Tracking your flexibility over time as you train. There are no requirements on how flexible you need to be and there is no correlation of your length of life or muscle strength with how flexible you are.
Honestly, I'm not positive myself. All I can say is that overworking your joints without enough cool-down time will put you at high risk for arthritis.
Your answer is the nuclear envelope, The nuclear envelope is a double membrane of the nucleus that encloses the genetic material. It separates the contents of the nucleus from the cytoplasm.
