The purpose of this study was to monitor the changes in breathing pattern, trunk muscle stabilization, and upper-body muscular power in Paralympic swimmers throughout a competitive season over three time points: October (T1), March (T2), and August (T3). Six top-level Paralympic swimmers voluntarily participated in this study. The Friedman test, the Bonferroni–Dunn multiple comparison post hoc analysis, and Kendall’s W concordance coefficient for the measure of effect were used. A significant difference was found in the breathing pattern, trunk stability, and upper-body power variables from the T1 to T3 season (p < .05). However, no significant changes were found in the T2 season. A long-term assessment of these fitness parameters may be of practical importance for better tailoring the training programs of top-level Paralympic swimmers.