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The design of portable equipment such as backpacks has a large influence on comfort and fatigue. Variation of the center of gravity changes the posture and muscle activation in a complicated fashion, and the same can be said for the way the straps put their forces on the bones of the body. This example shows a posture change from forward flexed to upright followed by a change of center of gravity of the backpack further away from the body. Notice how the model automatically compensates its posture to maintain balance.

Click here for an animation.