Hydration Blog

Topping Off Electrolytes

By Vishal Patel, 
Chief Nutritionist

One area of hydration that has gotten a lot of attention over the past couple years is the art of pre-loading. Pre-loading (I like to refer to it as topping off) your electrolyte stores will play a key function in exercise performance, particularly under tougher conditions such as extreme heat or endurance events. There are three main benefits to pre-loading:

Topping off magnesium/calcium stores

Magnesium and Calcium are crucial electrolytes that play roles in muscle function, contraction, and relaxation. These two minerals work together to ensure your muscles are functioning properly. Most athletes will have some form of magnesium deficiency (that they are unaware of). The issue is that the majority will never realize it unless they get a specific test done, taking skin or hair samples to test the magnesium count free-flowing within those barriers. Some scientists (including myself) also believe that loading up on these minerals prior to racing may even help prevent the onset of muscle cramps. To put it simply, your muscles essentially seize up when cramping occurs, so, having nutrients readily available to aid in that muscle contraction and relaxation may play important roles in delaying or preventing the onset of muscle cramps.

Topping off sodium/potassium stores

Especially important for heavy and/or salty sweaters, AND for racing environments that will cause an increase in core temperature at a faster rate than normal. When it's hotter out, or more humid than you’re used to, your body can bleed through your sodium and potassium stores pretty quick. It’s important to replenish those key nutrients (by having adequate stores, and hydrating!) to help retain fluids.

Peace of mind

Hydration is one aspect we can control during training and racing. Going into a race or hard work out in a euhydrated state will provide several benefits outside of the ones correlating to performance.

Pre-loading procedure

So how do you pre-load effectively? You'll need both carbohydrates (in the form of glucose or dextrose) and electrolytes (sodium, potassium, magnesium, and calcium). Aim for:

  • sodium: 360-400mg
  • potassium: 100-200mg
  • magnesium & calcium: at least 25mg
  • carbohydrates: minimum of 5g (to help speed up absorption)

within the nuun family, you'll want to use nuun active and plus for nuun. Nuun active will provide the base electrolyte profile you need to top off your stores. plus will provide carbohydrates (in the form of dextrose and sucrose to maximize gastric emptying) and some additional electrolytes (particularly a higher concentration of magnesium and calcium).

There are specialized pre-loading formulas out there, but I’ll admit I’m not convinced on the effectiveness. I feel there isn’t enough evidence based research to point to this specific formula to work the best. What we do know, is that you need electrolytes and some carbohydrates. I advise all of the athletes I consult with to add one tab of PLUS to your normal consumption of nuun during taper week.

POSTED IN Hydration


hi jenny - a great way to monitor your hydration status is your urine color. clear means you need more electrolytes and dark urine means you need more water (aim for light yellow). we aren’t currently planning to offer a gel, but we do currently have a carbohydrate-enhanced tab called plus! you can read more here https://nuun.com/blog/introducing-plus-for-nuun but by adding plus tabs to your active or energy, you add carbs to your electrolytes!

Any thoughts on designing a gel type carb/electrolyte replacement? I strongly believe my main issue when on long runs is a deficiency in magnesium/potassium and sodium because after about mile 11 or so, I feel like I hit a wall and it takes a lot to come out of it. My legs feel like blocks of cement are surrounding them and lately I’ve been having side aches during some runs and I know I’m not dehydrated. I drink a gallon of water a day and in that is at least 1 serving of nuun active or energy. I’m actually testing out drinking less water incase I’m flushing out electrolytes by drinking so much. I get starving on long runs and most gels/other edibles are lacking those nutrients that might be the key to my success.

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