Water and Staying Hydrated
April 4th, 2022
There is so much controversy surrounding this topic ever since Gatorade was pushed onto the market in the 80's and 90's. We have been told that we need sports drinks in order to perform at our peak and prevent dehydration.
What is the truth? Are sports drinks useful or just another piece of the obesity epidemic?
From the British Medical Journal:
"Water is the major constituent of the human body and the total body water content is tightly regulated. The goal is to
ensure that the water content of the cells and hence their size remains within a homeostatically regulated range. Humans evolved as long distance persistence hunters on the arid savannahs of south and east Africa. We inherited the capacity to regulate our body temperatures during prolonged exercise in dry heat despite quite large reductions in total body water-no other mammal has the equivalent capacity. Humans do not regulate fluid balance on a moment to moment basis. Because of our evolutionary history, we are delayed drinkers and correct the fluid deficits generated by exercise at, for example, the next meal, when the electrolyte (principally sodium but also potassium) deficits are also corrected. As a result, there is no need to completely replace any fluid deficit as it develops either at rest or during exercise. Instead people optimize their hydration status by drinking according to the dictates of thirst." (Noakes T. 2012)
When it comes to sports drinks and hydration in general, I think about adaptation. Does it make sense that humans would need a sugary beverage to maintain adequate hydration during exercise like a hunt or long migration? And if so, why does it not exist naturally on earth as a sugar based beverage? We have bountiful water exposures through nature. We have bountiful sugar exposures through food in nature. Yet, we do not have Gatorade or Powerade naturally. Yet, this may still be an ok beverage if there is science to back up it's need or shows an advantage to humans despite natural evolution of our species. The last requirement for me to use these beverages is that it does no harm over time.
What does the literature say?
It turns out from my take on the literature is that thirst and urine output (but not urine color) are great indicators of hydration status. There is solid evidence that dehydration is not a major risk of death during most sports where as over hydration is. The New England Journal of Medicine published a paper regarding death during marathons from hydration status. They showed that drinking too much is the risk factor for death regardless of beverage consumed from water to sports drinks. (Almond et. al. 2005)
From Dr. Peter Attia: "When can overhydration happen during exercise?
When people are exercising in typically high heat, which is requiring them to drink a lot and they’re doing so over a long period of time. A few times a year, you might hear about a story of somebody who died from hyponatremia during a marathon or an iron man. It’s usually someone who is out there exercising three, four, five hours. It’s usually under a pretty high heat condition, so they are a lot of water. When they’re sweating, they’re also losing sodium, but they are replacing it with probably just water altogether. So, they’re taking in all of this water. They’re not absorbing all of it, but they’re still absorbing a decent amount of it. And they’re constantly diluting, diluting, diluting their plasma. The heat isn’t necessary to get hyponatremia. It exacerbates the need for you to drink and that’s when you can really get into trouble. If you’re exercising for an hour, water is fine. But if you’re exercising a lot more than that, start thinking about the importance of bringing in the sodium that you’re going to need to offset the risk of hyponatremia" (Podcast #200 The Peter Attia Drive Shownotes)
What is the story then with dehydration?
Dehydration is defined as the loss of water, but not salt thus driving up the concentration of the bodies osmolality, solute to water ratio. This primarily occurs in the cell only. Water will leave or enter the cell in order to always try and balance the solute concentration in the vascular space. The body will always try and balance all biological functions.
Sweat tastes salty but is low in salt compared to the normal intra cell salt content. Thus, when you sweat you are losing water mostly, therefore, the replacement solution is primarily water.
Dehydration can and does affect overall athletic performance. This is primarily dependent on the length and intensity of the event. For example, sprinter would need to be adequately hydrated prior to the event and that would be sufficient, whereas, a long distance cyclist or runner will need pre-hydration and in race hydration to maintain optimal performance via the prevention of fluid shifts that follow dehydration. Sports where a lot of equipment is worn, football and hockey, would need more fluid intake than baseball per se. Then the ambient temperature of the room, hockey versus football, also plays a roll. You get the point. The variables are many. Most are logical.
