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PT provides a statistically significant and practically relevant improvement in vertical jump height with the mean effect ranging from 4.7% (SJ and DJ), over 7.5% (CMJA) to 8.7% (CMJ). These results justify the application of PT for the purpose of development of vertical jump performance in healthy individuals.
The 12-week program
resulted in significant increases in vertical jump height
for both training groups. The depth jump group
significantly improved their vertical jump height in all 3
jumps. None of the training methods improved
utilization of elastic energy. In activities involving
dynamic stretch-shorten cycles, drop jump training was
superior to countermovement jump training due to
neuromuscular specificity. This study provides support
for the strength and conditioning professional to include
plyometric depth jump training as part of the athlete's
overall program for improving vertical jumping ability
and concentric contractile performance.
After determining their op-
timal depth jump height, the subjects performed 3 sets of 10
depth jumps, each set with a different rest interval duration.
The 3 rest intervals between depth jumps were 15, 30, and
60 seconds and were counterbalanced for each subject. Max-
imal vertical jump height and vertical ground reaction forces
were calculated for each depth jump trial. The Peak Perfor-
mance Motion Measurement System was used to measure
vertical jump height and the Kistler force platform was used
to measure ground reaction forces. Two-way analyses of var-
iance revealed that rest interval length did not affect (p
0.05) vertical jump height or vertical ground reaction forces.
Therefore, this study demonstrated a 15-second rest interval
was sufficient for recovery during the performance of depth
jumps.
The experimental group which trained with the load that maximized mechanical power achieved the best overall results in enhancing dynamic athletic performance recording statistically significant (P < 0.05) improvements on most test items and producing statistically superior results to the two other training modalities on the jumping and isokinetic tests.
The results of a biomechanical analysis show no difference between DJ20 and DJ40 in mechanical output about the joints during the push-off phase. Peak values of moment and power output about the ankles during the push-off phase were found to be smaller in DJ60 than in DJ40 (DJ20 = DJ60). The amplitude of joint reaction forces increased with dropping height. During DJ60, the net joint reaction forces showed a sharp peak on the instant that the heels came down on the ground. Based on the results, researchers are advised to limit dropping height to 20 or 40 cm when investigating training effects of the execution of bounce drop jumps.
Maximum moment and power values were calculated for each joint. ANOVAs were used to compare the selected variables from DJ to the corresponding variables in CMJ. All variables from the selected joints were greater with DJ, and 29 of the 33 comparisons were significantly different (p <= 0.05). The corresponding joint moments for ankle, knee, and hip depth jumps were significantly greater than for CMJ. The modified plyometric jumps were shown to enhance the contribution of the muscles that extend the ankle, knee, and hip.
Peak muscle power output, measured using a countermovement vertical jump, significantly increased from pretraining to posttraining for group 1 (PLYOMETRIC TRAINING) (2.8%) and group 2 (PLYOMETRIC + AEROBIC TRAINING) (2.5%). Each group demonstrated a significant increase in fiber area from pretraining to posttraining for type I (group 1, 4.4%; group 2, 6.1%) and type II (group 1, 7.8%; group 2, 6.8%) fibers, but there were no differences between the groups. Following plyometric training, there is an increased power output that may in part be related to muscle fiber size.
Following the training period, the E group (PLYOMETRICALLY TRAINED) significantly improved 3-km performance (2.7%) and RE at each of the tested velocities, while no changes in V?O2max or Thla were recorded. CMJ height, 5BT, and MTS also increased significantly. No significant changes were observed in any measures for the C group. The results clearly demonstrated that a 6-week plyometric programme led to improvements in 3-km running performance. It is postulated that the increase in MTS resulted in improved RE. We speculate that the improved RE led to changes in 3-km running performance, as there were no corresponding alterations in V?O2max or Thla.
The PPU (PLYOMETRIC PUSHUP)
group experienced significantly greater improvements than
the DPU (DYNAMIC PUSHUP) group on the medicine ball put (p
0.03). There
was no significant difference between groups for the chest
press, although the PPU group experienced greater increases
The mini-trampoline appears to be an effective apparatus for
increasing the height of the vertical jump. Also, the mini-trampoline
seems to elicit better technique from many individuals: In terms of
balance, there was significantly less forward translation in the jump.
Range of motion, as indicated by knee flexion in the crouch, decreased
for most subjects. And the coordination of the thigh and shank was
relatively simultaneous after the training program.
The results showed that all the training treatments elicited significant (P<0.05) improvement in all of the tested variables. However, the combination training group showed signs of improvement in the vertical jump performance, the 50 yard dash, and leg strength that was significantly greater than the improvement in the other 2 training groups (plyometric training and weight training). This study provides support for the use of a combination of traditional weight training and plyometric drills to improve the vertical jumping ability, explosive performance in general and leg strength.
