fill in the missing letters in the box to come up with the complete word or phrase

1.it is a principle in which the load could be increased gradually overtime to remain effective and safe for best result
P_ _G R_S_ _O_

2.it produces significant force without any considerable change in the length of the muscle
S_ A T_C-M_V E_E_T

3.the acronym that we should follow in making our goals
S_A_ _

NONSENSE ANSWER REPORT!​