ABSTRACT
PURPOSE: Dance is a physically demanding activity, with 50-85% of dancers suffering injury during a single performance season. The majority of dancers' injuries are in the lower extremity (LE) and chronic in nature. These injuries often arise when causal factors are not identified early and addressed before they ultimately result in an injury. Practitioners often use movement screens such as the Functional Movement Screen™ (FMS™) to detect and quantify kinetic chain dysfunction. Prior researchers have suggested that these screens can stratify at-risk individuals and allow practitioners to devise targeted interventions to reduce their injury risk. However, whether the FMS™ can identify at-risk dancers remains unclear. Thus, the purpose of this study was to examine whether FMS™ scores predicted injury risk in collegiate dancers. METHODS: In this prospective study, 43 collegiate dance majors (34 female, 9 male; 18.3 ± 0.7yrs; 163.9 ± 7.3cm; 60.8 ± 8.1kg) in a program which emphasizes modern dance were scored on the seven FMS™ movements (scale 0-3, total maximum score=21) where 3=movement completed without compensation, 2=movement completed, but with compensation(s), 1=unable to complete movement, 0=pain during movement or during clearing tests as described in prior literature at the start of the academic year. An in-house certified athletic trainer documented dancer's overall and LE injuries over an academic year (40 weeks). Separate Receiver Operator Characteristic (ROC) curve analyses examined whether composite FMS™ score predicted (1) Overall or (2) LE injury status. RESULTS: The subjects FMS™ scores were 16.2 + 1.7 (range=11-19). Twenty dancers were injured, whereas 23 remained injury-free. Injured dancers had 55 overall (1.28 injuries/dancer) and 44 LE injuries (1.02 LE injuries/dancer). FMS™ score did not predict overall (AUC=.28, SE=.08, p=.02, 95%CI=.13-.43) or LE injury risk (AUC=.38, SE=.1, p=.21, 95% CI=.21-.56). DISCUSSION: While nearly half of the dancers in this group suffered from injury over the year, composite FMS™ scores did not predict overall or LE injury risk in collegiate dancers. Dancers face unique and challenging physical demands that distinguish them from traditional sport-athletes including greater ranges of movement during performance. Thus, the FMS™ may not be sensitive enough to distinguish 'appropriate' from 'excessive' mobility and adequately identify injury risk in dancers. Overall, it is suggested that practitioners should use caution before using the FMS™ as a primary screening mechanism to identify collegiate dancers at overall or LE injury risk. LEVEL OF EVIDENCE: 2.
ABSTRACT
Ambegaonkar, JP, Schock, CS, Caswell, SV, Cortes, N, Hansen-Honeycutt, J, and Wyon, MA. Lower extremity horizontal work but not vertical power predicts lower extremity injury in female collegiate dancers. J Strength Cond Res 32(7): 2018-2024, 2018-Dancers often perform powerful and explosive movements that require adequate lower extremity (LE) activity in horizontal and vertical directions. We examined whether these measures were interrelated and whether they predicted LE injury status in dancers using binary logistic regressions and receiver operator characteristic (ROC) curve analyses. Forty-three collegiate female dancers (18 ± 0.7 years; 162.6 ± 5.9 cm; 59.4 ± 7.1 kg) performed single leg hop (SLH, m) and vertical jump (VJ, cm) tests. Single leg hop and VJ distances were used to calculate SLH norm (as a % of body height) and vertical power (vPower, watts). Lower extremity injuries and dance exposure hours (DEhrs) were recorded for 16 weeks. Dancers had 51 injuries resulting in a 3.7/1,000 DEhr injury incidence rate (95% confidence interval [CI]: 2.7-4.7). Twenty dancers were injured, whereas 23 remained injury free. Injured dancers had significantly lower SLH norm than noninjured dancers (t = 2.7, p = 0.009, 85.2 ± 11.2% vs. 76.8 ± 8.4%, respectively), but vPower was similar (t = 0.6, p = 0.53, injured = 2,632.0 ± 442.9 watts, noninjured = 2,722.7 ± 480.0 watts). SLH norm, but not vPower significantly predicted injury status χ(1,43) = 5.9, p = 0.02. Specifically, an SLH norm cut-off value of 78.2% identified dancers at injury risk (area under the curve = 0.73, SE = 0.08, p = 0.01, 95% CI = 0.57-0.89, sensitivity = 0.75, specificity = 0.70). However, vPower was not able to identify dancers at risk (p = 0.36). vPower had moderate relationships with SLH norm (r = 0.31, p = 0.04). Compared with injured dancers, noninjured dancers had greater SLH norm but similar vPower. Only SLH norm predicted injury status in female collegiate dancers. Thus, the SLH test may possibly predict LE injury risk in dancers. Strength and conditioning coaches can prospectively use baseline SLH test screenings to identify dancers whose SLH is less than 78.2% of their height because these dancers may have increased probability of LE injury risk. Coaches can then include horizontal direction exercises when designing training programs and examine whether these programs reduce LE injury risk in female collegiate dancers.