The results obtained for DJ appeared to depend on jumping style. In a subgroup of subjects making a movement of large amplitude (i. e. bending their hips and knees considerably before pushing off) the push-off phase of DJ closely resembled that of CMJ. In a subgroup of subjects making a movement of small amplitude, however, the duration of the push-off phase was shorter, values for moments and mean power output at the knees and ankles were larger, and the mean EMG activity of m. gastrocnemius was higher in DJ than in CMJ. The findings are attributed to the influences of the rapid pre-stretch of knee extensors and plantar flexors after touch-down in DJ. In both subgroups, larger peak resultant reaction forces were found at the knee and ankle joints, and larger peak forces were calculated for the Achilles tendon in DJ than in CMJ.
The pooled estimate of the effect of PT on vertical jump height was 4.7% (95% CI 1.8 to 7.6%), 8.7% (95% CI 7.0 to 10.4%), 7.5% (95% CI 4.2 to 10.8%) and 4.7% (95% CI 0.8 to 8.6%) for the SJ, CMJ, CMJA and DJ, respectively. When expressed in standardised units (ie, effect sizes), the effect of PT on vertical jump height was 0.44 (95% CI 0.15 to 0.72), 0.88 (95% CI 0.64 to 1.11), 0.74 (95% CI 0.47 to 1.02) and 0.62 (95% CI 0.18 to 1.05) for the SJ, CMJ, CMJA and DJ, respectively. PT provides a statistically significant and practically relevant improvement in vertical jump height with the mean effect ranging from 4.7% (SJ and DJ), over 7.5% (CMJA) to 8.7% (CMJ). These results justify the application of PT for the purpose of development of vertical jump performance in healthy individuals.
Posttraining, both groups experienced improvements in vertical jump height (p < 0.05) and agility time (p < 0.05) and no change in sprint performance (p > 0.05). There were no differences between the treatment groups (p > 0.05). The study concludes that both DJ and CMJ plyometrics are worthwhile training activities for improving power and agility in youth soccer players.
Similar increases in VJ were observed in both groups after 4 wk (APT = 3.1%, CON = 4.9%; both P < 0.05); however, the APT (AQUATIC PLYOMETRIC TRAINING) group improved by an additional 8% (P < 0.05) from week 4 to week 6, whereas there was no further improvement in the CON group (-0.9%; P = NS). After 6 wk, both groups displayed significant improvements in concentric peak torque during knee extension and flexion at 60 and 180[degrees][middle dot]s-1 (all P < 0.05).
Conclusions: Plyometric training specifically potentiated the normalized EMG, tendon stiffness and elastic energy utilization in the myotendinous complex of the triceps surae. Although these changes are possibly essential determinants, only increases of tendon stiffness were observed to correlate with performance improvements.
The primary results of this experiment indicate that vertical jump was not significantly improved with short-term plyometric or squat training using the design and volume in this study. However, a six-week periodized squat training program did increase 1RM strength. Strength coaches may have to design programs with greater volume or longer duration to elicit significant improvements in vertical jump.
Results indicate that there are quantitative differences between plyometric exercises in the rate of force development during landing and the forces placed on the knee, though peak GRF forces associated with landing may not differ.
Based on the findings, it was concluded that plyometrics exercises with depth jumping and rebound jumping characteristics are best used in developing muscle strength of the lower extremities.
Correlation between all other variables was found not to be significant. Based on the finding of the study it was concluded that plyometrics training with repeated jumps horizontally and that which involves rebound jumping on the spot, are capable of improving leg muscle power in similar ways. Moreover, the study also concluded that, plyometrics training is capable of improving leg muscle strength and power significantly
Conclusion: Plyometric training increased single-fiber Ca2+ sensitivity, especially in type I fibers. These changes could not be explained by a modified TnT isoform expression pattern.
These results indicate that overhead goals may be incorporated during training and testing protocols to alter lower-extremity biomechanics and can increase performance.
In conclusion, the main findings of this study showed that 5 weeks of WBV training by means of this specific protocol did not improve knee-extensor and knee-flexor strength, knee-extension velocity, jump performance, force-time characteristic of the start action or sprint running velocity, when the WBV training was performed prior to conventional training sessions in sprint-trained athletes. It is suggested that the intensity and volume of the specific WBV protocol may not be high enough for these highly-trained athletes. Further research is necessary to demonstrate and to investigate the potential role of WBV in the training of sprint-trained athletes.
We conclude that combined WBV and CRT (CONVENTIONAL RESISTANCE TRAINING) did not additionally increase MVC and mechanical performance compared with CRT alone. Furthermore, WBV (WHOLE BODY VIBRATION TRAINING) alone did not increase MVC and mechanical performance in spite of increased GH.
Men, however, did not experience performance enhancing effects following any of the vibration sessions. While significant differences did not occur between time in either gender, the effects of the 45 sec WBV session in women were transient, lasting approximately five minutes. During the prescription of WBV, gender should be considered given that the results of this study seem to indicate that men and women respond differently to WBV. The results of this study suggest that WBV might be a useful modality as applied during the pre-competition warm-up.
