Viscoelastic creep of spine tissue, induced by submaximal spine flexion in sitting, can delay the onset of the flexion-relaxation phenomenon (FRP) and low back reflexes (LBR). Theoretically, these two outcome measures should be correlated; however, no studies have investigated this. This study aims to determine whether 30 minutes of near-maximal spine flexion will affect the onset of FRP and LBR in the lumbar erector spinae (LS) and lumbar multifidus (LM), and to examine the relation between these parameters. 15 participants were recruited (9F, 6M). Spine angle (between L1 and S2) was monitored synchronously with bilateral muscle activity in the LS (L1) and the LM (L4). FRP onset and LBR were measured in a randomized order before and after 30 minutes of slouched sitting. No significant difference was found for any muscle LBR onset time between pre and post-sitting (p > 0.05). A significant increase in FRP onset was found in the RLM (p = 0.016) following sitting. No significant correlation was found between the FRP and the LBR for any muscle. These results suggest that the LBR onset might not be as sensitive as an outcome measure to investigate shorter exposures of sitting as FRP.

坐位时脊柱屈伸过大引起的脊柱组织粘弹性蠕变会延迟屈曲松弛现象（FRP）和下背部反射（LBR）的发作。从理论上讲，这两个结果指标应相互关联。但是，尚无研究对此进行调查。这项研究的目的是确定近30分钟的最大脊柱弯曲是否会影响腰直肌（LS）和腰椎多裂症（LM）中FRP和LBR的发作，并研究这些参数之间的关系。招募了15名参与者（9F，6M）。在LS（L1）和LM（L4）中，与双侧肌肉活动同步监测脊柱角度（在L1和S2之间）。在闲坐30分钟之前和之后，以随机顺序测量FRP发作和LBR。坐前和坐后之间的任何肌肉LBR发作时间均无显着差异（p> 0.05）。坐位后RLM发现FRP发作显着增加（p = 0.016）。对于任何肌肉，在FRP和LBR之间均未发现显着相关性。这些结果表明，LBR发作可能不像调查FRP那样更短的坐姿暴露结果那样灵敏。