Hydration is crucial for keeping our bodies running smoothly, particularly during exercise. When we work out, we lose water through sweat, which helps cool us down. If we don't replace this lost water, we can become dehydrated, leading to a drop in blood volume. This makes it harder to maintain blood pressure and blood flow, putting extra strain on our cardiovascular system and making exercise feel tougher, increasing fatigue, and reducing performance.
To prevent health and performance declines, it's recommended to avoid losing more than 2% of your body mass in fluids, especially in hot and humid conditions.
Signs of dehydration can include:
- Thirst
- Dark urine
- Daily bodyweight fluctuations greater than 1%
- Headaches
- Increased effort perception
- Poor concentration
- Reduced urine output
More severe signs of dehydration include:
- Disorientation or confusion
- Rapid pulse
- Unconsciousness
Monitoring Hydration
1. Weight: Stable body weight first thing in the morning suggests good hydration. Fluctuations greater than 1% might indicate dehydration.
2. Urine: Dehydration can cause urine to be darker in color and less frequent.
3. Thirst: Feeling thirsty is a sign you need more fluids; many people are already dehydrated by the time they feel thirsty.
Rehydrating After Exercise
To fully rehydrate after exercise, you need to consume 125-150% of the fluid lost. For example, if you lose 1 kg (roughly equivalent to 1 L of fluid), you should drink 1.25-1.5 L of fluid post-exercise.
During moderate to intense exercise, you can sweat between 1-2 liters per hour, but in hot conditions, this can increase to over 2 liters per hour. For athletes, sweat rates can range from 3.5 liters to 8.8 liters per hour, especially when wearing protective gear. Generally, higher sweat rates lead to a greater loss of sodium and chloride.
In each liter of sweat, athletes primarily lose sodium and chloride. They can lose 460-1840 mg of sodium and 710-2840 mg of chloride. Other electrolytes like potassium, magnesium, and calcium are lost in smaller amounts: 160-390 mg of potassium, 0-36 mg of magnesium, and 0-120 mg of calcium per liter of sweat.
High-Risk for Dehydration
Certain conditions increase the risk of dehydration, including:
- Sustained or vigorous exercise in hot conditions
- Training in humid environments
- Living at altitude or traveling
- Experiencing diarrhea and/or vomiting
- Illnesses like gastroenteritis
Electrolytes for Rehydration
Replenishing electrolytes after exercise is essential for recovery and maintaining optimal body function. You can effectively restore electrolytes by consuming a combination of fluids and foods rich in these vital minerals. Drinks like sports beverages or electrolyte supplements provide a quick source of minerals such as sodium and potassium. Additionally, incorporating foods like bananas, oranges, and avocados can boost potassium levels, while dairy products, leafy greens, and nuts help replenish calcium and magnesium. Salty snacks like pretzels or adding a pinch of salt to meals can also help restore sodium levels. By combining these foods and drinks, you can effectively rehydrate and restore your electrolyte balance.
Electrolyte supplements can be helpful before, during, and after exercise:
- Before exercise: For daily hydration and pre-exercise, water may be enough. However, if dehydrated or planning to exercise intensely, an electrolyte supplement may be more effective.
- During exercise: For activities over two hours at moderate to high intensity, especially in heat, electrolytes help prevent large fluid losses.
- After exercise: Electrolyte drinks can boost rehydration effectiveness by helping the body retain more fluid.
Electrolyte drinks contain glucose and sodium, which enhance fluid absorption and retention. If sports drinks or supplements aren't available, salty foods with carbohydrates (like cereal, bread, or pretzels) paired with water can be an alternative.
For athletes: When choosing electrolyte supplements, look for HASTA or Informed-Sport certification to ensure they don't contain banned substances. Avoid supplements with unnecessary additives like minerals, caffeine, or amino acids, as they can be costly, potentially harmful, and risky for contamination.
My go-to Homemade Electrolyte Drink Recipe (no added sugar):
2 cups water
2 cups coconut water
2 cup 100% natural orange juice
1 tsp salt
Juice of 1 lemon/lime (optional)
(makes 3 servings)
Per serving: 400mg Sodium, 330mg Potassium, 136mg Calcium (if OJ is fortified), 26mg Magnesium, 12g carbs
Sweat Rate and Personalized Hydration Schedules
Sweat rate varies significantly among individuals, influenced by factors such as exercise intensity, environmental conditions, and personal physiology. During intense physical activity, especially in hot or humid environments, your body can lose substantial amounts of fluid and electrolytes, primarily sodium and chloride, through sweat. Accurately assessing your sweat rate is the first step in creating an effective hydration strategy.
Calculating Your Personal Sweat Rate
Working with a dietitian, you can determine your sweat rate through a simple yet precise process. Here’s how it typically works:
1. Pre-Exercise Weight Measurement: Weigh yourself before exercise in minimal clothing to get an accurate baseline.
2. Exercise Session: Engage in your typical workout for a set duration, usually an hour, under normal conditions.
3. Fluid Intake Monitoring: Record the amount of fluid consumed during the exercise session.
4. Post-Exercise Weight Measurement: Weigh yourself immediately after exercise, again in minimal clothing.
The difference in pre- and post-exercise weights, adjusted for fluid intake, provides your sweat rate. This data allows us to estimate fluid and electrolyte loss per hour of activity.
Developing Your Individualized Hydration Plan
Once we have your sweat rate, we can design a personalized hydration plan that includes:
- Fluid Replacement: Guidelines on how much fluid you need to consume before, during, and after exercise to stay adequately hydrated.
- Electrolyte Replacement: Recommendations on foods and drinks rich in sodium, potassium, magnesium, and calcium to replenish electrolytes lost through sweat.
- Timing and Frequency: Strategies on timing your fluid and electrolyte intake to optimize absorption and prevent dehydration.
Benefits of a Personalized Hydration Plan
By working with a dietitian to calculate your sweat rate and develop a tailored hydration plan, you can:
- Prevent Dehydration:Avoid the negative impacts of dehydration, such as reduced endurance, increased fatigue, and impaired cognitive function.
- Optimize Performance: Maintain optimal electrolyte balance to support muscle function, energy levels, and overall athletic performance.
- Enhance Recovery: Improve post-exercise recovery by ensuring your body is well-hydrated and replenished with essential electrolytes.
Partnering with a dietitian for personalized hydration planning empowers you to understand your body's specific needs and implement strategies that enhance your performance and overall well-being. If you're ready to optimize your hydration, lets chat.
Nicole Gonya RDN, LDN
