system
Given the following post, respond as if you're commenting on Reddit:
human
Does bouncing my leg up and down really fast burn calories?

I do this all the time, as I'm sure a lot of people do, and I was wondering if bouncing my leg accomplished more than making my family look at me when the kitchen cabinet starts shaking.
gpt
The short answer is yes the act itself burns calories, but what may surprise you is that **it actually allows your heart to not work as hard.**

When you sit or stand you create a substantial pressure gradient between your heart and feet. In order to keep the cells in your feet alive they need to be resupplied with oxygen. Your heart must work extra hard in order to pump blood back up this pressure gradient. However, this process is much easier if you are moving.

When you use your muscles they create dynamic forces on your veins which squeeze them, forcing fluid through the vein. All along the vein are 1 way valves which direct the blood back to your heart. By shaking your leg you are using the muscles in your leg to assist your heart. If you stand for a long period of time without flexing your muscles you will strain your heart to the point of passing out. Buckingham Palace Guards must take this into account to perform their duties.

Edit: Sorry. "Guard" not "soldier"