title: Fatigue Alters Landing Shock Attenuation During a Single-Leg Vertical Drop Jump.
abstract: BACKGROUND
  Landings in fatigue conditions are considered to be one of the factors that cause noncontact anterior cruciate ligament (ACL) injury. Additionally, it is known that fatigue alters lower extremity landing strategies and decreases the ability to attenuate shock during landing.
  
  
  OBJECTIVE
  To determine characteristics of knee kinematics and shock attenuation during the landing phase of a single-leg vertical drop jump in a fatigued condition. The hypothesis was that knee kinematics during the landing phase of a single-leg vertical drop jump would demonstrate a significant difference between before and after fatigue.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Thirty-four college females participated in this experiment. They were randomly assigned to either the fatigue (n = 17) or control group (n = 17). The fatigue group performed the single-leg vertical drop jump before and after the fatigue protocol, which was performed on a bike ergometer. Knee kinematics data were obtained from the 3-dimensional motion analysis system. The ratio of each variable (%) was calculated, comparing the pre- to postfatigue protocol. Unpaired t tests were used to compare changes in kinematic variables between the fatigue-induced group and control group.
  
  
  RESULTS
  Peak knee flexion angular velocity increased significantly in the fatigue group (106.1% ± 8.0%) in comparison with the control group (100.7% ± 6.6%) (P < .05). However, peak knee flexion angle and acceleration had no differences between each group. Peak knee adduction/abduction angle, velocity, and acceleration also had no differences between each group.
  
  
  CONCLUSIONS
  Fatigue decreased the ability to attenuate shock by increasing angular velocity in the direction of knee flexion during single-leg drop jump landing. These findings indicate the need to evaluate the ability to attenuate shock by measuring knee flexion angular velocity when fatigue is considered.
  
  
  CONCLUSIONS
  Measuring knee angular velocity during landings might be an important evaluation parameter in the consideration of the knee injury prevention.
authors.affiliation: Saitama Medical University Graduate School of Medicine, Moroyama, Saitama, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Tamura
authors.affiliation: Saitama Medical University Graduate School of Medicine, Moroyama, Saitama, Japan.; Saitama Medical University, Moroyama, Saitama, Japan.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Akasaka
authors.affiliation: Saitama Medical University Graduate School of Medicine, Moroyama, Saitama, Japan.; Saitama Medical University, Moroyama, Saitama, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Otsudo
authors.affiliation: Saitama Medical University, Moroyama, Saitama, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sawada
authors.affiliation: Saitama Medical University Graduate School of Medicine, Moroyama, Saitama, Japan.; Saitama Medical University, Moroyama, Saitama, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Okubo
authors.affiliation: Department of Rehabilitation, Zenshukai Hospital, Maebashi, Gunma, Japan.
authors.forename: Jyunya
authors.initials: J
authors.lastname: Shiozawa
authors.affiliation: Department of Rehabilitation, Yokohama Asahi Center General Hospital, Yokohama, Kanagawa, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Toda
authors.affiliation: Department of Rehabilitation, Kanetsu Hospital, Tsurugashima, Saitama, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Yamada
keywords: angular velocity; kinematics; knee injury prevention; lower extremity
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