A blood clot is a clump of blood cells and clotting factors that forms a solid mass within a blood vessel. The primary concern related to immobility is venous thromboembolism (VTE), which includes deep vein thrombosis (DVT), typically forming in a deep leg vein. If a clot dislodges and travels to the lungs, it causes a pulmonary embolism (PE), a potentially life-threatening event. Walking is a primary and highly effective preventative measure against these dangerous clots.
How Movement Prevents Clot Formation
The human body’s circulatory system relies on movement to return deoxygenated blood from the lower extremities back to the heart. Unlike arteries, leg veins must work against gravity and lack a strong muscular layer to propel blood flow. Prolonged sitting or lying down allows blood to pool, a condition known as venous stasis, which is a key factor in clot formation.
When you walk, the muscles in your lower legs, particularly the calf muscles, contract and relax rhythmically. This action creates the “calf muscle pump” or “venous pump.” As the muscles tighten, they squeeze the deep veins, effectively milking the blood upward toward the heart.
Inside the veins are one-way valves that prevent blood from flowing backward between muscle contractions. The calf muscle pump can propel up to 70% of the blood in the lower legs back toward the heart with each step. By maintaining this constant, unidirectional flow, walking actively prevents blood from becoming stagnant, which initiates the clotting cascade.
High-Risk Scenarios Requiring Increased Movement
Specific life events involving extended periods of immobility place individuals at a higher risk for developing DVT. Long-haul travel (by airplane, car, or train) is a common scenario where movement is restricted for four hours or more. During these trips, it is beneficial to get up and walk the aisles every hour, or stop the car to stretch and move the legs.
For those unable to move freely, such as during a long flight in a window seat, simple seated exercises are an effective substitute. Ankle pumps involve repeatedly flexing the foot by pulling the toes up toward the shin and then pointing them down, activating the calf muscles. Performing these exercises every 30 minutes helps maintain adequate circulation.
A second major risk scenario is prolonged bed rest following surgery, illness, or injury. Hospitalized patients are often instructed to move and walk as soon as their condition allows to restore normal blood flow. Even in bed, simple exercises like wiggling the toes, moving the ankles in circles, and pressing the feet against the footboard can provide the necessary muscular contractions to prevent blood stasis.
Sedentary desk jobs also pose a threat over time. Workers should set a reminder to stand up and walk for a few minutes every hour.
Recognizing the Signs of a Blood Clot
While movement is a powerful preventative tool, once a blood clot is suspected, walking is not a treatment and may be harmful. DVT typically occurs in one leg, and symptoms include sudden or gradual swelling in the affected limb. The area may also feel unusually warm, and the skin can appear red or discolored.
Pain or tenderness in the leg, often starting in the calf, is another common sign of DVT. This pain may feel like a severe cramp or a persistent ache that does not resolve with rest. If the clot breaks free and travels to the lungs, it becomes a pulmonary embolism (PE).
Symptoms of a PE demand immediate medical attention. These signs include a sudden onset of shortness of breath, chest pain that is sharper when taking a deep breath or coughing, and a rapid or irregular heartbeat. Other symptoms can include coughing up blood, dizziness, or fainting. Any combination of these symptoms warrants an immediate visit to an emergency room.
Comprehensive Strategies Beyond Walking
Preventing blood clots requires a multi-faceted approach beyond physical movement. Maintaining proper hydration is a key strategy, as dehydration causes blood volume to decrease, making the blood thicker and more viscous. This increased thickness elevates the risk of coagulation and clot formation.
Compression stockings can complement walking, particularly for those at higher risk. These specialized garments apply graduated pressure, being tightest at the ankle and gradually loosening up the leg. This external pressure helps squeeze the veins, preventing blood from pooling and aiding the natural upward flow back to the heart.
Addressing other underlying risk factors is also important. Excess body weight places increased pressure on the veins in the pelvis and legs, impeding blood flow. Smoking damages the lining of the blood vessels, making them more susceptible to clot formation. In high-risk individuals, a doctor may prescribe pharmaceutical intervention, such as anticoagulant medications, to thin the blood and reduce the body’s ability to clot.