9.2 Hydration and Electrolyte Balance

Staying hydrated is crucial for athletic performance. Dehydration can lead to physical and cognitive symptoms, impacting your ability to perform at your best. Recognizing the signs and calculating your fluid needs are key steps in maintaining proper hydration.

Choosing the right beverages for hydration goes beyond just drinking water. Electrolytes play a vital role in fluid balance and bodily functions. Understanding when to use water, sports drinks, or other options can help you optimize your hydration strategy for different types of activities and conditions.

Hydration Basics and Athletic Performance

Signs and symptoms of dehydration

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• Physical signs manifest as thirst, dry mouth and lips, decreased urine output, dark-colored urine, fatigue, dizziness, and headache
• Cognitive symptoms include decreased concentration, impaired decision-making, and mood changes (irritability, confusion)
• Physiological effects impact performance through increased heart rate, decreased blood volume, reduced sweat rate, and impaired thermoregulation
• Performance declines with decreased endurance, reduced power output, slower reaction times, and increased perceived exertion (feels harder to exercise)

Calculation of fluid needs

• Pre-exercise hydration requires consuming 5-7 mL/kg body weight 4 hours before exercise with additional 3-5 mL/kg 2 hours before if urine is dark
• During exercise fluid needs determined by sweat rate calculation: $\frac{(Pre-exercise weight - Post-exercise weight + Fluid intake - Urine output)}{Exercise duration}$
• Aim to replace 150-350 mL per 15-20 minutes of activity during exercise
• Post-exercise rehydration involves replacing 150% of fluid lost within 4-6 hours or $1.5 L per kg of body weight lost$
• Individual factors affecting fluid needs include body size and composition, metabolic rate, fitness level, and acclimatization
• Environmental conditions impacting hydration encompass temperature, humidity, altitude, and wind speed

Hydration Strategies and Beverage Choices

Water vs electrolytes in hydration

• Water functions as primary component of blood plasma, regulates body temperature, transports nutrients and waste products, and lubricates joints and tissues
• Electrolyte roles include sodium maintaining fluid balance and supporting nerve function, potassium regulating muscle contractions and heart rhythm, chloride helping maintain proper blood pH, magnesium supporting muscle and nerve function, and calcium aiding in muscle contractions
• Osmolality and fluid balance affected by electrolyte concentration influencing fluid movement between compartments, proper balance prevents hyponatremia (low sodium) and hypernatremia (high sodium)

Beverage choices for sports

• Water suitable for most activities lasting less than 60 minutes and best choice for low-intensity or short-duration exercise
• Sports drinks beneficial for activities lasting over 60 minutes or in hot conditions, provide carbohydrates and electrolytes, typically contain 6-8% carbohydrate concentration
• Electrolyte tablets or powders can be added to water for customized electrolyte replacement, useful for athletes with high sweat rates or sodium losses
• Coconut water serves as natural source of electrolytes but lower in sodium compared to sports drinks
• Milk and chocolate milk effective for post-exercise recovery, contains carbohydrates, proteins, and electrolytes
• Considerations for different sports include endurance events emphasizing electrolyte replacement, team sports focusing on quick hydration during breaks, and weight-class sports monitoring fluid intake to maintain weight