In Dr. Painter’s article (Masters of Internal Arts Lifted Weights!), he mentioned that sitting for long periods of time was not beneficial to the postural muscles and that gravity was one of the ways that these vital contributors to our body positioning ability are kept in optimal shape. Sitting as in meditation or in a work chair is not a bad thing if we keep an erect posture and we limit the amount of time we stay in one position.
Standing up from a sitting position can counteract the effects of lengthy sitting. Each time you stand the nervous system goes into action causing muscular contractions to occur. There is also a shift in body position resulting in inner thoracic pressure changes which stimulate the activity of hormones and lymphatic circulation. So it is healthy to stand up often when sitting for prolonged stretches of time.
It is possible to stave off some of the effects of atrophy that can occur in postural muscles especially in the spine if one maintains a correct alignment with gravity. In short, the head should be balanced over the shoulders and torso which are placed directly over the pelvis. Albeit the legs which are a major player in developing postural muscle strength are not involved with sitting at least the spinal column is getting some benefit by achieving alignment with the forces of gravity.
In the accompanying photos, we see the correct and incorrect positions for sitting and standing. The young lady in the first photo is sitting well but her head is lifted upward. Maintaining this position can have dire effects on the cervical vertebra which in turn can seriously inhibit blood flow to the brain as well as affecting internal organ function. Our second photo shows the correct alignment of head, shoulders, and spine and hips to minimize postural muscle atrophy while sitting. The third shows correct positioning for sitting in a chair for work or meditation. Note that the hips are on the edge of the seat to allow for the circulation of blood through the urogenital area.