Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.
2016–2017 Academy Awards Submission
Successful Defence: 28 October 2016
What did I do?
The first aim of my PhD involved reviewing the literature to determine whether common, established physical performance tests demonstrated predictive validity with regard to lower extremity injuries in athletic populations.
The second aim was to prospectively examine the association of physical performance tests performed in the preseason with injury acquired during the season.
Why did I do it?
As a clinician scientist, it is my personal belief, and one shared with others,1 2 that injury is best explained by a dynamic systems model. Within this model, there are numerous inter-related variables such that the change in one variable affects all other variables. As I spoke with clinicians, an increasing number were speaking with certainty that asymmetry on slowly performed tests was predictive of injury. This simple mechanism of testing did not seem to fit with the dynamic nature of athletic injury. I went in search of evidence on the predictive ability of current performance tests and to determine whether simple tests had any association with injury.
How did I do it?
First, I performed two systematic reviews of the quality of the literature and the quality of the statistical properties of physical performance tests related to injury in the lower extremity in athletes.3 4 Finding little valuable guidance from published literature, I used a consensus-based approach with our healthcare and conditioning team to develop a novel set of tests and used the tests over a 3-year period in a cohort of 349 National Collegiate Athletic Association Division I athletes from multiple sports.5 Athletes were assessed with 11 tests (including but not limited to single leg squat, double leg squat, side plank hip abduction and adduction and forward and lateral lunge) in the preseason and followed throughout the season with documentation of all injuries in a centralised database. After 3 years, factor analysis, a statistical method allowing examination of the interdependence of many variables (tests), was used to explore for latent constructs represented by individual tests. This method of analysis fits nicely with the dynamic systems model as opposed to say, performing a straight multiple regression with all tests as independent variables. After factor analysis, multiple regression was used to examine the relationship of these constructs (test combinations) to lower extremity injury.
What did I find?
From the systematic reviews, only one established test, the modified star excursion/lower quarter Y-balance test showed some injury-related predictive ability when composite reach score was less than 94% or in the presence of an anterior reach deficit of 4 cm or greater. However, the predictive validity of the Y-balance test had not been confirmed by independent research and was validated in a population (high school basketball players) who did not apply to the population that I was about to study. From the 3-year prospective study, factor analysis produced five constructs: active motion, hip stability, power, flexibility and motor control. Univariate regression found that active motion, hip stability and motor control were significant variables. Multiple regression indicated that no construct was associated with traumatic injury, that the constructs of active motion and hip stability were associated with overall injury (Nagelkerke R2 of 0.17) and that motor control was associated with overuse injury (Nagelkerke R2 of 0.08). Perhaps, most interesting was that past injury was not a predictor of future injury in either of these models.
What is the most important clinical impact/practical application?
The strengths of this dissertation are twofold: first, the mass appeal of the finding that simple, clinician-friendly, tests (single leg squat, double leg squat, forward lunge, lateral lunge, side plank hip abduction and adduction) and constructs (motor control, stability, and hip mobility) are associated with injury; second, that the constructs of active motion, hip stability and motor control modified the relationship between past injury and future injury (a virtual certainty according to previously published literature). In other words, medical professionals, exercise physiologists and coaches at all levels now have the ability to perform some simple test combinations to capture constructs that are associated with future injury in their athletes.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.