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The Relationship Between Knee Strength Capabilities, Postural Control and Slip Severity

Wyszomierski, Sarah Anne (2008) The Relationship Between Knee Strength Capabilities, Postural Control and Slip Severity. Master's Thesis, University of Pittsburgh. (Unpublished)

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Slips and falls are serious public health concerns in older populations. Understanding relationships between propensity to slip and biomechanical and physiological characteristics is important to identify factors responsible for slip-initiated falls and to improve slip/fall prevention. Thus, the first goal of this thesis was to investigate the relationship between knee flexion/extension strength and slip severity. Reduced muscle strength is associated with aging and falls. Knee corrective moments generated during slipping assist in balance recovery. Isometric knee flexion/extension peak torque, rate of torque development (RTD), and angular impulse were measured in 30 young and 28 older subjects. Motion data were collected for an unexpected slip during self-paced walking. Slips were characterized as non-hazardous or hazardous based on a 1.0 m/s peak slip velocity threshold measured at the slipping heel. Within-gender regressions relating strength to slip hazardousness and age group revealed significantly greater left knee extension RTD and angular impulse in young males experiencing non-hazardous versus hazardous slips. Findings were not evident in older males, who perhaps implement cautious walking styles, allowing less reliance on post-slip recovery reactions. Other strength variables were not associated with hazardousness. Thus, rapid knee extension force generation may assist balance recovery from hazardous slips.Decreased postural stability is also associated with aging and falls. Therefore, the second goal of this project was to investigate the association between ability to integrate sensoryinformation important for balance and slip severity. The Sensory Organization Test (SOT) was administered and COP standard deviation (COP ST DEV) and path length (PATH LENGTH) were calculated for each condition. COP ST DEV, PATH LENGTH, and variable ratios were regressed on age group and hazardousness within condition. Significantly greater PATH LENGTH and its subsequent effects on ratio variables associated with Condition 4, in which somatosensation was rendered inaccurate, were evident in individuals experiencing hazardous versus non-hazardous slips. Conditions in which vestibular or visual information was rendered inaccurate or missing were not associated with hazardousness. Somatosensory channels detect slips first at the shoe-floor interface and thus may be especially important in early detection and response to a slip.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Wyszomierski, Sarah
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairCham, Rakié
Committee MemberVan Swearingen, Jessiejessievs@pitt.eduJESSIEVS
Committee MemberRedfern,
Date: 8 September 2008
Date Type: Completion
Defense Date: 27 May 2008
Approval Date: 8 September 2008
Submission Date: 11 June 2008
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: MSBeng - Master of Science in Bioengineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: lower extremity; muscle force; muscle torque; postural stability; falls; sensory organization
Other ID:, etd-06112008-110452
Date Deposited: 10 Nov 2011 19:46
Last Modified: 15 Nov 2016 13:44


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