Effects of Horizontal and Vertical Vector Resistance Training on Swim Start Performance: An Eight-Week Intervention in Division One Collegiate Swimmers in Taiwan

Background: This study aimed to compare the effects of an eight-week horizontal versus vertical vector resistance training program on swim start performance and lower-limb neuromuscular function in competitive swimmers. Methods: A total of 16 collegiate swimmers (14 males and 2 females; height: 176.3 ± 10 cm; body mass: 68.8 ± 10.3 kg; age: 20.5 ± 2.3 year) were assigned to either a horizontal vector training (HOR) or a vertical vector training (VER) group and completed an eight-week training program. Pre- and post-intervention assessments included flight time, flight distance, underwater speed, 15 m swim speed, 25 m swim speed, and force–time metrics within both concentric and eccentric phases of the countermovement jump and squat jumps. Results: No group or interaction effects were observed. However, time effects were found for flight distance (↑ 4.1–5.5%), flight time (↑ 6.2–12%), 15 m swim speed (↑ 0.3–0.7%), and jump performance. The HOR showed more favorable within-group trends in regards to swim start performance and concentric performance of countermovement and squat jumps. Moderate correlations (r = 0.450–0.476) were found between changes in concentric jump variables and 15 m swim speed. Conclusions: These results suggest that both vertical and horizontal vector resistance training can improve lower-limb neuromuscular performance and swim start performance.