Anthropometric Profile in Different Event Categories of Acrobatic Gymnastics

Research in sport science points out that there are certain morphological characteristics which enhance the athletes’ chance to succeed. These features are specific to each sport, thus determining a reference profile that is necessary for a successful talent identification process (Claessens et al., 1999). Moreover, within the same sport, there are differences depending on the position, role or event category in which the athlete specializes (Ghobadi et al., 2013).

The morphological typology for anthropometric measurements, somatotype, body composition and proportionality has been studied in gymnastics disciplines of the International Federation of Gymnastics, such as Men’s and Women’s Artistic Gymnastics and Rhythmic Gymnastics (Bester and Coetzee, 2010a; Joao Fernandes, 2002; Poliszczuk et al., 2012; Massidda et al., 2013). However, in Acrobatic Gymnastics (AG) research is scarce (Slezynki and Swiat, 1997).

AG is experiencing strong growth in both participation and sporting levels. It is a motor and social sport, where one or more pairs synchronize their actions in a stable, regulated space where they could perform throws, figures and human pyramids (Vernetta et al., 2008). The gymnastic exercise involves combining individual and group elements synchronized to music, which is the essence of this discipline. In pairs and groups two fundamental roles are differentiated: bases, who carry out supporting and pitching roles, and tops, who perform elements of flexibility, balance and combinations thereof or great acrobatic jumps in the aerial phase propelled by the bases who then catch them again or on the ground (Vernetta et al., 2007). Gymnasts compete in different event categories: pairs (male, female or mixed) or groups (women’s trios or men’s four).

In 1997 Slezynski and Swiat conducted a study on the anthropometric profile of world class and Polish gymnasts and established specific profiles for each role and event category, showing that there were differences between the roles played. Another very recent work has confirmed this role differentiation (Taboada-Iglesias et al., 2015). However, there is a lack of studies establishing the distinct profile not only for the specific role in general, but for each event category in particular. Thus, this research study aimed to determine the anthropometric profile, somatotype, body composition and proportionality of the AG depending on the event category and the factors that predisposed the gymnast to performance.

The results were analyzed according to the role played, including a description of tops and bases in all event categories, but only the procedures performed by the same gender were compared.

Tables 1 and 2 show the mean and standard deviation of anthropometric measurements, of the BMI, somatotype and body composition of tops and bases in all event categories. Following comparative analysis, there were no significant differences between the different types of female tops (mixed pair, female pair and group) or between male bases (mixed pair - male pair). The only differences were found between types of female bases (female groups - female pairs), showing higher values in female pair bases.

When performing an analysis of the distribution of fatty tissue according to the skinfolds, it was noteworthy that the thigh fold had the highest value in all the tops and bases, while the biceps presented the smallest values (Figure 1).

Analyzing the BMI, the tops of all event categories were underweight, with tops in the female groups having the lowest values. In all groups of bases, there were no significant gender differences in the BMI and they were defined as of normal weight, however, the bases presented the lowest value in female groups as in the case of the tops.

As for a somatotype, the mesomorph component predominated in tops and bases in all event categories, with higher prevalence in male bases. The tops were defined as ecto-mesomorphs in the categories of male pairs and female groups and as balanced mesomorphs in patterns of female and mixed pairs. In female bases, the endomorphic component presented values similar to the mesomorphic one, defined as the central somatotype in female groups and mesomorph-endomorph in female pairs. In male bases, it was called balanced mesomorph. The somatocharts show that there was a mean tendency of each group and participant (Figure 2).

With regard to body composition of tops, the outstanding feature was the high percentage of muscle mass and low values of fat mass in all studied groups. Bases presented significant differences between the female gymnasts both in terms of the percentage of fat and muscle mass, muscle mass values being higher in female groups, whereas those of fat mass were higher in female pairs. In males, the highest values were obtained in the muscular component and the lowest in fat percentages, although without significant differences between them.

