Effect of vertical and horizontal plyometric training on physical fitness performance in 13–14-year-old untrained boys

Plyometric training (PT) is widely recognized as an effective method for enhancing physical fitness and motor competence. PT in different directions will also bring different returns. However, its effects on physical fitness in untrained adolescents, especially specific age group, remain unclear. This study aimed to compare the effects of vertical versus horizontal plyometric training on physical fitness in adolescent boys aged 13–14 years. One hundred untrained boys aged 13–14 years were recruited and randomly assigned to one of three groups: the vertical plyometric training group (VPT), the horizontal plyometric training group (HPT), and the control group (CG). The experimental period lasted 8 weeks and comprised 16 training sessions. Participants in VPT and HPT completed plyometric training twice per week with identical training volumes. Height, body mass, vertical jump, standing long jump, 50-m sprint, T-test, 1000-m run, and a 4-minute skipping test were measured before and after the experiment. Both vertical and horizontal plyometric training (VPT, HPT) significantly improved all performance indicators (P < 0.01), whereas the control group showed only minor gains in standing long jump and 50m sprint. Group differences between VPT and HPT were significant for standing long jump (Cohen’s d = -1.055, P < 0.001), 50-meter sprint (Cohen’s d = 0.251, P = 0.005), and T-test (Cohen’s d = 0.722, P = 0.007). These findings suggest that practitioners should recognize the benefits of plyometric training (PT) for untrained boys aged 13–14 years. Horizontal PT (HPT) yields improvements comparable to vertical PT (VPT) in vertical jump and endurance performance, but HPT is superior for standing long jump, 50-m sprint, and change-of-direction ability. Future research should examine combined protocols across different ages and sexes to better understand how PT influences the development of motor competence.