Background: Altered proprioception may be a factor in low back pain (LBP). Sustained end-range flexion appears to reduce proprioceptive acuity, as assessed by joint reposition sense, in healthy subjects. However, no study has investigated whether this occurs with shorter periods of lumbo-pelvic flexion or extension. The aim of this study was to examine the effects of a brief period (180 seconds) of sustained lumbo-pelvic spine extension and flexion on repositioning sense in pain-free subjects, compared to immediate repositioning sense (5 seconds). Methods: Lumbo-pelvic repositioning sense was measured in 17 pain-free subjects. Participants were required to replicate a defined target position of the lumbo-pelvic region after: (a) lumbo-pelvic extension of 5 seconds and 180 seconds; and (b) lumbo-pelvic flexion of 5 seconds and 180 seconds. Results: Two-way ANOVA¿s (duration x direction) found no significant differences (p>0.05) in repositioning accuracy, in terms of either absolute error (AE) or constant error (CE). There were no significant effects for direction (AE, p=0.244; CE, p=0.298), duration (AE, p=0.756; CE, p=0.657) or their interaction (AE, p=0.340; CE, p=0.288). Conclusions: Lumbo-pelvic repositioning sense was not altered after a brief period of either sustained extension or flexion. The duration which the postures were sustained for may have been insufficient to alter repositioning sense. While prolonged end-range lumbo-pelvic postures may increase vulnerability to pain and injury, it is unclear what constitutes a safe duration of exposure to end-range postures. © 2010 - IOS Press and the authors. All rights reserved.