Hydration for strength training: What you need to know

From the desk of
Luis Villaseñor
ScienceHydration for strength training: What you need to know

“What’s the best way to stay hydrated for strength training?”

I’ve gotten this question a lot in my coaching career. Strength training is a fairly general term — it can involve weightlifting, resistance bands, bodyweight exercises, or anything else that builds muscular strength and power. But the hydration strategy for any of these exercises involves optimizing your intakes of two things: water and electrolytes.

Sodium and potassium are particularly crucial at the cellular level. They help you maintain proper fluid balance, transmit nerve impulses, and facilitate muscle contractions and relaxation. Being low on water or electrolytes can disrupt these processes, causing muscle cramps, weakness, headaches, and fatigue—making every movement feel like you’re battling with quicksand.

Although you may sweat less during strength training compared to endurance exercise, you’re still losing fluids and electrolytes, and it’s critical to replace them to optimize your workout.

But I’m getting ahead of myself. In addition to the topics above, this article will cover fluid needs during resistance training, how potassium helps regulate blood pressure, and how magnesium can assist muscle performance. We’ll finish with some practical advice on electrolyte intake.

What is Euhydration?

Water is the lubricant that keeps all of your body’s organs floating and processes moving. It helps your blood flow through veins, your brain hover in your skull, your organelles rest in your cells, your waste move through your bowels, and so on.

For all this high praise, many people mistakenly believe that the goal of drinking water is solely to prevent dehydration. But in reality, it is to achieve a state called euhydration. When you’re in a state of euhydration, your body water is balanced within an optimal range—not too much, and not too little. Overhydration, in fact, can dilute your blood sodium content, leading to many of the same symptoms that present with dehydration (or worse). That brings me to my next point.

Our love of water is exacerbated by our tendency to neglect electrolytes, which are just as vital to achieve optimal fluid balance as water itself. When I say fluid balance, by the way, I’m not just referring to the total water entering and leaving your body. I’m also talking about the ebb and flow of water inside of, outside of, and between your cells and tissues.

If you’d like a deep dive on how sodium and potassium influence this ebb and flow, you can check out this article: What electrolytes do for you: Sodium-potassium pumps and fluid balance. But for our purposes today, you can simply proceed understanding that sodium and potassium are particularly crucial to achieving being properly hydrated and facilitating the nerve impulses which allow you to think, breathe, and move.

Fluid Needs During Resistance Training

If you lose over 2% of your total body water, you are officially in a state of hypohydration—dehydration is the process of losing water, while hypohydration is the result.

Hypohydration has been shown, in several studies, to impair endurance exercise performance because it affects your body’s ability to thermoregulate. In other words, when you can’t cool yourself properly, performance declines. But does it affect strength and power too? This isn’t so clear-cut.

In one small 2007 study, seven strength-trained men completed resistance circuits in three separate states of hydration: euhydration, hypohydration (2.5% loss of body mass), and severe hypohydration (5% loss of body mass). What happened? Less than you might expect. There were no significant differences in vertical jump height, peak lower-body power (jump squat), or peak lower-body force (back squat) between the hydration states. The one difference? When euhydrated, the athletes could perform more total work during a six-set back squat protocol.

Another study looked at rugby players hydrating for either aerobic or strength training. Interestingly, they found that the athletes performing strength training were more likely to overdrink. They lost less fluids through sweat than the aerobic group, but still guzzled water fairly aggressively. This mirrors my hunch that drinking too much (not too little) is the more common occurence for strength athletes.

Sodium and Potassium During Strength Training

Let’s revisit sodium and potassium, your body’s fluid-balancing electrolyte duo. When you strength train, your body’s electrolyte needs shift. Yes, of course you lose sodium and potassium through sweat during exercise, but there’s more to it than that.

For one, strength training leads to the secretion of a hormone called aldosterone. Aldosterone helps you hold onto a bit of sodium during exercise, which is good, but it also raises blood pressure and increases the excretion of potassium through urine.

