- Sharon Brennan-Olsen summarising three studies for an article in The Conversation
Why does the body need hips and knees?
Your knees bend and straighten. You hips do the same and swivel, swing and rotate freely. Together, these two joints are involved in every act of human locomotion. Look at the image below. The joints and muscles around them are built for an incredible amount of deep and powerful movement. Jumping, squatting, running, lunging are just the tip of the iceberg. The most mundane tasks to the most spectacular athletic feats, all need your knees and hips to bend, swivel, swing and rotate. Often at the same time.
Why do we lose this capacity?
The body has a very simple use it or lose it policy. This applies to all our faculties: intellectual, emotional and physical.
If you don't ask muscles to regularly produce force or fight against gravity, they lose their ability to produce force to move joints. The brain loses its ability to ask the muscle to do things. And the bone which was dealing with all these demands starts to lose density and mass.
The tendon that connects muscles to bones acts as the string connect the puppet master (muscle and brain) to the puppet (bone). Tendons need to be act as a spring and a stick to their job well. Without practice they turn into a loose rope.
Age makes things worse:
Why keep all that dense calcium lying around it there is no use for it? This problem worsens with age as our body gets worse at building bone and muscle. Keeping what you have needs a lot of work. And sadly most of us are not putting in the work.
Tell me what to do. How much to walk ? How much to run?
Look at the image. Now walk or run. How much are you bending those knees and hips? Nowhere close to how much they are built to travel. The muscles around these bones are built to produce force and tension through all of that range. Not just in the little arcs of movement we call walking.
There are exercises for rotating or swinging your hips with or without load. There are dozens of variants of squats, lunges, hinges and thrusts that you can do for the multitude of muscles and tap into all of things the hips and knees were built to do. You need to pick a few and practice them regularly. You don’t need a gym membership. Even stepping on and off a chair or stool in a controlled way will involve a lot more knee and hip than you think.
The cost of not doing these things is higher than we think. Activity costs us time and energy. But it’s a great deal when you consider the return in the form quality of life and peace of mind that you earn as you age with robust joints and muscles.