P70S6k occurs mostly in Type II fibres.

http://ajpendo.physiology.org/cgi/content/full/290/6/E1245

This suggests that type II fibres hypertrophy to a greater extent than type I.

P70S6k may also remain elevated for up to 36 hours after resistence exercise.

http://ajpcell.physiology.org/cgi/content/full/276/1/C120


P70S6k is maximally stimulated some 3-6 hours after exercise. From an evolutionary sense this is suspected, as after a hunt, they probably would not have eaten until 3-6 hours later.