4. Discussion
patellar tendinopathy
In this present research, we compared the effect of two various decline board angles on the clinical outcome of patients treated for patellar tendinopathy by performing eccentric quadriceps exercises. After 6 weeks of exercise, we found a significant improvement in the clinical scores of treated patients, with no significant difference between the patients who performed eccentric quadriceps exercises on the standard 25° decline board and those exercising on the 17° decline board. A smaller additional degree of improvement was visible at the end of the follow-up period (at 12 weeks), but, again, no statistical difference could be detected between the investigated groups, confirming that exercise performed on a 17° decline board provides equal therapeutical benefits to that performed on the standard 25° decline board.Eccentric quadriceps exercise has been introduced into the therapy of patients with patellar tendinopathy in order to avoid weakening the tendon during the rehabilitation period. The use of a decline board with a decline angle of 25° has been the cornerstone of therapy for the last two decades [The significant improvement in the measured clinical scores occurred after 6 weeks of the exercise. The long-term outcomes are of special interest in professional athletes [Our study has several limitations that need to be considered carefully. Although the patients, after enrollment into this study, received clear oral and written instructions to avoid any additional training during the treatment period, it was not possible to control them for their complete compliance with the given instructions during the whole 12-week period. All of the patients declared compliance with the instructions, but there is still a possibility that potential undeclared additional training could have confounded some of the findings for a few patients. As there is a large amount of data showing that exercises performed on the 25° decline board are superior to the exercises performed on the flat surface, it was not possible to include a group of the control patients exercising on the flat surface for ethical reasons. In addition, as this study was primarily oriented to the investigation of the potential clinical benefit, we made no effort to make the biomechanical measurements of the patients to study the activation of particular muscles. The possible influence of other angles of decline was not investigated, and it remains to be investigated in future investigations.We have shown that the usage of a 17° decline board does not affect the beneficial therapeutic effects of the eccentric exercises, but there are still many unanswered questions that should be studied in future investigations. In our study, we randomized the patients into the 17° decline board and the 25° decline board groups, but further biomechanical studies are necessary to try to identify predictors of ideal muscular activation such as height, weight, or type of the sport. These findings might lead to the personalization of the treatment by enabling physicians to choose the best angle of decline for the particular patient. A bioinformatic approach based on deep learning to analyze collected data might provide additional help to achieve these goals [