the center of gravity in human movement is always static
Center of mass In kinesiology and biomechanics, the center of mass is an important parameter that assists people in understanding their human locomotion. Typically, a human’s center of mass is detected with one of two methods: The reaction board method is a static analysis that involves the person lying down on that instrument, and use of their static equilibrium equation to find their center of mass; the segmentation method relies on a mathematical solution based on the physical principle that the summation of the torques of individual body sections, relative to a specified axis, must equal the torque of the whole system that constitutes the body, measured relative to the same axis.[23]
Muscle contraction Muscle contractions can be described based on two variables: length and tension.[1] A muscle contraction is described as isometric if the muscle tension changes but the muscle length remains the same.[1][3][4][5] In contrast, a muscle contraction is isotonic if muscle length changes but the muscle tension remains the same.[1][3][4][5] If the muscle length shortens, the contraction is concentric;[1][6] if the muscle length lengthens, the contraction is eccentric. In natural movements that underlie locomotor activity, muscle contractions are multifaceted as they are able to produce changes in length and tension in a time-varying manner.[7] Therefore, neither length nor tension is likely to remain the same in muscles that contract during locomotor activity.