The Effect of Combined Isometric and Plyometric Training versus Contrast Strength Training on Physical Performance in Male Junior Handball Players

Exploring resistance training methods is crucial for optimizing performance programs. Isometric muscle actions have gained popularity in athletic training, but their impact on dynamic performance is uncertain. Isolated isometric actions also lack ecological validity. We compared the effects of 8-week combined isometric and plyometric (COMB) training and contrast strength training (CST) programs on junior male handball players. Thirty-six male first national division players (17.6 ± 1.0 years) were enrolled and randomly assigned to COMB, CST, or control (CONT) groups (all n = 12). Sprinting, change of direction, ball throwing velocity, jumping, and strength were assessed pre- and post-intervention. A significant group × time interaction was observed between the COMB and CONT groups for 20 and 30 m sprints (p ≤ 0.002) and between the COMB and CST groups (p ≤ 0.042). The COMB group had the largest improvements in change of direction and the modified T-test, with significant group × time interactions between the COMB and CONT groups (p ≤ 0.021). Significant group × time interactions were observed between the COMB and CST groups and between the COMB and CONT groups for 3 step running throw (p = 0.003; p < 0.001), running throw (p = 0.02; p = 0.031), and jumping throw (p = 0.001; p < 0.001). Countermovement jump showed a significant group × time interaction (p = 0.014), with the COMB group outperforming the other groups. Generally, COMB yielded larger improvements than CST. Coaches should consider incorporating a combination of isometric and plyometric exercises for in-season strength training.