Before I get into the actual answer to this question lets first take a look at what these unsightly spider veins are.
What are Spider Veins?
Spider veins are formed when on of your blood vessels are weak and the pressure within the vessel causes it to dilate (open). The blood flow in these veins are not regular because the valves fail to pump the blood in the right direction which then leads to blood pooling in some areas - the exact place you see spider veins forming just under your skin.
Back to the question….
Because spider veins lack support and are not deep within your muscles they’re more prone to swelling when your veins are experiencing pressure.
Once your veins swell, the valves pumping your blood back to your heart through the veins don’t work as well, and the blood pools in your veins - which forms the little blue and red veins you see under your skin.
But there are a lot of other factors that cause spider veins as well:
Standing for a long time
Ultra vilolet ray exposure
Sitting corss legged for long periods of time
Wearing clothes that are tight
Damage or injury to your skin
Ideally, running and walking is great for vein health since it keeps your leg muscles working - especially your calves (lower back of your leg) which plays a vital role in keeping your blood moving through your veins correctly.
With running, the problem with spider veins occurs when you’re running for long periods of time on hard surfaces (eg. Marathon). The pressure of the constant pounding on the pavement could lead to spider veins. As your venous pressure increases - the spider veins could develop.
If you do want to run, try soft surfaces like a dirt trail, track or treadmill. These will absorb some of the pressure and limit your chances of having your veins swell.
You can also apply ice to areas your worried about to help decrease leg vein dilation. After your cool-down put some ice in a Ziploc bag and gently cool the back of your legs, calves and ankles.
Don’t’ give up running and it’s huge cardiovascular benefits because you think you might get spider veins. It’s important to strengthen your heart rather than focus on if you’re going to develop spider veins or not.