I think it's called infectious agent or something close to that.
Muscular strength has to do with what at what intensity you can do a task while muscular endurance has to with how long you can do a task
I was not used to it and it was difficult to follow a diet plan. so you really need a self-discipline to do it. Soon, I got used to it and I'm glad I followed the diet plan. I was surprised when I wore the clothes that did not fit me before but now they are loose in my body.