Drink Up: Staying Hydrated in the Heat of Summer This Spring
Imagine the following scenarios:
- It is a beautiful 70 degrees outside, so you decide to power walk for 30 minutes around the neighborhood. Ten minutes into the walk you suddenly are dry mouthed and realize you forgot your water bottle. You contemplate going back home, but figure you only have 20 minutes remaining, so continue to walk.
- Today is a scorcher, 95 degrees with high humidity, so instead of walking outside you go to the local mall and walk. Since it is air conditioned inside the mall, you walk for 45 minutes without drinking anything. When you finish your walk, you drive home, take a shower, prepare lunch, and while eating realize you have not had anything to drink since before you walked, which was 2 hours ago.
You might be able to relate to the above scenarios but may not understand the importance of drinking fluids while walking or even what to drink, especially if you are exercising for a short time.
Adequate fluid intake before, during, and after exercise will provide comfort, enhance performance, and promote safety by reducing the risk of dehydration and symptoms associated with dehydration such as muscle cramps, dizziness, fatigue, heat exhaustion, and heat stroke.1 Dehydration generally occurs when there is fluid loss and no replenishment of fluid. The risk of dehydration increases during heat, humidity, high altitudes, and other environmental conditions, therefore it is crucial to ensure your body is properly hydrated.2
There are multiple ways to determine the amount of fluid to consume per day, but these equations only account for weight. The equations do not factor in age, sex, amount of activity performed on a daily basis, or environmental conditions. Here is one equation that you can use: (kg body weight – 20) x 15 + 1500 = mL fluid per day. So, if you weigh 140 pounds (63.6 kg) you will need 2,154 mL of fluid per day or roughly 9 (8 oz.) cups of fluid per day.3
Besides calculating out the amount of fluid to consumer per day, there are two relatively easy methods to determine if you are consuming adequate daily amounts of fluid:
- Monitoring urine output volume and color: a large amount of light colored, diluted urine means you are hydrated, whereas dark colored, concentrated urine may indicate dehydration.
- Weighing yourself before and after exercise: Weight loss after exercise generally means you need to consume more fluid to bring that weight back and weight gain indicates you are drinking too much fluid.4 That’s right, if you are ecstatic when you step on the scale after working out and notice you lost 2 pounds, it is due to fluid loss and not much fat loss.
If you have been through the beverage/juice aisle lately in the grocery store or supermarket, you are bombarded with hundreds of different types of beverages. Even in the pharmacy department and health food stores there are a variety of beverages for people who want to lose weight, increase energy, gain muscle mass, and so on. And of course there is the good old beverage we get from our homes: tap water. Now, add these options to the commercials about the best type of drink to consume in certain situations or an article about the latest and greatest sport drink enhancer, and it can become very confusing to determine the best fluid to consume while exercising. One way to help determine which fluid to drink is to think about the environment you will be exercising in (hot, cold, humid, dry, etc.), the duration of exercise (20 minutes or 2 hours), and the intensity of exercise (running at 6 mph or walking at 1 mph).
For instance, based on the earlier scenarios, water would be the best choice since the length of exercise is short (30 to 45 minutes) and the conditions are ideal, warm, or air conditioned. Yet, there are several people, possibly you, who do not like the taste of water. If so, you can purchase calorie free flavored water enhancers, such as MiO, Crystal Light, or other types of low calorie powdered mixes. If you are on a budget, you can always cut up some fresh fruit such as lemons, limes, or oranges and toss them into your water to hide that water taste.
On the other hand, if you were to exercise outside in 95 degrees with high humidity or for longer than one hour, then a sports drink would be the better choice to replace electrolytes (sodium and potassium) lost from sweat. If you want to lose or maintain weight, then a low calorie sports drink such as G2 or Propel would be a better choice. I would discourage you from consuming soda, energy drinks, teas, and coffee, as these drinks are not meant to replace loss fluids and may cause discomfort such as belching, nausea, and bloated feeling especially from the carbonation of the soda and energy drinks.5
Finally, you may wonder if the other beverages that claim to aid in weight loss or increase muscle mass actually work. I should have emphasized claim because many do not work, so spend your money on vegetables, fruit, and other healthy foods.
To recap, fluid is important to drink while exercising to prevent dehydration and enhance performance. You will know if you are properly hydrated by not losing or gaining weight and having lightly colored urine. Finally, the fluid you choose depends on the environmental conditions, intensity, and duration of activity. So, now that we have covered proper hydration, I need to grab my water bottle and go for a power walk.
Jeanette Andrade, MS, RD, CDE
Jeanette Andrade, MS, RD, CDE joined Kaplan University in the spring of 2008 as a faculty member and has taught several courses in the Nutrition Science Department. Prior to coming to Kaplan University, she was a clinical dietitian and worked in both inpatient and outpatient settings. In August 2010, she began her PhD in human resource education specializing in learning technologies.
Ms. Andrade holds a bachelor’s degree in nutrition from University of Illinois at Urbana-Champaign and a master’s degree in dietetics with an emphasis on nutrition education from Eastern Illinois University. She is a registered/licensed dietitian and is certified in diabetes education.