What Electrolytes Actually Are and What They Do
This article is part of the PRactical Guide to Fitness & Nutrition Myths.
Electrolytes are minerals that carry an electric charge when dissolved in fluid. The primary ones relevant to exercise are sodium (critical for fluid balance, nerve conduction, and muscle contraction), potassium (works with sodium to regulate fluid balance), magnesium (involved in over 300 enzymatic reactions), calcium (essential for muscle contraction and nerve signaling), and phosphate (involved in energy production).
You lose electrolytes primarily through sweat and urine. The question is whether normal training depletes these minerals enough that supplementation is necessary — or whether your diet and water intake handle it just fine. The greens powder industry uses the same playbook — selling a solution to a deficiency that most of their customers don't actually have.
The Muscle Cramp Myth: What Actually Causes Cramps During Lifting
One of the most persistent pieces of gym folklore is that muscle cramps are caused by electrolyte depletion — specifically low sodium or magnesium. The evidence, however, tells a different story.
The dominant current hypothesis for exercise-associated muscle cramping is the neuromuscular fatigue model, not the electrolyte depletion model. Research led by Dr. Martin Schwellnus and colleagues has shown that cramps during exercise are most strongly associated with muscle fatigue and altered neuromuscular control, not with changes in serum sodium, potassium, or magnesium.
In studies comparing cramping to non-cramping athletes, the crampers and non-crampers often show similar blood electrolyte levels. Muscle cramps during training are usually a fatigue issue — the fix is better pacing, programming, or more training volume over time. Reaching for an electrolyte drink mid-session is treating the wrong problem.
The ACSM Guidelines: When You Actually Need Electrolytes
The American College of Sports Medicine has published evidence-based guidance on exercise and fluid replacement. The key thresholds:
Exercise lasting less than 60 minutes at moderate intensity: plain water is sufficient for most people.
Exercise lasting more than 60 minutes, particularly in hot or humid environments: electrolyte replacement becomes relevant — primarily sodium, to replace sweat losses and help maintain the drive to drink.
Endurance events lasting 3+ hours (marathons, triathlons, long cycling): electrolyte replacement is genuinely important. Neglecting it can lead to hyponatremia (dangerously low sodium), which is a medical emergency.
The picture that emerges: electrolyte supplementation is a tool for a specific context — extended exercise, heat, and high sweat rates — not a daily necessity for the average gym session. If you're training for 45–60 minutes in a temperature-controlled gym, a bottle of water is the correct hydration strategy.
Who Does Genuinely Benefit from Electrolyte Supplementation
There are real use cases where electrolyte supplementation makes sense:
Endurance athletes: Training for anything involving 90+ minutes of continuous aerobic effort. Sodium in particular helps prevent hyponatremia when drinking large amounts of water over several hours.
People training in heat or humidity: When ambient temperature is high and you're sweating heavily for extended periods, electrolyte losses become meaningful.
Heavy sweaters: If you notice your skin feels gritty after workouts or see white salt stains on your clothes, you might be in this category.
Keto dieters: People following ketogenic diets have higher electrolyte requirements because insulin suppression causes increased renal sodium excretion. This is one of the more legitimate and well-documented use cases.
People in a large caloric deficit: When eating well below maintenance calories, you're often eating less sodium and potassium than at baseline.
The Food-First Approach
Here's the unsexy truth: a reasonably varied diet provides adequate electrolytes for most gym-goers without any supplementation whatsoever.
Sodium is present in virtually any non-fast food diet. Potassium comes from bananas, potatoes, sweet potatoes, beans, and leafy greens. Calcium from dairy, fortified plant milks, and leafy greens. Phosphate from essentially any protein-containing food.
The one mineral worth paying attention to for lifters is magnesium — it's involved in sleep quality, muscle function, and recovery, and dietary gaps are common. But you can address this with standalone magnesium glycinate or citrate for a fraction of the cost of a premium electrolyte product. Avoid proprietary blends — the same issue as AG1 — if you can't see the doses, you can't evaluate the product.
Most people who lift 3–5x per week in a standard gym environment, eating a reasonably varied diet, do not need to supplement electrolytes.
Frequently Asked Questions
Should I drink electrolytes before a lifting session? For most people doing a standard 60-minute gym session, no. Pre-hydrating with water is sufficient. If you're doing a 2+ hour session, training in significant heat, or you're a heavy sweater, adding sodium-containing electrolytes has legitimate support.
Do electrolytes help with muscle cramps during lifting? Current evidence suggests most exercise-associated muscle cramps are caused by neuromuscular fatigue, not electrolyte depletion. Better programming, adequate rest between sets, and building work capacity over time are more appropriate responses.
Is LMNT actually good? LMNT has better dosing than many competitors — particularly its 1000mg sodium per serving. It's a decent product for people in the genuine use cases above. For most gym-goers training under 60 minutes, it's a premium price for something you don't need.
What about magnesium specifically? Magnesium is worth paying attention to. Dietary intake is commonly low in the general population, and it plays roles in muscle function, sleep quality, and recovery. Standalone magnesium glycinate or citrate is a reasonable and cheap supplement to consider.