When I work with any athlete, one of the first questions I ask is, "What is your sweat rate?".
Ninety-five percent of the time, I get a blank stare. When creating a performance nutrition plan, knowing your sweat rate is critical to make sure fluid replacement during exercise is adequate (but not too high). Here is why:
The importance of water
Water plays major roles in the body at any given time, but especially during exercise. During exercise, water inside your body cools your core and muscles, keeping you from overheating too quickly. This helps you perform stronger and longer. In addition, water transports nutrients to your muscles for use in exercise metabolism and then "cleans up" by transporting metabolites away from your muscles to be filtered and excreted. Water plays a key role in preventing dehydration, which also keeps the athlete mentally "on" throughout the workout. Finally, water acts as a cushion to your organs to protect them in case of impact during sports.
Why you should know your sweat rate
What I refer to as a "sweat rate" is defined as exactly how much water an athlete loses per hour of exercise. It is important to know your number because sweat rates vary widely from athlete to athlete. Females generally range from 2-5cups/hr and males range from 4-7 cups/hr. However, variables such as air temperature, humidity and amount/type of clothing/pads can change sweat rate day to day. Once I know an athlete's sweat rate, that tells me how much fluid per hour we need to replace during exercise.
How to calculate sweat rate
To figure out your sweat rate, pick a workout that is at least one hour long. Weigh yourself before and after that workout. Do not pee during the workout (unless you want to measure it), and keep track of how much fluid you take in during that workout. After the workout ends, take a look at how much weight you lost compared to how much fluid you drank. If your weights are about the same before and after, the amount of fluid you drank matched how much fluid you lost in sweat. If, however, your weight dropped during the workout, you did not drink enough fluid and need to increase your intake next time. By using this simple method, you can easily estimate your sweat rate. When doing this test, it is a good idea to note temperature and humidity during the test for future reference. If you are a triathlete, be sure to do separate biking and running tests, as most athletes have a different rate for each.
So, get to work! Figure out that sweat rate so you can replace fluids adequately to fit your individual needs this summer.
Your Nutrition Coach,
About the Author
Kate is the owner of RDKate Sports Nutrition, where she helps athletes learn what to eat, when to eat it and when to supplement. She services athletes nationwide via remote consulting, as well as teams on-site throughout Michigan and Illinois. Kate holds a master’s degree in nutrition with an emphasis in exercise physiology. She is both a registered dietitian and one of only ~650 RDs in the United States to be board-certified as a specialist in sports dietetics.
As a runner, triathlete, fat tire rider and snowboarder, Kate understands the physical and mental challenges of being a top athlete. Kate has previously consulted with Olympic, NFL, NBA and NCAA Division I, II and III athletes. She truly brings both her knowledge and experience to the table as a sports dietitian nutritionist. Visit her website at http://rdkate.com/RDKate
_Blog.php; from there you can navigate to her weekly blog, Eat to Compete, and connect with her on Twitter orFacebook. Contact her directly at RDKate@RDKate.com.