Individual muscle contributions to vertical impulse by SOL, GAS, VAS, GMAX and the sum of the other muscles for the control (white) for the 25% (grey) and 50% (black) conditions. The sum of the other muscles includes HAM, RF, IL, GMED and PR. Muscles that made negative contributions to the vertical impulse (IL and BFsh) were excluded. Dotted lines indicate the magnitude of the control values.