Tag: hydration

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Electrolytes

Electrolytes

Are Electrolyte Supplements Necessary?

It depends! The goal of electrolyte supplementation is to replace lost sweat which supports rehydration and helps maintain thermal balance. More likely circumstances where sweat rate increases include 1) engaging in prolonged intense exercise (>1h), 2) working outdoors 3) engaging in activity at higher temperature, humidity, or elevation.

How Much Fluid do I Need? Calculating Sweat Rate

Sweat rate can vary greatly from person to person for the same activity; a useful way to personally assess how much sweat must be replaced by fluid is by measuring your sweat rate:

1. Before exercise, weigh yourself in a minimal amount of clothing you can train in.

2. Take defined amount of fluid with you for the training session and drink as needed during the session….e.g. 20 oz.

3. After the workout, towel off excess sweat and weigh yourself again in minimal clothing.

Example: let’s say I run for one hour. I weigh 150.2 lbs. initially and drank 20 oz. (1.25 lb.) of water during the workout. After the workout I weighed 148.3 lbs:

Fluid loss = initial weight – final weight – weight of fluid consumed.

150.2 – 147.3 – 1.25 = 1.65 lbs. = 16 oz./hr.

For high intensity exercise extending 90 minutes or more, it becomes increasingly important to ensure fluid regulation and fuel supply. Sip a drink containing electrolyte (and carbohydrates) throughout exercise.

Comparison of Electrolytes

The below table compares popular electrolyte brands versus the reference ranges in 1 L (33.8 oz.) of human sweat. Electrolytes are reported in milligrams (mg) and values reported are per the manufacturer serving size. Replacement of sodium and potassium lost through sweat are more important than calcium and magnesium, which are lost at a lower rate and easier to replace through diet. Certain products such as Tailwind, regular Gatorade, Skratch also incorporate a tangible amount of carbohydrate to support training performance (but you may require additional carbohydrate supplementation).

Many of these products cost a premium for extremely low cost individual components. The lowest cost and most customizable way to supplement electrolytes it to make your own.

ProductServingSodium (Na+)Potassium (K+)Magnesium (Mg+)Calcium (Ca+)Carbohydrate Added / Simple Sugar Type
Human Reference Range (in 1L of sweat)
500-2000100-5000-1000-100
BodyArmor Flash IV1 pack / 7 g50070065801g
Dripdrop ORS1 stick / 10 g3301853909g (sucrose and fructose)
Gatorlyte1 pack / 15 g4203009510012g (sucrose))
Liquid IV1 stick / 16g5603700013g (sucrose and glucose)
LMNT1 pack / 6 g10002006002g
Nunn Sport1 tab / 5 g30015025134g (glucose)
Pedialyte1 pack / 9 g260180007g (glucose)
Saltstick Fast Chews2 tabs / 3.2 g100306102g (glucose)
Tailwind Endurance1 scoop / 27g31090122725g (glucose and sucrose)
Gatorade1 pack / 35 g230700034g (sucrose and glucose)
Skratch Hydration1 scoop / 22 g40050505019g (sucrose and glucose)
Mustard Packet*1 pack / 7g800000 g
Pickle Juice*1 shot / 30 mL2600000 g
Pedialyte Advanced1 pack / 17 g6503700012g (glucose + fructooligosaccharides))

If you would like other products added to this table, email me and I will add.

Do Electrolytes Prevent Exercise-associated Muscle Cramps?

The cause of exercise-associated muscle cramps is not well understood and not attributable to a single factor. [1] Many studies in endurance athletes show no association between cramping and level of hydration and blood electrolyte concentrations. System-wide full body cramping or bilateral cramping does appear to have a stronger association with hydration status and blood electrolytes.

