustained loud noises such as rock concerts and some group exercise classes tends to occur gradually and the person might not realize that he or she is experiencing permanent damage. People with this type of hearing deficit might notice a ringing in the ears, that they need to turn the television volume higher, feel that everyone (especially women and children) seem to be mumbling, or they might misunderstand statements that others are making, particularly in group settings.

The Better Hearing Institute offers several resources for people who think they may already have a hearing deficit, such as a:

• hearing loss simulator
• free online hearing check

Earplugs or a Plug for Lower Volume? - Photo by Light Current at Wikimedia Commons

Options for Creating a Healthier Environment for Exercise

As folks prepare to take an exercise class, they might ensure that they have well fitting athletic shoes, clothing that will not restrict, a full water bottle, an empty bladder. Some people now use earplugs when taking group exercise classes. Is that really necessary? Some might say yes while others would like to see a healthier environment for all students and the instructor(s).

Many gyms assume that people will not take a group exercise class unless the music is booming. Some participants will stop coming to classes, cancel a membership, and go elsewhere if they do not have music volumes at high levels in exercise classes. This group, which typically includes younger generations, may be quite vocal about their wishes and might be more likely to have somewhat of a herd mentality in which an entire group might join or cancel a membership to a health club.

However, a silent majority may prefer lower volumes in classes. Many in this group, which typically includes older adults, may be internally motivated and will often seek out other opportunities within the facility that meet their exercise needs while protecting their hearing. They may remain silent because they were taught not to complain or may assume that the facility will turn a deaf ear to their concerns. Perhaps they are simply choosing their battles.

Options for advocating for a hearing-friendly group exercise class include:

• Requesting that the instructor decrease the music and microphone volumes.
• Speaking with the group exercise coordinator about the issue.
• Voicing concerns with the director of the facility.

Documenting these concerns with specific details may carry more weight with the appeal for a change. Sometimes classes may be louder when the group exercise coordinator is not in the building. If some instructors are offering classes with safe music volumes, consider regularly attending those classes. Many instructors are only allowed to maintain a schedule if their class numbers meet a minimum expectation.

Unfortunately, many facilities and/or instructors ignore requests for quieter music in group exercise classes. Instructor enthusiasm and variety can more than make up for a lower volume of music, but facilities and/or instructors may simply look the other way and continue to crank up the volume for the sake of keeping as many members as possible. They may assume that the seniors, who are often the consistent members that may stay for many years, will simply adapt to alternate schedules rather than make the move to another facility.

If one facility refuses to accommodate a safety issue such as providing safe noise levels in group exercise classes, other facilities in the area might be able to provide a more suitable workout environment. When looking for a gym with the intention of taking group exercise classes, it is wise to visit the facility a few times and see for oneself whether or not music volume is controlled adequately before investing in a membership.

Noise Levels in Aerobics Classes

The bad news is that many gyms offer group exercise classes with dangerously high music levels that could contribute to permanent hearing loss in the future. Although instructor training and facility policy often includes limits on noise level, that safety issue is often overlooked in order to attract more members. However, an informed consumer might be able to encourage a healthier environment. Most people attend exercise classes in order to achieve better health and should not have to sacrifice their hearing in order to do so.

Find more articles at Fit Tips 4 Life site map.

Sources:

• Environmental Protection Agency article "Listen Up! Play it Safe With Your Ears. Play it Safe With Your Health" accessed on April 5 2012. (also includes puzzles and games related to ear health)
• IDEA Health and Fitness Association July 2001 article "Recommendations for Music Volume in Fitness Classes" accessed on April 5, 2012.
• George Mason University Physics and Astronomy article "Is Your Aerobics Class Making You Deaf?" accessed on April 5, 2012.
• United States Department of Labor Occupational Safety and Health Administration (OSHA) December 12, 2008 statement "Occupational Noise Exposure" accessed on April 5, 2012.