Biking to hydration ??
How much water should I drink while mountain biking to stay hydrated?
- Mountain bikers and cyclists should drink to the dictates of their thirst. This means drinking to satiate thirst, and stopping once thirst has been quenched.
mtb & drinking to thirst
“When cyclists drink to the dictates of their thirst, they do not experience impairments to hydration status that could be harmful to their health”
In outdoor endurance type sports & activities, including disciplines of MTB, there are two opposing hydration philosophies:
1) Drinking to thirst is more than sufficient
Drinking to thirst is more than sufficient, and your body knows how to regulate proper levels of hydration through homeostatic and anticipatory thirst mechanisms.
2) Drink before you're thirsty
Many studies claim that as little as a 2% drop in body weight (from sweating) will hinder performance and further decreases in hydration will lead to further detriments of performance and eventually heat exhaustion or heat stroke.
The American College of Sports Medicine (ACSM) and the Institute of Medicine (IOM) both say that you cannot rely on your thirst mechanism and recommend drinking beyond thirst. It should be noted that this message is commonly accepted in mainstream media, due in part to the advertising campaigns of large sports drink companies.
“Every year, more athletes are injured by hyponatremia than dehydration”
Many people over-complicate hydration and believe that the human body is incapable of regulating safe levels of hydration.
However, a huge body of unbiased research says otherwise:
“The real fairy tale is that humans must be instructed on how to drink during exercise. Rather, if they would just “listen to their bodies” and to those internal homeostatic controls developed over millions of years through the process of biological selection, they would do just fine.”
-Renowned sports scientist Dr. Tim Noakes
This article is for recreational mountain bikers who are riding for enjoyment and not for competition.
Elite & professional cyclists and XC MTBers who employ ‘functional dehydration’ techniques where they purposely dehydrate by 4% (or more) to enhance the power to weight ratio is beyond the scope of this article and not recommended.
Hydration & recreational athletes
The majority of studies that research hydration & performance focus on elite and professional athletes. Only a few studies are available that look at the hydration needs of recreational athletes.
These studies focus on marathon races or multi-day endurance events that have little relation to recreational MTBers who ride for enjoyment in nature while being in the company of good friends.
However, the few studies that exist regarding recreational MTBing and cycling conclude that it’s rare to experience dehydration if properly hydrated at the beginning of the trail and under normal climatic conditions.
Factors Influencing dehydration during mtb
“Hydration refers simplistically to body water
content, but functionally, it involves the volume,
composition and distribution of body water, all of
which are important but dynamic and difficult to
measure collectively.”
There are a host of factors that influence the process of dehydration, however, three primary factors should be considered:
Environmental conditions
Duration of the ride
Intensity on the trail
1) Environmental Conditions
Temperature, elevation, humidity, wind speed, and strength of UV radiation of the sun.
Environmental conditions - Ambient temperature above 77°F (25°C) results in noticeable levels of sweating while MTB. Radiation - With every gain of 3280 feet (1000 m) in altitude, there is an increase in UV-A and UV-B exposure by approximately 10% to 20%.
Common local wisdom while living at altitude is for every 1000 feet in elevation gain it takes 5% more energy to breathe.
Why? Increased radiation & more breathes = loss of fluid from more breathes (and that just barely scratches the complex surface)
2) and 3) Duration & Intensity
Duration of singletrack or MTB trail / Intensity of the trail - Duration and intensity are related and both require proper preparation.
Knowing the elevation gain, and length of the trail plus trail conditions ahead of time is important for packing fluids, snacks, and other essential gear
What are the main electrolytes?
sports drink & hypocrisy
“The populations’ level of knowledge about the current recommendations for water intake and hydration were mainly wrong”
A 2007 study titled Lobbyists for the sports drink industry: an example of the rise of “contrarianism” in modern scientific debate noted the hypocrisy of science and so-called ‘sports drinks’.
