Variation in lumbar spine mobility measured over a 24-hour period.

An electronic device for the measurement of three-dimensional movements, the Polhemus Navigation Sciences 3Space Isotrak system, was used to measure the range of movement in the lumbar spine of: (1) 10 young adults pre- and post-normal night-time sleep; (2) 10 young adults tested every 2 h over a 24-h period. The results obtained for the 10 subjects tested pre-/post-sleep showed there to be significant decreases in flexion, extension and lateral bend post-sleep. Axial rotation was not seen to alter significantly. The results obtained for the 10 subjects tested over a 24-h period showed movement during the day to be significantly more than at night. A decrease in the range of all movements except extension was observed when testing subjects in the early hours of the morning (after they had been supine for a minimum of 4 h) relative to the range observed from mid-afternoon to early evening.