The leg vein swells up when I do sit-ups. Why?

Hello,

Welcome to icliniq.com.

I read your concern. The swollen-up vein could be a varicose vein. And if you keep doing some activities that increase the pressure in the lower body or abdomen, it can give rise to immense pressure preventing the backflow of blood to the heart via veins. So, there is swelling in the veins. If you continue to do the same activity then you may lead to damage the valves in the vein. Now, at this stage, you may have a check-up with a cardiologist to know the exact cause of the swelling. However, nothing to panic about. Until then, I request you not to indulge in those activities that bring swelling in the vein as a precautionary measure. You may continue with moderate activities that will anyway help you achieve the same result.