Long hours of sitting during car journeys can lead to dangerous blood clots, a condition known as deep vein thrombosis (DVT). When a person remains seated for extended periods, blood flow in the legs slows down and pools in the veins, creating an ideal environment for clot formation. The calf muscles, often called the 'second heart', normally help pump blood back to the heart. However, during prolonged sitting, these muscles become inactive, reducing venous return and increasing clot risk. Dr Rema Malik, a vascular surgeon, highlighted this hidden danger and recommended three key rules: taking breaks every two hours for walking and calf raises, staying well-hydrated with water, and performing ankle pumps every thirty minutes while seated. Certain groups face higher risk, including those with previous DVT history, recent surgery, active cancer, obesity, pregnancy, or hormone therapy use. Simple exercises like ankle flexions, calf raises, and regular walking breaks can significantly improve circulation and reduce clot formation risk during travel.
Why Long Drives Increase Blood Clot Risk
Dr CM Nagesh, Senior Consultant Cardiologist at Cardea Super Specialty Hospital, explains that prolonged sitting triggers venous stasis, where blood pools in the deep leg veins. When knees remain bent and feet stay still, the calf muscle pump becomes inactive, preventing normal blood return to the heart. The seat edge pressing against the back of the thigh or knee further compresses veins and slows blood flow. As blood remains idle, contact time between clotting factors and vessel walls increases, raising clot formation risk. Even two hours of quiet sitting can elevate thrombotic tendency in leg veins. Dehydration, immobilization, and stress can thicken blood further, tipping the balance towards clotting. Simply put, long immobility leads to less muscle pump activity and higher clot risk.
Effective Exercises and Preventive Measures for Travellers
Dr Nagesh recommends several evidence-based movements to maintain healthy circulation during long drives. Ankle pumps involve moving feet up and down 30 times per minute for five minutes, which increases blood flow velocities in leg veins. Calf raises and heel lifts help contract calf muscles, while leg extensions break static posture. Walking or standing breaks every one to two hours reactivate the calf pump. Wearing compression stockings (15-30 mmHg) reduces vein distension and improves flow. Staying hydrated prevents blood thickening. Travellers should set reminders every 45-60 minutes to stop and walk for 2-3 minutes. While driving, lifting heels and flexing ankles 20 times per leg every 10-15 minutes helps. High-risk individuals should consult specialists if experiencing swelling, warmth, or pain.
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