hydrating for performance: A Guide for Athletes

Of all the strategies athletes use to enhance performance, from complex training periodization to advanced nutritional tactics, hydration is fundamental. It is a cornerstone of both performance and recovery, sitting alongside sleep and nutrition. A small decrease in body water, even just 2% of your body mass, can significantly impair aerobic endurance, reduce maximal strength and power, and negatively affect your mood and cognitive performance. Furthermore, dehydration is a key risk factor for exertional heat illnesses.

This guide will walk you through how to assess your hydration status, understand the critical role of electrolytes, and build a smart, personalized hydration plan that accounts for timing and environmental conditions.

The first step in optimizing your hydration is to assess where you currently stand. While lab-based methods exist, several simple and practical field techniques can help you monitor your hydration daily.

• Track Your Body Weight: Acute changes in body mass are primarily driven by changes in body water. Weighing yourself before and after a training session is an easy way to estimate your fluid loss. The goal is to prevent losing more than 2% of your body mass during exercise. You can also establish a baseline for your normal hydration level by tracking your first morning body weight for three consecutive days.
• Check Your Urine Color: This is a simple visual marker of your current hydration status. Using a urine color chart, you can get a quick reading. A color of 4 or greater on an 8-color scale indicates dehydration. You should aim to maintain a pale yellow or straw color. For the most accurate assessment, check your first morning urine sample.
• Listen to Your Thirst: Thirst is a fundamental signal, but it's important to know that it is often perceived only after a 1% or 2% loss in body mass has already occurred.
• Combine the Clues: A best-practice approach is to use a combination of these markers. The "WUT" method—checking your first morning (W)eight, (U)rine color, and (T)hirst sensation—is a practical way to guide your daily fluid intake. If two or more of these indicators suggest you are dehydrated, it is very likely that you are.

When you exercise, you don't just sweat out water; you also lose essential minerals called electrolytes. Sodium is the most important electrolyte for athletes to consider. It plays several crucial roles:

• It helps the body absorb water and stimulates glucose absorption.
• It helps maintain thirst, which encourages you to continue drinking.
• Significant losses are associated with exertional heat illnesses like heat exhaustion and heat cramps.

Sweat rates and the amount of sodium lost in sweat vary considerably from one athlete to another. While precise measurement requires lab testing like the whole-body wash-down method or less-accurate regional sweat patches, all athletes can benefit from ensuring their hydration plan includes electrolyte replacement.

A successful hydration strategy is not just about how much you drink, but when you drink. Your plan should be broken down into three phases: before, during, and after your training or competition.

Before Exercise: Start Hydrated

Your goal is to begin every session fully hydrated, a state known as euhydration, with normal plasma electrolyte levels.

• To achieve this, it's recommended to consume 5 to 7 milliliters (mL) of fluid per kilogram (kg) of body mass at least 4 hours before exercise.
• If you haven’t produced urine or if it is dark and concentrated, you should drink another 3 to 5 mL per kg of body mass about 2 hours before the session. This timing allows your body to absorb the fluid it needs while leaving sufficient time for any excess to be urinated out.

During Exercise: Prevent Excessive Losses

The goal during activity is to prevent excessive dehydration (more than 2% body mass loss) and significant electrolyte deficits.

• Planned Drinking vs. Drinking to Thirst: While drinking to thirst may be adequate for shorter workouts (<60-90 minutes) or those in cooler conditions, it can be insufficient during high-intensity exercise in the heat. In these demanding situations, athletes who only drink when thirsty tend to replace only about 60% of their fluid losses. Therefore, a planned drinking strategy, created based on your individual sweat rate, is superior for preventing performance decline.
• How Much to Drink: A general guideline is to drink 0.4 to 0.8 liters per hour (L/h), depending on your sweat rate, opportunities to drink, and comfort.
• What to Drink: For exercise lasting less than 60-75 minutes, water is generally sufficient. For longer or more intense sessions, a sports drink containing carbohydrates (30-60 grams per hour) and electrolytes is beneficial to replenish fuel stores and replace what's lost in sweat.

After Exercise: Rehydrate and Recover

Following your session, the goal is to fully replace any fluid and electrolyte losses to optimize recovery.

• For rapid rehydration, especially if you have another event within 12 hours, you should aim to consume 1.5 L of fluid for every 1 kg of body mass you lost. Consuming a volume greater than your loss is necessary to account for ongoing fluid losses through urine.
• Include Sodium: It is critical to consume fluids with added electrolytes or to eat salty foods with your drinks. Sodium maximizes fluid retention by reducing urine losses and helps maintain your thirst.

Proper hydration is critical, as even a small 2% decrease in body mass from water loss can impair aerobic endurance, strength, and power. Electrolytes, especially sodium, are a crucial part of this equation.

Why are electrolytes important? 

Electrolyte loss is a key factor associated with exertional heat illnesses like heat cramps and heat exhaustion. Sodium is considered the most important electrolyte for athletes as it helps the body absorb water, stimulates glucose absorption, and maintains thirst, encouraging you to drink more. A significant sodium deficit can occur during intense exercise, such as in ice hockey, where sweat loss is high.

How can you replace them? 

Your goal after exercise should be to fully replace fluid and electrolyte losses. When you need to rehydrate, especially if another event is coming up soon, choose fluids with added electrolytes or consume salt-rich foods alongside your fluids. This will maximize fluid retention by reducing urine losses. It's also wise to incorporate electrolytes at mealtime to support your overall hydration strategy. Because sweat rate and electrolyte content vary considerably between individuals, a personalized hydration plan is ideal.

Training and competing in the heat significantly increases your risk of dehydration. High humidity is especially challenging because it hampers your body's primary cooling mechanism: the evaporation of sweat.

When exercising in hot conditions, your hydration strategy must be more aggressive. Consider practical adjustments like training during the coolest parts of the day and using active cooling techniques such as cold towels to manage heat stress.

By personalizing your approach and practicing your strategies during training, you can ensure that you stay properly hydrated, allowing you to perform at your best while staying safe.

Now that you have the knowledge, it’s time to put it into action. Here are a few ways to take the next step in dialing in your hydration and fueling strategies:

1. Book a Consultation – If you’re serious about elevating your performance, schedule a consultation with me. Together, we’ll create a personalized nutrition and hydration plan that fits your training demands, environment, and goals.
2. Upgrade Your Hydration Game – Electrolyte replacement is a cornerstone of effective recovery and performance. I recommend Transparent Labs Hydrate, which provides a clean and effective way to support fluid balance. Use the link here for 10% off your order.
3. Put It Into Practice – Start tracking your daily hydration status using the WUT method (Weight, Urine, Thirst) and apply the before/during/after framework outlined in this guide. Small, consistent actions compound into big results.