What Science Tells Us About Exercise Hydration

One of the major questions that we get is whether you can trust your thirst level to judge when to drink more fluids. As is common in the nutrition world, the answer is "it depends." Most of the time, your body doesn't generate a "thirst" response until about 1.5% of water is lost. Now if you're inactive, thats not a huge deal, but from an athletic performance point of view, its huge. Add on top of that the individual response to exercise ("sweater" vs. "non sweater") and making generalized statements about this topic is extremely difficult.

What science-based recommendations can we make? The Institute for Medicine determined that an adequate intake for men is ~3 liters and ~2.2 liters for women. Of course, there's a bunch variables that could cause you to want to drink more (and sometimes less) than these amounts. Another approach is to use your urine color as an indicator of hydration. Aiming for a goal of "slightly yellow" with ~5-6 urinations through a day seems to be a helpful goal for most people. Of course, supplements that have yellow coloring such a multivitamins, B vitamins, tumeric, etc. can skew the urine color so just just aware of that when considering this approach.

As a performance based nutrition coach, I'm definitely interested in how dehydration can impact human performance. We do know that the 1-2% dehydrated state can have a fairly large impact on performance in both endurance and more strength based efforts. However, we also know that OVER-hydrating can have negative impacts on performance as well if hyponatremia (low blood sodium levels) occurs. In extreme cases, this can actually be life-threatening.

What Should I Drink During Exercise? 

Athletes should be drinking about 8-10 ounces of water 20-30 minutes prior to exercise with another 5-7 ounces for every 20-30 minutes of exercise that follows, in an ideal world. For longer efforts, adding some carbohydrates to the water can improve the absorption of water into the blood circulation, along with any electrolytes that are included as well. Interestingly, several amino acids are also capable of helping to improve hydration as well, notably glutamine, alanine cysteine and glycine. All that said, most research indicates that exercise sessions lasting an hour or less are not negatively impacted by simply drinking water.

Should I Be Mixing Supplements Into My Water?

There's only a few things that I think are worth giving a try. Remember, everyone's a little different so ultimately your response to these approaches will be different as well.

1. Himalayan salt: There is some evidence to show that a small dose (a pinch?) of Himalayan salt can help remove some of the burden we place on the adrenal glands through our day to day stresses. I personally keep the dose small and just do it for a single glass of water in the morning.
2. Magnesium citrate: You might be surprised to learn that ~75% of Americans are deficient for magnesium. This is important because studies show that low magnesium levels can impact testosterone production, increase blood pressure and also reduces the efficiency of neuromuscular firing. Dosing can range from 300-500 mgs for the average person.

Is There Any Benefit To "Alkalized" Or Alkaline Water?