The Influence of Maturity Status on Anthropometric Profile and Body Composition of Youth Goalkeepers

The anthropometric profile assessment is an important aspect to consider during the growth stages of youth sport practitioners due to its usefulness in controlling maturity status and overall health. We performed an anthropometric profile evaluation in a sample of youth goalkeepers (n = 42) during a training camp, dividing them into three categories based on their years from peak height velocity (YPHV). We also checked if the selection of goalkeepers was associated with the birth quartile. The results showed that most of the participants’ anthropometric parameters followed the normal trend according to the maturation stages. However, several subjects showed an overweight/obese condition and/or high waist circumference. Non-optimal values were found, mostly in the group of goalkeepers around the PHV. In addition, no selection based on birth quartile was seen. Therefore, the anthropometric profile and body composition of youth goalkeepers are physiologically affected by maturity status. However, several subjects were found to be overweight/obese and at cardiometabolic risk, suggesting that children and adolescents, although practicing sport, should pay attention to potentially contributing factors such as the attainment of the recommended levels of physical activity, lowering sedentary time, and adopt a healthy lifestyle.


Introduction
Anthropometry is a valuable technique for assessing the size, proportions, and composition of the human body [1]. Common anthropometric measurements include height, weight, skinfolds, and circumferences, frequently used as nutritional status indexes, health, and growth [2]. In particular, anthropometry and the derived body composition parameters are useful tools to evaluate both the children and adolescents at the different stages of growth [3]. In this regard, Mirwald et al. developed a formula to obtain the peak height velocity (PHV) [4]. PHV is defined as the maximum velocity of growth in stature or the growth spurt in height, and it represents a valid indicator of somatic maturity status [3]. Moreover, years from PHV (YPHV) are obtained subtracting the age of PHV from chronological age, and characterize a non-invasive method to assess the trend of maturity in children [4].

Age and Maturity Status
According to the estimated age at PHV, the maturity status was defined based on the Mirwald et al. equation [4]. Participants were classified into three groups based on their YPHV: pre-PHV (offset <−1 years), circa-PHV (≤±1 years), and post-PHV (offset >+1 years), as a previous study reported [41].

Statistical Analysis
The Shapiro-Wilk test was performed to check the normality of the data. The analysis of variance (ANOVA) was used to determine the differences between maturity status group (defined as fixed factor) in body composition and anthropometric parameters (defined as dependent variables), and partial eta squared (η 2 p ) was calculated to indicate the effect-size (small = 0.01, medium = 0.06, large = 0.14) [42]. When the analysis of variance (ANOVA) showed significant results, a Tukey's post hoc test was used to confirm where the differences occurred. Pearson's correlation coefficient was used to determine the extent of correlation between YPHV and anthropometric measures. Following the appropriate indications [43], the magnitude of correlations was considered as: r = 0.00-0.09, negligible; r = 0.10-0.39, weak; r = 0.40-0.69, moderate; r = 0.70-0.89, strong; r = 0.90-1.00, very strong. Finally, when the necessary conditions were met, the chi-square (χ 2 ) test for independence was used to check the association between maturity status and the selected categories (BMI, waist circumference, birth quartile, growth velocity, and achievement of peak growth). When data were not normally distributed, the Kruskal-Wallis with Dunn's post-hoc test was used instead of ANOVA and Tukey's post hoc, and Spearman's Rho was used instead of Pearson's r. Descriptive data are presented as mean ± standard deviation, while categorical data as frequency (count and percentage of the group, total count, and percentage of the total). The statistical significance was set at <0.05. Table 1 shows the descriptive statistics for the participants' anthropometric and body composition variables divided by maturity offset.

