title: Optimal Body Size and Limb Length Ratios Associated with 100-m Personal-Best Swim Speeds.
abstract: OBJECTIVE
  This study aims to identify optimal body size and limb segment length ratios associated with 100-m personal-best (PB) swim speeds in children and adolescents.
  
  
  METHODS
  Fifty national-standard youth swimmers (21 males and 29 females age 11-16 yr; mean ± SD age, 13.5 ± 1.5 yr) participated in the study. Anthropometry comprised stature; body mass; skinfolds; maturity offset; upper arm, lower arm, and hand lengths; and upper leg, lower leg, and foot lengths. Swimming performance was taken as the PB time recorded in competition for the 100-m freestyle swim. To identify the optimal body size and body composition components associated with 100-m PB swim speeds (having controlled for age and maturity offset), we adopted a multiplicative allometric log-linear regression model, which was refined using backward elimination.
  
  
  RESULTS
  Lean body mass was the singularly most important whole-body characteristic. Stature and body mass did not contribute to the model, suggesting that the advantage of longer levers was limb-specific rather than a general whole-body advantage. The allometric model also identified that having greater limb segment length ratios [i.e., arm ratio = (low arm)/(upper arm); foot-to-leg ratio = (foot)/(lower leg)] was key to PB swim speeds.
  
  
  CONCLUSIONS
  It is only by adopting multiplicative allometric models that the above mentioned ratios could have been derived. The advantage of having a greater lower arm is clear; however, having a shorter upper arm (achieved by adopting a closer elbow angle technique or by possessing a naturally endowed shorter upper arm), at the same time, is a new insight into swimming performance. A greater foot-to-lower-leg ratio suggests that a combination of larger feet and shorter lower leg length may also benefit PB swim speeds.
authors.affiliation: 1Faculty of Education, Health, and Wellbeing, University of Wolverhampton, Walsall, UNITED KINGDOM; and 2Center for Applied Biological and Exercise Science, Coventry University, Coventry, UNITED KINGDOM.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Nevill
authors.forename: Samuel W
authors.initials: SW
authors.lastname: Oxford
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Duncan
mesh_terms: D000293:Adolescent; D000886:Anthropometry; D054874:Athletic Performance; D049628:Body Size / Q000502:physiology*; D002648:Child; D003163:Competitive Behavior; D005260:Female; D006801:Humans; D008297:Male; D013550:Swimming