title: The Effects of Leg Kick on Swimming Speed and Arm-Stroke Efficiency in the Front Crawl.
abstract: OBJECTIVE
  To analyze the effects of swimming pace on the relative contribution of leg kick to swimming speed and to compare arm-stroke efficiency (ηF) assessed when swimming with the arms only (SAO) and while swimming front crawl (FCS) using individual and fixed adjustments to arm-stroke and leg-kick contribution to forward speed.
  
  
  METHODS
  Twenty-nine master swimmers (21 men, 8 women) performed SAO and FCS at 6 self-selected speeds from very slow to maximal. The average swimming speed (v), stroke frequency (SF), and stroke length (SL) were assessed in the central 10 m of the swimming pool. Then, a 2nd-order polynomial regression was used to obtain values of v at paired SF. The percentage difference in v between FCS and SAO, for each paired SF, was used to calculate the relative contributions of the arm stroke (AC) and leg kick (LC) to FCS. Then ηF was calculated using the indirect "paddle-wheel" approach in 3 different ways: using general, individual, and no adjustments to AC.
  
  
  RESULTS
  The LC increased with SF (and speed) from -1% ± 4% to 11% ± 1% (P < .05). At the lower FCS speeds, ηF calculated using general adjustments was lower than ηF calculated using individual adjustments (P < .05), but differences disappear at the fastest speeds. Finally, ηF calculated using individual adjustments to LC in the FCS condition did not differ with ηF assessed in the SAO condition at all the investigated speeds.
  
  
  CONCLUSIONS
  The relative contributions of the arm stroke and leg kick should be individually estimated to reduce errors when calculating arm-stroke efficiency at different speeds and in different swimmers.
authors.forename: Ricardo Peterson
authors.initials: RP
authors.lastname: Silveira
authors.forename: Flávio Antônio
authors.initials: FA
authors.lastname: de Souza Castro
authors.forename: Pedro
authors.initials: P
authors.lastname: Figueiredo
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Vilas-Boas
authors.forename: Paola
authors.initials: P
authors.lastname: Zamparo
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D054874:Athletic Performance / Q000502:physiology* / Q000523:psychology; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D013550:Swimming / Q000502:physiology*; D055815:Young Adult
keywords: Froude efficiency; lower-limb contribution; upper-limb contribution