Figure 3.

Typical traces for lift of a light (A) and a heavy (B) object. Traces show the evolution of GF and LF (top traces) and of their derivatives (GF and LF rates; bottom traces). A, When lifting a light object after having picked up a heavy one (dotted lines), the GF peak and GF rate are higher than if the previous object was a light one (solid lines, see arrows *). B, When lifting a heavy object after having picked up a light one (dotted lines), the GF peak and GF rate are lower (see arrows *) and the loading phase longer (see arrows **) than if the previous object was a heavy one (solid lines). The horizontal dashed line represents the load of the light (A) and heavy (B) objects.