Calcium

Calcium is a macromineral and electrolyte important for bone and tooth strength, muscle contraction, nerve signaling and blood clotting. In the context of sports drinks, it is considered a minor electrolyte because sweat losses are small compared with sodium and potassium.

Why Calcium Matters for Athletes

Calcium supports many physiological processes that are critical during exercise. It enables muscles to contract and relax, facilitates the transmission of nerve impulses and contributes to normal heart rhythm. It also combines with phosphate to form the structural matrix of bones and teeth, providing strength and durability. Although calcium is often associated with bone health, the body uses it continuously to regulate blood clotting, maintain normal acid–base balance and help enzymes function properly. Because less than one percent of the body’s calcium circulates in blood, it must be replenished regularly. During prolonged activity, athletes can lose calcium in sweat, but research shows these losses are very small – typically around 0.1 to 1.3 mmol per litre of sweat, or about 20 mg/L. Compared with sodium or potassium, this amount is negligible, and there is limited evidence that supplementing calcium in sports drinks improves performance. Calcium intake recommendations for adults range from about 1,000 to 1,300 mg per day, depending on age and sex. Insufficient intake over time can weaken bones and increase the risk of osteoporosis, while excessive intake may lead to kidney stones or abnormal heart rhythms. Athletes can meet their needs through a balanced diet that includes dairy products, fortified plant milks, leafy greens, nuts and seeds. Vitamin D, magnesium and phosphorus are also important because they aid calcium absorption and utilization.

Everyday Sources and Sweat Losses

Good dietary sources of calcium include milk, yogurt, cheese, canned fish with bones, fortified cereals and vegetables such as collard greens and broccoli. Consuming these foods helps build and maintain bone mass and ensures a steady supply of calcium to support muscle function. Sweat calcium losses during exercise are low compared with sodium and potassium, so most sports hydration products contain only trace amounts of this mineral. A liter of sweat typically contains around 20 milligrams of calcium, whereas the average athlete loses hundreds of milligrams of sodium per liter. For most people, replacing calcium through food and staying hydrated with water or electrolyte beverages that focus on sodium is sufficient. Athletes who train intensely or have high sweat rates should still monitor their overall calcium intake, especially if their diet excludes dairy.

Calcium’s primary roles in bone health, muscle contraction and nerve signaling make it essential for all people, including athletes. However, because sweat losses are small and daily requirements are easily met through diet, calcium is not a central ingredient in most sports drinks. Maintaining a balanced diet rich in calcium and staying hydrated with appropriate fluids will support performance and recovery.

Related Terms: Phosphate, Sodium chloride, Potassium chloride, Magnesium citrate, Calcium chloride