Movement assessments are used to determine injury risk, physical competency, and returnto-activity. The Functional Movement Screen (FMS) was developed to identify movement competency and susceptibility to injury. Although this tool is frequently used, its efficacy and validity have not been conclusively determined. The three studies presented in this thesis explored the validity of the FMS through comparison to existing validated tests and statistical measures of internal validity.

The purpose of Study 1 was to determine if performance in the FMS and the Y-Balance Test (YBT) were related. The YBT is a measure of dynamic postural control, a component of functional movement. This study showed partial correspondence between the tests, though the correlation was not strong enough to consider them interchangeable nor that dynamic

ostural control was a large component of the FMS score The purpose of Study 2 was to investigate the factorial validity of the FMS. This is particularly important as the aggregate score of the FMS test is used to determine injury risk. Exploratory factor analysis of a sample of healthy adults revealed that the FMS has a multidimensional factor structure, and therefore using the aggregate score of the FMS is not

appropriate. The purpose of Study 3 was to assess whether the factor structure of the FMS is consistent across different populations. We compared exploratory factor analyses and factor congruence of the FMS in a general population sample, varsity athletes, and firefighters. We observed a two-factor structure that varied in composition between groups, suggesting that the factor structure of the FMS may differ, according to population.

Overall, this thesis determined that the aggregate score of the FMS is not a valid tool for evaluating functional movement. Although the FMS does appear to partially quantify dynamic postural control, it is also characterized by a lack of consistency between populations, and a multidimensional factor structure. This suggests that the aggregate score should not be used to interpret an individual’s movement proficiency or susceptibility to injury