title: The Effect of Intensity on 3-Dimensional Kinematics and Coordination in Front-Crawl Swimming.
abstract: BACKGROUND
  Coaches are often challenged to optimize swimmers' technique at different training and competition intensities, but 3-dimensional (3D) analysis has not been conducted for a wide range of training zones.
  
  
  OBJECTIVE
  To analyze front-crawl 3D kinematics and interlimb coordination from low to severe swimming intensities.
  
  
  METHODS
  Ten male swimmers performed a 200-m front crawl at 7 incrementally increasing paces until exhaustion (0.05-m/s increments and 30-s intervals), with images from 2 cycles in each step (at the 25- and 175-m laps) being recorded by 2 surface and 4 underwater video cameras. Metabolic anaerobic threshold (AnT) was also assessed using the lactate-concentration-velocity curve-modeling method.
  
  
  RESULTS
  Stroke frequency increased, stroke length decreased, hand and foot speed increased, and the index of interlimb coordination increased (within a catch-up mode) from low to severe intensities (P ≤ .05) and within the 200-m steps performed above the AnT (at or closer to the 4th step; P ≤ .05). Concurrently, intracyclic velocity variations and propelling efficiency remained similar between and within swimming intensities (P > .05).
  
  
  CONCLUSIONS
  Swimming intensity has a significant impact on swimmers' segmental kinematics and interlimb coordination, with modifications being more evident after the point when AnT is reached. As competitive swimming events are conducted at high intensities (in which anaerobic metabolism becomes more prevalent), coaches should implement specific training series that lead swimmers to adapt their technique to the task constraints that exist in nonhomeostatic race conditions.
authors.forename: Kelly
authors.initials: K
authors.lastname: de Jesus
authors.forename: Ross
authors.initials: R
authors.lastname: Sanders
authors.forename: Karla
authors.initials: K
authors.lastname: de Jesus
authors.forename: João
authors.initials: J
authors.lastname: Ribeiro
authors.forename: Pedro
authors.initials: P
authors.lastname: Figueiredo
authors.forename: João P
authors.initials: JP
authors.lastname: Vilas-Boas
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Fernandes
mesh_terms: D000293:Adolescent; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D019344:Lactic Acid / Q000032:analysis; D008297:Male; D018763:Muscle Fatigue; D013550:Swimming / Q000502:physiology*; D014741:Video Recording; D055815:Young Adult
chemical_list: D019344:Lactic Acid
keywords: angular kinematics; biomechanics; linear kinematics; swimming performance; video analysis