More than likely, hydration status and blood electrolytes are a contributing factor for cramping, but more recent evidence suggests that exercise-associated muscle cramps may be mediated by muscle fatigue that alters neuromuscular control. Note in the table above there is an * by pickle juice and mustard. The beneficial action of these sodium sources may not be the sodium itself as it relates to cramp prevention. Rather they are sources of acetic acid, a compound of interest related to prevention or shortening the duration of cramps [2-4]. The proposed mechanism of acetic acid is to decrease alpha motor neuron activity through oropharyngeal neural reflexes. In short, a strong sensory stimulus could cause alpha motor neurons to become less excited which could prevent or reduce the severity of a cramp.  

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References

1. Miller KC, McDermott BP, Yeargin SW, Fiol A, Schwellnus MP. An Evidence-Based Review of the Pathophysiology, Treatment, and Prevention of Exercise-Associated Muscle Cramps. J Athl Train. 2022 Jan 1;57(1):5-15.

2. Hooper Marosek SE, Antharam V, Dowlatshahi K. Quantitative Analysis of the Acetic Acid Content in Substances Used by Athletes for the Possible Prevention and Alleviation of Exercise-Associated Muscle Cramps. J Strength Cond Res. 2020 Jun;34(6):1539-1546.

3. Hoffman MD, Stuempfle KJ. Muscle Cramping During a 161-km Ultramarathon: Comparison of Characteristics of Those With and Without Cramping. Sports Med Open. 2015;1(1):24.

4. Miller KC, Mack GW, Knight KL, Hopkins JT, Draper DO, Fields PJ, Hunter I. Reflex inhibition of electrically induced muscle cramps in hypohydrated humans. Med Sci Sports Exerc. 2010 May;42(5):953-61.

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Staying Hydrated

Staying hydrated – it’s important. Water supports many roles in human health and performance, including regulation of body temperature, delivery of nutrients to cells, organ function, lubrication of joints and ligaments, and mitigating infection. Hypohydration (result of dehydration), or hyperhydration (excessive rehydration), can lead to performance impairment. At the extremes, it poses a significant risk to health and life. Through proper replenishment of fluids, euhydration (body water balance) contributes to optimum performance.

Human water and water loss

The human body is 60-70% water. Fat tissue stores about 10% water, while muscle tissue is about 70% water. Given that a high proportion of our total weight is attributable to water, it’s intuitive that hydration status can play a meaningful role in day-to-day fluctuations in body weight. Excluding activity, adults lose anywhere from about 30 to 100 oz. water/day (~ 1 to 3 L) in the process of dehydration. About 60% is lost through urine, 35% through evaporation from the respiratory tract and sweat, and about another 5% in poo.

The impact of dehydration on performance

Appropriate fluid intake to limit dehydration is the single most effective way to maintain exercise capacity during training. Depending on physical and environmental factors, an additional 15 to over 170 oz. (~ 0.5 to 5L) of water per hour can be lost through sweat during exercise. Replenishment of water during a variety of activities demonstrates improved physiological function [1] and time to exhaustion [2]. Failure to replace water has demonstrated significant consequences to performance and risks health issues.

Blood flow to exercising muscles is reduced during dehydration. This reduction in blood flow leads to impaired performance. Even at only a 2% loss of body water, endurance and strength-power capacity begins to substantially diminish. Beyond 3% bodyweight loss starts to impose significant health risk. The amount of liquid required to maintain favorable water balance is variable between individuals, but often necessitates drinking before thirst begins. During exercise, most people do not typically get thirsty until they have already lost a meaningful amount of fluid through sweat. Generally, thirst is a lagging indicator of hydration status.

Rehydration

Rehydration and maintenance of body water balance is achieved by consumption of drinks AND foods. Approximately 50% of water is recovered by drinking water and 30% by drinking other fluids. About 20% from food. While we don’t think too much about eating water, many whole foods are loaded with it. Most fresh fruits and vegetables are over 90% water by weight, egg and cooked potato is >70% water. Seafood, meats, poultry, cooked rice, are 60-65% water. Processed foods have lower water content, for example bread (35-40%), cake (15-30%), and biscuits and crackers (1-5%). Therefore, individuals with a diet comprising a higher percentage of processed foods.

