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Age-related variation in anthropometric and maturity characteristics of soccer goalkeepers aged 11-14 years
Autor(es): Gonçalves, Ricardo R.; Severino, Vitor; Silva, Manuel J. Coelho e;
Figueiredo, António J.
Publicado por: Imprensa da Universidade de Coimbra URL
persistente: URI:http://hdl.handle.net/10316.2/3363
DOI: DOI:http://dx.doi.org/10.14195/2182-7087_1_4 Accessed : 15-Oct-2022 05:26:36
digitalis.uc.pt
RESEARCH IN SPORT PHYSICAL ACTIVITY AND
ANNALS OF
FACULDADE DE CIÊNCIAS DO DESPORTO E EDUCAÇÃO FÍSICA DA UNIVERSIDADE DE COIMBRA IMPRENSADA UNIVERISDADE DE COIMBRA
2011
1
AGE-RELATED VARIATION IN ANTHROPOMETRIC AND MATuRITY CHARACTERISTICS OF SOCCER GOALKEEPERS AGED 11-14 YEARS
3 • SPORT TRAINING
• 71 Ricardo R. Gonçalves1, Vitor Severino2, Manuel J. Coelho e Silva3,
António J. Figueiredo4
ABSTRACT
The purpose of this study was to compare variation in body size and physique consid- ering somatic maturity status of young sub-elite soccer goalkeepers within two com- petitive age-groups. The sample included 17 sub-elite male soccer goalkeepers in two competitive age-groups, 11-12 years (n=8) and 13-14 years (n=9) proceeding from three clubs in the midlands of Portugal. Height, weight, arm span, body mass index, bicristal/biacromial ratio, sitting height/height ratio and four skinfolds were measured.
Somatotype of Carter & Heath was calculated. Somatic maturity was assessed using the maturity offset and percentage of predicted mature height (%PMH). To analyse differences between young soccer goalkeepers of contrasting age-groups, the Mann- Whitney U test was performed. In sequence, the 11-12 and 13-14 years old groups differed significantly in chronological age, maturity offset and %PMH (p <0.01). Esti- mates for age at peak height velocity, expected to occur, respectively at about 13.97 years of age (95% CI: 13.63-14.31) and 14.07 years (95% CI: 13.62-14.53) show that the older group already experienced this event in 0.15 years (95% CI: -0.33-0.63). For anthropometric characteristics differences were found for weight (p <0.05), height, arm span and sitting height (p <0.01), but not for the other variables. In conclusion, variation in body size associated with the age-group in young soccer goalkeepers is mostly related to growth and maturation and the use of somatic indicators can be a very practical and useful instrument for coaches.
KEYwORDS: Soccer goalkeeper. Body size. Somatic maturity. Selection.
1 Ricardo R. Gonçalves, Faculdade de Ciências do Desporto e Educação Física da Universidade de Coimbra, Estádio Universitário, Pavilhão III, 3040 – 156, Coimbra, Portugal. E-mail: r.rebelo.g@portugalmail.pt.
2 Vítor Severino [vitorjss@gmail.com].
3 Manuel J. Coelho e Silva [mjcesilva@fcdef.uc.pt].
4 António J. Figueiredo [afigueiredo@fcdef.uc.pt].
72 •
INTRODuCTION
Studies regarding young soccer players have been increasing in the last decade (Malina, Peña Reyes, Eisenman, Horta, Rodrigues, & Miller 2000; Stratton, Reilly, Williams, & Richardson, 2004; Figueiredo, Gonçalves, Coelho e Silva, & Malina 2009), empathizing that size, mor- phology and characteristics of young athletes have an important role in selection or exclusion process. These observations, in addiction with several studies (Peña Reyes, Cardenas-Bara- hona, & Malina, 1994; Helsen, Hodges, Van Winckel, & Starkes, 2000; Malina, Eisenmann, Cumming, Ribeiro, & Aroso, 2004c) suggest that soccer is a sport that systematically excludes late mature athletes in relation to those situated on the average and, especially, early matur- ing boys, as chronological age and specialization of the game increase.
The mean heights and weights from a series of studies of young soccer players from about 9 to 18 years of age in Europe and Americas tend to fluctuate above or below the reference medians for non-athletic youth during childhood and early adolescence (about 8-14 years).
