Top 10 Hydration Tips for Marathon Runners from
The Gatorade Sports Science Institute

1. Know Your Sweat Rate and Follow Your Own Hydration Plan - Everyone sweats at their own rate, so don’t copy what others are doing. To figure out your personal sweat rate, weigh yourself before and after training and competition with the goal to weigh the same before and after exercise. If you lost weight, drink more next time. If you gained weight, cut back on your fluids. Sweat rates can vary depending on environmental conditions, so be sure to calculate your sweat rate in various conditions.
2. Experiment with Hydration and Fueling Early in Your Training - Find out what will be offered on course and consider training with it. By the time you get to your competition, you’ll know what works best for you and what to avoid.
3. Check the Color of Your Urine - An easy way to tell if you’re properly hydrated is to check the color of your urine. If your urine is pale like lemonade, that’s a sign of good hydration. Crystal-clear urine often indicates over-hydration and the need to cut back. Dark urine (like the color of apple juice) may signal dehydration and the need to drink more.
4. Choose the Right Beverage - When training for an endurance event like a marathon, your beverage choice matters. Water can actually turn off the thirst mechanism too quickly, making it harder to stay hydrated over the long haul. Instead, look for a beverage with electrolytes and carbohydrates to help replace the electrolytes you lose in sweat, promote rapid absorption, and supply energy. 1
5. Don’t Over-Drink During Training or Competition - Whatever your beverage preference is, it’s essential not to over-drink. Over-hydrating can lead to a dangerous condition called hyponatremia. The risk of hyponatremia can be reduced by making certain your fluid intake does not exceed your sweat loss and by ingesting sodium-containing beverages or foods to help replace the sodium lost in sweat.
6. Fuel Pre-Competition and During Competition - Fuel your body 2 to 3 hours before training and competitions. Consume high-energy foods like breads, cereals, pasta, rice, fruits, and vegetables. During activity, endurance athletes should consume between 30 and 60 grams of carbohydrate per hour to help fuel muscles and sustain your optimal performance.1
7. Consume the Right Amount of Carbohydrates During Competition - Research has shown that a 6% carbohydrate solution leaves the stomach as quickly as water.2 More concentrated levels of carbohydrate stay in the gut longer and may cause gastrointestinal distress during stop-and-go exercise. If consuming gels, bars or concentrates, be sure to drink plenty of water to dilute the carbohydrate level to about 6% (14 to 15 grams per 8 ounces).
8. Replace Sodium - Sodium is the most critical electrolyte to replace. Sodium intake helps the body “hold on” to more of the fluid consumed and may reduce the risk of heat illness, cramping, and hyponatremia. During training and competition consider a sports drink with additional sodium like Gatorade Endurance Formula (200 mg of sodium per 8 ounces). If you notice your sweat stings your eyes, your skin feels gritty after exercise, or your clothing is caked with white residue, you may be a salty sweater and should consider adding salty foods like pretzels and chicken soup to your diet before and after the event.
9. Replace Weight Loss During Activity With Fluids – If you did lose weight during training or competition, make sure you gain the weight back before your next session. After exercise, drink approximately 20 to 24 ounces of fluid for each pound not replaced during training or competition.
10. Consume Protein Post-Exercise - Protein consumed during exercise may impede hydration and has no conclusive performance benefit. The best time to consume protein is post-exercise for muscle recovery.3