Stature change has been used to indicate the stress associated with specific tasks. Interpretation of stature change is often related to the diurnal change found in healthy participants. However, it has not been determined whether individuals with chronic Low Back Pain (LBP) experience a similar diurnal pattern. The aim of this study is to investigate diurnal stature change in individuals with and without CLBP.

Eight participants with LBP and eight matched asymptomatic controls took part in the investigation. Twenty-four stature measurements were made across a 24 hour period using a standing stadiometer. Differences between the two groups were analysed using two-way ANOVAs (time x group). Correlations between stature change and levels of low-back discomfort were examined using Spearman’s rho.

A clear diurnal variation was found for both groups, with the trough to peak variation in stature of 17.9 mm (LBP) and 17.6 mm (control) groups did not differ significantly (P > 0.05). Both groups experienced their greatest stature change in the 1^st hour after rising 31.3% (LBP) and 44.6% (Control) of the total stature change. Towards the end of the day stature in the chronic LBP group reached a plateau while the control group continued to shrink. Between 2pm and 6pm both groups demonstrated a previously unreported recovery of stature. Reasons underlying this finding could be hormonal, behavioural or due to hydration status and require further investigation. A significant correlation was found between low-back discomfort and stature change in the LBP group, whereby when stature was lost greater discomfort was experienced and when stature recovery discomfort decreased.