Effects of Equal Volume But Different Plyometric Jump Training Intensities on Components of Physical Fitness in Physically Active Young Males

An 8-week single-blind randomized controlled trial was conducted to compare the effects of separate programs of equal volume, but different intensity, plyometric jump training (PJT) on physical fitness in healthy adults. Thirty-eight physically active males (mean age: 21.8±2.5 years) participated. Subjects’ were randomly assigned to one of three PJT groups or a control (CON, n=9) according to their jump performance. PJT was conducted at maximal (PJT-100, n=10), high (PJT-80, n=9) or moderate (PJT-65, n=10) intensity within each group. Baseline and follow-up tests were carried-out for the assessment of countermovement jump height [CMJ], CMJ height with arm swing [CMJA], and drop-jump height from a 20-cm drop-box [DJ20], linear speed (30-m), and change-of-direction speed (CODS) (Illinois-CODS test). Results revealed significant group×time interactions for CMJ, CMJA, DJ20, 30-m sprint, and CODS (all p<.001; d=0.39-0.76). Post-hoc analyses showed significant improvements in all five fitness measures for PJT-100 (all p<0.01, ∆3.7-13.5%, d=0.26-1.4). For PJT-80, three out of five fitness tests demonstrated significant change (CMJ: p<0.001, ∆5.9%, d=0.33; CMJA: p<0.001, ∆7.0%, d=0.43); CODS: p<0.001, ∆3.9%, d=0.9) and for PJT-65 only 1 test was significant (CMJ: p<0.05, ∆2.8%, d=0.15). No significant changes were observed in CON. Except for similar gains in DJ20 and 30-m sprint in PJT-100 and PJT-80, gains in physical fitness were, in general, greater (p<0.05) following PJT-100 vs. PJT-80 vs. PJT-65 vs. CON. Therefore, maximal PJT intensity may induce larger physical fitness gains, although high and moderate intensities may also be useful, but to a lesser extent.