Your heart has a colossal task: to pump blood 24/7, 365 days a year, from your first breath to your last. However, this muscle, which weighs between 250 and 350 grams in an average human, needs support. Enter the calf muscles—your "second heart." They assist the heart by working against gravity, pushing blood upwards from the lower part of the body to the heart.What Are Calf Muscles?They are a group of muscles located in the back of the lower leg. The calf muscles are primarily responsible for helping a person walk, run, jump, and stand on their toes. However, they are pivotal to the cardiovascular system as well. They help squeeze the veins in the lower legs, aiding the upward return of blood toward the chest. Notably, this "second heart" only activates when you move your legs, which poses a problem for individuals who sit or stand for extended periods during their workday. Dr Teresa Wu, a vascular medicine physician, explained to Time.com, "The blood flow back to the heart has to fight the force of gravity, which keeps everything down. Without a natural pumping mechanism, blood struggles to return to the heart."How Do Your Calf Muscles Pump Your Blood? Every time your calf muscles contract, they open one-way valves inside the leg veins, pushing blood upwards toward the heart. When the calf relaxes, these valves close, preventing blood from flowing back into the legs. This is how they ensure regular movement of blood in the body. However, if a person spends too much time sitting or standing, it can lead to increased pressure in the veins. This may damage these valves over time, making them "leaky" and causing blood to pool in the legs.The loss of calf muscle pump function can result in symptoms of chronic vein disease, such as swelling, leg fatigue, and varicose veins. In rare cases, it can even lead to blood clots, particularly when individuals remain seated for long durations, such as during lengthy flights.Sedentary Behavior Obstructs This ProcessAn inactive "second heart" contributes to what researchers refer to as "sitting disease." Various studies have proven that prolonged sedentary behaviour has long-term impact on your heart health. Recnetly, the American Heart Association (AHA) warned that excessive sitting can raise the risk of heart disease. Conversely, standing for long periods without movement can also be detrimental. Dr Sharonne Hayes, a cardiologist at the Mayo Clinic, notes that the standing desk trend has inadvertently increased rates of venous issues, as people tend to stand still rather than move.One Step Process To Activate Your Second HeartThe simplest way to activate your second heart is to walk. Movement of the legs and calf muscles promotes circulation. Experts encourage individuals with desk or standing jobs to walk as often as possible. For those unable to get up, such as during long flights or while at work, toe raises—flexing the foot up and down—can mimic walking, helping to keep blood flowing. Moreover, elevating the legs for 15 to 30 minutes each night can also alleviate swelling, especially for those with chronic vein disease. Wearing compression socks can provide support for individuals who spend significant time sitting or standing. So, the next time you think about ensuring proper blood flow in your body, don’t forget to do your leg raises.