Staying hydrated during exercise isn’t just good for your body; it’s good for your brain. That’s the word from the American Physiological Society, whose recent press release cites research that studied recreational cyclists (average age 55) who competed in a large cycling event on a warm day (78–86 degrees F), and who took a “trail-making” executive function test—quickly and accurately connecting numbered dots using paper and pencil—before and after the event. The researchers tested the cyclists urine before they exercised and divided them into two groups—normal hydration and dehydrated—based on their hydration status, then compared the results on the test. They found that the normal hydration group showed noticeable improvement in the completion time of the trail-making test after cycling when compared to their pre-cycling test, as expected, because exercise generally improves executive function. And while the dehydrated group also completed the post-event test faster than than the pre-event test, the time difference was not statistically significant. The bottom line: hydration make the brain work better.