Which action requires the most muscles on your body?

Answer 1

The clever answer that I can think of is stepping on a rusty nail and subsequent infection with C. tetani. Untreated, the resulting state of tetanus will pathologically involve every single muscle in the body. Aside from that, humans perform so many different actions that it is hard to think of any single one that requires the "most" muscles in the body. If someone asked me this question, I might suggest running as an answer. Running utilizes all of the muscles in the legs for strength, and all the muscles in the trunk and arms for balance, and even a couple of muscles in the head and neck--not to mention the cardiac muscle to increase blood flow to the whole body. If you read an article in Nature magazine by Bramble and Lieberman, from 2004 I believe, you will see that some evolutionary biologists believe that much of the human body--including most of the musculature--has been optimized to give maximal efficiency while running.