Limb Symmetry Index in Collegiate Dancers Using the Modified Star Excursion Balance Test and Single Leg Hops.

Abstract

Introduction: Dance is physically demanding and often involves unilateral movements performed within a small base of support. Prior authors have reported that dancers use one leg preferentially over the other (ie, lower extremity asymmetry). Increased leg asymmetry-quantified using the Limb Symmetry Index (LSI), is associated with increased injury risk. Clinicians often use LSI to make return-to-performance decisions (eg, >85% performance on injured vs non-injured limb). However, limited research has examined leg symmetry in collegiate dancers. Purpose: To examine LSI in collegiate dancers using the modified star excursion balance test (mSEBT) and single-leg hop test (SLH). Methods: 120 healthy collegiate dancers (105 females, 15 males; 18.31 ± 0.80 years; 164.18 ± 7.12 cm; 61.18 ± 8.46 kg) performed the mSEBT (normalized to % leg-length: LL) in the anterior, posteromedial, and posterolateral directions and the SLH test (normalized to % body height: BH) across both legs using previously published guidelines. mSEBT scores were averaged for all three directions per leg. SLH scores were averaged per leg. LSI was calculated as (lower value/higher value) × 100 to obtain a percentage. Results: Mean mSEBT scores were 95.7 ± 14.2%LL (lower score) and 96.6 ± 14.3%LL (higher score). Dancers LSI for mSEBT was 99.1 ± 0.9%. Mean SLH scores were 82.8 ± 13.3%BH (lower score) and 86.4 ± 13.5%BH (higher score). Dancers LSI for SLH was 95.9 ± 3.5%. Conclusions: Dancers' LSI% was greater than 90% for mSEBT and SLH, concurrent with the normal values of LSI > 90% in healthy, physically active adults. Dancers displayed lower leg symmetry. Practitioners can thus use the contralateral leg as a reference for return-to-performance decisions following injury in dancers. LSI should be integrated into a comprehensive screening process to identify large (>85%) asymmetries and guide training programs post-injury to assist educators and practitioners' evidence-based return-to-performance decisions. Future researchers should examine LSI in other dance genres and across levels.Level of Evidence: 2C.