It's summertime and the sweating comes easy for children. Whether they are enjoying a pickup game of basketball or competing at a sports camp, how does a parent know the appropriate amount of liquid refreshment to offer?
Part of the mystery lies in whether the child's body produces a lot of salt while engaged in a difficult workout.
Staying hydrated and avoiding heat illness are two areas Dr. Brendon McDermott at The University of Tennessee at Chattanooga understands, and he often is asked about his research in this area. McDermott, assistant professor, clinical coordinator for the Graduate Athletic Training Program and co-director of the Applied Physiology Laboratory has one overarching goal: to prevent heat-related deaths, particularly in athletes.
One of McDermott's current studies focuses on student athletes who cramp during intense movement, creating an extra layer of exercise performance frustration. There are two prevailing theories about the cause of cramps. Some researchers believe those who produce higher amounts of salt when they sweat harbor an electrolyte imbalance which initiates a cramp, while others blame neuromuscular fatigue. By measuring the sweat and salt outputs of students who cramp compared to a control group of those who don't, with common factors such as age, weight and similar levels of activity, McDermott hopes to unravel this painful mystery.
Even if your child has not complained of cramping while exercising, there are some tips to keep in mind. Hydration guidelines have evolved for the average person, but who exactly is the average person? Each body reacts differently, and replenishment needs depend on the individual, according to McDermott.
"Sweat rate is very simple to calculate: Weigh yourself before exercise, with as little clothing as possible; exercise for half an hour, and don't drink or use the bathroom for that half hour. Weigh yourself again, wearing the same amount of clothing to see how much you've lost," McDermott said.
To get a true picture of sweat rate, this test should be done in the cold, in the heat and at different intensities of exercise. It will then be easier to gauge whether your child is a heavy or light sweater.
If that sounds like a lot of work, there's a quicker way to assess hydration needs, and it's focused on the delicate matter of, ahem, passing a different kind of water.
"You can monitor your urine color. It should have a light yellow tinge to it. Lemonade is much better than apple juice. If you're delving into the iced tea realm, it's time to drink. It's normal to have darker urine in the morning," McDermott said. "As for frequency, some people are camels, other people urinate frequently."
McDermott explains body size is not the main factor in sweat production. During his training for an Olympic marathon, accurate measurements showed Alberto Salazar lost nearly 10 pounds of water an hour. He only weighed 145 pounds.