Summer Running Guide

SUMMER RUNNING: Sweat Facts

06.26.2018
Dan Darcy

You know the feeling. It’s a beautiful summer day and you’re itching to get out for a run. You head off on what is supposed to be a nice easy run and before you know it, you’re feeling like total garbage. 

You’ve just been hit by the DEHYDRATION monster! Dehydration can manifest in a few different ways during your workout, including:

  • FEELING THIRSTY

  • HEADACHE/FEELING FAINT

  • FATIGUE (beyond normal fatigue from your workout)

  • LACK OF PERSPIRATION

Dehydration can seriously affect your performance, even if you’re just out for a leisurely jog. A fluid loss of just 2% of your body weight has been proven to impair exercise performance. That’s just 48 ounces of fluid for a 150lb person. And that can include incremental fluid loss throughout the time period leading up to your workout.


SPIKE YOUR WATER: Learn more about Nuun and Skratch Labs, two of our favorite hydration supplements


But how much fluid do you need during exercise to ensure that you don’t dehydrate? Try out the Sweat Test. (It’s easiest to calculate your fluid needs if you base the sweat test on a run of 60 minutes, and it helps if you weigh yourself naked.)

  1. WEIGH YOURSELF RIGHT BEFORE YOU GO OUT TO RUN

  2. KEEP TRACK OF YOUR FLUID INTAKE DURING YOUR RUN

  3. WEIGH YOURSELF IMMEDIATELY AFTER YOUR RUN

PRE-RUN WEIGHT (in ounces) – POST RUN WEIGHT (in ounces) + FLUID INTAKE DURING YOUR RUN (in ounces) = YOUR TOTAL FLUID NEED PER HOUR

Of course, this measurement is approximate, and dependent on many variables. But it will give you at least an idea of what you should be taking in during exercise. You might be surprised how much fluid you need!

Bottom line here? Drink early, drink often.

BUT WHAT IS ACTUALLY HAPPENING IN YOUR BODY TO CAUSE DEHYDRATION?

When you work out, your heart rate rises, causing a bump in your body temperature. That temperature increase causes your brain to send neurological signals to your sweat glands, telling them to get to work.

Your body produces sweat. The process of sweat evaporating off the skin removes heat from the skin, which in turn helps cool the rest of the body (remember, your skin is the body’s largest organ!)

WHAT’S IN SWEAT, ANYWAY?

Sweat is made of 99% water and trace amounts of other minerals – the largest concentration of these is SODIUM (salt), followed by potassium, calcium, and some other minerals.

Keep sodium in mind – it is a very important ELECTROLYTE. Electrolytes are critical in allowing cells to generate energy, maintain cell wall stability, and to function in general. They generate electricity, contract muscles, move water and fluids within the body, and just generally do a whole lot of important things inside the body.

The more your internal body temperature increases, the more you sweat. Your body needs to pull that fluid from somewhere – and after your body takes the water you’ve drank (or ate), it then relies on the fluids surrounding your cells, which negatively effects cell function. So it makes sense that the better hydrated you are, the happier your exercise experience will be!

The increase in core body temperature comes more quickly and becomes more extreme on a very hot or humid day. Additionally, humidity stifles the sweat evaporation process. So your hydration needs are much higher in these conditions.

Think of your body as a huge tank full of water. Ideally, you’d start each run with this tank as full as it can possibly be (i.e. ‘well-hydrated’) and replenish the tank as it empties (as you sweat).

Stop by your nearest Marathon Sports to check out all the great hydration gear we have for you, from NATHAN, Amphipod, Hydro Flask, Nuun, Skratch, and more!

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