Ergonomic sitting is consciously sitting in a way that optimizes one's potential for productive work while minimizing the possibility of injury over time. For many people, this means being able to sit in one position for longer than usual without experiencing pain. The kind of sitting apparatus required for this type of sitting may differ depending on the task at hand, but an office chair is a common tool in this kind of sitting. Given the differences in the bodies of humans depending on build, age, and other factors, the exact method of sitting may vary among different people.
There are a variety of tools that have been developed to encourage ergonomic sitting. Chairs are likely the most common ergonomic sitting tools. Kneeling chairs, adjustable chairs, and active sitting chairs are all tools used for ergonomic sitting, each conforming to a different philosophy of ergonomics. In addition to these tools, there are pieces of furniture designed to encourage a person to sit properly in the chair, such as footrests, desks, and reading stands.
The human body is usually considered a flexible and durable machine, and it is unlikely that sitting comfortably in a normal chair for short periods of time will cause any kind of long-term damage. Most people find that it becomes necessary to sit ergonomically when sitting makes up a major part of one's day. Even then, ergonomic sitting is much more useful for reducing soreness and pain on a daily basis than preventing long-term damage. No matter how one is sitting, it is not usually good for the body to be sedentary throughout the day.
Ergonomic sitting is a conscious act, because even if one is sitting in an optimally designed chair that encourages proper use, if one is not using it in the way it was intended to be used, one receives none of the benefits. One example of misuse of is slouching in an ergonomic office chair, as these chairs were designed to provide lumbar support. Also, if the chair is not a good fit for the user or it has not been adjusted properly, one will experience pain eventually.
It is possible that some aspects of ergonomic sitting are cultural rather than physical. Different people are accustomed to different traditions of sitting and therefore define only certain sitting positions as ergonomic. One physical explanation is that it can be very comfortable and productive for people of a certain culture to sit cross-legged on the floor or a stool, while for others this quickly becomes uncomfortable. Part of this phenomenon is due to the strengthening of certain sitting muscles and not others, because sitting is an activity rather than a passive act. Over time, a person can adapt, turning almost any kind of sitting into fairly ergonomic sitting.