Does it really hold that chimps are up to 5-10 times physically stronger than humans, as I happened to learn by watching a 'National Geographic' documentary?

Also, on "en.allexperts.com", I found this:

"As for the strength of the animals, a chimp in the wild has the strength of 4 to 7 adult men, however generally five adult men..
An orangutan has the strength of 5 to 8 adult men, however generally 7 adult men.
A gorilla has the strength of 9 to 12 adult men, however generally about 11."

as well as:

"Compared to humans, anthropoid apes are top heavy and use their arms to support their weight when moving. Humans concentrate more of their muscle weight in their legs and so, compared to anthropoid apes, have relatively weak arms."

Yet some scientists, like e.g. John Hawkes, cite various texts in which these beliefs are discredited by examples where dynamometer showed results of how hard a man and a chimp can pull: chimps, he says, might be regarded as twice as strong as humans, but hardly any more than that.

What do you know or think about this?