Human movement forward dynamics

There are two fundamentally different approaches to studying the biomechanics of human movement forward dynamics and inverse dynamics. Either can be used to determine Joint kinetics (e.g., estimate joint moments during movements). 

For the remainder of this chapter, we will concentrate on the inverse dynamics approach for the study of human movement. Inverse dynamics is more commonly used than forward dynamics for studying human movement. A forward dynamics approach will be addressed in a subsequent chapter (Chap.6, Biomechanics of the Musculoskeletal System, by Marcus G. Pandy and Ronald E. Barr). 

FIGURE 5.1 Forward dynamics approach to studying human movement This simplified figure depicts the neural command and forces for three muscles and the moments and joint angles for a two-joint system. See text for details. 

In this chapter we have examined forward and inverse dynamics approaches to the study of human motion. We have outlined the steps involved in using the inverse approach to studying movement with a particular focus on human gait. This is perhaps the most commonly used method for examining joint kinetics. The forward or direct dynamics approach requires that one start with knowledge of the neural command signal, the muscle forces, or, perhaps, the joint torques. These are then used to compute kinematics. 

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