title: Biomechanical gender differences of the ankle joint during simulated half-squat parachute landing.
abstract: BACKGROUND
  A search of the literature did not reveal known gender differences in biomechanics during parachute landing.
  
  
  METHODS
  Eight male and eight female healthy adults participated in this experiment. Each individual jumped from platforms with three different heights (low: 0.32 m; medium: 0.52 m; and high: 0.72 m) and landed on flat ground in a standard half-squat parachute landing technique. The ground reaction force (GRF) normalized to bodyweight (BW), ankle joint kinematics, and the surface electromyogram (EMG) signals of the tibialis anterior (TA) and lateral gastrocnemius (LG) were measured. Two-way ANOVA was used to analyze the effects of the dropping height and gender factors.
  
  
  RESULTS
  The anterior-posterior GRF (men 1.01 BW; women 0.79 BW), rate of loading (men 260 BW x s(-1); women 127 BW x s(-1)), and absolute EMG amplitude of TA (pre-landing: men 219 microv; women 129 microv; post-landing: men 573 microv; women 288 microv) in the men's group were significantly higher than in the women's group, whereas peak angular velocity of dorsiflexion in the women's group (1627 degrees x s(-1)) was significantly higher than in the men's (1188 degrees x s(-1)).
  
  
  CONCLUSIONS
  Women are prone to transform the kinetic energy to the ankle motion, whereas men are more likely to transform it to friction. The co-contraction of the ankle flexor and extensor differs between genders. These factors may be associated with the higher incidence of parachute injuries among women reported by some authors.
authors.affiliation: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
authors.forename: Wenxin
authors.initials: W
authors.lastname: Niu
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: He
authors.forename: Yubo
authors.initials: Y
authors.lastname: Fan
authors.forename: Qinping
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D000843:Ankle Joint / Q000502:physiology*; D001359:Aviation; D001696:Biomechanical Phenomena / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D012737:Sex Factors; D013177:Sports / Q000502:physiology*; D013647:Task Performance and Analysis; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult