Male Spine Motion During Coitus

DOI: 10.1097/BRS.0000000000000518 Study Design. Repeated measures design. Objective. To describe male spine movement and posture characteristics during coitus and compare these characteristics across 5 common coital positions. Summary of Background Data. Exacerbation of pain during coitus due to coital movements and positions is a prevalent issue reported by low back pain patients. A biomechanical analysis of spine movements and postures during coitus has never been conducted. Methods. Ten healthy males and females engaged in coitus in the following preselected positions and variations: QUADRUPED, MISSIONARY, and SIDELYING. An optoelectronic motion capture system was used to measure 3-dimensional lumbar spine angles that were normalized to upright standing. To determine whether each coital position had distinct spine kinematic profi les, separate univariate general linear models, followed by Tukey’s honestly signifi cant difference post hoc analysis were used. The presentation of coital positions was randomized. Results. Both variations of QUADRUPED, mQUAD1 and mQUAD2, were found to have a signifi cantly higher cycle speed than mSIDE ( P = 0.043 and P = 0.034, respectively), mMISS1 ( P = 0.003 and P = 0.002, respectively), and mMISS2 ( P = 0.001 and P < 0.001, respectively). Male lumbar spine movement varied depending on the coital position; however, across all positions, the majority of the range of motion used was in fl exion. Based on range of motion, the least-to-most recommended positions for a male fl exion-intolerant patient are mSIDE, mMISS2, mQUAD2, mMISS1, and mQUAD1. Conclusion. Initial recommendations—which include specifi c coital positions to avoid, movement strategies, and role of the