## 4 Discussion

Table 4: Associations between anthropometric parameters and physical fitness components based on multilinear regression analysis. discriminate fat mass, and given that high fat mass can negatively impact physical fitness parameters such as cardiorespiratory fitness [20; 21], we hypothesized that anthropometric parameters that were significantly associated with fat mass would be negatively associated with cardiorespiratory fitness. The results of the present study corroborate this hypothesis, indicating that increases in the sum of four skinfolds, subscapular skinfold, waist circumference and waist-to-height ratio are significantly associated with increased fat mass percentage, and significantly associated with decreased VO\({}_{\text{2 peak}}\), thus showing that anthropometric parameters can be applied for monitoring fat mass and cardiorespiratory fitness in HIV-diagnosed children and adolescents. Furthermore, considering that HIV-diagnosed children and adolescents can present alterations in fat mass distribution/accumulation [4; 5] as well as a low cardiorespiratory fitness [7; 8], and that there is a need to monitor physical fitness in this population, including the measurement of four skinfolds and waist circumference in a follow-up routine can provide relevant information for monitoring fat mass percentage and cardiorespiratory fitness in this population. The investigation of the association between anthropometric parameters and fat-free mass, BMC and BMD was based on the results of a previous study that investigated the usability of anthropometric parameters, such as bone diameters, for monitoring bone parameters in HIV-diagnosed children and adolescents [32]. It was also based on the assumption that there is an association between bone development and fat-free mass, considering that improvements in bone structure through the recruitment of mineral cells are related to the mechanical load applied to bones, which in turn depends on the capacity of muscle force production [56]. Considering this relationship between muscle force production and bone development [56], it was hypothesized that bone diameters could also be associated with muscle strength/endurance. However, while humeral diameter, femoral diameter and the sum of diameters were significantly associated with fat-free mass, BMC and BMD, a significant association with handgrip strength was only observed in the simple linear regression, and was not sustained in the multilinear regression analysis. Thus, the results from the present study only support the assumption that bone diameters can be used in monitoring fat-free mass, BMC and BMD in HIV-diagnosed children and adolescents. Regarding muscle strength/endurance, a previous study with HIV-diagnosed children and adolescents investigated the relationship between BMI and muscle strength/endurance, reporting that BMI was significantly associated with handgrip strength but not significantly associated with values from the standing broad jump test, abdominal endurance, or the number of modified push-ups [17]. The authors argued that BMI was associated with handgrip strength because increases in BMI can be related to increases in fat-free mass [22; 25] positively affecting isometric tests [23; 24], and suggested that variables such as age, sex and fat mass percentage could be more useful than BMI in investigating muscle strength/endurance [17]. In addition, previous studies described how fat mass could negatively affect muscle strength/endurance, which is often measured using tests that involve body movement, such as the standing broad jump, the abdominal endurance, and the modified push-ups test [23; 24]. Thus, we hypothesized that anthropometric parameters that were significantly associated with fat mass could negatively affect the standing broad jump, abdominal endurance, and modified push-ups results. The results from the present study corroborate this hypothesis, indicating that increased values for calf skinfold were associated with decreased distance values in the standing broad jump test.