What's the adjective for concentrical? Here's the word you're looking for.
Included below are past participle and present participle forms for the
verbs concenter and concentre which may be used as adjectives within certain contexts.
(physiology) (of a motion) in the direction of contraction of a muscle. (E.g. extension of the lower arm via the elbow joint while contracting the triceps and other elbow extensor muscles; closing of the jaw while flexing the masseter).