Incline plyometrics-induced improvement of jumping performance

Abstract

The aim of this study was to examine the effects of incline plyometrics training on muscle activation and architecture during vertical jumping and maximum strength. Twenty male participants were divided in two training groups which followed after a 4 week training program. The incline plyometrics group (n = 10) trained by performing consecutive jumps on an inclined surface (15°) while the plane plyometrics (PP) group (n = 10) performed the same jumps on a plane surface. Both groups trained four times per week and performed 8 sets of 10 jumps in each session. Subjects performed squat jumps, counter movement jumps and drop jumps (DJ) prior to and immediately after the training period, while the electromyographic activity of the medial gastrocnemius (MGAS) and tibialis anterior muscles and the architecture of MGAS were recorded. Maximal isokinetic and isometric strength of the plantar flexors were performed. Analysis of variance showed that only the IP group improved fast DJ height performance by 17.4 and 14.4% (20 and 40 cm, p < 0.05). This was accompanied by a significantly higher MGAS activity during the propulsion phase (24% from 20 cm and 50% from 40 cm, p < 0.05) of the DJ and a longer working fascicle length (5.08%, p < 0.05) compared with the PP group. There were no significant changes in isokinetic and isometric strength of the plantar flexors after training for both groups. The increase of jumping performance, after incline plyometrics should be taken into consideration by coaches, when they apply hopping exercise to improve explosiveness of the plantar flexors.

Effect of lower-body plyometric training on athletic performance and muscle–tendon properties

“…For example, Kyrolainen et al 25) reported that maximal voluntary knee extension torque did not change after a 15-week plyometric training regimen. Additionally, Kannas et al 26) observed no significant increase in maximal voluntary plantar flexion torque.…”

“…Foure et al 34) reported that the fascicle length and pennation angle of the triceps surae muscles did not change after 14 weeks of plyometric training. Kannas et al 26) also reported no significant change in fascicle length or pennation angle of the medial gastrocnemius muscle after 4 weeks of hopping training. In contrast, Blazevich et al 37) reported increased fascicle length and decreased pennation angle of the vastus lateralis muscle after a 5-week plyometric training regimen.…”

“…In addition, most studies in this area revealed that plyometric training induced changes in neural activity during athletic performances (with the exception of Kyrolainen et al 25) ). For example, Kubo et al 10) and Kannas et al 26) reported that electromyographic activity of the triceps surae muscles during the concentric phase of the DJ increased after plyometric training. Furthermore, Chimera et al 27) reported that after 6 weeks of plyometric training, preparatory adductor activity and abductor-to-adductor co-activation increased, indicating that plyometric training induced the change in muscle activation strategies.…”

“…In contrast, Burgess et al 43) and Wu et al 44) reported significant increases in Achilles tendon stiffness after 6-and 8-week plyometric training regimens, respectively. Furthermore, Kannas et al 26) reported increased tendon elongation during isometric plantar flexion after 4 weeks of hopping training without increased maximal voluntary contraction force, indicating that tendon stiffness decreased after plyometric training. In the above studies, tendon stiffness was determined in isometric contraction.…”

Effect of plyometric training on the fascicle length of the gastrocnemius medialis muscle

“…There were other studies that investigated the relationship between muscle stiffness and muscle strength 11) , or investigated changes in ankle angle 10) , and several other studies 12,13) . However, changes in muscle structures such as fascicle length (FL) and pennation angle by PT were not identified 14,15) . In many studies 4,9,10) , that involved exercises consisting of whole-body training such as a counter-movement jump and depth jump, it was guessed which could easily compensate for weak muscles.…”