I usually have my patients walk for 30-45 minutes immediately after their sclerotherapy procedure (to prevent blood clots). They can resume exercise the next day. I recommend that they refrain from abdominal crunches for several days following the procedure, although this may be on the conservative side. In theory, contracting your abdominal muscles (via sit-ups, etc.) makes it harder for the blood to be pushed up your leg back to your heart. Wearing compression stockings and avoiding excess/unnecessary abdominal muscle contraction for several days following the procedure allows the walls of the treated blood vessels to stay in contact with one another (as opposed to having excess blood between/separating them), which allows the body to break down the blood vessels as intended.