How Strength Might Help Flexibility

I have been doing some strength training for the past couple months to compliment my yoga practice. From the start I have been worried that lifting weights and doing exercises to build strength would limit the range of motion in my muscles and joints. I have been monitoring the depth of my postures as I start to lift more weight, and to my surprise all my postures have gotten deeper. I have seen absolutely no stiff side effects to the weight lifting. Quite the opposite, really. I think the strength training is making me more flexible. I have two theories why that may be true.

1) Stronger muscles mean that I can engage with more power. With more back strength I can straighten my back more. With more abdominal and quad strength I can pull my upper body and lower body together with more force. But the place where I have noticed it the most is in my hips. I have been doing Squats, Deadlifts and One-Legged Bridges (like the Bridge pose in yoga) that have made a huge difference in the strength of my hips, gluts, hamstrings and quads. So in a posture like Tree Pose, I have much more strength to pull my knee back. I never realized how the strength of one muscle can aid the stretch of another.

2) My second reason is a little bit more theoretical. I think that the strength in my muscles is increasing the stability of my joints. And since "flexibility" is a neurological relationship between the muscles, the nerves and the brain by which our nervous systems halt further movement when they sense danger, I think that increased stability in my joints is relaxing my nervous system. My body can sense greater stability and therefore it is willing to permit greater length and greater depth. More strength means less chance of injury, so a deeper stretch is possible.