WHAT HAPPENS TO THE ARTERIES OF THE DESK-BOUND? Plaque doesn't just grow on your teeth. It can also form inside your arteries -- the blood vessels that carry oxygen and blood to the heart, brain and other parts of the body. Arteries have an inner layer of muscle. When it is damaged, plaque can form, sometimes leading to a bulge in the wall of the artery. The bulges can grow big enough to cause the inner lining to rupture. The body responds by sending clotting fibers to the damaged site. Minerals, especially calcium, can become trapped in the net of fibers, and so can fats like cholesterol. The minerals and fats build up over time, causing the arteries to narrow. Blood can't flow so easily through the restricted arteries. The arteries can also become clogged, stopping blood flow completely.
HOW WE WALK: Walking is different from a running gait because only one foot at a time lifts off the ground. During forward motion, the leg that leaves the ground swings forward from the hip, like a pendulum. Then the leg strikes the ground with the heel and rolls through the toe in a motion similar to an inverted pendulum. The motion of the two legs is coordinated so that one foot or the other is always in contact with the ground -- a so-called 'double pendulum' strategy. The process of walking recovers about 60 percent of the energy expended thanks to the pendulum dynamics and the ground reaction force. The legs act as long levers that transfer ground reaction force to the spine.