title: An Examination of the Stretch-Shortening Cycle of the Dorsiflexors and Evertors in Uninjured and Functionally Unstable Ankles.
abstract: OBJECTIVE: To determine if there were differences in concentric peak torque/body-weight (PT/BW) ratios and concentric time to peak torque (TPT) of the dorsiflexors and evertors in uninjured and functionally unstable ankles using a stretch-shortening cycle (SSC) protocol on an isokinetic dynamometer. DESIGN AND SETTING: We employed a case-control study design to examine the test subjects in a climate-controlled athletic training/sports medicine research laboratory. SUBJECTS: Thirty subjects volunteered to participate in this study, 15 with unilateral functional ankle instability and 15 matched controls. MEASUREMENTS: Participants were assessed isokinetically using an SSC protocol for the dorsiflexors and evertors at 120 and 240 degrees.s(-1), bilaterally. Strength was assessed using PT values normalized for body mass. Concentric TPT measurements were also compared between the groups. RESULTS: No differences in concentric PT/BW ratios or concentric TPT were evident between the groups (P >.05). Additionally, there were no differences in these measurements between the ankles for the same motion and speed between the ankles in the subjects with functional instability. CONCLUSIONS: Using the SSC protocol as a measure of ankle function and the stretch-reflex phenomenon, we found no evidence to support the notion that differences in strength and TPT in the active, conscious state exist between those with functional ankle instability and a group of healthy control subjects.
authors.affiliation: University of Florida, Gainesville, FL.
authors.forename: Gary K
authors.initials: GK
authors.lastname: Porter
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Kaminski
authors.forename: Brian
authors.initials: B
authors.lastname: Hatzel
authors.forename: Michael E
authors.initials: ME
authors.lastname: Powers
authors.forename: MaryBeth
authors.initials: M
authors.lastname: Horodyski