Performance trends in master freestyle swimmers aged 25-89 years at the FINA World Championships from 1986 to 2014.

Performance trends in elite freestyle swimmers are well known, but not for master freestyle swimmers. We investigated trends in participation, performance, and sex difference in performance of 65,584 freestyle master swimmers from 25-29 to 85-89 years competing in FINA World Masters Championships between 1986 and 2014. The men-to-women ratio was calculated for each age group, and the trend across age groups was analyzed using single linear regression analysis. Trends in performance changes were investigated using a mixed-effects regression model with sex, distance, and calendar year as fixed variables. Participation increased in women and men in older age groups (i.e., 40 years and older). Women and men improved race times across years in all age groups and distances. For age groups 25-29 to 75-79 years, women were slower than men, but not for age groups 80-84 to 85-89 years. In 50, 100, and 200 m, women reduced the sex difference from 1986 to 2014 in age groups 30-34 to 75-79 years. In 400 m, women reduced the gap to men across time in age groups 40-44, 45-49, and 55-59 years. In 800 m, sex difference became reduced across time in age groups 55-59 and 70-74 years. In summary, participation increased from 1986 to 2014 in women and men in older age groups, women and men improved across time performance in all distances, and women were not slower compared to men in age groups 80-84 to 85-89 years. We expect a continuous trend in increasing participation and improved performance in master freestyle swimmers.