Correlation between Years from Peak Height Velocity (YPHV) and Anthropometric Measures
Correlation analysis showed that YPHV had a significant relationship with weight, height, arm span, sitting height, MAC, MAMC, MAA, MAMA, AFI, WC, W/Hr, %PAH, BMI, FM, %FM, and FFMI. Table 2 contains the complete panel of correlations.  On the other hand, AS/Hr, SH/Hr, subscapular skinfold, MAFA, PAH, FMI, and triceps skinfold did not show a significant correlation with YPHV, although triceps skinfold was close to statistical significance, presenting a weak negative correlation (r = −0.288, p = 0.065). As stated before, the participants were assigned to the three groups representing the different maturity status (pre-PHV, circa-PHV, and post-PHV), based on their YPHV.
When the data met the required conditions, the χ 2 test of independence was used to check if the association between the groups of goalkeepers and the selected categories were present. Otherwise, the number of subjects and frequencies were calculated (Figure 1).
The selected categories were: BMI (divided into "normal weight" and "overweight/obese"), WC (divided into "not at risk" and "at risk"), birth quartile (divided into "first/second" and "third/fourth"), W/Hr (divided in "normal" and "high"), and achievement in peak growth (divided in "reached" and "not reached").
An association between maturity status and WC categories (χ 2 = 8.956, p = 0.011) was seen (Figure 1a). The circa-PHV group showed the highest number of subjects with a WC >90th percentile and thus was considered at risk regarding this factor (i.e., 10 subjects, representing 71.43% of the circa-PHV group). In the pre-PHV group, 4 subjects (33.33%) were considered at risk, and in the post-PHV, 3 goalkeepers (18.75%) were in the same condition. Taking into account the entire sample of goalkeepers, 17 of them (40.48% of the total) had a WC >90th percentile, while 25 (59.52% of the total) had a normal WC. When the data met the required conditions, the 2 test of independence was used to check if the association between the groups of goalkeepers and the selected categories were present. Otherwise, the number of subjects and frequencies were calculated (Figure 1).
The selected categories were: BMI (divided into "normal weight" and "overweight/obese"), WC (divided into "not at risk" and "at risk"), birth quartile (divided into "first/second" and "third/fourth"), W/Hr (divided in "normal" and "high"), and achievement in peak growth (divided in "reached" and "not reached").
An association between maturity status and WC categories ( 2 = 8.956, p = 0.011) was seen (Figure 1a). The circa-PHV group showed the highest number of subjects with a WC >90th percentile and thus was considered at risk regarding this factor (i.e., 10 subjects, representing 71.43% of the circa-PHV group). In the pre-PHV group, 4 subjects (33.33%) were considered at risk, and in the post-PHV, 3 goalkeepers (18.75%) were in the same condition. Taking into account the entire sample of goalkeepers, 17 of them (40.48% of the total) had a WC >90th percentile, while 25 (59.52% of the total) had a normal WC.
Moreover, as expected, a strong association between maturity status and peak growth achievement was seen (Figure 1b BMI and W/Hr data did not meet the required criteria to run the 2 test (Figure 1d,e respectively). However, in the pre-PHV group, 4 subjects (33.33%) were overweight/obese, while in the circa-PHV group, 8 subjects (57.14%), and in the post-PHV group 3 (18.75%) subjects were overweight/obese as well. Overall, on the 42 participants, 15 (35.71% of the total) were in overweight/obese condition, and 27 (64.29% of the total) were normal weight.
Finally, two subjects in the pre-PHV group (16.67%) and two subjects in the circa-PHV group (14.29%) presented a high W/Hr.

Discussion
In the present study, we investigated the influence of maturity status on the anthropometric profile and body composition of youth goalkeepers from different soccer teams, dividing them considering their somatic maturation state according to their YPHV. In addition, we evaluated whether a RAE was present in the different groups of goalkeepers.
The main results were that, although participating in sport, the group of youth goalkeepers included a high percentage of subjects with unhealthy body composition and that the worst condition was found for the circa-PHV group. Secondly, regarding the RAE, participants in the first and second half of the year were almost equally distributed, and no association was found regarding the number of goalkeepers of the first/second birth quartile and state of maturity. This result agrees with literature reporting that selection based on maturity is more evident in high-level teams [18]. On the other hand, despite the lack of association between goalkeepers' birth quartile and state of maturity, the circa-PHV group was composed mainly of participants who reached the peak growth Moreover, as expected, a strong association between maturity status and peak growth achievement was seen (Figure 1b; χ 2 = 29.143, p = <0.001). Indeed, all the participants appertaining at the pre-PHV group (n = 12, 100.00%) had not reached the peak growth, whereas all the subjects in the post-PHV group had reached the peak growth (n = 16, 100.00%). Regarding the circa-PHV, five subjects (35.71%) had not reached the peak growth, while 9 of them (64.29%) had reached it. Hence, half of the goalkeepers (n = 21, 50.00% of the total) had reached the peak growth, and the other half (n = 21, 50.00% of the total) had not reached it.
BMI and W/Hr data did not meet the required criteria to run the χ 2 test (Figure 1d,e respectively). However, in the pre-PHV group, 4 subjects (33.33%) were overweight/obese, while in the circa-PHV group, 8 subjects (57.14%), and in the post-PHV group 3 (18.75%) subjects were overweight/obese as well. Overall, on the 42 participants, 15 (35.71% of the total) were in overweight/obese condition, and 27 (64.29% of the total) were normal weight.
Finally, two subjects in the pre-PHV group (16.67%) and two subjects in the circa-PHV group (14.29%) presented a high W/Hr.

