Abstract
This study explores the function of the lower leg muscle pump (calf muscle pump, CMP) as a flow diverter pump that maintains low ambulatory venous pressure (AVP) during locomotion. It examines the dynamics of venous pressure changes, muscle activity, and arterial blood supply in healthy individuals performing various exercises. The findings underline the critical role of the CMP in directing blood from superficial to intramuscular veins, thereby ensuring efficient venous return and preventing venous hypertension.
Introduction
The calf muscle pump (CMP) is pivotal in venous hemodynamics, particularly in preventing chronic venous disease (CVD). During locomotion, CMP modulates ambulatory venous pressure (AVP), defined as the reduction of superficial venous pressure in response to muscle activity. This study evaluates the CMP’s dual role as an ejector and a suction mechanism, providing a nuanced understanding of venous blood flow during exercise.
Methods
A prospective experimental design was employed with nine healthy volunteers. Venous pressure and muscle activity were measured using catheterization, surface electromyography (sEMG), and Doppler ultrasound during walking, running, and plantar flexion exercises. Pressure gradients and unit power of muscle pump ejection (NE) and suction (NS) were calculated to assess the CMP’s function relative to arterial blood flow.
Key Findings
- Pressure Dynamics and Flow Diversion:
- During walking and running, the CMP maintained a consistent venous pressure gradient, directing blood flow from superficial to intramuscular veins via perforators.
- The anterior tibial muscle (ATM) and gastrocnemius muscle worked synergistically, alternating between suction and ejection phases, ensuring efficient venous return.
- Exercise Intensity and Pressure Regulation:
- Pressure gradients decreased with increased stride frequency, ensuring proportional blood flow to accommodate heightened arterial inflow.
- NE and NS exhibited exponential growth with increasing exercise intensity, correlating closely with arterial blood flow.
- Superficial Venous Pressure Stability:
- Despite increased arterial blood supply, superficial venous pressure remained stable during walking and running, contrasting with higher pressures observed during plantar flexion due to limited CMP activity.
Discussion
The CMP functions as a two-component mechanism, involving coordinated contractions of antagonist calf muscles. This synergy redirects venous blood horizontally from superficial to intramuscular veins, bypassing the high-resistance axial venous pathways. The findings demonstrate that optimal CMP performance is essential to prevent venous hypertension during exercise.
Conclusion
The study highlights the CMP’s role in maintaining venous pressure equilibrium during natural locomotion. Its efficiency in managing arterial inflow and ensuring venous outflow underscores its importance in preventing CVD. Future research should explore its application in managing venous insufficiency and developing therapeutic interventions.
Source:
Tauraginskii, R. A., Lurie, F., Simakov, S., et al. (2024). The human lower leg muscle pump functions as a flow diverter pump, maintaining low ambulatory venous pressures during locomotion. Journal of Vascular Surgery: Venous and Lymphatic Disorders. Read the full text.