The biceps action is "________" to the tricep?!

Question: i'm doing a crossword puzzle and the question is: the biceps action is "________" to the tricep. what is the blank? it;s a 12 letter word, here is what i have so far "_ _ t _ _ _ _ _ s _ i _"

please help, thanx

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Answers: i'm doing a crossword puzzle and the question is: the biceps action is "________" to the tricep. what is the blank? it;s a 12 letter word, here is what i have so far "_ _ t _ _ _ _ _ s _ i _"

please help, thanx

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antagonistic?

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antagonistic

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