However, in later adolescence (14 + years) mean heights are at or below reference medians, while the mean weights are above the reference medians (Malina, 2003). The relationship between height and weight is consistent with data for somatotype. The adolescent soccer players tend to have, on average, a mesomorphic somatotype, with balanced contributions of endomorphy and ectomorphy (Coelho e Silva, Figueiredo, Sobral, & Malina, 2004). The data from Figueiredo (2007) and Seabra, Maia, & Garganta (2001) found the same trend for the mesomorphic dominance observed in elite senior soccer players (Carter & Heat, 1990).
Young soccer players’ maturational status is generally assessed in the context of skeletal or sexual indicators. The use of somatic indicators such as peak height velocity (PHV) or percentage of predicted mature height (%PMH) is still scarce among literature probably be- cause of the longitudinal nature of data. Philippaerts et al. (2006) studied the morphological maturation in 33 Belgian youth soccer players over a five year period. The estimation of age at PHV was 13.8 ± 0.8 years, whereas peak height velocity and peak weight velocity were 9.7
± 1.5 cm/year and 8.4 ± 3.0 kg/year, respectively. The reported values of Figueiredo (2007) from 159 Portuguese young soccer players estimate the occurrence of PHV between 14.0 and 14.5 years, calculated subtracting the maturity offset calculated value to chronological age.
In the context of the selection process, studies that include position related variation are still scarce, particularly the characterization of young soccer goalkeepers. Available data in an- thropometry revealed significant positional differences for height (Wong, Chamari, Dellal, &
Wisløff, 2009) and weight (Gil, Gil, Ruiz, Irazusta, & Irazusta, 2007a), resulting in higher values for body mass index (BMI) when compared to other tactical positions. Results for young goal- keepers also revealed the highest fat, in terms of skinfolds and fat percentage. Nevertheless, the given profiles don’t take into account the age-related variation considering maturity status.
The purpose of this study was to compare the growth and maturity status of young sub-elite soccer goalkeepers in two competitive age-groups, 11–12 and 13–14 years. Variation in body size and physique considering somatic maturity status was specifically compared.
• 73
METHODS
The sample included 17 sub-elite male soccer goalkeepers aged 11.41–14.89 (13.15 ± 1.27) from three clubs in the midlands of Portugal. The athletes were grouped in two-year age categories: 11-12 (n = 8) and 13-14 (n = 9) years-old according to the competitive struc- ture of youth soccer in Portugal. The study was approved by the Scientific Committee of the University of Coimbra and each club. All subjects and their parents or guardians were fully informed of the procedures involving data recording and signed a consent form.
Height, weight, arm span, sitting height, biacromial and bicristal breadths and four skin- folds (triceps, subscapular, suprailiac and medial calf) were measured following the protocol described in Lohman et al. (1988). Body mass index (BMI, weight/height²), bicristal/biacromi- al and sitting height/height ratios (Malina, Bouchard, & Bar-Or, 2004b) and sum of skinfolds (Figueiredo, Gonçalves, Coelho e Silva, & Malina, 2009), driven from the anthropometric measures, were calculated. The endomorphic, mesomorphic and ectomorphic components of the somatotype were also calculated (Carter & Heath, 1990).
Biological maturation was assessed using somatic indicators. The Mirwald, Baxter-Jones, Bailey, & Beunen (2002) equation offers a non-invasive and feasible approach to estimate maturity status for males. In the determination of maturity offset it is necessary to collect the following information from the observation date (i.e., cross-sectional): chronological age (CA), height, weight, sitting height and leg length. The result of the equation estimate the distance, in years, of an individual to the PHV:
– 9.236 + (0.0002708 x (leg length x sitting height)) – (0.001663 x (CA x leg length)) + (0.007216 x (CA x sitting height)) + (0.02292 x ((weight/height) x 100))
A negative value indicates that a subject didn’t reach yet the PHV, while a positive result means the subject already pass through PHV (Figueiredo, 2007). Although maturity offset does not provide an indication of tempo, it does provide an indication of timing between individuals to allow for comparisons between biological maturity groups.
Another non-invasive method is the procedure suggested by Khamis & Roche (1994 and 1995) for predicting the percentage of mature height (%PMH) reached in a certain moment.
