Fluid and Hydration During Exercise

Summer brings increasing miles and increasing temperatures. Long, hot rides can cause problems if you do not adjust your fluid intake. When you exercise, your body loses water through sweat, which is used to keep your body cool. Many people do not drink enough water a day, even when inactive. It is vital to regularly drink fluids while exercising, to ensure you are maintaining proper fluid balance in your body. An adult body must excrete a minimum of about 17 ounces or 2 cups of urine per day to carry away waste products generated by activities. So the amount of fluid should be adjusted to maintain this level, since the kidneys can adjust to high fluid intake to maintain proper fluid balance. You must properly hydrate before, during and after a workout. Cyclists should know the value of adequate hydration. Water is the most commonly overlooked exercise aid. 

Sudden dehydration from heat or excessive exercise can be life threatening. Thirst usually guides most people to drink. However, even though thirst drives a person to seek water, it lags behind the body’s fluid needs. According to the National Athletic Trainer’s Association, adult fluid intake recommendations during exercise are as follows: drink 20 ounces 2 hours prior to exercise; drink about 8 ounces every 10-20 minutes during exercise; and drink 16-24 ounces after exercise for every pound of body weight lost during exercise. Not all fluids must be water. Fluid comes from all beverages and about 20-25% is from food. Dehydration is serious, but drinking too much can also be harmful, since it can cause low blood sodium levels (hyponatremia). Alcohol and caffeine are diuretics, so drink them sparingly.  

Fluids that contain minerals for fluid balance are excellent for rehydration. Those minerals are potassium, sodium, chloride and somewhat calcium. Researchers at Ohio State University found that performance was improved by 12.5% when carbohydrates were consumed an hour before exercise. They recommend 40-75 grams of carbs, pre-workout. On very hot days, even drinking a slushy made from your favorite sports drink can also help to cool your core while hydrating you. 

Choice of drinks depends on duration of activity. For less than an hour, water is great. For activities greater than an hour, drinks with 4-8% carbohydrates and sodium are best. Researchers at University of Texas found that consuming carbs during maximum efforts help to delay fatigue. They recommend 40-80 grams (or 160-320 calories) of carbs for every hour of cycling, which you can get from drinks, gels and sports bars. Some drinks, like Accelerade, have a 4:1 carb/protein ratio, with 21 grams of carbs per scoop of drink powder. The brand advertises that this formula fuels athletic performance, endurance, hydration and recovery. Accelerade Hydro has about half the calories, carbs and protein as the original endurance formula. Find the drink that works best for you. 

Drink up for happier pedaling!

Sallie Urffer
Performance Bicycle Store Associate


Important Note: These tips provide a basic overview of cycling-related hydration and nutrition, but should not be considered exhaustive. If cycling is a major part of your life, or if you are dealing with a particular health issue, seek out a qualified sports nutritionist.

Nutrition and Hydration