## 4 Discussion  
The purpose of this study was to investigate the complementary role of MI on VO2 max and lactate levels in professional football players with Grade II ankle sprains during the return-to-play period. The findings demonstrated that the MI intervention had a significant therapeutic effect as a complementary modality alongside conventional physical therapy balance training protocols, particularly on VO2 max and lactate variables. Statistically significant differences were observed between the two groups (MI intervention and placebo) before and after the 4-week intervention period. MI has been proven to be an effective complementary therapeutic modality, in addition to a conventional physical therapy, in sports injury management and rehabilitation [13, 27, 30, 45, 46, 47], and also in sports performance optimization [25, 48]. However, most of the studies evaluate the effects of MI with respect to sports performance in healthy athletes and not during the return-to-play period after a sports injury, such as a Grade II ankle sprain. In our study, the results of VO2 max tests, which were performed using BP through ergospirometry showed statistically significant results 'within subjects' after 4 weeks of MI interventions between the two groups (first, MI intervention group and second, placebo group). A greater improvement was observed between the two phases in the first MI intervention group compared to the second placebo group. Additionally, statistically significant differences were revealed for the first MI intervention group compared to the second placebo group. To the best of our knowledge, this is the first single-blind randomized clinical trial aimed at exploring the complementary role of MI on VO2 max in professional football players with a Grade II ankle sprain during the return-to-play period. While numerous studies over the past decades have investigated the effects of MI on sports performance, they have generally focused on healthy athletes from diverse sports backgrounds, often with limited sample sizes. Furthermore, these studies typically did not include physical capacity parameters, such as VO2 max [20, 26, 49, 50]. A key study by [PERSON] et al. [49] was among the first to examine the impact of MI on motor performance through measurements of oxygen consumption (VO2) and pulmonary ventilation (VE) using ergospirometry. The findings of this study revealed a statistically significant improvement in VE and heart rate in the experimental group, along with a modest enhancement in VO2 within the MI intervention group. Similarly, to our methodological approach, their study explored oxygen uptake as well, but they did not explore the VO2 max variable using BP through ergospirometry to evaluate physical capacity. Also, their study included only eleven healthy amateur athletes from various athletic backgrounds, and therefore their findings could not be generalized with respect to sports performance indices. In our study, the lactate variable demonstrated statistically significant differences within subjects, comparing pre-intervention and post-intervention (4 weeks) levels between the two groups (first, MI intervention and second, placebo group). These differences were observed in lactate accumulation in peripheral blood samples after completing the Bruce Protocol (BP). Additionally, significant differences were found between the two groups, with the first MI intervention group showing a notable reduction in lactate levels compared to the second placebo group. This finding is consistent with the study by [PERSON] et al. [50], in which motor working memory was evaluated by using a sequence of reproduction tasks in order to investigate whether working memory performance was affected by blood lactate levels. Participants derived from the non-athletic population, and they executed a cycling exercise protocol in addition to a working memory task. Their findings showed that high levels of blood lactate worsen types of working memory.