Purpose: This study aimed to investigate lung capacity, anaerobic exercise capacity, and fitness in high school swimmers before and after the COVID-19 pandemic. Methods: This study was conducted on 30 male high school swimmers and evaluated lung capacity, anaerobic exercise capacity, and fitness before and after the COVID-19 pandemic. The study analyzed measurement variables obtained from the group through IBM SPSS Statistics version 22.0, and an independent sample t-test was used to compare and analyze the lung capacity, anaerobic exercise capacity, and fitness of swimmers before and after the COVID-19 pandemic. Results: Statistically significant differences in back strength, sit-up, repeated jumps, whole-body reaction, and trunk forward flexion were found between the groups before and after the COVID-19 pandemic. The evaluation of the lung capacity and anaerobic exercise capacity of swimmers before and after COVID-19 pandemic did not find statistically significant difference between the groups. Conclusion: This study showed significant differences by group and will provide guidance on the development of a systematic training program for swimmers.