Fast and Slow Jump Training Methods Induced Similar Improvements in Measures of Physical Fitness in Young Females

This study aimed to contrast the impacts of an exercise intervention using either bounce drop jump (DJ; fast stretch-shortening cycle exercise) or countermovement jump (CMJ; slow stretch-shortening cycle exercise) on measures of physical fitness in young females. A total of 23 young females (age: 19.7 ± 1.0 years, height: 159.8 ± 4.2 cm, body mass: 54.3 ± 14.3 kg) were randomly assigned to either DJ (n = 12) or CMJ (n = 11) training, which spanned 6 weeks. Pre- and posttraining assessments were conducted for 10 m and 30 m linear sprints, change-of-direction speed, CMJ, DJ (jump height, contact time, and reactive strength index), standing long jump, triple-hop distance, and isometric strength. Apart from the variance in jump technique, both interventions were standardized in terms of total repetitions, intensity, and surface type. No significant Group × Time effect was observed in any dependent variables (all p > .05). A significant time effect was observed in 10 m (p < .001, effect size [ES] = 0.70) and 30 m (p < .001, ES = 0.79) linear sprint, CMJ height (p = .012, ES = 0.34), DJ contact time (p = .012, ES = 0.34), and triple-hop distance (p = .006, ES = 0.38). Both DJ and CMJ training interventions led to comparable improvements in linear sprints, CMJ height, DJ contact time, and triple-hop distance. These findings suggest that the duration of ground contact during intervention exercises (i.e., fast vs. slow stretch-shortening cycle) did not significantly influence initial (6 weeks) physical fitness adaptations in young females. However, extending these results to highly trained groups (e.g., athletes) warrants further investigation.