Effects of six-week plyometric training incorporated with augmented feedback on ground reaction forces
Date Issued
2011
Date
2011
Author(s)
Liao, Tzu-Chieh
Abstract
Plyometric training is normally adopted in athletes’ power training that can improve muscle strength, jump height, and tendon stiffness. However, as muscle performances after plyometric training such as jump height improved, it is inevitable that ground reaction forces during landing will also increase and further cause non-contact sports-related injuries. However, no current study has examined the effects of plyometric training on ground reaction force. Past researches had used neuromuscular training, verbal instructions, or feedback to alter the landing mechanics of athletes. However, no study has examined whether plyometric training incorporated with augmented feedback to landing skills would have similar effects. Therefore, the purpose of this research was to examine the effects of six-week plyometric training incorporated with augmented feedback to landing skills. According to the purpose, two study objectives were developed: 1) to examine whether plyometric training was effective in influencing ground reaction forces, landing performance, isokinetic muscle strength, vertical jump height, and anaerobic power and 2) to examine whether extra augmented feedback given was effective in influencing ground reaction forces, landing performance, isokinetic muscle strength, vertical jump height, and anaerobic power.
The current research was a prospective, double-blind and randomized controlled trial. There were 21 college-level male adults recruited for the research and randomized allocated to PYT+AF and PYT groups. Participants received their major measurements during pre-, mid-, and post-training testing sessions. The major measurements included variables of kinetic and kinematic during landing from a countermovement jump, landing performance, muscle performance, and sports performance. The research used force platform, motion analysis system, isokinetic testing system, jump-and-reach system, and Margaria power test to examine the variables. The participants were required to perform countermovement jump for the measurement of kinetic and kinematic variables as well as the measurement of vertical jump height. Isokinetic testing system was used to examine the muscle strength of lower extremities while Margaria power test was used to examine the anaerobic power of the participants. 2×3 ANOVA with repeated measures was used to compare the differences between groups and between different testing sessions. Friedman test would be used instead if the variables were not normally distributed. All statistical analyses were calculated using SAS 9.2. The significant level was set as α=.05 while the power was set at 0.8.
The results of the current research were: 1) six-week plyometric training incorporated with augmented feedback significantly improved vGRF, growth gradient, landing time, and degree of knee flexion angle during jump-landing task when impulse remained unchanged, 2) the training significantly improved eccentric muscle strength but not concentric muscle strength and muscle torque steadiness, and 3) the training significantly improved vertical jump height as well as power and was independent of the groups the participants were allocated in.
These results concluded that plyometric training incorporated with augmented feedback was effective in improving the jumping and landing performance simultaneously. Nevertheless, the retention effect of the training was unknown as well as its effect on the reduction of injury rates. This was the first research that examined the effect of plyometric training on ground reaction forces, the results suggested that ground reaction forces might increase after training. If additional augmented feedback was given, it could minimize the magnitude of impact forces. As more and more coaches and athletes adopted plyometric training into their training regime, augmented feedback could prevent the negative effects that brought by plyometric training. Future researches and coaches should add on augmented feedback into the plyometric training protocols so as to reduce the potential risks.
Subjects
plyometric training
landing mechanics
ground reaction forces
augmented feedback
Type
thesis
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