“limitative factor” vs “limiting factor”

Solution 1:

Limitative relating to limits, having to do with limits.

Limiting imposing a limit.

The -ive suffix in the adjective limitative would indicate that a noun modified by that adjective would relate or pertain to limits, that it has some of the characteristics of a limit, or while itself not being a limit per se could function much like one or as one. That constellation of meanings is only nibbling at the edges of what is needed in the sentence.

In other words, researchers considered a number of limitative factors, i.e. factors of a kind that could serve to impose a limit. But the most important of the limiting factors, i.e. factors actually imposing a limit, was speed of muscle contraction.

Solution 2:

If you consider similar word pairs, such as

punitive-punishing
diminutive-diminishing
corroborative-corroborating
relative-relating

... you'll see that in each pair the first word's function is to modify something that has possibilities, whilst the second one is used when describing something concrete: a certainty.

Just a theory.