Along with tight adductors (see last week's post), many people also have tight thigh muscles.
Unfortunately, they either get the token 5 second stretch or aren't stretched properly at all.
If you have been neglecting these stretches, go easy on this one for a start as you will likely find your legs a lot tighter than you thought for.
If you are office based or spend a lot of your time sitting then I would recommend using this exercise as part of your warm up.
I would also recommend putting some cushioning underneath the knee as hard floors are quite unforgiving.
This is my, mostly, Personal Trainer musings and information which I hope you'll find helpful!