I'm getting back into exercising regularly but don't have a handle on stretching. In the past I remember being told to stretch in my warm-up, but now I'm hearing that isn't a good idea.
So I'm confused: Should I stretch during warm-up or not?
It depends on what you define as stretching. There are two main types of stretching: static and dynamic. Most people equate stretching with the former.
In a static stretch, you take a joint to its comfortable end point and hold it, usually for 20 seconds or more.
Static stretching is passive, and for the most part, relaxing, and should be saved until the cool-down portion of the workout. For warm-ups, go with dynamic flexibility exercises.
Dynamic stretches produce improved range of motion by actively moving the muscle. The muscle you are "stretching" lengthens while its opposite (or antagonist) muscle contracts.
Dynamic flexibility exercises are active - they increase the heart rate, wake up the nervous system, and prepare you for the more intense workout to come.
Still confused? Let me give you an example. In a static hamstring stretch, you lie on your back and straighten one leg in the air. A dynamic stretch would be the "Frankenstein" - you stand with your arms extended in front at shoulder height, then walk across the floor by bringing one leg up at a time. Keep the leg straight as it lifts off the ground.
When you are structuring your warm-up make sure the intensity progresses gradually, and the stretches you include correspond to the muscular and flexibility needs of the exercise you are warming up to do.