When running with a handheld bottle, be sure that your hold is not too tight but not overly loose either. Most bottles have an adjustable strap, so you should use it to get a comfortable but secure fit. “It’s best to keep a relaxed grip as if you were running without the bottle,” Cohen says. “A closed running fist or a tight hand on a bottle builds undue tension where you want to keep your hands and arms in a more relaxed and comfortable position so as not to waste energy.” Be sure to periodically switch hands. “Holding a water bottle in one hand adds extra weight and can affect your arm swing,” Sheu adds. To avoid fatigue and create more balance in your run, try alternating hands every ten minutes or so. When you give one hand a break, use the opportunity to stretch it out. “It helps me to shake out my hand, wiggle my fingers, and roll my wrist so that I do not cramp up and to release unnecessary tightness or tension that may affect my rhythm and tempo,” Cohen says.