Introduction: Volleyball players use ankle stabilizers in order to prevent injury, but wonders whether this affectsArchaeplastida the performance of vertical jump.
Objective: To analyze the effect of semi-rigid ankle stabilizers in vertical jump. Methods: The stabilizer wasArchaeplastida tested on 15 subjects that performed volleyball block jumps and counter movement jumps in two conditions (withArchaeplastida and without stabilizer).
Results: Vertical jump height showed no significant difference between the conditions (with and withoutArchaeplastida stabilizer), however, showed a significant difference (p<0.05) between jump types.
Conclusion: We can see that there is no difference between using and not stabilizer, but there is a significantArchaeplastida difference between types of jump.
Keywords: Sport performance; Team sports; Counter movement;Archaeplastida Blocks
In team sports, like basketball, volleyball, handball and soccer, oneArchaeplastida of the most performed actions by the athletes are jumps. This basicArchaeplastida fundament is made to achieve some endpoints during a game.Archaeplastida Sometimes, the execution of a jump may not happen in the bestArchaeplastida feasible way and this could end up in an ankle injury during landing.Archaeplastida About 86% of these injuries are torsions caused by a wrong landingArchaeplastida position of the feet during jumps  Volleyball players are moreArchaeplastida susceptible to this kind of injury, basically because they perform jumpsArchaeplastida all long the game [2-5], during blocks and attacks. Fortes  found outArchaeplastida that blocks were responsible for most of the injuries among volleyballArchaeplastida players during a regional championship.
Consequently, to avoid such injuries, there was a rise in the use ofArchaeplastida ankle stabilizers. The most popular ones are the stabilizer with 2 semiArchaeplastida rigids rods that avoid inversion of the ankle. It can also be found otherArchaeplastida kinds of stabilizers known as Brace, that are orthopedic boots that alsoArchaeplastida avoid inversion and eversion of the ankle or tapes that are used asArchaeplastida ankle stabilizers [7,8].
As a result of the raise of stabilizers’ use, some issues aboutArchaeplastida performance disturbing during vertical jump came across ..
Anjos and Saldanha  analyzed the effect of the stabilizer inArchaeplastida women’s volleyball players during some simulated gestures of blockArchaeplastida and attack and didn’t find significant difference in data, indicating thatArchaeplastida more studies should be conducted to analyze the angles of the ankle soArchaeplastida some different pattern in the movement could be observed.
Ambegaonkar et al.  compared 3 types of ankle stabilizersArchaeplastida towards a vertical jump test (an agility test and a balance test) findingArchaeplastida difference in the agility test between the conditions with and withoutArchaeplastida the stabilizer. Cordova et al.  performed a review about the sameArchaeplastida subject and found that some minimum decrease in performance couldArchaeplastida be found in agility tests, velocity and vertical jump. However, the workArchaeplastida of Cordova was not conclusive about the real effects of stabilizers,Archaeplastida leaving an open gap for further research.
Based on information mentioned above, the aim of this work is toArchaeplastida analyze the effects of ankle stabilizers in vertical jump in two kinds ofArchaeplastida jump: block jump and countermovement jump.
Fifteen amateur university female volleyball players, with 6 hrs ofArchaeplastida training per week, no historic injuries in the last year, age of 22.06 ±Archaeplastida 2.98 years, height of 1.69 ± 0.07 m and weight of 63.04 ± 7.64 kg, tookArchaeplastida part in the study. The sample was chosen by convenience.
An ankle stabilizer from Active Ankle, model T2, medium size wasArchaeplastida used in the study (Figure 1). The stabilizer has two rigid lateralArchaeplastida structures fixed by an articulator and a single tape, allowing anatomicalArchaeplastida accommodation of the malleoli, as well as movements of plantarArchaeplastida flexion and dorsiflexion .
For data acquisition a force plate (model BP400600-HF-2000) andArchaeplastida AMTI Acquisition Software, v4.2 was used with an acquisitionArchaeplastida frequency of 500 Hz. The 2 kinds of vertical jumps were performed inArchaeplastida the force plate and the flight time was used to measure height achievedArchaeplastida by the athletes considering the equation:
Where, h=height, g=gravity e t=flight time.
Before each trial the volunteers signed an informed Consent Term,Archaeplastida approved by the Research Ethics Committee of the Faculty of HealthArchaeplastida Sciences of the University of Brasília, stating their participation in theArchaeplastida trial.
