Stretching feels great — there’s no argument there. But, contrary to what you learned in P.E. class, you don’t want to stretch before exercising. "When working out, your muscles need to contract as powerfully as possible," explains L.A.-based personal trainer Mike Donavanik, CSCS. "By statically stretching beforehand, you place your muscles in a stretched state and inhibit the muscles' ability to contract quickly and intensely." Studies have also shown that statically stretching before exercising can actually hinder your performance.
So, save the backward bend for the end of your spinning class and the quad stretch for after you run. Instead, try a dynamic warm-up before you train. These are movements (versus getting into a stretch and holding it) that will gradually increase your heart rate, explains Donavanik. "It will also prime the muscles, joints, tendons, and ligaments helping to prevent injuries."
A dynamic warm-up can include anything from jumping jacks to arm circles and high knees. "Ideally, your dynamic warm-up should be specific to the workout you’re about to do," Donavanik says. So, you can even incorporate the exercise from your workout into your pre-workout routine — if you’re going to be doing a lot of squats, add some deep, slow, controlled squats into your warm-up to help prep your body and open your hips.
This isn’t a free pass to skip stretching — flexibility is still one of the major tenets of fitness — just save it for the end. Sweat, then stretch.