Tight hamstrings can be released by contracting the quadriceps muscle.

“So, for instance, if you have tight quadriceps, you can do the opposite. You can contract your hamstring very intensely for let's say 10 seconds, or 20 seconds, or 30 seconds.”

“Okay, so if you are somebody who has tight hamstrings, there could be a variety of reasons for that, but part of the reason is likely to be neural and you can release that neural spindle reflex by contracting the opposite antagonistic muscle, which in this case is the quadriceps.”

“What most of you will find is that you have an immediate increase in hamstring flexibility, or your range of motion has increased.”