When we exercise for a while in hot conditions and with padding, we lose water, sodium and chloride through sweat. We lose much more water than salt through sweat and respiration. The more that we lose, the more our cells may function sub optimally. Sodium is involved in maintaining fluid volume in the blood vessel and cell membrane electrical potential which is involved in muscle contraction and nerve signaling. Chloride is also involved in these same pathways. You can really look at these two ions the same way as they make up salt, sodium chloride.
"Healthy humans regulate daily water balance remarkably well across their lifespan despite changes in biological development and exposure to stressors on hydration status. Acute or chronic body water deficits result when intakes are reduced or losses increase, but day-to-day hydration is generally well maintained so long as food and fluid are readily available. Total water intake includes drinking water, water in beverages, and water in food. Daily water needs determined from fluid balance, water turnover, or consumption studies provide similar values for a given set of conditions. A daily water intake of 3.7 L for adult men and 2.7 L for adult women meets the needs of the vast majority of persons. However, strenuous physical exercise and heat stress can greatly increase daily water needs, and the individual variability between athletes can be substantial." (Sawka et. al. 2005)
Measuring weight loss as a percent of body weight has been used as a proxy for water loss. Greater than 2% weight loss is associated with significantly less athletic ability over time. Less than 1% in general has little effect negatively. You start to see alterations in ability over 1% by metrics, however, this is hard to self perceive in activity. 5% water loss or greater is associated with dizziness, cramping, fatigue and you are in a danger zone.
Maintaining adequate hydration is a key to a healthy workout or sporting event and water is the best choice for most workouts. Try to avoid getting thirsty while working out which can occur by getting small and frequent sips of water throughout and event where possible. Glucose or sugar are almost never needed.
So, what about the carbohydrates in sports drinks during exercise? "The main advantage for athletes to drink a Glc-Fru mixture, during an exercise, is the capacity to absorb a greater amount of exogenous CHO in the systemic circulation, which can be used immediately as energy fuel or can be directed toward the liver or the muscle glycogen stocks. Furthermore, isotonic Glc-Fru mixtures cause less intestinal problems than Glc alone, probably due to their faster digestion and absorption, explaining some of their beneficial effects on sports performance". (Orru et. al. 2018) These needs are entirely not necessary unless you are an ultra athlete like the cyclists of the Tour De France or Marathon runners. And even then Gatorade and Powerade are not the best choice because there is too much sugar in them. I personally drink water and little to nothing else for 95% of my workouts. If I do use an electrolyte beverage, I use Liquid IV.
Post exercise carbohydrates were discussed in the last newsletter, but suffice it to say that these beverages are rarely if ever necessary for peak performance during exercise.
When it comes to young children and sports, I fall on the side of water is the key and sports drinks have no place in training with very rare exceptions for triathletes and high endurance performers at these young ages. Once a person gets to the elite level of sports, then there may be a case for some electrolyte solution because of the prolonged training.
Sports drinks, 12 ounces, contain on average 5 teaspoons or 21 grams of sugar per serving. Like chronic soda and juice consumption, sports drinks used outside of vigorous athletics has been shown to increase obesity, drive fat deposition and can lead to insulin resistance and diabetes over time. They should be avoided in general. And, oh by the way, most kids are drinking them as a routine beverage damaging teeth and livers around the country. Not good!
Take home points:
1) Hydrate with water when thirsty and increase volumes on super hot days or when wearing lots of padding
2) Pre-hydrating before events makes common sense
3) Know whether you sweat well or do not and plan accordingly on hot days
4) Avoid sugar enhanced sports drinks as they have limited to no role in most athletics
5) Always bring extra water on long hikes or events that are away from a water source
Johns Hopkins Heat Stroke Page
Sawka Nutrition Reviews
Davis Sports Medicine
Committee on Nutrition Pediatrics
Pediatric Child Health
Peter Attia AMA #33