Purpose: To assess the effect of 5-week training-cessation period on performance and load–velocity profile-related variables. Methods: Twenty-four competitive swimmers (15 male and 9 female: 19.2 [3.7] and 17.3 [2.3] y, 50-m front-crawl 550 [70], and 572 [51] World Aquatics points, respectively) performed a 50-m front-crawl all-out swim, a load–velocity profile, and a pull-up test before and after a 5-week off-season period. Kinematic variables, blood lactate concentration, and rating of perceived exertion were monitored during the load–velocity profile tests. Results: Performance was impaired 1.3% for males (P < .01) and 3.8% for females (P < .01). Neither anthropometric changes (males r² = .277, females r² = .218, P > .05) nor the physical activity performed during the off-season (males r² = .329, females r² = .094, P > .05) attenuated performance impairments. While males counteracted the stroke-rate decline (P < .05) by increasing stroke length (P < .05) in the majority of the race, females did not, leading to a decline in clean swimming speed (P < .05). The maximum load at zero velocity decreased (P < .05) during the load–velocity profile test. In addition, males showed an increased blood lactate concentration (P < .05), whereas females decreased the maximum velocity at zero load (P < .01) and stroke rate (P < .01). No change in the slope was observed for either sex (P > .05). Conclusion: Following a 5-week off-season period, sprint swimming performance declines (males 0.34 s; females 1.15 s). The load–velocity profile and related variables evidenced deterioration, showing changes in blood lactate concentration, maximum load at zero velocity, average velocity during the third trial, and stroke rate.