title: Influence of passive stiffness of hamstrings on postural stability.
abstract: The aim of the study was to explore whether passive stiffness of the hamstrings influences the strategy of maintaining postural stability. A sample of 50 subjects was selected; the final analyses were based on data of 41 individuals (33 men, 8 women) aged 21 to 29 (mean = 23.3, SD = 1.1) years. A quasi- experimental ex post facto design with repeated measures was used. Categories of independent variables were obtained directly prior to the measurement of the dependent variables. In stage one of the study, passive knee extension was measured in the supine position to assess hamstring stiffness. In stage two, the magnitude of postural sway in antero-posterior direction was measured, while varying the body position on a stabilometric platform, both with and without visual control. The margin of safety was used as a measure of postural control. The magnitude of the margin of safety increased significantly between the open-eye and closed-eye trials. However, although we registered a visible tendency for a larger increase of the margin of safety associated with lower levels of passive hamstrings stiffness, no significant differences were found. Therefore, this study demonstrated that hamstring stiffness did not influence the strategy used to maintain postural stability.
authors.affiliation: Department of Kinesitherapy and Special Methods of Physiotherapy, Academy of Physical Education, Katowice, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Kuszewski
authors.affiliation: Department of Kinesitherapy and Special Methods of Physiotherapy, Academy of Physical Education, Katowice, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Gnat
authors.affiliation: Department of Human Motor Behavior, Academy of Physical Education, Katowice, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Sobota
authors.affiliation: Department of Kinesitherapy and Special Methods of Physiotherapy, Academy of Physical Education, Katowice, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Myśliwiec
keywords: margin of safety; muscle stiffness; postural control; stability