Discussion
In the present study, we investigated the influence of maturity status on the anthropometric profile and body composition of youth goalkeepers from different soccer teams, dividing them considering their somatic maturation state according to their YPHV. In addition, we evaluated whether a RAE was present in the different groups of goalkeepers.
The main results were that, although participating in sport, the group of youth goalkeepers included a high percentage of subjects with unhealthy body composition and that the worst condition was found for the circa-PHV group. Secondly, regarding the RAE, participants in the first and second half of the year were almost equally distributed, and no association was found regarding the number of goalkeepers of the first/second birth quartile and state of maturity. This result agrees with literature reporting that selection based on maturity is more evident in high-level teams [18]. On the other hand, despite the lack of association between goalkeepers' birth quartile and state of maturity, the circa-PHV group was composed mainly of participants who reached the peak growth (64.29%). This result suggests that it is important to pay particular attention to the state of maturity when children are very close to the growth spurt.
As expected, the state of maturity status affected the anthropometric profile and body composition of the goalkeepers. The statistical analysis showed differences in most of the measured variables, indicating an adverse condition regarding body composition for the goalkeepers, mainly in the circa-PHV group compared to the post-PHV group.
For example, although there were differences in age and maturity state, the weight and BMI were similar between circa-PHV and post-PHV, indicating a possible excess in body fat in the younger participants. This aspect was confirmed by comparing body skinfolds and derived body fat measures such as %FM and FMI. We found that triceps skinfold was higher in the circa-PHV, as well as %FM and FMI (Table 1). Although %FM was higher in pre-PHV compared to the others, when fat mass was normalized for height, the circa-PHV group emerged as that with the poorest body composition. Furthermore, the subscapular skinfold was similar among the three groups of goalkeepers but also, in this case, the higher value was found in the circa-PHV.
Considering the entire sample of goalkeepers, 17 (40.48% of the total) showed a high WC that indicated abdominal obesity and increased cardiometabolic risk. A higher number of subjects with abdominal obesity were in the circa-PHV group. Moreover, W/Hr was different between the three states of maturity, and both the pre-PHV and the circa-PHV presented two goalkeepers having the W/Hr higher than 0.5. Waist circumference shows a high correlation with visceral adipose tissue, plasmatic level of lipids, lipoproteins, and the hormone insulin [34], and W/Hr represents a predictor of cardiovascular risk in children and adolescents [28,34].
Assessing anthropometric variables and body composition close to puberty is crucial because it could also predict adult body composition and future health [44]. Typically, in males, there is an increase in FM at 8 years to 14 years, then FM tends to decrease at about 16 years and subsequently tends to reach a plateau [45]. According to this evidence, the subjects appertaining at the circa-PHV group showed increasing adiposity values in our study. However, a major part of them showed pathological conditions and anthropometric values that place them at risk for cardiovascular and metabolic diseases. Furthermore, it is demonstrated that goalkeepers tend to be heavier, taller, and have larger skinfolds than outfielders [13]. However, although it seems that during puberty, FM typically increases and that goalkeepers present higher anthropometric values, in this study, such conditions are exacerbated. Indeed, factors other than normal growth trends could cause such non-optimal condition for circa-PHV.
Overall, an important consideration is that many of the examined youth goalkeepers were in a condition of overweight/obesity and/or presented high WC and W/Hr. In recent years, a worrying increase in pediatric adiposity was observed almost worldwide [46]. Several non-heritable factors contributed to this obesity pandemic among children and adolescents, including nutrition, physical activity, sports participation, sedentary behavior and electronic devices usage, and parental modeling [46][47][48][49][50]. In the present study, a large proportion of participants showed an unfavorable body composition, despite sport participation. In this regard, it is well known that physical exercise and training are potent stimuli that elicit positive adaptation [51][52][53][54][55][56][57][58][59][60]. However, a previous study indicated that youth soccer players might fail to reach the recommended physical activity levels during days without sports practice. Furthermore, the less active they were off-training, the less they moved during training practice [21]. Thus, such off-training behaviors could be a major cause of the condition found in our sample [61,62].
In addition, goalkeepers tend to have a lower energy expenditure than outfielders, and such a situation is also reported for high-level professional athletes [63]. Thus, more attention should be paid to youth goalkeepers playing in lower-level teams.
Finally, anthropometry is a valuable tool for monitoring harmful situations associated with adiposity, hormonal status [37], and the extent of cardiovascular risk among children and adolescents [38], as well as avoiding early selection.

Limitations
In this study, we do not measure the levels of physical activity of the participants. However, such an assessment could be useful in future studies investigating anthropometric profile and body composition in youth populations.

Conclusions
In conclusion, this study evaluates the anthropometric profile trend of a group of goalkeepers, taking into account the state of maturity. The majority of the variables followed the physiological trend occurring during puberty. However, among the entire examined group, a non-optimal anthropometric situation for many subjects indicated an increased risk of cardiometabolic disease. The results of this study add shreds of evidence that also youth goalkeepers participating in sport could be at health risk, and thus attention should be made to factors known to affect body composition and health (e.g., physical activity, sedentary time, and nutrition habits). Thus, monitoring the anthropometric profile and body composition of children and adolescents participating in sport should be an essential aspect to consider in evaluating possible risk conditions and adopting effective countermeasures.