- last post: 01.01.0001 12:00 AM PDT
While it only takes 12lbs of force to snap a femur in half, it is strong enough vertically to hold up a pick-up truck.
The reason why 90% of humans will experience back pain is due to the fact that you walk upright. All of your weight it piled veritcally onto thin discs of cartallige(sp?) which break down with age.
Every time you take a step, forces up to 3 times your body weight send shock waves up your legs and into your back. When running, forces can be doubled.