Think of your tissues like a sponge, says Matt Berenc, director of education at the Equinox Fitness Training Institute. A dry sponge will absorb some liquid when dipped in water, but it’ll take in much more if you squeeze it while it’s immersed. “The action in the sponge helps water move into it,” he explains. “Similarly, contracting and relaxing your muscles allows fluids to pump through them.”
If you hydrate and then stay seated for several hours or guzzle a glass of water right before bed, you're not optimizing your H2O intake. But if you move, more fluids enter your tissues so you can function at a higher level, Berenc says. “Water must flow in and out of the tissues to aid in the transport of nutrients and oxygen they need to perform at their best.”
The bottom line:
To make each sip as hydrating as it can be, Berenc recommends this: Challenge yourself to drink at least eight ounces every hour or two. About 10 to 15 minutes after drinking the water, walk a flight of stairs, do a lap around the block, or stretch through large ranges of motions to help tissues absorb water.