title: The Effect of Fatigue-Induced Changes in Eggbeater-Kick Kinematics on Performance and Risk of Injury.
abstract: OBJECTIVE
  To investigate the effects of fatigue on the vertical force and kinematics of the lower limbs during maximal water polo eggbeater kicking.
  
  
  METHODS
  Twelve male water polo players maintained as high a position as possible while performing the eggbeater kick with the upper limbs raised out of the water until they were unable to keep the top of the sternum (manubrium) above water. Data comprising 27 complete eggbeater-kick cycles were extracted corresponding to 9 cycles of the initial nonfatigued (0%), 50% time point (50%), and final fatigued (100%) periods of the trial. Vertical force, foot speed, and hip-, knee-, and ankle-joint angles were calculated.
  
  
  RESULTS
  Mean vertical force (0%, 212.2 N; 50%, 184.5 N; 100%, 164.3 N) progressively decreased with time. Speed of the feet (0.4 m/s), hip abduction (2.9°), and flexion (3.6°) decreased with fatigue, while hip internal rotation (3.6°) and ankle inversion (4°) increased with fatigue. Average angular velocity decreased for all joint motions.
  
  
  CONCLUSIONS
  Eggbeater-kick performance decreases with fatigue. Inability to maintain foot speeds and hip and ankle actions with progressing fatigue diminishes the ability of the player to produce vertical force during the cycle. Increased internal rotation of the hip when fatigued and the large eversion/abduction of the ankle during the cycle may be predisposing factors for the prevalence of patellofemoral pain syndrome observed among eggbeater-kick performers. Appropriate training interventions that can limit the effects of fatigue on performance and injury risk should be considered.
authors.affiliation: Inst of Sport, Physical Education and Health Sciences, University of Edinburgh, Edinburgh, UK.
authors.forename: Nuno
authors.initials: N
authors.lastname: Oliveira
authors.forename: David H
authors.initials: DH
authors.lastname: Saunders
authors.forename: Ross H
authors.initials: RH
authors.lastname: Sanders
mesh_terms: D000842:Ankle / Q000502:physiology; D001265:Athletic Injuries / Q000503:physiopathology; D001696:Biomechanical Phenomena; D012090:Cumulative Trauma Disorders / Q000503:physiopathology; D005221:Fatigue / Q000503:physiopathology*; D006615:Hip / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D016059:Range of Motion, Articular; D012307:Risk Factors; D012399:Rotation; D013550:Swimming / Q000293:injuries* / Q000502:physiology*; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water