Huh? Yeah, I know, it doesn’t really make sense. . . or does it?
Consider this: when you sit down to stretch your hamstrings and wait at least 20 seconds, the stretch usually lengthens, or at least becomes more ease-full. But what do you do when no amount of waiting or even pushing into the stretch (not recommended) just isn’t getting the results you want?
Physiology to the rescue! Post Isometric Relaxation (PIR) = more stretch length, and it’s easy. As you are sitting with your legs in front of you, gently engage your hamstrings. (Hint: Instead of trying to push your hamstrings into the floor, just engage your heels gently into the floor while keeping your quads relaxed.) Only use about 20-25% of your strength to do this. Hold the flex for 6-8 seconds. Relax relax your legs completely and then lean into the stretch again. Generally, you will have increased the stretch a lot! Feel free to repeat this 3 or 4 times.
Of course, your ability to achieve these results will depend on a lot of different factors and there are all sorts of subtleties and vagaries involved in getting the most out of any stretch. But play with the idea on all of your stretches and see what comes of it! I suspect you’ll be pleased.