The Effect of Time of Day on Lumbar Repositioning Sense Variability in Asymptomatic Participants with Seated Sedentary Behavior Over Two Consecutive Days

Prolonged sitting is associated with sedentary behavior and lumbar repositioning error (LRPE), a factor linked to low back pain (LBP). The measurement of LRPE is commonly used to assess the effectiveness of interventions in preventing LBP. However, the impact of time of day and day-to-day variability on LRPE measurements during a sitting condition remains unclear. The primary aim of the current study is to investigate whether the variability of LRPE in the sitting condition is influenced by the time of day and 2 consecutive days among asymptomatic participants. Fifty asymptomatic participants were enrolled, and LRPE measurements were taken before and after a 30-minute sitting condition conducted in the morning and afternoon over 2 consecutive days. The findings revealed no significant difference in LRPE magnitude between morning and afternoon sessions. However, a slight increase in variability was observed in the afternoon (initial sitting: 1.21 cm, post-sitting: 1.27 cm) compared to the morning (initial sitting: 1.10 cm, post-sitting: 1.16 cm). These findings suggest that future LRPE investigations can be conducted either in the morning or afternoon. However, it is crucial to control for measurement times due to the influence of variability on LRPE outcomes. The study also demonstrated specific levels of natural variation in LRPE measures across different days and times of the day. Any changes beyond the reported results can potentially be attributed to the effects of the intervention. HIGHLIGHTS A meaningful response should exceed the values of 1.10 cm (initial sitting) and 1.16 cm (after the 30-minute sitting) in the morning, and 1.21 cm (initial sitting) and 1.27 cm (after the 30-minute sitting) in the afternoon between consecutive days Controlling measurement time is crucial in lumbar repositioning error investigations to mitigate the impact of variability on outcomes This information guides future investigations and establishes meaningful benchmarks for assessing intervention effectiveness GRAPHICAL ABSTRACT