The paper was written by renowned sports scientist Dr. Tim Noakes, who said,
“that has caused some people to be skeptical as to the true function of the Gatorade Sports Science Institute (GSSI) which has funded more than 120 studies in the past 17 years.”
A 2009 article from the Nutrition Bulletin noted that:
“drinking plain water is generally better than drinking nothing at all, but drinking a properly formulated carbohydrate-electrolyte sports drink may allow for an improved exercise performance with benefits being gained from both its carbohydrate content and the water and electrolyte content.”
The “research bulletin” finished with the standard CONFLICT of INTEREST statement, which stated:
“The writing of this article was supported by a grant from the Coca Cola Company. The author has received grants to undertake hydration-related research from Britvic, DairyCrest, GlaxoSmithKline, Gatorade Sports Science Institute, Kraft, Mars/Masterfoods, PepsiCo, The Coca Cola Company and The Milk Development Council.”
A 2016 article from Nutrición Hospitalaria (Hospital Nutrition) after studying over one-thousand volunteers in 4 countries noted that:
“The populations’ level of knowledge about the current recommendations for water intake and hydration were mainly wrong.”
Urine color & dehydration & MTB
“The science of dehydration has led to another widely held belief that is not based on robust evidence—that the colour of urine is a good guide to hydration levels”
Urine & Color
Many people believe that the color of their urine is a good gauge of their current level of hydration.
Urine color is determined by the amount of urochrome present in it.
Pale color urine = Large volumes are excreted, which dilutes the solutes
Dark urine color = Small volumes are excreted because the solutes are concentrated
Can you tell the hydration level by urine color?
The short answer is it depends (mostly no), but as a general rule, determining hydration status through urine color has many limitations.
When one is pedaling uphill while drinking lots of fluid from the hydration bladder and then urinating, the color of the urine doesn’t mean anything.
Urine Hydration chart - (Image Source: Wikimedia Commons)
hydrate the day before your MTB ride
Going for a long and grueling ride the day after a night of drinking and partying is a recipe for dehydration.
Optimal Hydration & The Day Before
One component that sports scientists can agree on is that you should start the MTB trail or cycling route euhydrated. This means you should be optimally hydrated before riding your favorite singletrack.
Eating and drinking nutrient-rich foods and beverages, while avoiding excessive alcohol and caffeine consumption the day prior will set you up for a faster ride, and will decrease your chances of dehydration and its side-effects.
It should be noted that it’s rare to experience symptoms of dehydration for recreational MTBers & cyclists who start the trail in a state of optimal hydration. However, if you’re already dehydrated before the bike ride, chances are you will suffer mild symptoms of dehydration at the very minimum.
Over-hydration
Since the late-1990s more athletes have been injured from over-hydration (hyponatremia) than from dehydration.
How do you avoid hyponatremia (over-hydration)?
Drink to the dictates of your thirst. This means drinking to satiate thirst, and stopping once thirst has been quenched.
Fluid losses through sweat and urine are dynamic and variable across individuals and MTB conditions.
Wilderness and Environmental Medicine says,
“using the sensation of thirst as a real-time guide to fluid ingestion during exercise appears safe and effective and eliminates both of the detrimental extremes of fluid balance (dehydration and overhydration).”
“Avoid overdrinking during exercise”
Final Thought
The human body has a perfectly good homeostatic mechanism for detecting and responding to dehydration and that mechanism is called thirst. Humans wouldn’t have survived the last 200,000 years if the body didn’t have clear physiological signals that dehydration was occurring.
If you are confused as to what proper hydration is, just listen to your body and have a drink when you feel thirsty. Next time you’re out riding singletrack, stop and enjoy the view, and a nice tasty beverage……as your thirst dictates.
Jesse - Master of Science in Health and Human Performance - Bachelor of Science in Kinesiology. Jesse lives in Valdivia, Chile and is Director of Pedal Chile. Hobbies: Avid snowboarder & mountain biker, especially enjoys riding the singletrack on the active-volcano near Pucón. Voracious reader of non-fiction and narrative non-fiction.
References:
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