title: Kinematic changes during a 100-m front crawl: effects of performance level and gender.
abstract: OBJECTIVE
  This study analyzed kinematic changes during a 100-m front crawl to investigate the effects of performance level and gender, comparing 12 high-speed males, 8 medium-speed males, 8 low-speed males, and 8 high-speed females.
  
  
  METHODS
  Assessments were made throughout the race in a 25-m pool divided into five zones of 5 m. Velocity (V), stroke rate (SR), and stroke length (SL) were calculated for each 25-m length (L1 to L4) and for each 5-m zone. Four stroke phases were identified by video analysis, and the index of coordination (IdC) was calculated. Three modes of arm coordination were identified: catch-up, opposition, and superposition. The leg kick was also analyzed.
  
  
  RESULTS
  The high-speed male swimmers were distinguished by higher V (1.89 m.s(-1)), SR (0.78 Hz), SL (2.16 m per stroke), propulsive phase (54%), and IdC (3.8%) (P < 0.05), and by the stability of these values throughout the race. The medium- and low-speed males had an opposition coordination (-1% < IdC < 1%) during the third length of the 100 m. Because of fatigue in length 4, they spent more time with the hand in the push phase (possibly because of a decrease in hand velocity) and changed to superposition coordination (medium-speed males: IdC = 2.78%; low-speed males: IdC = 1.12%) (P < 0.05). This change was ineffective, however, as SL continued to decrease throughout the 100 m (P < 0.05). The main gender findings were the greater SL of the males versus the females (1.81 m per stroke) (P < 0.05) and the similar IdC of both high-speed groups (females: 4.4%).
  
  
  CONCLUSIONS
  The high-speed swimmers were characterized by higher and more stable SL and IdC. The principal gender effect was greater SL in the males than in the females.
authors.affiliation: CETAPS Laboratory, University of Rouen, Faculty of Sports Sciences, Rouen, France. ludovic.seifert@univ-rouen.fr
authors.forename: Ludovic
authors.initials: L
authors.lastname: Seifert
authors.forename: Didier
authors.initials: D
authors.lastname: Chollet
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Chatard
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm; D001696:Biomechanical Phenomena; D003163:Competitive Behavior / Q000502:physiology*; D005260:Female; D005602:France; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007866:Leg; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D012737:Sex Factors; D013550:Swimming / Q000502:physiology*; D013647:Task Performance and Analysis