Habitual posture and weekly time spent sitting do not contribute to the lumbopelvic curvature during active unilateral knee extension in sitting test.

[Purpose] To investigate whether habitual pelvic posture and time spent sitting are primary contributing factors to performance in the active unilateral knee extension in sitting test in young people. [Participants and Methods] The participants' ages ranged from 20 to 40 years. LUMOback, a wearable electronic device, was used to measure the proportion of the days spent in a neutral pelvic posture (posture score) and time spent sitting over a week. The lumbopelvic sagittal curvature from T12 to S2 (θ) during the active unilateral knee extension in sitting test was also assessed using a flexible ruler. A multiple regression analysis was performed with the primary independent variables of the posture score and time spent sitting, undertaking priori considerations of potential confounders of sex, and pain condition on the θ value. [Results] Eighty participants (21.7 ± 3.8 years) were enrolled in the study (24 males and 56 females). Neither the posture score nor time spent sitting statistically significantly contributed to the θ value. [Conclusion] Neither the proportion of the day spent with neutral pelvic posture nor time spent sitting detected by LUMOback was the primary contributing factor to the active unilateral knee extension in sitting test performance.