## 4 Discussion
### Training Programming  
Table 4 shows the overview of research where the IFT 30-15 is used for training programming. The Vift obtained by the 30-15 IFT test is simultaneously connected with aerobic capacity, anaerobic capacity (or at least with the portion of the used AVR), the neuromuscular system and internal recovery. Based on this, [PERSON] suggests that the test should be used in order to reproduce and evaluate physical capacities that occur during high-intensity interval training that includes change of direction. The 30-15 IFT is highly-specific, not for sports but for training that is usually used in sports with impermanent-intermittent intensity [35]. A study conducted on a sample of 17 adolescent handball players aimed to compare the effects of repeated sprint abilities (RSA) and HIIT. Vift was used as a value based on which the training was programmed. This model has shown to be positive; that is, as the more effective model to increase physical performance (mean and peak HR, CMJ, 10 m sprint, RSA, peHR recovery) [4]. The same author conducted research with a similar theme a year later, where 33 elite handball players were included, separated into a HIIT group and a group whose training was based on specific handball training (HBT). In this study, both training programs were shown to be equally efficient to approximate progress in performance (10 m sprint, CMJ, RSA, ball throwing speed and iEI) [38]. [PERSON] has also tried to gather as much evidence and relevant facts as possible that would confirm the precision of using the 30-15 IFT in order to individualize interval training. Among a mixed sample composed of handball and basketball players, both male  
and female, he presented the results of a large number of variables on the basis of which he concluded that the mentioned test is a precise and useful tool for the individualization of programming [32]. In order to check the reliability of HR, HRV and parasympathetic reactivations after training, [PERSON] et al. [33] used the mentioned test to program training of different intensities (45%Vift). In another study, [PERSON] et al. have evaluated the sensitivity of NIRS (near-infrared spectroscopy) procedures for different intensities in field training using Vift to program the intensity and volume of training [34]. [PERSON] [17] determined the influence of the length of the section during the 30-15 IFT (28 m and 40 m) on the maximum speed of running, sprinting, jumping and change of direction, all among a sample of 50 athletes playing different sports (soccer, tennis and handball). The study shows that tennis players have higher MRS during the 30-15 IFT-28. In addition, there is a relation between MRS and CMJ, 20-m sprint, as well as between agility test 5-0-5 performances. The results of this study support the interchangeable use of both 30-15 IFT-40 and 30-15 IFT-28 in team sports [17].  
The last recorded study conducted by [PERSON] et al. [39] was conducted on a sample of 114 elite rugby players divided into four age groups--U16, U18, U20 and seniors--with the aim of comparing differences in values of Vift, as well as to compare body-weight ratio with the final speed obtained in the test. The mentioned research is a good example of reference values in the rugby population.  
The contribution of this research to is that even though there are studies that all show reliability and validity of the 30-15 IFT, there is no review concerning program training using this test, which has displayed to be of extreme importance in team sports.  
The drawback of this research may lie in the fact that the authors did not have complete access to all databases. The authors decided to summarize all studies under the same analysis set. The limitation of this review is that it only concerned team sports. However, in the future, it is possible to conduct 30-15 IFT research on individual sports, as well as separate research on men and women.