Someone who is tense is unlikely to hit out, because the muscles that move joints are contracted symmetrically.
Someone who is restless or agitated is more likely to hit out.

The tone of our somatic muscles is varied through muscle spindles, which is why we get tension headaches unexpectedly.
Yawning and stretching standardise the length of somatic muscle fibres.

Facial tension shows a stare, widened, unblinking eyes and immobility of the cheeks and mouth.

Tennis players skip between points to relax tensed muscles into the ready position, in which potential movements reverberate with a degree of activation that is under inhibitory control.

Tennis players who tighten the muscles of their dominant forearm at moments of success increase the risk of tennis elbow, due to tearing of the muscle fibres of extensor carpi radialis brevis from their attachment to the lateral epicondyle of the humerus.