Now consider if you were already low on sodium, perhaps from drinking too much water. What happens then? You guessed it: your adrenal cortex dumps a bunch of aldosterone into your system. While it’ll try its best to hang onto that precious sodium, it simply cannot make up for significant sodium deficiency. It can, however, still flush potassium down the drain. Now you’re low on sodium AND potassium.

This is not good for longevity, performance, or health in general, so pay attention to how you feel. If you’re deficient in sodium, you may experience headaches, low energy, muscle cramps, confusion, nausea, and irritability. And if you’re low on potassium, similar symptoms (especially muscle cramps) can result, along with an increased risk of high blood pressure.

This is why it’s super important to consume adequate sodium and potassium in your diet, and alongside water during exercise. Next up: Magnesium.

Magnesium For Strength

Most everyone agrees that magnesium (Mg) is crucial for muscle function and exercise performance. Magnesium helps convert the energy you gather from food into a form of energy that your cells can take advantage of. Yup, I’m talking about adenosine triphosphate—ATP, baby. Magnesium is one essential component required to produce this cellular energy.

That’s a solid case for ensuring that you’re not magnesium deficient—but does it then follow that magnesium supplementation increases strength and power? The science isn’t totally clear there.

In one study, 18 to 30 year olds supplementing magnesium had greater strength gains in the quadricep region compared to controls. But in this meta-analysis on 14 randomized clinical trials, researchers found that “evidence does not support a beneficial effect of Mg supplementation on muscle fitness in most athletes and physically active individuals who have a relatively high Mg status.” These researchers, however, go on to admit that taking magnesium does appear to improve strength in magnesium-deficient populations, which makes sense.

Up to 30% of people may be subclinically deficient in magnesium (meaning it won’t show up on a blood test, but that doesn’t mean you’re anywhere near consuming what’s optimal). If you’re a part of the larger 70%, your workouts may stand to benefit from bumping up your magnesium intake.

What Affects Hydration Needs During Strength Training?

As a general rule, strength training has lower hydration requirements than endurance training. Nonetheless, if you’re furiously deadlifting in a hot room wearing a sweat suit, you’ll want to have lots of electrolyte water on hand. The key variable here is sweat. More sweat leads to greater hydration needs. Here are the main factors affecting sweat loss:

  • Temperature. The hotter it is, the more you’ll sweat while training.
  • Humidity. Lifting weights in a steamy jungle would be a super sweaty situation.
  • Breeze. A nice breeze can evaporate sweat more quickly, cooling you off more efficiently.
  • Clothing. More clothes mean less airflow and more trapped heat, leading to faster sweat rates.
  • Duration and intensity. Harder and longer bouts of exercise deplete fluids and sodium faster.

Diet is also worth mentioning here. Whole foods diets are especially low in sodium, since most sodium in Standard American Diet (SAD) comes from from packaged and processed foods. So if you eat pretty healthy foods most of the time, don’t be shy with the salt shaker.

Interestingly, if you’re on a low-carb or keto diet, or if you practice fasting, you probably need more fluids and electrolytes. Low-carb diets are diuretic, and cause increased excretion of water, sodium, and potassium—and a similar phenomena occurs in a fasted state. These fluids and electrolytes need to be replaced, but it can be difficult to replace them on a low-carb diet which limits how much electrolyte-rich foods (like potatoes, bananas, and oranges) one can consume.

At a baseline, daily intake we recommend 4–6 grams sodium, 3.5–5 grams potassium, and 400–600 mg magnesium for people who actively prioritize a quality diet and consistent exercise.

Strength Training Hydration Strategy

Hydrating for resistance training isn’t super complicated. The winning strategy can be summed up in one sentence: Drink water to thirst and prioritize electrolytes.

When you drink to thirst, it’s unlikely you’ll drink too much or too little water. Thirst is a tightly calibrated system, and it’s tuned to help you stay in a state of euhydration. Adding electrolytes (especially sodium and potassium) to your fluids helps replace what’s lost through sweat so you can power through your workout and recover faster.

Mix up a DIY electrolyte drink in your kitchen, or try LMNT—our tasty electrolyte drink mix with a science-backed ratio of electrolytes. That’s it! You’re ready to stay hydrated during your next lift.

Stay strong and Stay Salty.

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