Stretching In The Middle Of Workout. Not a good idea. DO NOT stretch between the sets or right after work out. Your muscles are build in a way that they extend in a certain pattern during the workout. Stretching during the time when muscles are extended and tight after the set is damaging to the muscle tissues. Have you ever seen a professional athlete stretching between exercises. Doubtful. You will almost always see athletes jumping and moving their arms to keep the muscles warm if the next exercise is not right after the previous one, but you can never see them stretch during the training or between the sets. Do a lot of stretching before the workout, not in the middle or after. You can stretch after workout, but you have to let time pass a little. About 2 hours is enough. So you want to stretch, perfect, excellent, great - Stretch BEFORE or about 2 hours and more after work out.