Calculate Your Sweat Rate

by coach Matt Russ

Your sweat is 99% water, your blood is 90% water, and your muscle mass is 75% water. When you loose this precious fluid body functions become adversely affected including muscle function. Blood volume drops and the heart has to work harder to pump oxygen and nutrients to the muscles. Gastrointestinal distress becomes a risk due to delayed stomach emptying. Your body has difficulty cooling itself and core temperature rises.

Knowing how much fluid you need to take in is very valuable for athletic performance. In order to calculate this you must estimate how much your body will loose in a given condition. Sweat rate is individual and will also be affected by temperature, humidity, wind, and even the clothes you wear. I have a sweat rate calculator for my athlete's but you can calculate your sweat rate by weighing yourself without clothes 1 hour before training and directly after. Record the amount of fluid you consumed during training and the amount of fluid lost during training in oz. (1 lb. = 16 oz.), then add the two numbers together to calculate sweat loss. Divide the sweat loss by the number of minutes trained, then multiply that number by 60 min. to determine individual sweat rate per hour (ex. 40 oz. sweat rate / 120 min. of exercise = .33 oz per minute lost during exercise ) x 60 min. = 20 oz. sweat rate per hour.

Set your watch alarm to beep every 15 min. and consume � of this number (5 oz.). Remember that sweat rate will vary according to conditions so make sure you test yourself regularly. Although dehydration is less of a performance factor in cold weather, it is still a factor so do not disregard dehydration in the winter; especially if you are a profuse sweater. If you hydrate properly you will not show any loss in weight post exercise.

Matt Russ has coached and trained elite athletes from around the country and internationally for over ten years. He currently holds expert licenses from USA Triathlon, USA Cycling (Elite), and is a licensed USA Track and Field Coach. Matt is head coach and owner of The Sport Factory, and works with athletes of all levels full time. He is a free lance author and his articles are regularly featured in a variety of magazines such as Inside Triathlon, and Triathlete. Visit www.thesportfactory.com for more information or email him at coachmatt@thesportfactory.com