Tennis Electrolytes: What You Need and Why Sodium Matters Most
The electrolyte conversation most tennis players are getting wrong
Ask most tennis players what electrolytes they need and many would say potassium — probably because of the long-standing association between bananas and athletic performance. Ask a tennis sports scientist the same question and the answer is different: sodium. And specifically, sodium citrate.
The distinction matters for how you fuel a match.
What tennis players actually lose in sweat
Tennis players can sweat more than 2.5 liters per hour in warm conditions, according to research from Kovacs (2006). The composition of that sweat is specific: predominantly sodium, with smaller amounts of potassium, magnesium, and chloride.
Kovacs' research specifically identifies sodium depletion — not potassium — as the primary electrolyte driver of tennis-related muscle cramping and performance decline. This is an important distinction because most sports drinks are formulated around potassium as the headline electrolyte, while sodium is often underdosed for the specific demands of tennis.
Why sodium citrate specifically — not just table salt
There's a meaningful difference between sodium chloride (table salt) and sodium citrate as an electrolyte source. Sodium citrate has a higher bioavailability and is better tolerated gastrointestinally during exercise. More importantly for tennis players, a published clinical study found that sodium citrate supplementation specifically improved shot consistency and number of games won during a simulated tennis match.
That's not a general sports performance claim — that's a tennis-specific outcome measured in a tennis-specific context. Shot consistency and games won. Those are the metrics that matter on court.
Magnesium — the underrated one
Magnesium plays a critical role in muscle function and neuromuscular transmission. In the context of tennis — a sport where cramping can end a match — adequate magnesium matters. However, not all magnesium forms are equal. Magnesium oxide, commonly used in supplements, has poor bioavailability. Magnesium glycinate, a chelated form, absorbs significantly better and is substantially gentler on the digestive system — relevant for anyone who has ever experienced GI issues during a long match.
What about potassium?
Potassium matters — it's involved in muscle contraction and fluid balance. But in the context of tennis-specific losses, it plays a supporting role to sodium rather than a primary one. Adequate potassium is necessary but chasing high potassium numbers while underserving sodium misses the priority hierarchy that the research suggests.
The practical takeaway
When choosing a hydration product for tennis, look at the sodium content first — and look at the source. A sodium-forward formula with sodium citrate specifically, supported by magnesium glycinate and adequate potassium, maps more closely to what tennis research actually recommends than most general sports drinks on the market.
