Squat Style Long Jump in Junior High School Extracurricular Activities: The Impact of Box Jump and Depth Jump Plyometric Training

Abstract

The development of neuromuscular coordination and leg muscle explosive power during early adolescence is critical to optimizing horizontal-to-vertical force transition in the long jump. However, evaluating appropriate plyometric modalities to maximize adaptations without causing excessive fatigue remains necessary. This quasi-experimental study with a matching-by-subject design compared the effectiveness of Box Jump and Depth Jump training on improving squat-style long jump performance. Thirty early adolescent athletes (24 males, 6 females; aged 12–15 years) were selected via purposive sampling and assigned to a 6-week intervention (3 sessions/week; 35-cm box height). Data were analyzed using paired-samples and independent-samples t-tests. Both groups showed significant performance improvement within themselves (p<0,001). More importantly, gain score analysis found that Depth Jump training produced significantly larger performance improvement than the Box Jump training (t(28) = -3,500, p=0,002, d=1,28), with the average of 0,90 m (23,44%) improvement for Depth Jumps vs. 0,61 m (15,84%) for the Box Jumps group. In summary, Depth Jump training is superior in improving leg muscles explosive strength because of the optimized Stretch Shortening Cycle (SSC) and myotatic reflex during the amortization phase. It is suggested that physical education teachers and coaches should apply Depth Jumps training with controlled drop heights to safely enhance reactive strength in young athletes.