I've recently realised that I have very tight hamstrings - when lying flat on the ground, I can only lift each leg around 75 degrees off the floor when doing this:
Though I'm keeping my legs straight, maybe I should bend them slightly?
My goal is to get past 90 degrees, but I don't want to compromise strength or explosive power, particularly for jumps and sprints. Given this, my reading says to do an exercise that reaches peak extension of the hamstring whilst subjecting the muscle to a substantial force.
I'm home-gymming with a very basic setup at the moment, so the less equipment required, the better. What exercise(s) should I do? I've tried the exercise shown above with rubber cords and some gradual movement, though my arms don't provide enough resistive force for my hamstrings.