The biomechanical function of the foot pump in venous return from the lower extremity during the human gait cycle: An expansion of the gait model of the foot pump

Abstract

The gait cycle has been modelled for energetics and musculoskeletal health and disease, but little has been published in relation to the function of gait as a mechanism in maintaining haemodynamic homeostasis through the lower limb. Blood returns from the lower limb drawn to the heart by the low pressure at the vena cava through hydrodynamic forces. Resisting these hydrodynamics forces are gravitational and frictional forces. The deficit between the forces acting for venous return from the lower limb by hydrodynamics and those acting against antegrade flow, is filled by extrinsic mechanical mechanisms including the respiratory pump, skeletal muscle pumps and the foot pump. The efficiency of the lower limb skeletal muscle pump and foot pump are likely linked to gait kinetics and kinematics. A model is proposed that attempts to expand upon previous gait models of the foot pump as part of the kinetic and kinematic events that occur during gait, whilst also developing the argument that the foot pump needs to be divided into passive-pressure phases, and combined active-muscular/passive-pressure phases during gait. This model suggests that non-weightbearing arch profiles will have little influence on the combined active/passive-pressure phases of the foot pump, while the ability to develop compliance and stiffness within the foot at the requisite periods of the gait cycle is likely to influence foot pump efficiency.

Keywords: Foot compliance; Foot pump; Foot-gait model; Pronation; Venous return.