# Could Mini-Trampoline Training Be Considered as a New Strategy to Reduce Asymmetries?
## 4 Discussion  
This study aimed to investigate the effects of the SJ training on subject's dynamic balance performance and to observe BA and UA Indexes acute changes after the SJ training intervention in healthy young adults. The relevant findings of the present study suggested that SJ training positively affected the UA Index for the SJG, by significantly reducing the lower limb balance asymmetry. Furthermore, considering the relationship between the UA Index \(\Delta\) change and UA Index baseline values, results showed that subjects with higher UA Index baseline values had higher UA Index \(\Delta\) change after the SJ intervention. On the other hand, a marginal and not significant effect of the SJ on BA Index was found. Plyometric training, such as repetitive jumps, represents a dynamic form of resistance training that involves displacements of the center of gravity resulting in improved dynamic postural control [28; 29]. Thus, SJ training preserves both the characteristics of the stretching-shortening cycle and the displacements of the center of gravity, which characterize any type of polymetric training. It has been shown that glyometric training had chronic effects on the dynamic balance of young athletes in basketball [30; 31] soccer [32], and rhythmic gymnastics [33]. Alongside this, few studies have investigated the acute effects of glyometric training on the balance performance of young athletes in weightlifting [34], volleyball [35] and football [36] or in recreationally trained individuals [37]. Although dynamic balance is considered a physical ability that requires long-term intervention training protocols in order to be improved, different studies have indicated that a single glyometric intervention has the potential to improve balance performance [34]. In line with these previous studies, findings from the present study confirmed that SJ training acutely improved WB performances. In fact, the main difference was observed between the SJG in POST (22.2 \(\pm\) 6.8 s) and CON in PRE (15.5 \(\pm\) 7.1 s) intervention for the WB balance performance on the dominant limb with respect to the non-dominant one. Recently, [PERSON] and colleagues [21] have fully investigated the minimal detectable change values to determine significant changes in dynamic performance on the WB. Accordingly, the emerged mean difference of 6.7 s between the POST intervention of the SJG and PRE intervention of the CON might be considered a real change in WB dynamic balance performance. Therefore, these results suggested that SJ training could be considered in training programs to acutely enhance dynamic balance. However, further research to evaluate the acute effect of SJ on the dynamic performance assessed by WB in several populations is needed. Figure 4: Means and standard deviations of Unilateral Asymmetry Index between the Bilateral Asymmetry equal and change categories. Repeated jumps training may also cause fatigue and joint instability by negatively affecting postural control and increasing the BA Index [38]. In line with this assumption, a previous study showed that excessive jumps training cause muscle fatigue, decrease the concentric peak power and the stretching reflex and increase the magnitude of the BA Index in young athletes [39]. On the contrary, despite the 30 min of SJ workout performed in our study, no significant differences in BA Index between SJG and CON groups in PRE and POST evaluation were found. These results might be due to the selected workout. In fact, although the selected workout was standardized in terms of execution, performing repetitive jumps on a mini-trampoline may not have influenced the magnitude of BA Index. Thus, accurately selecting the type of polyometric training and type of surface where the jumps are executed might decrease the effects of fatigue on BA and consequently reduce the performance loss during balance dynamic performances. The literature identified that a UA threshold of \(>\)15% is considered as the real UA [1; 40].