Rehydration can be accomplished with drinks other than water. Check out this information about the Beverage Hydration Index.  

How do I know if I’m hydrated?

Thirst alone may not be the best indicator. A multi-factor approach such as the WUT (Weight-Urine-Thirst) self-assessment method can provide a better picture of likelihood of hypohydration for athletes. If you have two or more of these markers, it’s likely you are hypohydrated, and highly likely if you have all three.

WEIGHT

Day to day body weight losses in excess of 1.1% may be an indication of hypohydration (assuming free access to food and drink) . Weigh yourself first thing in the morning every day. For example, a 1.1% loss would be 1.65 lb. for a 150 lb. individual. Take this information into context with thirst and urine characteristics.

URINE (Volume and Color)

Urination is more frequent when body water is high, and less when body water is low. Therefore, if water loss is high due to sweating from exercise, less urine may be produced even if fluid intake is increased. Further, reduced urine production results in darker color and is somewhat indicative of hydration status. Use a urine assessment chart like the one below (and remember that the toilet contains water, which will dilute the color). A reduction in urine frequency with darkening of color may be an indication of hypohydration along with weight and thirst as indicators.

THIRST

Thirst can be a lagging indicator of hydration status; even if you aren’t thirsty, you may still be hypohydrated. If you are thirsty, take this information into context with change in weight and urine characteristics.

Habits to stay hydrated

1. Have a glass of water when you wake up in the morning

2. Eating contributes to hydration. Nearly all veggies and fruits are more than 90% water – keep up with these in your diet to support hydration!

3. Rule of thumb for general water intake per day = 1/2 bodyweight in ounces or more depending on your physiology, general activity and environment.

4. If you’re behind on water intake before training, 15-20 oz. in the two hours leading up, and another 5-10 oz. 20 minutes before.

5. During training – replace fluids based on your sweat rate. A typical replacement range is 17-70 oz. (0.5 – 2L) per hour of fluid. If training longer than an hour it might be a good idea to drink back some sweat (electrolytes) plus carbohydrate if warranted. Read about electrolytes and how to calculate sweat rate here.

Hope you found this post informative! Reach out anytime with questions.

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1. Nassis GP, Geladas ND. Effect of water ingestion on cardiovascular and thermal responses to prolonged cycling and running in humans: a comparison. Eur J Appl Physiol. 2002 Dec;88(3):227-34.

2. Samuel N. Cheuvront & Robert W. Kenefick (2016) Am I Drinking Enough? Yes, No, and Maybe, Journal of the American College of Nutrition, 35:2, 185-192

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Beverage Hydration Index

The beverage hydration index provides the relative hydrating ability of different fluids relative to water. How do different drinks compare and what makes some beverages more hydrating than others?

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It’s useful to understand how different beverages can help maintain daily water balance in the body. Understanding how some beverages promote longer-term fluid retention, especially considering prolonged exercise and/or warmer climates is of practical benefit.

Common perception is that regular water and sports drinks containing electrolytes are more beneficial for hydration, and drinks such as coffee, tea, soda, and alcohol are dehydrating. Is this true?

In 2016, a team of researchers in the UK performed a fascinating study [1] comparing how well 13 different drinks were retained in the 2-4 hours immediately after consumption. Seventy-two volunteers consumed 1L of different fluids and then had their urine output monitored to indicate how much had been retained.

Correcting for differing water content, each beverage was given a Beverage Hydration Index (BHI) score. Still water was used as the reference point, with a rating of ‘1’. The higher the BHI, the more fluid was retained.

