## 4 Discussion
In the present study, the limited training experience of the athletes combined with the short-term training stimulus most probably suggest the absence of a training by vision interaction effect, since the preadolescent male and female athletes were not equipped with such a competitive and/or expertise level to efficiently engage their vestibular and/or proprioceptive systems in the regulation of balancing tasks while their vision was being restricted. A final note is dedicated here with regard to the study's secondary purpose that was related to a possible training intervention by sex interaction effect. As reported in the results, the statistical analyses did not yield a significant interaction effect in any balance or lower limb explosive performance measure. Taking into consideration the fact that most of the previous related work has examined male athletes [9; 10; 11; 16; 21; 41; 42], it would have been interesting to present a comparison based on sex. However, the absence of any interaction effect suggested that male and female preadolescent athletes responded in a similar manner to the combined training intervention, and, for that reason, respective results were not presented. Neurophysiological adaptations have been reported to be induced by balance training [53], whereas pyrometric training can elicit neuromuscular responses [54]. However, a significant interference of gender with the effect of pyrometric training on balance performance was not found in a recent meta-analysis [55]. On the other hand, young female athletes were previously reported to show greater adaptive responses when pyrometric training interventions were of longer duration (>16 sessions), had greater weekly training frequency (>2 times) as well as longer durations in each session (\(\geq\)30 min) [56]. This study's short-term training stimulus in combination with the inter-individual differences in the athletes' estimated biological maturation might justify the absence of different responses between the male and female soccer athletes. There are several limitations to be considered in this study. A main limitation was not evaluating the training load, since, despite the inclusion criteria requiring that the athletes had participated in 80% of the team's training sessions in the last 3 months before the start of the study, the observed variation in biological maturity status among the athletes cannot exclude the possibility that the training load was perceived as low for some athletes and as high for some others. Another important limitation is that the menstrual cycle of the female athletes was not controlled for. Even though the age range of the athletes fell within the time period where menarche typically occurs (10-16 years of age), a record and attempt to measure them at the same stage of their menstrual cycle post-training should have been made. Further, the sample team was competing in a regional soccer league, which probably implies that a part of the soccer training was specific to their playing position. Static balance was not assessed in relation to playing position due to the small sample size. Therefore, the possibility that the absence of a significant training intervention effect might be partly related with a variation in balance performance as a result of playing position-related training-induced postural adaptations [57; 58] should be considered.