The fastest female butterflyswimmers were younger than the fastest male butterfly swimmers

Introduction: The age of peak freestyle swimming speed was reported to be at ~17 years for women and ~19 years for men. However, the age of peak swimming speed for other strokes such as butterfly is not known. Objectives: We investigated whether the age of peak swimming speed and peak swimming speed changed across years in elite butterfly and freestyle swimmers at national level (Switzerland) between 1994 and 2011. Methods: Changes in swimming speed and age of the annual ten fastest swimmers across years were investigated using linear regression analyses and two-way analysis of variance (ANOVA). Results: For both butterfly and freestyle, the age of peak swimming speed was ~19 years for women. For men, the age of peak swimming speed was at ~22 years over all distances with the exception in 200m freestyle with ~21 years. The age of peak swimming speed increased for women in 50m from ~19 years to ~21 years, in 100m and 200m butterfly from ~18 years to ~20 years while it remained unchanged in 50m, 100m and 200m freestyle at ~19, ~18 and ~20 years, respectively. For men, the age of peak swimming speed was constant for butterfly at ~24, ~23 and ~21 years, respectively, and for freestyle at ~23 years in 100m and ~22 years in 200m across years with the exception of a decrease in 50m freestyle from ~23 years (1994) to ~22 years (2011). Both women and men increased peak swimming speed over all distances. Sex difference in peak swimming speed increased in butterfly from 10% in 1994 to 12% in 2011 in 50m to 200m and in freestyle in 100m from 12% in 1994 to 14% in 2011 while it remained unchanged in 50m and 200m freestyle at 12% and 10%, respectively. Conclusion: To summarize, in butterfly swimming, women seemed to achieve peak swimming speed at ~19 years and men at ~21-22 years. For practical applications, a career as butterfly swimmer may endure longer in men compared to women.