Lifting a weight 10 times is a kind of ISOTONIC contraction. Holding a heavy machine part steady while securing it in place may be categorized as ISOMETRIC contraction. Lifting heavy cans and putting them on a shelf may be called an ISOTONIC contraction. Flexing your leg muscles and holding the flex is an ISOMETRIC contraction. Lifting your heavy book bag several times is good ISOTONIC contraction.
Answer:
due to human are using resources faster than they can be renewed replace and clean up.
A) they allow an athlete to exercise longer
(i just took the quiz)
That would be cardio work
