title: Anterior cruciate ligament deficiency reduces walking economy in "copers" and "non-copers".
abstract: OBJECTIVE
  Patients with ACL injury requiring surgical treatment (non-copers) demonstrate altered neuromuscular control and gait pattern compared with those returning to their pre-injury activities without surgery (copers). Pathological gait pattern may increase the energy cost of walking. We compared the energy cost of flat, uphill, and downhill walking between ACL-deficient and healthy individuals and between "copers" and "non-copers".
  
  
  METHODS
  Nineteen young males with unilateral ACL injury were allocated into "copers" and "non-copers" according to their ability to return to pre-injury activity without ACL reconstruction. Lysholm and IKDC scales were recorded, and a control group (n = 10) matched for physical characteristics and activity levels was included. All participants performed 8-min walking tasks at 0, +10, and -10 % gradients. Energy cost was assessed by measurement of oxygen consumption (VO2). HR and ventilation (VE), respiratory exchange ratio (RER), and VE/VO2were also measured.
  
  
  RESULTS
  VO2and HR were higher in ACL-deficient patients than in controls during walking at 0, +10, and -10 % gradients (p < 0.01-0.05). There were no differences between "copers" and "non-copers" in VO2and HR for any gradient. No differences were observed in VE, RER, and VE/VO2among the three groups.
  
  
  CONCLUSIONS
  The walking economy of level, uphill, and downhill walking is reduced in ACL-deficient patients. Despite the improved functional and clinical outcome of "copers", their walking economy appears similar to that of "non-copers" but impaired compared with healthy individuals. The higher energy demand and effort during locomotion in "copers" and "non-copers" has clinical implications for designing safer rehabilitation programmes. The increased energy cost in "copers" may be another parameter to consider when deciding on the most appropriate therapeutic intervention (operative and non-operative), particularly for athletes.
  
  
  METHODS
  II.
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, Thessaloniki, 56403, Greece.
authors.forename: Efthymios
authors.initials: E
authors.lastname: Iliopoulos
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, Thessaloniki, 56403, Greece. kyros@med.auth.gr.
authors.forename: Nikiforos
authors.initials: N
authors.lastname: Galanis
authors.affiliation: Sports Medicine Unit, 2nd Orthopaedic Department, Papageorgiou General Hospital, Thessaloniki, Greece.
authors.forename: Michael
authors.initials: M
authors.lastname: Iosifidis
authors.affiliation: Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece.
authors.forename: Andreas
authors.initials: A
authors.lastname: Zafeiridis
authors.affiliation: 1st Department of Orthopaedics, Papanikolaou General Hospital, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Pericles
authors.initials: P
authors.lastname: Papadopoulos
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, Thessaloniki, 56403, Greece.
authors.forename: Michael
authors.initials: M
authors.lastname: Potoupnis
authors.affiliation: Department of Sport Medicine and Biology of Exercise, School of Physical Education and Sport Science, University of Athens, Athens, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Geladas
authors.affiliation: Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece.
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Vrabas
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, Thessaloniki, 56403, Greece.
authors.forename: John
authors.initials: J
authors.lastname: Kirkos
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000534:rehabilitation; D001265:Athletic Injuries / Q000175:diagnosis / Q000503:physiopathology* / Q000534:rehabilitation / Q000601:surgery; D005684:Gait / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D000068958:Return to Sport / Q000502:physiology*; D000070857:Walk Test; D016138:Walking / Q000502:physiology
keywords: ACL; ACL reconstruction; ACL-deficient; Energy cost; Energy expenditure; Oxygen consumption