Stability versus instability: The human body is unstable and made for movement. Part 2

Another important aspect of to the principles of human movement is that we can easily change our base of support. The base of support is the area beneath a person that includes every point of contact the person makes with the supporting surface. The bigger the base of support the less effort our muscles have to make to keep us upright and the more comfortable we generally feel.
Think of the difference of standing upright for half an hour without moving much, versus sitting on a chair, versus lying on the floor. When we are standing up, the entire weight of our body is balanced on our two feet and we usually become uncomfortable in this position quite quickly and may start fidgeting or wanting to move around. The act of standing still is perceived as quite a lot of effort in the body.

In sitting our base of support is wider. It is our entire pelvis placed on the chair and our two feet placed on the floor. In lying down our base of support is the whole body. As our base of support widens, our level of comfort usually increases but our freedom of movement decreases. Moreover, to get off the floor and start moving in a specific direction requires a lot more energy than moving in a specific direction when we are already standing. So, the bigger the base of support the less work the body has to make, the more comfortable we feel and the more our range of movement is limited.
Simply put, there is a clear tradeoff between our freedom of movement and our ability to react swiftly to any situation, and the size of our base of support and our perceived level of comfort.
You can experiment with all these principles in the video lesson called: “The Human body: Some principles of movement”. You can also learn about the base of support in sitting, in my video lesson: “Better sitting in 10 minutes”.