The Vital Role of Your Calves: More Than Just Muscle
Your calf muscles, specifically the gastrocnemius and soleus, have earned the nickname “the second heart” thanks to their crucial role in blood circulation. These muscles contract while walking, flexing, or standing, and squeeze the veins in the lower leg, pushing deoxygenated blood back up toward the heart and opening one‑way valves that prevent pooling. (Pawlowski, 2023) The “second heart” only works when your legs move, and prolonged sitting or standing without movement can impair this natural pump, resulting in conditions like varicose veins, chronic venous insufficiency, edema, or even deep vein thrombosis. In fact, impaired calf muscle pump is an independent predictor that increases mortality. (Halkar et al., 2020) The study, published in Vascular Medicine in December 2020, investigates whether impaired calf muscle pump (CMP) function—responsible for helping return blood from the lower extremities to the heart—predicts overall mortality. Researchers at the Mayo Clinic evaluated 2,728 adult patients over 12 years and found CMP's role in maintaining cardiac preload and output underscores its potential as an indicator of circulatory health.
Your heart can only pump out as much blood as it gets back. When you’re lying down, it’s pretty easy for blood to flow back to the heart. But when you’re standing or sitting, gravity pulls blood down into your legs, making it harder for the blood to return. That means your body needs a way to push the blood back up to your heart. To help with this, your body uses your leg muscles. These muscles squeeze and push the blood upward every time you move. The calf muscles do most of the work, the foot muscles help get things started, and the thigh muscles help finish the job. The two most crucial muscles in your calf, the gastrocnemius and the soleus, have short, slanted muscle fibers—like feathers pointing at an angle. That kind of muscle is called a pennate muscle. Because of how they're built, these muscles are really good at providing strength and helping you stay balanced, but they aren’t super stretchy or flexible. These muscles work closely with something called the Achilles tendon, which is like a strong rubber band in your ankle. When you move, the muscles and the tendon work together like a spring: they hold energy and then bounce it back to help give you momentum. Now, let’s compare that to your gluteus maximus—the big muscle in your butt. That one has long, straight fibers that run in the same direction as how you move. That means it’s great at helping you do big, strength-requiring movements—such as jumping high, swinging heavy things, or running fast. This illustrates an important point, that all muscles behave differently, and come together like a great symphony to help us adapt for functional movements. Today, however, we sit a lot more than our ancestors did, so many people have weak soleus muscles. Because the soleus muscle stores blood, if these muscles aren’t working well, blood can get stuck in your legs, causing problems like swelling, leg cramps. You can help by doing toe lifts, squats, or activities like yoga and Tai Chi. There are also special tools and machines that help stimulate the muscles if movement is hard for you. Keeping your “second heart” strong helps your real heart—and the rest of your body—stay healthy.
Hamstrings—muscles located at the back of the thigh—are described by experts at Harvard as working “double duty” when daily movement demands exceed the capacity of weakened glutes. In sedentary lifestyles, hamstrings often overcompensate for inactive gluteal muscles, significantly upping their workload and susceptibility to strain or injury. Without balanced strength and flexibility, they become prone to tears. Sports science research advises building muscle symmetry between hamstrings and quadriceps, emphasizing that hamstring strength supports posture, improves athletic performance, and minimizes injury risks during rapid movements like sprinting or changing direction. (Harvard Health, 2019) Harvard Physical Therapist Matt Natanson highlights that tight hamstrings frequently result from compensatory overload and a chain reaction triggered by prolonged sitting, which weakens glutes and tightens hip flexors. We need the Glutes to do their primary job: helping us lift heavy things! All the muscles in your body accomplish similar, yet distinct functions. Some muscles are better at helping you move big and far, and others are better at holding things steady or helping you push hard. For hamstrings, prioritize targeted exercises like leg curls, Romanian or stiff‑leg deadlifts, bridges, or single‑leg variations to build strength and flexibility safely Addressing muscle imbalance—especially strengthening glutes and stretching hip flexors—helps relieve hamstring overload and reduce fatigue and injury risk. (Exercises for the Knee’s Range of Motion | Livestrong, n.d.)
In essence, your lower body—from calves to hamstrings—acts like a circulatory and mechanical powerhouse: calves facilitate blood return with the rhythm of each step, while the hamstrings support both hip motion and knee flexion. Neglecting either leads to circulation issues or musculoskeletal strain. The solution? Stay actively engaged, cultivate balanced strength across muscle groups, and move often—your body’s second heart (and its compensatory muscles) will thank you.
References:
Maloney, L. (n.d.). Hamstring pain when stretching | Livestrong. LIVESTRONG.COM. https://www.livestrong.com/article/396328-hamstring-pain-when-stretching/
Halkar, M., Inojosa, J. M., Liedl, D., Wysokinski, W., Houghton, D. E., Wennberg, P. W., Lin, G., Kane, G., Fischer, K., Rooke, T. W., Saadiq, R., Bonikowske, A., & McBane, R. D. (2020b).
Calf muscle pump function as a predictor of all-cause mortality. Vascular Medicine, 25(6), 519–526. https://doi.org/10.1177/1358863x20953212
(Halkar et al., 2020)
Pawlowski, A. (2023, October 2). Activate Your Second Heart With 1 Exercise To Boost Health. TODAY.com; TODAY. https://www.today.com/health/diet-fitness/what-is-the-second-heart-rcna117576
Harvard Health. (2019, January 1). Are your hamstrings working double duty?https://www.health.harvard.edu/staying-healthy/are-your-hamstrings-working-double-duty