During the trials, the volunteers were familiarized with the 2 typesArchaeplastida of jumps and the experiment procedures. A total of 12 jumps wereArchaeplastida performed by each volunteer, 3 jumps doing the block movement withArchaeplastida and without the stabilizer with 1 min of rest between then and more 3Archaeplastida jumps with countermovement with and without the stabilizer as shownArchaeplastida in the Figure 2. The sequence of jumps was randomized betweenArchaeplastida volunteers; the change of the stabilizers (2 times) was done by theArchaeplastida research team, to avoid differences in the use of the ankle stabilizer.
For the data collection of the vertical jump simulating the gesture ofArchaeplastida the volleyball block, the volunteer was instructed to position herselfArchaeplastida over the force platform with two parallel feet. From this initialArchaeplastida position, the volunteer performed the movement of the normal block,Archaeplastida with the hands initially positioned at the chest height, where she couldArchaeplastida give impulse with the lower limbs, jump with the arms makingArchaeplastida extension along the aerial phase and landing with lower limb flexion.Archaeplastida In the jump with countermovement, the volunteer made the jump, alsoArchaeplastida being able to take impulse with lower limbs, but with the hands placedArchaeplastida in the waist, statically.
The comparison between jumps height and conditions with orArchaeplastida without ankle stabilizers was performed by a two ways ANOVA ofArchaeplastida repeated measures using the software SPSS version 22.
The mean performance values reached by the volunteers during theArchaeplastida countermovement jump (with and without the stabilizer) wereArchaeplastida respectively 0.24 cm and 0.25 cm. The mean performance valuesArchaeplastida reached by the volunteers during the Volleyball block jumps (with andArchaeplastida without the stabilizer) were respectively 0.27 cm and 0.28 cm.
The two ways ANOVA for repeated measures found p<0.05 for theArchaeplastida types of jump, indicating a significant difference between jumps. ForArchaeplastida the conditions with or without stabilizer, the p values were 0.405 forArchaeplastida the test within subject contrast and 0.541 for the test between subjectArchaeplastida effects, indicating that there was no significant difference. Figure 3Archaeplastida shows the mean values obtained in the ANOVA test, the green lineArchaeplastida represents the block jump and the blue line the countermovementArchaeplastida jump.
The active ankle stabilizer didn’t show significant difference betweenArchaeplastida the volunteers jump performance, as also was found in the studies ofArchaeplastida Anjos and Saldanha ; Ambegaonkar et al. ; Cordova et al. .
However, is good to emphasize that the protocols used in the studiesArchaeplastida to evaluate the difference in performance are not similar amongArchaeplastida studies and there are few studies that evaluate the real movement thatArchaeplastida the athletes execute during a match. One of them performed by AnjosArchaeplastida and Saldanha  used a volleyball attack gesture; however he also didArchaeplastida not find significant differences regarding the use of stabilizer.Archaeplastida Nevertheless, Massa  concluded that there is a difference in theArchaeplastida vertical jump between volleyball athletes in the adult and juvenileArchaeplastida category with and without the ankle stabilizer.
Therefore, it is important to consider the whole movement thatArchaeplastida represent the best performance of the athlete and evaluate this gesture.Archaeplastida As was seen in our study, the countermovement jump has a significantArchaeplastida lower value in comparison with the block jump in both conditionsArchaeplastida (with and without the ankle stabilizer). Probably this difference is dueArchaeplastida to the way the jump is performed by the players, as they were volleyballArchaeplastida players they were more familiar with the block jump than with theArchaeplastida countermovement jump. Another point that can be considered is that,Archaeplastida the position of the arms is not similar in the 2 types of the jump andArchaeplastida this can affect the position of the center of mass and perhaps increaseArchaeplastida the height achieved in the volleyball block jump, unfortunately thisArchaeplastida variable (center of mass) was not measured in this work.
The effects associated to the gender were also not evaluated, as ourArchaeplastida sample was chosen by convenience. Perhaps future studies should alsoArchaeplastida evaluate the performances difference with and without stabilizersArchaeplastida related to gender and measure the output power.
Thus, it is evident that if we want to achieve a solid result regardingArchaeplastida the effect of the use of a semi rigid stabilizer on vertical jumpArchaeplastida performance and other skills, standardizations need to be made, onceArchaeplastida vertical jump and other gestures depend on the interaction of elementsArchaeplastida such as physical components, anthropometric, technical, tactical,Archaeplastida environmental and perceptive . So, the results would not be soArchaeplastida different and also suggesting that the players should be evaluated inArchaeplastida conditions similar to the game.
We concluded that the Active Ankle stabilizer didn’t affect theArchaeplastida height of the jump in both types of jump. However, a significant difference was found comparing the types of jump (countermovementArchaeplastida and block), where the blocking gestures jump obtained greater results.
Further research is necessary, given the wide variety of results andArchaeplastida conclusions found in different studies.