Thirty minutes identified as the threshold for development of pain in low back and feet regions, and predictors of intensity of pain during 1-hour laboratory-based standing in office workers.

This study with 40 office workers investigated a) the effect of time spent standing on low back and lower limb pain during 1-hour laboratory-based task; b) the minutes after which significant increase in pain are likely; and c) which individual, physical and psychosocial factors predicted pain. The primary outcome was bodily location of pain and intensity on a 100mm Visual Analogue Scale recorded at baseline and every 15 minutes. Measurements included trunk and hip motor control and endurance. Self-report history of pain, physical activity, psychosocial job characteristics, pain catastrophizing and general health status were collected. Univariate analysis and regression models were included. The prevalence of low back pain increase from 15% to 40% after 30 minutes while feet pain increased to 25% from 0 at baseline. The intensity of low back and lower limb pain also increased over time. Thirty minutes was identified as the threshold for the development and increase in low back and feet pain. Modifiable factors were associated with low back pain intensity - lower hip abductor muscle endurance and poorer physical health and with feet symptoms - greater body mass index and less core stability