Does arm angle/position at touchdown influence the landing phase?
If the take-off and landing conditions are the same, as for a bouncing elastic ball, we would expect there to be correlations, due to ballistics, between the force components of the same direction because the angle of the GRF during take-off would be complementary to that for landing. Although these correlations are observed in jumping frogs, the unexpected, additional correlation between the Z-force of propulsion and the Y-force of landing indicates that this landing angle of the GRF is actively changed. The angular momentum and the difference in stiffness between the front- and hindlimbs are the most plausible causes of this angle change. The role of the front limbs during landing proved to be considerable. Two types of jumps were observed, depending on whether the impact peak was mediated by the arms or by the body. Although the peak forces were on average larger when the body mediated the forces, no clear arm function limits could be detected in peak force, power or work. A mechani
