# Trend Forecasting in Swimming World Records and in the Age of World Record Holders
## 3 Results  
Table 1 shows the frequency of WRs in freestyle events over the decades according to sex. While there was a trend for a higher frequency of WRs in both groups between the 1960s and the beginning of the 21 st century, it has slowed down in the last decade.  
\begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline  & \multicolumn{10}{c}{**Decades**} \\ \cline{2-11}  & **1920–1929** & **1930–1939** & **1940–1949** & **1950–1959** & **1960–196** & **1970–1979** & **1980–198** & **1990–1999** & **2000–2009** & **2010–2019** \\ \hline Males & & & & & & & & & & \\
50 m & – & – & – & – & – & 3 & 15 & 2 & 7 & – \\
100 m & 3 & 3 & 3 & 4 & 7 & 9 & 5 & 1 & 8 & – \\
200 m & 4 & 1 & 2 & 9 & 17 & 9 & 8 & 3 & 8 & – \\
400 m & 5 & 3 & 4 & 10 & 13 & 14 & 7 & 4 & 5 & – \\
800 m & 6 & 7 & 5 & 5 & 6 & 13 & 3 & 3 & 4 & – \\
1500 m & 6 & – & 2 & 4 & 9 & 11 & 3 & 4 & 1 & 2 \\ \hline Females & & & & & & & & & & & \\
50 m & – & – & – & – & – & 2 & 13 & 2 & 8 & 1 \\
100 m & 7 & 6 & 10 & 5 & 13 & 3 & 2 & 11 & 2 & – \\
200 m & 3 & 6 & – & 5 & 7 & 14 & 2 & 1 & 8 & – \\
400 m & 7 & 9 & 2 & 2 & 13 & 12 & 2 & – & 6 & 3 \\
800 m & – & 4 & 1 & 6 & 9 & 19 & 4 & – & 1 & 5 \\
1500 m & 4 & 3 & 2 & 1 & 10 & 11 & 2 & – & 1 & 6 \\ \hline \end{tabular}
\end{table}
Table 1: The frequency of WRs in freestyle events (long-course pool) over the decades according to sex.  
Table 2 shows the differences between decades in mean WRs according to sex. There was a natural trend of improvement in WRs over the decades, with a strong effect in all of the events analyzed.  
Table 3 shows the differences between decades in the mean age of world record holders according to sex. Preliminary data analysis reveals a nuanced pattern in the age of world record holders. While certain events (e.g., 50 m and 100 m) show a consistent trend of swimmers achieving records at older ages over the decades, other events (e.g., 200 m, 400 m, 800 m, and 1500 m) display variations.  
Figures 1 and 2 show the forecast models for the next two WRs in male and female freestyle events, respectively. The future observations show a natural improvement in WRs for both sexes in the upcoming decades.  
Figure 1: Forecast models for predicting male WRs in all freestyle events (panel **(A)**, 50 m; panel **(B)**, 100 m; panel **(C)**, 200 m; panel **(D)**, 400 m; panel **(E)**, 800 m; panel **(F)**, 1500 m). Fit: line of best fit, UCL: upper confidence limit; LCL: lower confidence limit; WR: predicted time for world record.  
Figure 2: Forecast models for predicting female WRs in all freestyle events (panel **(A)**, 50 m; panel **(B)**, 100 m; panel **(C)**, 200 m; panel **(D)**, 400 m; panel **(E)**, 800 m; panel **(F)**, 1500 m). Fit: line of best fit; UCL: upper confidence limit; LCL: lower confidence limit; WR: predicted time for world record.  
Figures 3 and 4 show the forecast models for the next two ages of male and female world record holders, respectively. The future observations show that the age of male world record holders seems to stabilize in shorter events and decrease in longer distance ones, while for females, general stabilization should be expected for the majority of the events.  
Figure 4: Forecast models for predicting age of female world record holders in freestyle events (panel (**A**), 50 m; panel (**B**), 100 m; panel (**C**), 200 m; panel (**D**), 400 m; panel (**E**), 800 m; panel (**F**), 1500 m). Fit: line of best fit; UCL: upper confidence limit; LCL: lower confidence limit.  
Figure 3: Forecast models for predicting age of male world record holders in all freestyle events (panel (**A**), 50 m; panel (**B**), 100 m; panel (**C**), 200 m; panel (**D**), 400 m; panel (**E**), 800 m; panel (**F**), 1500 m). Fit: line of best fit; UCL: upper confidence limit; LCL: lower confidence limit.