Is it possible to drink too much water?

The answer might surprise you.

Click here to see the Wikipedia definition for hyponatremia.

Adequate hydration is as important as calorie replacement to an athlete’s performance, yet dehydration continues to be a condition many experience. This is especially true in cycling where evaporative losses are significant and can go unnoticed. Sweat production and losses through breathing can exceed 2 quarts per hour. To maximize your performance pre-hydration is important, and it is essential that fluid replacement begin early and continue throughout a ride.

Approximately 75% of the energy your body produces is converted to heat rather than being delivered to your muscles to power your pedal stroke. Keeping your body cool and re-hydrated during exertion will result in greater efficiency, higher power output, extended endurance, and a quicker, more thorough recovery. Say good-bye to the Wet Spot!

Individual fluid and electrolyte needs are widely variable during physical exercise due to differences in metabolic rate, body mass and size, environmental conditions (e.g. temperature, humidity, wind, solar load, clothing worn), heat acclimatization status, physical fitness, activity duration, and genetic variability. Sweat rates can vary from 0.5L/hr to more than 3 L/hr. Similarly, sodium concentration may vary from less than 460 mg/L to more than 1840 mg/L
American College of Sports Medicine
Roundtable on Hydration and Physical Activity: Consensus Statements


Before your ride.

Proper hydration begins long before your ride does. About two hours before your ride, drink 15-20 ounces of water. Thirty minutes before your ride, you should down another 10-15 ounces. If you ride early in the morning, then hydrate throughout the night. If you’re wondering whether or not you’re hydrating adequately, try weighing yourself in your bike gear just as you head out the door. If you replenish your fluid loss successfully during your ride, you’ll weigh about the same when you return.

During your ride.

Hydrating before your ride is important. Getting those fluids down during your ride is essential. Even when cycling short distances and durations at a slow to moderate pace, hydration plays a serious role in how you feel. Warmer temps, longer rides, and increased intensity make your hydration strategy even more crucial. As a general guide, you should consume at least 5-8 ounces of water for every 15 minutes of cycling.