Skeletal muscles are held to the bones with the of:

tendons

ligaments

joints

C= $20.45, you do how many songs multiply that by each song cost and add $9.95

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)