Inflexible knees and hamstrings?

I have been doing yoga on and off for a year, but have recently become devoted to it over the past 2 months. I’m still a beginner, and have done lots of weight training and dance in the past.
I have Yoga Journal videos with Rodney Yee and Patricia Walden, and they are awesome. What I have noticed though, is that they always emphasize “pressing your thighs down” when in staff pose and when doing sitting forward bends. When I do this I notice that my feet and calves tend to pop up off the floor.
If I prevent my calves and feet from poking up a bit, then my thighs are not pressed down, and I feel the stretches a lot less. I am wondering if I am hyperextending my knees? I really don’t think so…I’m thinking my knees may just be unflexible. I have flexible hamstrings and butt muscles, but my back and hip flexibility limits me sometimes. I am wondering if the flesh of my thighs (which I do pull to the side for these positions) is preventing me from pressing down correctly?
Another related issue to this seems to be that when I do pilates, there is a move where you have to anchor your legs and butt to the floor while rolling from lying down to a upright seated position. I find it impossible to keep my legs anchored during this. When I initiate the rolling up, my legs and feet always retract a good 2-3 inches into my body.
Any ideas on why these things occur or if they can change? Will these problems hinder my practice? Thank you.

Fiona,

I am also a devotee of the Gaim/Living Arts DVDs. It was Rodney Yee, in fact, who illustrated just how tight not only my hamstrings and knees were, but even tighter, my hips.

My advice is to acquiesce to the fact that those muscles, joints and connective tissues are indeed tighter than a string on a violin. And understand that you’re not alone. The American Chiropractic Association says that more than 60 % of all lower back pain can be traced to inflexible hamstrings and hips. I was 30 the first time I stood with knees straight and my palms on the floor and it would be another two years before I would reach the floor in wide-angle forward bend or rest my head comfortably on my shins during seated forward bend.

The amazing thing was that after many months of slow, nurturing and dedicated work not only did I experience full extension, but a lifetime of lower back problems and morning stiffness evaporated when I did.

It’s sometimes difficult to wrap our western minds around the idea that an asana can be benificial even if we’re not quite at the same stage of flexibility we see demonstrated by our instructors. Often times, relinquishing our predetermined goal in favor of the immediate here-and-now experience is exactly the lesson our body is trying to convey.

Namaste,
BrianClt