How do you think american football will be different: 10 Years from now-
and 50 years from now?

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)

Adescription of  congestive heart  failure, its symptoms, risk factors, and treatment. to the  heart muscle  other than by artery or blood  flow  problems; signs of  heart  failure may not  meanthe patient has  heart  failure and they quit alcohol, or at least consume alcohol within the national recommended  limits.