Mechanical Engineering - Theses
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ItemThe relationship between performance on a single leg squat task and clinical measures of strength, balance and functional performance( 2012)The single leg squat task is frequently used in clinical sports medicine to provide a simple and convenient assessment of lower-extremity dynamic control. It is commonly used to screen for abnormal hip and knee motions, which have been implicated in the subsequent development of lower limb injuries. The single leg squat is thought to be a particularly important assessment tool when examining people with patellofemoral pain syndrome; a common overuse injury often found in runners that is frequently associated with altered lower-extremity control. Clinicians often assume that poor functional task ability indicates underlying deficits in lower limb strength, balance or functional capacity in general. However, such subjective visual assessments rarely undergo investigation and this relationship has not yet been empirically studied. This study investigated the relationship between performance on the single leg squat task using a qualitative rating scale of Good, Fair and Poor categories, and a range of specific outcome measures, including hip and trunk strength, hip range of motion, lower limb alignment, as well as sports-specific tests of functional capacity and balance. 79 healthy runners were recruited, as runners demonstrate a high incidence of lower-limb injury, and screening for altered hip and knee movement patterns may help to identify those considered most at risk for developing overuse running conditions such as patellofemoral pain syndrome. Single leg squat performance was videotaped for subsequent visual assessment by a panel of physiotherapists. Participants were tested on several objective clinical measures including hip strength (via hand-held dynamometry), hip rotation range of motion (with a gravity inclinometer), lower-limb alignment (static knee valgus and foot posture), sports-specific tests of functional capacity (one-leg rise, side hop and hop for distance measures) and balance (measured as centre of pressure excursion on a Wii Balance Board). The main findings were that female participants with Poor performance on the single leg squat task had significantly reduced hip abduction strength (p = 0.011) and functional capacity on the one-leg rise (p = 0.043) and side hop (p = 0.007) measures than those rated as Good. This difference was not found for male participants. Hip range of motion and lower limb alignment measures were not associated with single leg squat performance for either men or women. For a subset of participants (n = 49), Poor single leg squat performers displayed significantly worse balance as indicated by greater mediolateral postural sway on the Wii Balance Board, compared to the Good group (p = 0.001). Identification of impairments associated with Poor single leg squat performance can aid clinicians in planning prevention strategies for athletes at risk of patellofemoral pain. Further research is required to investigate whether similar associations exist within different sporting participants and for individuals with lower limb injury in particular patellofemoral pain. As clinical expertise and emerging research into patellofemoral pain syndrome indicates that treatment strategies can result in greater improvements if these treatments are targeted towards the subgroup of people who exhibit the underlying impairments, early identification of people with abnormal lower extremity dynamic control via a simple clinical tool, could help to guide practitioners in the prescription of preventative treatments.