Introduction:
Repeated-sprint training (RST) and plyometric jump training (PJT) are key methods in youth conditioning, targeting distinct yet complementary systems – RST enhances metabolic efficiency and fatigue tolerance, whereas PJT develops muscle power and neural activation.

Aim of the study:
This study aimed to directly compare the effects of RST and PJT on aerobic capacity and short-term maximal intensity performance in youth team-sport athletes.

Material and methods:
Thirtyone trained athletes aged 15-17 years participated and were randomly allocated to either the RST or PJT group. Training sessions were conducted three times per week for eight weeks. The RST protocol consisted of short, maximal sprints with limited recovery to stimulate aerobic and anaerobic pathways, whereas the PJT protocol incorporated multi-joint jumping drills to improve explosive strength. Performance measures included aerobic fitness (Yo-Yo Intermittent Recovery Test Level 1 [Yo-Yo IR1]), sprint ability, jump height, lower-body strength, and agility, all of which were assessed before and after the intervention.

Results:
The RST group showed greater improvements in aerobic capacity and repeated-sprint ability, including a 2.8-unit increase in Yo-Yo IR1 and a 9.8-s reduction in total sprint time. In contrast, the PJT group demonstrated larger gains in jump performance (CMJ +6.1 cm; SJ +6.4 cm) and lower-body strength (+6.0 kg). Performance decrement improved by 7.9% in RST and by 1.8% in PJT, while agility remained unchanged in both groups.

Conclusions:
Both RST and PJT proved effective but in distinct performance domains. RST predominantly enhanced aerobic and fatigue-related parameters, whereas PJT improved neuromuscular strength and explosive power. Integrating both training modalities within a structured periodization model may optimize the comprehensive development of youth athletes. Future research should address longer training durations, different maturation stages, and sport-specific applications to refine evidence-based conditioning strategies for young players.