Abstract
Participation and performance trends in age group athletes have been investigated for different sport disciplines, but not for master swimmers. The knowledge on this topic is still missing for a particular stroke such as backstroke. Changes in participation and performance of male and female age group backstroke swimmers (≥25 years) competing in 50, 100 and 200 m pool swimming at the FINA World Masters Championships held between 1986 and 2014 were investigated using mixed-effects regression analyses. The overall participation was n = 26,217 including n = 13,708 women and n = 12,509 men. In 50 m, female (age groups 85-89 years; p = 0.002) and male participation (age groups 55-59; p = 0.030 and 80-84 years; p = 0.002) increased, while female participation decreased in age groups 55-59 (p = 0.010) and 60-64 years (p = 0.050). In 100 and 200 m, participation increased in age groups 45-49, 50-54, 65-69, 70-74, 80-84 years. Swimmers in age groups 25-29 to 95-99 years improved performance over all distances. Women were slower than men in age groups 25-29 to 80-84 years, but not in age groups 85-89 to 95-99 years over all distances. In 50 m and 100 m, the sex difference decreased in age groups 40-44 (p = 0.007 and p = 0.005), 45-49 (p = 0.017 and p = 0.034), 50-54 (p = 0.002 and p = 0.040), to 55-59 years (p = 0.002 and p = 0.004). In 200 m, the sex difference decreased in age groups 40-44 (p = 0.044) and 90-94 (p = 0.011), but increased in age group 25-29 years (p = 0.006). In summary, in age group backstroke swimmers, (1) participation increased or remained unchanged (except women in age groups 55-59 and 60-64 years in 50 m), (2) swimming performance improved in all age groups from 25-29 to 95-99 years over all distances, (3) men were faster than women in age groups 25-29 to 80-84 years (except age groups 85-89 to 95-99 years) over time and all distances.