Calf muscles help veins return blood from the legs to the heart. Activities such as walking, running, rising onto the balls of your feet, and moving your ankles cause these muscles to compress nearby blood vessels, propelling blood upward. For this reason, the calves are sometimes referred to as the “second heart,” although they cannot replace the primary circulatory organ.
Venous pressure is significantly lower than arterial pressure, and one-way valves prevent blood from flowing back down toward the feet between muscle contractions. When this mechanism functions normally, blood does not pool in the legs. Dysfunction, however, can lead to ankle swelling, a sensation of heaviness and pain in the legs, and venous issues.
A 2020 study involving 2,728 adults undergoing vascular examinations at the Mayo Clinic in Minnesota revealed a link between poor calf-muscle pump function and increased mortality. After 10 years, the mortality rate was approximately 6% among those with normal function, compared to roughly 18% among those with impaired function. However, the researchers did not claim that weak calf muscles were the direct cause of death.
A larger 2024 study covering nearly 6,000 patients observed the same correlation. The less blood the calf muscles propelled during movement, the higher the risk of death. Individuals with the weakest pump function faced a risk more than twice as high as that of participants with efficient blood propulsion.
Activities such as regular walking, running, climbing stairs, and performing repeated calf raises help maintain the function of the calf-muscle pump. Those who work in a seated position for long periods are advised to stand up and walk around briefly at least once an hour. If that is not possible, you can move your feet up and down or lift your heels while keeping your toes on the floor.
Standing still for long periods also fails to ensure proper muscle activity. Persistent swelling, sudden pain, redness, or a sensation of warmth in one leg require medical evaluation, as these could be signs of a blood clot. Small-scale studies have also shown that prolonged heel-raising exercises can influence how the body processes glucose and fats; however, they are not a substitute for walking, physical activity, or necessary medical treatment.
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