The participial phrase in the sentence is "who need greater initial power for a short dash." The word "needing" can be inferred as related to "sprinters," but here, "who need" functions like a relative clause describing "sprinters."
If you're looking for the standard participle alone, "beginning" and "using" in a broader context can refer to actions taken by the runners and sprinters, though they aren't explicitly stated in your sentence.
In this sentence, "crouch" could also imply a participial form as "crouching."
However, if you mean a direct participle, none are present explicitly here.