The means and standard deviations typical of the Z values of proportionality assessment using the Phantom stratagem are set out in Figure 3 and the comparison was made between groups of event categories of bases and tops. Among the female tops, significant differences were established for the bistyloid breadth of the wrist. The tops of mixed pairs differed from the other two event categories by presenting higher values in this variable, the highest value of proportionality being found in all tops. The values obtained by females were between −2.5 and 3, while those obtained by the males were between −2.5 and 2. In the proportional distribution of skinfolds, it was found that those of the trunk obtained lower values than those of the limbs according to the event category, all presenting values between −2.5 and −0.50. Thus, the tops of all event categories were proportionally smaller than the model established by the Phantom stratagem in virtually all variables, and in particular the bistyloid breadth of the wrist, biacromial breadth, biliocristal breadth, trochlear condyle of the humerus and bicondyle breadth of the femur were worth noting, except for the latter in female pair tops.

Significant differences were found in the minimum abdominal fold in female bases, although groups presented lower values. The values obtained by females were between −2 and 1, while those obtained by males were between −2 and 2.5.

Analyzing the proportional distribution of skinfolds, it was found that all folds in both females and males had values between −2 and 0. In turn, the folds of the trunk presented lower values than those of the extremities according to the event category, and this was more pronounced in females. Female bases were proportionally smaller than the model established by the Phantom stratagem in virtually all variables. Figure 3 shows that the proportionality of male event categories was also slightly higher in mixed pair bases compared to male pairs, except in breadth, sitting height, diacromial diameter and bicondyle of the femur.

Finally, a binary logistic regression analysis was conducted by introducing the event category as a dependent variable in two categories: 0 (female pair bases) and 1 (female group bases). The model correctly classified 82.7% of the cases. The Hosmer and Lemeshow test indicated the goodness of fit of the model at the level of 67.1%. The model included variables of breadth, sitting height, biliocristal diameter, minimum abdominal circumference and the percentage of fat mass, as well as a constant. The Nagelkerke R square indicated that the model explained 39.9% of the cases and the Omnibus test indicated that the model was improved by adding these variables, concluding that the model was significant (p<0.01).

The probability of being a base in a female pair is given by the following equation: P (Base FP) = 1/1 + e (−27.792 + 0.124 × height + 0.138 × sitting height −0.893 × D biliocristal + 0.188 × P, + 0.314×% of minimum abdominal fat).

According to this equation, a gymnast presenting high values for body height, sitting height, minimum abdominal circumference, the percentage of fat and low bilocristal diameter is more likely to play the role of a base in a female pair, rather than in female groups (Table 3).

The aim of this study was to determine the anthropometric profile, somatotype, body composition and proportionality in AG, as there are only few scientific studies that have analyzed these characteristics and even fewer by event category according to competition rules. The major findings were the absence of statistically significant differences (p < 0.05) between groups of female tops in different event categories (female groups, female pairs and mixed pairs) and among male bases in the two event categories analyzed (male pairs and mixed pairs). However, there were significant differences between female bases of groups and pairs, anthropometric measures being a decisive factor when guiding gymnasts in both event categories. Greater values in body height, sitting height, abdominal circumference and the percentage of fat mass were determinants in the event category of female pairs, whereas higher values in the biliocristal diameter were conclusive for bases in female groups.

The mesomorph component is predominant in all event categories for both bases and tops, other components presenting varying values depending on the event category. The tops in all the event categories analyzed presented high percentages of muscle mass and low values of fat mass. Proportionality indices showed that, except for the mixed pair bases, all gymnasts obtained negative body mass values. Similarly, both tops and bases in all event categories presented proportionally very low skinfold values. The results of body composition according to roles showed a higher percentage of fat mass in female pair bases compared to the lower values of male pair tops. For the bone percentage, the bistyloid diameter of the wrist had a higher proportionate value in all female tops.

Finally, the binary regression analysis indicated that possessing high values for body height, sitting height, minimum abdominal circumference, the percentage of fat and low bilocristal diameter were the best predictors of performance in the base role in female pairs.

As a result of our findings, since there were no significant differences between the roles performed by the male tops or bases, it seems that the anthropometric measures are not determining factors to guide a gymnast toward one event category or another, since he/she can achieve the same success in any of them. The orientation should be established by other criteria related to the motor, functional and psychological characteristics required by this sport. However, this is not the case of female bases, as there are significant predictive values, as indicated above, for them to perform in pairs or in groups.

Finally, this study provides reference values of anthropometric characteristics, body composition and somatotype of Spanish elite gymnasts in different acrobatic gymnastic event categories. This information provides a reference frame for coaches to improve talent detection and identification in acrobatic gymnastics and thus, help improve athletes’ performance.