First, let's make sure we understand what the article (and underlying research) actually says, and then see how this would apply to our classes. From the article:
Many people take it for granted that they should start their exercise routines with some stretching on the spot, perhaps hoping it will loosen them up for their work-out. Most fitness experts now agree this kind of static stretching before exercise is not just counter-productive, but potentially harmful.
The article goes on to cite various experts and even the Centers for Disease Control and Prevention.
Did you note that subtle adjective “static” slipped in before the word “stretching” in the above quote? The key to understanding the research and the point the author should have made is found in knowing the differences between static stretching and dynamic stretching.
Static stretching is best performed after the body is warmed up, often times at the end of a workout, and would include leg splits and other slow motions intended to increase reach or flexibility.
Dynamic stretching typically mimics the movements used in sports (or martial arts) and would include things like rotating the arms, swinging the legs, or deep knee bends. Dynamic stretching never includes forcing arms, legs, or joints beyond their maximums with external effort. For example, one should not use their hands to twist their neck.
In Tang Soo Do, we begin each session with dynamic stretching (after a brief meditation) that involves the very movements which will be emphasized and accelerated in class. Large arm circles, waist twists, and jumping jacks loosen the large muscle groups and elevate the heart rate. Typically, the first half of my classes are very aerobic in nature, with the striking and kicking elements occurring in the second half.
Sometimes, especially in the warmer seasons, we will deviate from the norm and perform some static stretching after the class is warmed up.
Cold static stretching at the outset of an exercise routine is non-productive and should be avoided. Similarly, one should not wake up each morning and without any physical preparation, head out of the house at a dead sprint. D’oh!
Use dynamic stretching before an exercise program, and static stretching at the end, or after the body is warmed up and ready to go.