PMID- 25085609 OWN - NLM STAT- MEDLINE DCOM- 20150409 LR - 20250529 IS - 1522-1598 (Electronic) IS - 0022-3077 (Print) IS - 0022-3077 (Linking) VI - 112 IP - 3 DP - 2014 Aug 1 TI - Neuromechanical interference of posture on movement: evidence from Alexander technique teachers rising from a chair. PG - 719-29 LID - 10.1152/jn.00617.2013 [doi] AB - While Alexander technique (AT) teachers have been reported to stand up by shifting weight gradually as they incline the trunk forward, healthy untrained (HU) adults appear unable to rise in this way. This study examines the hypothesis that HU have difficulty rising smoothly, and that this difficulty relates to reported differences in postural stiffness between groups. A wide range of movement durations (1-8 s) and anteroposterior foot placements were studied under the instruction to rise at a uniform rate. Before seat-off (SO) there were clear and profound performance differences between groups, particularly for slower movements, that could not be explained by strength differences. For each movement duration, HU used approximately twice the forward center-of-mass (CoM) velocity and vertical feet-loading rate as AT. For slow movements, HU violated task instruction by abruptly speeding up and rapidly shifting weight just before SO. In contrast, AT shifted weight gradually while smoothly advancing the CoM, achieving a more anterior CoM at SO. A neuromechanical model revealed a mechanism whereby stiffness affects standing up by exacerbating a conflict between postural and balance constraints. Thus activating leg extensors to take body weight hinders forward CoM progression toward the feet. HU's abrupt weight shift can be explained by reliance on momentum to stretch stiff leg extensors. AT's smooth rises can be explained by heightened dynamic tone control that reduces leg extensor resistance and improves force transmission across the trunk. Our results suggest postural control shapes movement coordination through a dynamic "postural frame" that affects the resistive behavior of the body. CI - Copyright (c) 2014 the American Physiological Society. FAU - Cacciatore, Timothy W AU - Cacciatore TW AD - UCL Institute of Neurology, London, United Kingdom. FAU - Mian, Omar S AU - Mian OS AD - UCL Institute of Neurology, London, United Kingdom. FAU - Peters, Amy AU - Peters A AD - UCL Institute of Neurology, London, United Kingdom. FAU - Day, Brian L AU - Day BL AD - UCL Institute of Neurology, London, United Kingdom brian.day@ucl.ac.uk. LA - eng GR - G0802073/MRC_/Medical Research Council/United Kingdom GR - 084870/Z/08/Z/WT_/Wellcome Trust/United Kingdom PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20140514 PL - United States TA - J Neurophysiol JT - Journal of neurophysiology JID - 0375404 SB - IM MH - Adult MH - Aged MH - Exercise Movement Techniques/*methods MH - Female MH - Humans MH - Leg MH - Male MH - Middle Aged MH - Models, Neurological MH - Movement/*physiology MH - Muscle, Skeletal/physiology MH - Postural Balance/physiology MH - Posture/*physiology MH - Professional Competence MH - Torso PMC - PMC4122698 OTO - NOTNLM OT - Alexander technique OT - balance OT - movement OT - muscle tone OT - posture OT - sit-to-stand EDAT- 2014/08/03 06:00 MHDA- 2015/04/10 06:00 PMCR- 2014/05/14 CRDT- 2014/08/03 06:00 PHST- 2014/08/03 06:00 [entrez] PHST- 2014/08/03 06:00 [pubmed] PHST- 2015/04/10 06:00 [medline] PHST- 2014/05/14 00:00 [pmc-release] AID - jn.00617.2013 [pii] AID - JN-00617-2013 [pii] AID - 10.1152/jn.00617.2013 [doi] PST - ppublish SO - J Neurophysiol. 2014 Aug 1;112(3):719-29. doi: 10.1152/jn.00617.2013. Epub 2014 May 14.