Effect of Time of Day on the Magnitude of Stature Change Response Variability in Participants with Chronic Low Back Pain on Consecutive 2 Days

Measurements of stature change have been used to compare spinal loading in the sitting posture. However, it is difficult to interpret whether the stature change response recorded is truly due to an intervention or to the natural fluctuation of stature change response between the days. The aim of this study was to investigate the effect of time of day (morning and afternoon) on the variability of stature change in participants with chronic low back pain (CLBP) on 2 consecutive days. Forty-four participants with CLBP attended 2 sessions (morning and afternoon) of stature change testing on 4 separate days. A stature change response of more than 0.985 mm in the morning and 1.149 mm in the afternoon on 2 consecutive days indicates that an intervention itself has influenced stature change measurement in CLBP participants. The magnitude of stature change response on different days and times of day established specific levels of natural variation meaning changes above these levels can be attributed to intervention effects in participants with CLBP. HIGHLIGHTS The findings suggest that it is important to control the time at which stature change investigations are conducted Seated stadiometry measurement, changes above 0.985 mm (morning) and 1.149 mm (afternoon) can be attributed to intervention effects between consecutive 2 days The results of the current study presented no significant difference in magnitude of stature change response in the morning versus the afternoon in chronic low back pain participants GRAPHICAL ABSTRACT