Human posture

Human positions refer to the different physical configurations that the human body can take.

There are several synonyms that refer to human positioning, often used interchangeably, but having specific nuances of meaning.

While not moving, a human is usually in one of the following basic positions:

Although quiet standing appears to be static, modern instrumentation shows it to be a process of rocking from the ankle in the sagittal plane. The sway of quiet standing is often likened to the motion of an inverted pendulum. There are many mechanisms in the body that are suggested to control this movement, e.g. a spring action in muscles, higher control from the nervous system or core muscles.

Although standing isn't dangerous per se, there are pathologies associated with it. One short term condition is orthostatic hypotension, and long term conditions are sore feet, stiff legs and low back pain.

Sitting requires the buttocks resting on a more or less horizontal structure, such as a chair or the ground. Special ways of sitting are with the legs horizontal, and in an inclined seat. While on a chair the shins are usually vertical, on the ground the shins may be crossed in the lotus position or be placed horizontally under the thigh in a seiza.

Squatting is a posture where the weight of the body is on the feet (as with standing) but the knees and hips are bent. Squatting may be either:

In contrast, sitting, involves taking the weight of the body, at least in part, on the buttocks against the ground or a horizontal object such as a chair seat. It is possible to squat with one leg and assume another position (such as kneeling) with the other leg. may involve squatting, kneeling or a combination of the two. Among Chinese, Southeast Asian, and Eastern European adults, squatting often takes the place of sitting or standing.

...
Wikipedia