## 4 Discussion  
### The CUN-BAE for Intervention Goals  
Although the BIA approach is commonly applied in athletes' routines, additionally, this study explored the concordance between the BIA and the CUN-BAE. Since reasonable accuracy between the two different methods was found, individual errors may prevent the replacement of the BIA approach with the CUN-BAE in interventional studies. More specifically, in terms of the total sample of high-performance athletes studied, this study found an agreement between the BIA method and the CUN-BAE equation method in calculating BF%. However, our study suggested that on average, the CUN-BAE method measured 2.7% more BF than the BIA. Our findings were consistent with the results published by [PERSON] et al. [50], which referred to a correlation between the CUN-BAE equation method and the BIA method in calculating BF%. However, it was found that the CUN-BAE method overestimated the BIA's calculation of BF%. In contrast, [PERSON] et al. [51] found a significant absolute agreement between the CUN-BAE equation and the BIA for the BF% in middle-aged southern Indians. Also, these authors highlighted that the 'CUN-BAE provides precise BF% estimates similar to the BIA method making it suitable for routine clinical practice when an access to BF% measurement devices is limited' [51].  
In addition, according to our study results, the evidence of the validity of the CUN-BAE rests on low differential bias and moderately sized limits of agreement (95% CI: \(-\)6.5; 7.1). Thus, where the Bland-Altman plot system does not reflect statistics for seeing whether the limits of agreement are exceeded or not [45], our study can only speculate that the CUN-BAE's usefulness a priori cannot be related to clinical implications or interventional study results. This inductive hypothesis was confirmed by the results obtained from this study, where the level of evidence of the CUN-BAE's validity varied in different athlete groups according to age, sex, and sports specialty.  
Particularly, for the subsamples of male athletes aged 18 or over as well as those competing in endurance sports, our study found proportional biases between the two measurements, the CUN-BAE equation and the BIA. In this case, the findings of our study meant that the CUN-BAE equation for measuring BF% was more appropriate for females, junior athletes (aged from 14 to 18), and those competing in strength-power sports. Regardless of this, when the athletes' sex was considered, the CUN-BAE substantially overestimated the BF% in the female athletes overall compared to that measured using the BIA. This difference may exist due to the disparities in the fat distribution patterns among male and female athletes. It has been well documented that females have a higher BF% (in terms of subcutaneous fat), which can influence the outcomes derived from the CUN-BAE equation. This finding of our study presupposes the necessity of further research in order to customize the algorithms of the CUN-BAE equation depending on sex variations due to biological variances.  
Furthermore, scientific research has shown that lipid metabolism during endurance exercise is related to increased fatty acid turnover, as endurance-trained athletes have a high oxidative capacity [52]; therefore, athletes representing aerobic sports have a relatively lower BF%. In addition, the carbohydrate and fat metabolism in the body is more labile during adolescence. It should be highlighted that the results produced by using the CUN-BAE equation may be applied to populations of adolescents, too. Nonetheless, the CUN-BAE equation created via the Bod-Pod approach could also be reconsidered and coupled with variables related to sports activities during future research.