I recommend stretching after a workout out for approx. 10 mins.
Static stretching prior to a workout with “cold muscles” is not wise
as you are at risk of injury or muscle tears. A 10 min. cardio warm up should be done…pick your weapon of choice (treadmill, elliptical, bike) and /or joint mobility warm up, gradually increasing the intensity to about 70%
Greater flexibility gains can be had by stretching after a workout. A very important, but often overlooked time is to stretch the antagonist and any hyperactive muscle prior to a certain exercise. For example, I was just working with someone who has tight semimembranosus and semitendonosus. They are too active when he squats so I had to massage and stretch those so that they would be inhibited. Now the correct muscles will fire when he squats. The purpose of stretching the antagonist muscle before is to improve the neuromuscular firing to the agonist muscle. Before my clients perform rows I have them stretch their chest. This allows greater ROM in the shoulder and for the the chest not to be tight and prevent as much firing in the rhomboid muscles and other scapular retractors.
There is a lot of controversy surrounding when to stretch, however, there might never be a conclusive answer. Do what is best for you. Consider that stretching helps to prevent injury by keeping the muscular system ready and able to move, if you don’t use your full range of motion, you will lose range of motion. Also remember there are many ways to perform stretching exercises (like dynamic, static, & PNF), so which type of stretching exercises you choose to use may come with a different recommendation on when to perform those exercises. So be sure to stretch as often as possible, ideally at least at the end of each of your workouts and when the body is warm, experiment with different types of stretching and different times of stretching and see what works best for you.
I believe the purpose of stretching is to increase flexibility which will help your overall fitness and help you stay injury free. That being the case, I recommend actual stretching at the end of the workout. It would be pointless at the beginning as your muscles have not worked hard enough or long enough to benefit.
I stretch for relaxation at the end of a workout. I can focus more inward, breathe deeply, and feel my body relax (Ahhhhhh:)
How and when one stretches depends on what activity you’re performing and what your ultimate goals are. For instance, I would encourage longer, deeper stretching only AFTER a workout (or when the body’s core temperature is raised). Stretching while cold (or not sufficiently warm) is a bad idea (especially in the hour or so after getting out of bed).
I think anything “stretch-like” done before a workout should be gentle, focussing more on range of motion than trying to get into the deepest stretch. Further, if we’re speaking of athletes, there is some evidence to show that pre-event stretching hampers their performance significantly.
Hope this helps.