Spinal health and sitting: A link to the 24 hour movement continuum

Prolonged sitting is widely recognized as a risk factor for low back disorders and low back pain. Several harmful mechanisms have been proposed, affecting intervertebral discs, posterior lumbo-pelvic ligaments and fasciae, and muscles of the lumbo-pelvic-hip complex. Sitting position is commonly accompanied with some degree of lumbar flexion while in the (semi)static conditions. If such posture is maintained for prolonged periods of time, the spinal tissues slowly deform, leading to a reduction of tissue resistance to loads and eventually (micro)trauma. The tissue strain when sitting is highly dependent on the sitting posture (slouched, upright, reclined etc.) and individual’s spinal tissue health. However, loading of the passive tissues (dynamic loading is favourable) and muscle activation during engaging in physical activity is essential for maintaining and strengthening the tissues’ health. Then a period of rest (i.e. unloading) must be followed, so that the adaptive tissue response could occur. Also, it was shown that insufficient sleep time, high levels of sedentary behaviour, physical inactivity and high levels of physical activity make the existing low back pain worse, while associations with first-time low back pain are not clear. The studies often investigated a single behaviour in isolation. Since there is a strong rationale based on biological plausibility and epidemiological studies, and because time is finite during the day, further studies should take into account all movement behaviours in a 24-hour period. To the best of our knowledge, little is known about the combined effect of time spent in sleep, sedentary behaviour and physical activity on low back pain and low back disorders.