Background: Recovery interval duration is a HIIT programming variable that may influence performance maintenance across repeated efforts. Evidence on this effect during aquatic HIIT remains limited. Aim: To analyze the effects of 15s, 30s, and 60s recovery intervals on repetition performance during aquatic HIIT in physically active men. Methods: Thirteen physically active men (18-40 years) completed three randomized aquatic sessions, one for each recovery condition. The protocol was performed in a swimming pool with water depth at the xiphoid process, without added external resistance, and consisted of five rounds of four exercises: jumping jack, ski, step up on a submerged 30-cm step, and squat jump. Each bout lasted 30s, with passive standing recovery between consecutive exercises and instruction to perform at high intensity. In each session, 20 repetition counts were recorded, one for each 30s bout; performance corresponded to the mean of these counts. Rating of perceived exertion (RPE-CR10; target 9-10) and heart rate were recorded after each bout. Data were analyzed using repeated-measures ANOVA and Bonferroni post hoc tests. Results: A significant condition effect was observed for mean repetitions (F(2,24)=4.796; p=0.018; *p²=0.286). Post hoc analysis indicated higher performance with 60s than with 15s (mean difference=-1.746 repetitions; 95%CI=-3.112 to -0.380; p=0.012), with no differences between 15s and 30s or between 30s and 60s. Conclusion: The 60s recovery interval resulted in higher repetition performance than 15s, whereas 30s did not differ from the other conditions. Recovery duration between exercises should be considered to sustain repetition volume during aquatic HIIT.
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