When competing in video games it is very important to have fast reaction times and nimble fingers. I don't know that much about this topic but i was wondering whether body types affect gaming performance. For example, if one was playing on a mouse and keyboard with a very thin build. If they increased their muscle mass in their arms; would this decrease their reaction times and skill. My thought is that it would ruin muscle memory that was previously built. It would also take longer for the body's neurons to contract the arm muscles and move fingers in response to an event on the computer screen. I think that having a high muscle mass would cause the fingers to become less nimble and more stiff. Also i think that reaction times decrease once a person is past the age of 20. Is any of this true or backed up with any kind of scientific evidence?