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The role of M. popliteus in unpredictable and in self‐initiated balance provocations
Author(s) -
Stensdotter AnnKatrin,
Holmgren Christer,
Dalén Tore,
HägerRoss Charlotte
Publication year - 2006
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.20057
Subject(s) - knee joint , physical medicine and rehabilitation , kinematics , balance (ability) , medicine , jumping , joint (building) , psychology , physical therapy , surgery , physics , engineering , physiology , classical mechanics , architectural engineering
The purpose of this study was to determine whether m. popliteus (POP) activity would contribute to the control of knee joint position in unpredictable and in self‐initiated provocations of standing balance. Ten healthy women (age 25.2 ± 4.5 years, means and SD) without known knee pathology were tested for postural reactions (1) to unpredictable support surface translations in anterior and posterior directions, and (2) in self‐initiated balance provocations in a reaction time (RT) forward reach‐and‐grip task. Electromyographic activity was recorded from POP and other leg muscles plus the deltoid muscle. Three‐dimensional kinematics were captured for the knee joint and the body centre of mass was calculated. POP was active first of all the muscles recorded, regardless of translation direction, and knee joint movements elicited were either knee extension or external rotation of the tibia. In the RT task, the POP was active after initiation of reaching movement, and there was little consistency in the kinematic response. POP activity was not direction specific in response to support surface translation, but appeared triggered from reactive knee joint movement. The response to the support‐surface translation suggests that POP served to control knee joint position rather than posture. In the RT task, we could not deduce whether POP activity was attributed to knee joint control or to postural control. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:524–530, 2006