**3. Results**

The characteristics of the participants, including age, body composition, and physical fitness, are shown in Table 1. Although anthropometric data show a statistically higher weight (+7.5%, *p* = 0.010) and height (+3.7%, *p* < 0.001) in the boys, there were no statistically significant differences in relation to BMI (*p* = 0.241) between the boys and the girls. In addition, the boys showed a lower percentage of body fat (−33.4%, *p* < 0.001), but a significantly higher waist circumference (+5.8%, *p* < 0.001).

However, by relativising the average data of the boys and the girls to the different levels of body composition established by Moreno et al. (2006, 2007) [57,58], it is confirmed that the values of BMI, waist and % of body fat are classified as 'medium' in each of the parameters (see Figure 1).


**Table 1.** Anthropometric characteristics and physical fitness variables (*n* = 387).

Note: SD = Standard Deviation, BMI = Body Mass Index, Waist = Waist Circumference, CRF = Cardiorespiratory Fitness. \* Expresses statistically significant differences between boys and girls (*p* < 0.05).

**Figure 1.** Classification of the mean levels of body composition variables based on the average levels established by Moreno et al. (2006, 2007) [57,58].

In relation to the physical fitness components, the boys showed significantly higher performances in each of the tests (*p* < 0.001). However, when categorising the average levels of the boys and the girls to the different levels of physical fitness established by Ortega et al. (2011) [59], the average value of the boys is established as an average value and the girls show high levels. In endurance, the boys show a high level and the girls very high (see Figure 2).

**Figure 2.** Mean levels of physical fitness variables based on the average levels established by Ortega et al. (2011) [59].

*Int. J. Environ. Res. Public Health* **2018**, *15*, 2632

In addition, Table 1 highlights no differences in the KIDMED-index when comparing both the boys and the girls. Analysing the participants in the different categories established based on the percentage of body fat %, statistically significant differences were observed between both (*p* = 0.003), where more girls showed high and very high values and a lower % ranked in low and medium (see Figure 3).

**Figure 3.** Proportion of boys and girls in each of the Alpha Fitness categories based on the percentage of body fat.

When performing a stratification of the sample based on the degree of adherence to MD, 14.99% showed low adherence, 60.72% an average level, and 24.29% a high level. When comparing body composition in relation to the degree of adherence to MD, it was found that, although there were no statistically significant differences in girls, boys showed a higher % of body fat among those who had a low adherence (21.84%) in comparison to a medium (16.79%) or a high adherence (16.21%) (*p* = 0.006) (see Table 2). When categorising the average levels with the classification established by Moreno et al. (2006, 2007) [57,58], the boys and the girls with different levels of adherence to MD present a medium level in the % of body fat and waist circumference (see Figures 4 and 5). On the contrary, when comparing the normative levels of the mean levels of these variables with the categorisation established by Moreno et al. (2006, 2007), it is verified that both genders present average levels in waist circumference and body fat percentage [57,58]. However, in the BMI variable in the boys, even though there were no differences (*p* > 0.05), the average level of subjects with low adherence to MD is rated as a high level, whereas those who show a medium or high adherence present an average level.

**Figure 4.** Mean levels of body composition variables in the boys based on the grouping by Moreno et al. (2006, 2007) [57,58].


**Figure 5.** Mean levels of body composition variables in the girls based on the grouping by Moreno et al. (2006, 2007) [57,58].

The results of the fitness tests showed a higher performance in endurance, both for the boys and the girls, among the participants with a medium or high adherence to MD than those with low adherence (*p* < 0.05) (see Table 2). Moreover, when comparing the endurance classification of the average levels in the boys with a low adherence with the normative levels established by Ortega et al. (2011), these are medium [59], while those that have a medium or high adherence are high (see Figures 6 and 7).

Furthermore, the boys with a high and medium score in the MD have a significantly lower fat percentage and run faster on the 4 ×1 0 m sprint test in comparison to those with a low adherence to MD (*p* = 0.002), with no such difference being found in the girls. However, the average levels of the girls with a low level of adherence to MD were medium, whereas the girls with a medium or a high adherence were classified as high according to Ortega et al. (2011) (ALPHA fitness test) [59]. Regarding the jump test, no statistically significant differences were found in relation to adherence to MD. The same happened with the hand grip test, although the average levels of manual grip strength are classified as low in the boys and the girls with a high adherence to MD compared to the medium levels of participants with a low and medium adherence to MD.

**Figure 7.** Mean levels of the physical fitness variables in the girls based on the average levels established by Ortega et al. (2011) [59].
