Maintaining a nearly immobile stance for hours at a time is known as

Catalepsy

Explanation:

Catalepsy: (From the Greek katalambanein, suspend.) Momentary loss of voluntary contractility of the muscles of animal life, with hypertonia that opposes any attempt at mobilization, and attitude of the trunk members to preserve the attitudes that are printed on them . It is the flexibilitas cerea of ​​the old authors. Catalepsy is observed in schizophrenia, hysteria, hypnotic sleep, in the course of different psychoses, and also in Parkinsonian and post-encephalitic syndromes.

Catalepsy is a biological state in which the person lies motionless, in apparent death and without vital signs, when in fact he is in a conscious state, which in turn can vary in intensity: in certain cases the individual is in A vague state of consciousness.

Catalepsy, comes from catapult, and narcolepsy, a conjunction of both words, which in Greek means, not so dead. Extreme rigidity, increased muscle tone and absence of voluntary mobility, which constitutes a symptom of catatonia.