Biomechanical quantification of deadbug bridging performance in competitive alpine skiers: Reliability,reference values,and associations with skiing performance and back overuse complaints

Objectives(1) To study the reliability of quantifying rear-chain stabilization capacity during deadbug bridging (DBB), (2) to provide reference values for competitive alpine skiers, and (3) to study associations with age, anthropometrics, maturation, skiing performance and back overuse complaints.DesignCross-sectional.SettingBiomechanical field experiment including questionnaires.Participants12 healthy subjects (reliability experiment); 133 skiers of the U16 category and 38 of the elite category (main experiment).Main outcome measuresDBB performance was quantified using 3D motion capture as the maximum amplitude of the relative vertical displacement of two pelvis markers (DBB_displacement). Additionally, in U16 skiers, age, anthropometrics, maturation, skiing performance, and back overuse complaints were assessed.ResultsThe reliability experiment revealed an ICC(3,1) and 95% CI of 0.81 [0.61, 0.93]. Within-subject SEM was 3.89 mm [3.16 mm, 5.12 mm]. Depending on sex and category, medians of DBB_displacement in skiers ranged between 29 mm and 45 mm. DBB_displacement differed between elite and U16 skiers (p < 0.001), but not between sexes. In U16 skiers, DBB_displacement was independent of age, anthropometrics, and biological maturation, however, associated with skiing performance and back overuse complaints (p < 0.05).ConclusionThe proposed approach may be considered an adequate method to quantify athletes’ rear-chain stabilization capacity.