thik about this .... some male chimps are 4 times stronger than a regular human male adult
a silverback .... welll ..you do the math 
There is a thread on this very topic started by me, which is now at the Z board. Gorillas have the upper body strengh of 20+ Humans for several reasons:
- They have much more absolute muscle mass than Humans.
- 80% of their muscle mass is in the torso, vs only 30% for Humans, who's most muscle mass is in the buttocks and quadriceps..
- Their muscles attach to the tendons in positions that give them far superior leverage.
- Their tendons are 4 times thicker than Humans' and their bones much denser, allowing them to produce much more intense bursts of strengh.
- They have a much higher proportion of type II muscle fibers than Humans.
All this results in a creature with the upper body strengh of more than 20 Humans. A chimp has the upper body strengh of 5 Humans, and gorillas are roughly 4 times stronger than chimps.
SUCKMYMUSCLE