Sweat Rate

Sweat Rate As a mid distance swimmer in college, my average races lasted less than two minutes. With races this short, things like sweat rate and nutrition were not nearly as important as they are in endurance sports. I quickly found that out last season competing in triathlons. In the pinnacle race of my season, the Xterra World Championship, I was crippled by a series of cramps during the run. In an effort to make sure this doesn’t become an issue again, I am doing some hydration and nutrition experimenting in training. One of the easiest tests that you can do as a start to diagnosing cramping issues in endurance events (anything over an hour), is a sweat rate test. This basically involves weighing yourself before and after a one hour race effort without hydrating. I completed one for the first time today on a treadmill at the JCC and here are my results: Before weight: 179.5 lbs After weight: 173.5 lbs Avg HR: 162 bpm Treadmill Speed: 9.5mph (no fan) Temp: approx 70 degrees With a pound of sweat being equivalent to 15.4 ounces, this works out to 92.4 ounces of fluid loss! As I suspected, this is extremely high. According to articles from Runner’s World and active.com, the average person loses between 27.4 and 47.3 ounces/hr. The highest on record was 125 ounces/hr by former Olympic distance runner Alberto Salazar. Most doctors recommend not losing more than 2% of your body weight over the course of an endurance event. In my particular case, I would need to consume approximately 15 ounces/15 min while running. Since sweat rate changes with different sports, temperatures, humidities, and altitudes, this is only the first of a series that I plan to complete this year. However, I think this is great baseline information for making sure I maximize my potential in the future.