The predicting variables are height, weight and mean parental height, being the former vari- ables multiplied by coefficients associated to the chronological age of the subjects:
Intercept + height (height coefficient) + weight (weight coefficient) + midparent height (midparent height coefficient)
The maturational indicator is given by the percentage of predicted mature height reached in the moment of measurement:
74 •
% predicted mature height = (height at the moment / predicted mature height) x 100 In order to characterize young soccer goalkeeper descriptive statistic was calculated by competitive age-group for all variables. Estimated range of values likely to include the true value of the variable was set at 95% (95% CI = mean ± 1.96 x standard error). Considering the limited number of goalkeepers available per age-group a non-parametric analysis was conducted using the Mann-Whitney U test in order to evaluate the hypothesis that there are significant differences in anthropometric characteristics between the 11–12 and 13–14 years age-groups. Effect size estimates for the given non-parametric procedures were calculated according to Rosenthal (1991) (r = Z/(√n)). Using Hopkins (2002) as a guide, correlations were considered as trivial (r < 0.1), small (0.1 < r < 0.3), moderate (0.3 < r < 0.5), large (0.5 < r <
0.7), very large (0.7 < r < 0.9), and nearly perfect (r < 0.9). SPSS Statistics version 17.0 was used with a p<0.05 level of significance.
RESuLTS
Descriptive statistics of players by biological maturity within each competitive age-group is summarized in Table 1. The 13-14 years-old players were significantly older (r = -0.84, p
<0.01) and advanced in somatic maturity status (maturity offset: r = -0.84, p <0.01; and
%PMH: r = -0.70, p <0.01) having, on average, already crossed the PHV in 0.15 years (95%
CI: -0.33-0.63). Estimates for age at PHV, expected to occur at about 13.97 years of age (95% CI: 13.63-14.31) for the 11-12 years age-group and 14.07 years (95% CI: 13.62-14.53) for the 13-14 years age-group, found no differences.
Table 1. Mean and 95% confidence interval for chronological age (CA) and maturity indicators by age-group. Estimates on effect size and results of the Mann-Whitney U test are also indicated.
11-12 (n=8) 13-14 (n=9)
variable mean 95% CI mean 95% CI r p
chronological age (years) 11.95 (11.62-12.28) 14.22 (13.85-14.59) -0.84 <0.01 Maturity Offset (years) -2.02 (-2.46-(-1.58)) 0.15 (-0.33-0.63) -0.84 <0.01 age at phv (years) 13.97 (13.63-14.31) 14.07 (13.62-14.53) -0.09 0.70
%pmh (%) 84.9 (82.8-87.0) 91.6 (89.7-93.4) -0.70 <0.01
Table 2 summarizes the results for all anthropometrical characteristics according to age- group. Differences in height (r = -0.77, p <0.01), weight (r = -0.58, p <0.05), arm spam (r
= -0.77, p <0.01) and sitting height (r = -0.77, p <0.01) among the two competitive groups
• 75 were significant. Anthropometric derived measures and somatotype values do not differed significantly among goalkeepers of contrasting age-group.
Table 2. Mean and 95% confidence interval for anthropometric dimensions by age-group.
Estimates on effect size and results of the Mann-Whitney U test are also indicated.
11-12 (n=8) 13-14 (n=9)
variable mean 95% CI mean 95% CI r p
height (cm) 147.9 (142,0-153,8) 166.9 (161,6-172,2) -0.77 <0.01
Weight (kg) 42.9 (37,5-48,2) 59.8 (50,9-68,6) -0.58 <0.05
arm span (cm) 147.5 (140,6-154,4) 171.5 (165,2-177,8) -0.77 <0.01
sitting height (cm) 75.5 (72,5-78,5) 84.5 (81,6-87,4) -0.77 <0.01
sitting height/height ratio (%) 51.1 (50,1-52,0) 50.6 (49,9-51,3) -0.21 0.39 bicristal/biacromial ratio (%) 72.8 (70,0-75,6) 73.1 (70,3-76,0) -0.07 0.77
body mass Index (%) 19.4 (18,1-20,7) 21.2 (19,1-23,4) -0.23 0.34
sum of skinfolds (mm) 42.0 (28,3-55,7) 33.8 (23,9-43,7) -0.23 0.34
endomorphy 3.4 (2,2-4,6) 2.4 (1,7-3,1) -0.29 0.23
mesomorphy 4.7 (4,3-5,1) 4.4 (3,8-5,0) -0.21 0.39
ectomorphy 2.9 (2,2-3,5) 3.3 (2,5-4,1) -0.25 0.31
In both somatotypes, mesomorphy was the most representative category. However, the 11-12 years-old group had a higher value for endomorphism (figure 1) and the 13-14 age- group a higher value for ectomorphism (figure 2).
Figure 1. Distributions of somatotype of soccer goalkeepers within the 11-12 years old group.
76 •
Figure 2. Distributions of somatotype of soccer goalkeepers within the 13-14 years old group.
DISCuSSION
Observations in growth and maturation for the given young soccer goalkeepers sample were consistent with other studies representing heterogeneous samples (Malina, 2003).
