Underlying Theoretical Components of the Functional Movement Screen

Abstract

The purpose of this study was to determine the number of constructs that can be identified in the Functional Movement Screen and determine which of the individual tests loaded into each construct. Three hundred and thirty male and female subjects, between the ages of 17 and 24, were recruited from a division I varsity athletics program. Subjects were asked to wear athletic shorts, a fitted athletic shirt, and athletic shoes. All subjects completed all seven FMS tests (Deep Squat, Hurdle Step, In-Line Lunge, Shoulder Mobility, Active Straight-Leg Raise, Trunk Stability Push-Up, and Rotational Stability). Athletes who completed the screen immediately following sport participation were excluded (N= 6) and those who wore ankle braces or any high-top shoe were also excluded (N=2). Two athletes were excluded because they suffered from delayed onset muscle soreness that inhibited their ability to perform the screen. One athlete was removed from the study because of a wrist injury that prevented the completion of all seven tests. Each test was completed, at most, three times and the best score was used for the final score. The FMS tests were evaluated on a four-point grading scale, 0-3, with a possible total score of 21. After exclusion criteria were evaluated, 319 subjects’ data was analyzed for this study. Of those who completed the screen 283 (88.3%) had no previous knowledge of the FMS and 36 (11.3%) had previously done the screen. Age of subjects was 19.7 ± 1.4 years. Subjects’ height was 178.1 ± 0.7 cm and weight was 73.7 ± 14 kg. Fourteen varsity sports were included in this study. Data was analyzed using exploratory factor analysis. Descriptive statistics and frequencies were also calculated. The exploratory factor analysis revealed that six of the seven items fit into three factors that met the criteria of an eigenvalue of 1.0 or greater and had a portion of more than 5% of the variance. Factor 1 included deep squat, hurdle step, inline lunge, and active straight leg raise and accounted for 9.8% of the variance. Theoretically, these four tests loaded together because they all test lower extremity mobility and stability. All of the tests within this factor require proper mobility of the ankle, knee, and hip for the exercise to be done correctly. Factor 2 included the rotary stability test and accounted for 5.5% of the variance. This is the only test within the FMS that has the individual in a quadruped position. Further, the rotary stability test measures stability of the core, shoulders, and pelvis in a multi-plane movement pattern. Factor 3 included the push-up test and accounted for 5.1% of the variance. This test is the only test that challenges the upper body in a closed-kinetic chain manner and assesses spinal stability in a neutral position. Overall, these 3 factors accounted for 20.4% of the variance in the performance of the functional movement screen. For this analysis, the suppression threshold was set at 0.3. At this threshold, each test only loaded into one factor. The shoulder mobility did not load onto any factor. Overall, this study is the starting point in establishing a theoretical framework for the FMS.