Spend a day with any guide, outdoor educator, or experienced adventurer and you will likely hear them (somewhat) jokingly remedy any situation, from headaches to a sprained knee, with a swig of water. The joke stems from the very real need to regulate our hydration levels more diligently while participating in highly physical activities, and in truth there are a wide variety of maladies caused by dehydration.
Dizziness, confusion, dry mouth, low energy, and decreased urine output are all common early signs of dehydration (1). Beyond just feeling awful, a moderately dehydrated person may start making poor decisions which can quickly escalate into dangerous situations or more serious heat related illnesses. Your best line of defense is preemptively drinking before entering into hot environments and/or partaking in exercise.
Proper hydration not only prevents you from feeling crummy but also has awesome benefits for overall health. A well watered body means lubricated joints, a leisurely pumping heart, and kidneys happily filtering away bad toxins and waste (2). More obviously, you will feel energetic, powerful, cooler, and be quicker to recover.
How awesome is sweating!? Over 4 millions sweat glands are found on the human body, most densely in the feet, armpits, forehead, and palms (3). During periods of high activity the human body can sweat out up to 1.4 liters of water per hour. Once all that water is sitting on the skin, evaporation does its job to cool your body temperature. The rest of the water goes towards keeping your mouth and eyes moist, flushing away waste, dissolving minerals and nutrients, and carrying those nutrients to your cells (4).
We are made up of roughly 60% water, which means we have to put a lot of H2O back in our bodies. Luckily, 20% of our fluids come simply from eating (5). In case you weren't already convinced that fruits, veggies, and greens are awesome, here is further proof (6).
| Food | Weight (g) | Water Weight | Percent Water |
| Strawberries | 160 | 146 | 92 |
| Cantaloupe | 160 | 144 | 90 |
| Orange | 140 | 122 | 87 |
| Apple | 138 | 116 | 84 |
| Cucumber | 52 | 50 | 96 |
| Tomato | 123 | 115 | 94 |
| Carrot | 72 | 63 | 87 |
| Spinach | 28 | 26 | 92 |
There is no set volume for how much water a person needs. On a low activity day two liters might be plenty versus a high activity day where five liters is more necessary. Distance, time, heat, humidity, personal needs, and level of activity all influence how fast you use water, while the availability and cleanliness of water sources provide a means to replenish stocks. Pounding five liters of water can get pretty boring, so try adding mixes or infusions to keep things interesting. Diluted sports drinks add flavor and electrolytes- just be aware of any added sugars. Or try throwing a few slices of lemon, ginger, mint, or cucumber into a water bottle for some natural flavor and added benefits. Coconut water mixed half and half with normal water is another healthy and tasty option.
To carry the water use either a hydration bladder, dromedary, or water bottle(s). A dromedary or hydration bladder offers high capacity without adding bulk, whereas water bottles allow you to add mixes and are easier to fill as streams. Carry enough or plan on picking it up so that you are covered with a little extra for each section of your trail.
If you are not already hydrated, get your body caught up at least two hours before you start. It is very challenging to get hydrated if you start behind. Waking up in the morning and arriving from a drive are two times where the body is typically dehydrated and require some extra liquids.
Your goal is to replenish water at the same pace that you are sweating it out. Thirst is an adequate gauge for low activity days, but basing hydration levels off of your urine is better during high activity periods. The ideal urine is a slightly pale yellow and copious (high volume).
Pale Yellow:
You're perfectly hydrated!
Clear:
You're drinking too much, cut back.
Transparent Yellow:
You're in pretty good shape.
Darker Yellow:
Okay, but it's time to start catching back up.
Amber:
You're way behind, stop what you are doing and drink up now!
Orange:
Possibly from taking Vitamin B, but could be caused by liver problems too.
If you are peeing more than once an hour and it is completely clear it's time to cut back. Hyponatremia, or overhydration, occurs when sodium levels in your blood are abnormally low (7). This generally only happens to high performance endurance athletes such as marathoners and triathletes. By eating a small amount of salty food while drinking you can keep these level in-balance and not be concerned about hyponatremia issues. The more practical reason for not over drinking is that it will allow you to carry less water and not stop as often.
By keeping vigilant about hydration levels your body will feel stronger and your mind will be clearer. Take an active approach by drinking regularly and monitoring your urine output. Soon, proper hydration will become second nature and you can remedy your partner's ailments by reminding them to drink up!