Taking as reference the data provided by Centers for Disease Control and Prevention and the normative position of youth soccer players presented from Malina, Bouchard, & Bar- Or (2004), both age-groups presented an average value for height which was between P25% and P50%, whereas weight mean values were above medians, between P50%
and P75%. Malina, Eisenmann, Cumming, Ribeiro, & Aroso (2004c) found similar results for height and weight in young soccer players for different field positions (defense, mid- field and forward).
Significant differences in anthropometric characteristics were noted, suggesting the trend for the young goalkeepers’ selection on the basis of its body size (Wong et al., 2009; Gil et al., 2007a). Young soccer goalkeeper had a propensity to show more weight compared to height, reflected in the higher value of BMI for the 13-14 age-group (21.2; 95% CI: 19.1- 23.4). On the other hand, the same age-group presented a much lower value for adiposity (33.8; 95% CI: 23.9-43.7) given by the sum of four skinfolds. Our observations support the limited use of BMI since its report can be misleading given the considerable growth in fat-
• 77 free mass during normal male adolescence and the generally larger size and fat-free mass of adolescent athletes (Malina, 2003).
Until the first half of the growth spurt the limbs grow at a higher rate than the trunk, leading to a decrease in the sitting height/height ratio. After the growth spurt, the upper body grows at a higher velocity than the limbs which leads to a slight enhancement of this ratio at the end of puberty (Malina, Bouchard, & Bar-Or, 2004b). Results for sitting height/
height ratio revealed a slight decline between the 11-12 year group (51.1; 95% CI: 50.1- 52.0) and the 13-14 year group (50.6; 95% CI: 49.9-51.3), suggesting that the trunk velocity haven’t reached its peak at this ages.
Results for maturity status suggested that variation in body size associated with the age- group in young soccer goalkeepers is mostly related to growth and maturation. The distribu- tion of soccer players on the criterion of chronological age in age-groups has as consequence a comprehensive difference in size, composition and performance, being the 13-15 years old period the most heterogeneous (Figueiredo, 2007). Within the same age-group, differences found between two subjects with the same chronological age places the late maturity goal- keeper on a disadvantageous position when competing with his advanced peer, which may contribute to the exclusion of potentially talented youngsters because they are smaller, thin- ner and deficient in muscle mass and muscular strength and power. It has been suggested that talent in young soccer players is largely explained by physical precocity (Helsen, Hodges, Van Winckel, & Starkes, 2000). Unfortunately, our analyses do not considered individual dif- ferences in the tempo of the adolescent spurt and its potential role in the selection process for a specific position, only timing.
Our results for age at PHV fall within the amplitude between 13.8 and 14.2 years for the European population referred by Malina et al. (2004a) and the Portuguese young soc- cer players range between 14.0 and 14.5 years (Figueiredo, 2007). When compared to Belgian youth soccer players our results seem to overestimate the age of occurrence of the PHV (Philippaerts et al., 2006).
The use of maturity offset allows coaches to place players on their individual growth curve and adequate and enhance benefits of training programs during periods of rapid growth and maturation. The determination of predicted mature height can also add information for monitoring the maturational development of players, providing coaches a more accessible instrument without having necessity to use skeletal age in order to being able to take strict decisions. In addition, coaches also need to be aware for the qualitatively different sport-specific aspects associated to the goalkeeper position such as technical and tactical skills and consider it on the dynamic nature of growth, develop- ment and maturation.
78 •
CONCLuSIONS
The issue of young soccer player has been of great interest, including position re- lated variation, but no data seems to be available on the specific position of goalkeeper.
In accordance to the purpose, data revealed considerable age-related variation in body size and maturity status appears to be significantly different by age-group, suggesting that body size variation is mostly related to growth and maturation in this age range. However, physical characteristics as reflected in growth and maturity status are just a part of a complex matrix of biocultural characteristics (Malina, 2003) interconnected to the specific demands of the goalkeeping position. Coaches need to be aware of changes in size, function, and skill associ- ated with maturation, and their behavioral implications (Coelho e Silva, Figueiredo, Sobral, &
Malina, 2004). The use of somatic indicators can reveal of great utility for coaches providing a reference or control point for the drawing of individual programs considering the sensi- tive periods of responsiveness to a specific training regime. In the meantime, more studies regarding the characterization of young soccer goalkeepers using a more extensive pool of variables are needed.
ACKNOwLEDGMENTS
We gratefully appreciate the patience and cooperation of the young athletes, coaches and parents.
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