title: Dynamic Neuromuscular Control of the Lower Limbs in Response to Unexpected Single-Planar versus Multi-Planar Support Perturbations in Young, Active Adults.
abstract: OBJECTIVE
  An anterior cruciate ligament (ACL) injury involves a multi-planar injury mechanism. Nevertheless, unexpected multi-planar perturbations have not been used to screen athletes in the context of ACL injury prevention yet could reveal those more at risk. The objective of this study was to compare neuromuscular responses to multi-planar (MPP) and single-planar perturbations (SPP) during a stepping-down task. These results might serve as a basis for future implementation of external perturbations in ACL injury screening programs.
  
  
  METHODS
  Thirteen young adults performed a single leg stepping-down task in eight conditions (four MPP and four SPP with a specified amplitude and velocity). The amplitudes of vastus lateralis (VL), vastus medialis (VM), hamstrings lateralis (HL), hamstrings medialis (HM) EMG activity, medio-lateral and anterior-posterior centre of mass (COM) displacements, the peak knee flexion and abduction angles were compared between conditions using an one-way ANOVA. Number of stepping responses were monitored during all conditions.
  
  
  RESULTS
  Significantly greater muscle activity levels were found in response to the more challenging MPP and SPP compared to the less challenging conditions (p < 0.05). No differences in neuromuscular activity were found between the MPP conditions and their equivalents in the SPP. Eighteen stepping responses were monitored in the SPP versus nine in the MPP indicating that the overall neuromuscular control was even more challenged during the SPP which was supported by greater COM displacements in the SPP.
  
  
  CONCLUSIONS
  The more intense MPP and SPP evoked different neuromuscular responses resulting in greater muscle activity levels compared to small perturbations. Based on the results of COM displacements and based on the amount of stepping responses, dynamic neuromuscular control of the knee joint appeared less challenged during the MPP. Therefore, future work should investigate extensively if other neuromuscular differences (i.e. co-activation patterns and kinetics) exist between MPP and SPP. In addition, future work should examine the influence on the neuromuscular control of the magnitude of the perturbations and the magnitude of stepping height and stepping distance.
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Malfait
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Staes
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Aijse
authors.initials: A
authors.lastname: de Vries
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Annemie
authors.initials: A
authors.lastname: Smeets
authors.affiliation: Research Institute for Sport and Exercise Sciences, Faculty of Science, Liverpool John Moores University, Liverpool, United Kingdom.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Hawken
authors.affiliation: Research Institute for Sport and Exercise Sciences, Faculty of Science, Liverpool John Moores University, Liverpool, United Kingdom.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Robinson
authors.affiliation: Research Institute for Sport and Exercise Sciences, Faculty of Science, Liverpool John Moores University, Liverpool, United Kingdom.
authors.forename: Jos
authors.initials: J
authors.lastname: Vanrenterghem
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Sabine
authors.initials: S
authors.lastname: Verschueren
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000502:physiology; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000517:prevention & control*; D007719:Knee Joint / Q000502:physiology*; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D055815:Young Adult