Comparing the 13 different beverages to water:

  • Oral rehydration solution aka ORS (e.g., Diarolyte, Pedialyte), orange juice, and milk are statistically more hydrating than water
  • Teas, sodas, and sports beverage (e.g., Powerade) statistically provide similar hydration to water
  • Black coffee and lager appear only very mildly dehydrating relative to water

The BHI highlights that there are several factors influencing the hydrating and dehydrating properties of different fluids, through changes in the rate at which the fluid is emptied from the stomach and absorbed in the small intestine versus how much is extracted in urine.

  • Volume of liquid consumed and rate of consumption influence rate of stomach emptying and absorption. To improve fluid retention it’s preferable to frequently sip fluids than to chug large volumes. Fast consumption of large volumes will more often than not result in the water passing through without as much storage in the body water pool. Why pee more without all the hydration benefit?
  • Other nutrients can strongly modulate hydration properties. Electrolytes, carbohydrate, protein, and fats in beverages delay stomach emptying and fluid absorption to varying degrees – the presence of these nutrients in fluids support hydration.
  • Presence of diuretics such as caffeine and alcohol can increase rate of excretion, and therefore can have a dehydrating effect. However, this appears to be highly dependent on other nutrients in the drink as well as the concentration of caffeine and alcohol. Low amounts of caffeine and alcohol are not especially dehydrating compared to water.

24-h hydration status does not appear to be very different in people drinking just water versus water plus a variety of other drinks, including water, cola, and fruit juice, provided that an adequate total volume is consumed. [2] Therefore, regarding specific drink selection within context of your overall nutrition and goals, consider the following:

  • Am I drinking enough overall fluid day to day to maintain hydration?
  • Am I sweating due to intense and/or prolonged training, training in warmer or more arid environments with infrequent opportunity to drink?
  • Do I need increased energy availability for prolonged training, or quickly restore muscle glycogen (for a second training bout)?
  • Protein: Will the milk help me better meet daily protein requirements?
  • Do I need additional calories or are zero-calorie options a better choice?
  • Is my stomach empty? BHI is an isolated measurement that was evaluated in the fasted state. Food will slow down fluid absorption and excretion rate.

Notes about caffeine and alcohol

A single high dose of caffeine, for example that contained in an energy drink (100 -200 mg) is unlikely to have a massive dehydration effect; as dosages approach and exceed 300 mg the additional volume of urine excreted may become significant. [3]

Alcohol content of the lager used in the study did not increase urine excretion over other drinks, but the effect of the alcohol may have been modulated by other nutrients in the beer. Counter to this idea, a different study specifically reported 12% greater urine excretion after ingestion of 1 L lager beer containing 4% alcohol compared with the ingestion of the same volume of a nonalcoholic control beer. [4]

While a few of the studied drinks were more hydrating than water, there are many drinks that are very similar to water which will support daily hydration needs. A few recommendations:

  • Start the day with a glass of water
  • EATING water will also support hydration. Consider that nearly all whole vegetables and fruits are >95% water by weight.
  • Replenish fluids during and after training. ORS is an excellent choice for prolonged intense exercise to replace sweat. Additional carbohydrates may be necessary to maintain energy availability for extended training. It’s lowest cost to make your own, or purchase products such as Pedialyte, Nuun, DripDrop.
  • Milk is an all-star as a post-workout beverage to support rehydration, total protein intake, and glycogen re-synthesis. Ron Burgundy is wrong!
Beverage Hydration Index

[1] Maughan, RJ, Watson, P., et al, A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index, Am J Clin Nutr 103: 717-723, 2016.

[2] Tucker M.A., Ganio M.S., et al. Hydration status over a 24-h period is not affected by ingested beverage composition. J Am Coll Nutr 34:318–27, 2015.

[3] Maughan R.J., Griffin J., Caffeine ingestion and fluid balance: a review. J Hum Nutr Diet 16:411–20, 2003.

[4] Hobson R.M., Maughan R.J. Hydration status and the diuretic action of a small dose of alcohol. Alcohol, 45:366–73, 2010.

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