Two-Mass Model for Human Running Vertical Forces (video) Southern Methodist University Share Print E-Mail Loading video... Caption The two-mass model theorizes that running vertical force-time waveforms consist of two components, each corresponding to the motion of a portion of the body's mass. A smaller component corresponds to the impact of the lower limb with the running surface, as represented by the Impulse 1 curve in red. A larger component corresponds to the accelerations of the remainder of the body's mass, as represented by the Impulse 2 curve in green. The total vertical force-time waveform is a sum of these two components, as represented by the blue curve. Credit (Credit: SMU) Usage Restrictions Please credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.