Morais, J. E.Kilit, BulentArslan, ErsanBragada, José A.Soylu, YusufMarinho, Daniel2025-04-072025-04-072025Morais, J.E.; Kilit, Bulent; Arslan, Ersan; Bragada, José; Soylu, Yusuf; Marinho, Daniel (2025). Effects of On-Court Tennis Training Combined with HIIT versus RST on Aerobic Capacity, Speed, Agility, Jumping Ability, and Internal Loads in Young Tennis Players. Journal of Human Kinetics. ISSN 1640-5544. 95, p. 173-1851640-5544http://hdl.handle.net/10198/34388The purpose of this study was to compare the effects of on-court tennis training (OTT) combined with high-intensity interval training (HIIT) or repeated sprint training (RST) on the physiological, kinematic, kinetic, and perceptual responses of young tennis players. Twenty-four male tennis players (age 13.6 ± 0.3 years) were randomly assigned to either the OTT + HIIT group (n = 12) or the OTT + RST group (n = 12) three times per week for six weeks. Both groups trained for the same total training time with passive rest in each session. A number of physiological, performance and perceptual responses were measured before and after the 6-week training intervention. All variables showed a significant improvement over time, with maximal oxygen uptake showing the greatest improvement (p < 0.001, η2 = 0.97). The 5-m sprint (p = 0.044, η2 = 0.17), repeated sprint ability (p = 0.021, η2 = 0.22), and T-drill agility (p = 0.048, η2 = 0.17) showed a significant group effect. The OTT + RST group had a lower internal training load (better scores), a lower rate of perceived exertion (better scores), and higher scores in the Physical Activity Enjoyment Scale (PACES) at both times compared to the OTT + HITT group. These results demonstrate that OTT + RST appears to be a more effective training approach to improve speed and agility-based performance responses with more enjoyment in young tennis players.engChange of directionRacket sportsCombined trainingTechnical abilityPerceived exertionjournal article10.5114/jhk/1896911899-7562