Hydration is crucial for ensuring optimal performance during physical activity. However, it is not just a question of water: mineral salts play a fundamental role in maintaining electrolyte balance and preventing muscle cramps, fatigue and energy slumps. In this article, we will explore how and when to replenish hydration and mineral salts during sport, with the support of scientific literature.

Why is hydration important in sport?

During physical activity, the body loses fluids through sweat to regulate body temperature. This loss includes water and minerals such as sodium, potassium, magnesium and chlorine, which are essential for maintaining electrolyte balance and muscle function.

Dehydration of even 2% of body weight can significantly reduce physical performance, affecting endurance, strength and cognitive ability. This is highlighted by a study by the American College of Sports Medicine (ACSM), published in the Journal of Sports Medicine, which emphasises that adequate hydration is essential for maintaining physical and mental abilities during sports (link to study).

What are the main minerals to replenish?

1. Sodium: Essential for maintaining fluid balance and preventing muscle cramps. Sodium is the mineral most abundantly lost through sweat.
2. Potassium: Helps regulate muscle and nerve function, counteracting the effects of dehydration.
3. Magnesium: Important for muscle contraction and fatigue prevention.
4. Chlorine: Maintains electrolyte balance and aids digestion.

When should water and minerals be replenished?

Before physical activity:

• Drink 500-600 ml of water about 2 hours before exercise.
• Ensure that electrolyte levels are balanced by eating a meal rich in minerals.

During physical activity:

• For activities lasting less than 60 minutes, water is generally sufficient.
• For sessions longer than 60 minutes, especially in hot conditions, it is advisable to supplement with an isotonic drink containing:
  • 20-30 mmol/L of sodium.
  • 4-8% carbohydrates to provide energy, as recommended by the American College of Sports Medicine in their study on isotonic drinks for endurance sports.

After physical activity:

• Replenish 150% of the fluids lost during activity within 4-6 hours.
• Be sure to include a source of electrolytes, such as a specific drink or foods rich in minerals (e.g. fruit, vegetables and nuts).

Signs of Dehydration and Electrolyte Imbalance

Some signs of dehydration include:

• Feeling thirsty.
• Dark, concentrated urine.
• Fatigue and decreased performance.

Signs of electrolyte imbalance may include:

• Muscle cramps.
• Nausea or dizziness.
• Irregular heartbeat.

What does science say about sports hydration?

Recent studies emphasise the importance of a personalised hydration strategy:

• American College of Sports Medicine (ACSM): Recommends balancing fluid intake with sweat loss to avoid both dehydration and overhydration, which can lead to hyponatraemia. These recommendations were published in the ACSM’s official guidelines for sports nutrition, available on their official website (link to study).
• British Journal of Sports Medicine: Highlights that isotonic drinks are particularly effective for maintaining performance in endurance sports. A study published in 2021 analyses the effectiveness of electrolyte solutions on endurance athletes, emphasising their role in improving hydration and endurance (link to study).

Conclusion

Replenishing water and mineral salts is essential for optimising sports performance and preventing problems related to dehydration. Adopting a personalised strategy based on the duration and intensity of physical activity is key to achieving maximum benefits.

Including isotonic drinks and foods rich in electrolytes in your sports nutrition plan can make all the difference to your athletic performance and recovery.