The Influence of the Dominant Leg on Angle Trunk Rotation and Postural Symmetries in Adolescent Male Soccer Players: A Comparative Study

Theodorou, Eleni; Chalari, Eleanna; Hadjicharalambous, Marios

doi:10.3390/sym17010094

Open AccessArticle

The Influence of the Dominant Leg on Angle Trunk Rotation and Postural Symmetries in Adolescent Male Soccer Players: A Comparative Study

by

Eleni Theodorou

¹,

Eleanna Chalari

²

and

Marios Hadjicharalambous

^1,*

¹

Human Performance Laboratory, Department of Life Sciences, School of Life and Health Sciences, University of Nicosia, 1700 Nicosia, Cyprus

²

Department of Sport and Physical Education, Faculty of Health Sciences, Aegean College, 105 64 Athens, Greece

^*

Author to whom correspondence should be addressed.

Symmetry 2025, 17(1), 94; https://doi.org/10.3390/sym17010094

Submission received: 25 November 2024 / Revised: 19 December 2024 / Accepted: 20 December 2024 / Published: 9 January 2025

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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Abstract

:

Background: The current study examined whether there is an association between the dominant leg (DL) and the side of angle trunk rotation (ATR) and evaluated postural asymmetries and anthropometric characteristics between adolescent male soccer players and non-athletes across different age groups (11–14 years). Methods: This study included 502 male participants: 291 soccer players (age: 13 ± 2 years; height: 158 ± 17 cm; weight: 50.6 ± 12 kg) and 211 non-athletes (age: 13 ± 2 years; height: 158.3 ± 11 cm; weight: 50.5 ± 21 kg). The participants were categorized into four age groups: 11, 12, 13, and 14 years. Using a scoliometer, the primary (A) and secondary (B) ATR measurements were recorded and categorized into subgroups of 0–2, 3–5, and ≥6 degrees. A Chi-square test and a Mann–Whitney U-test were employed to analyze the raw data. Results: In soccer players, a significant association was found between the DL and primary ATR (p < 0.001). Conversely, non-athletes exhibited a significant association between the DL and secondary ATR only (p < 0.05). No significant differences were observed in the anthropometric characteristics and ATR for the 11-year-old boys (p > 0.05). For the 12-year-old boys, there was a significant difference in the ATR-A region (p < 0.01). For the 13-year-olds, significant differences were found in height, ATR-A region, ATR-B side, ATR-B region, and ATR-B degrees (p < 0.05). The 14-year-old soccer players demonstrated significant differences in ATR metrics compared with non-athletes in the same age group (p < 0.01). Conclusions: The results indicate that older adolescent soccer players exhibited a higher ATR tendency compared to non-athletes. This suggests that daily soccer training and DL usage contribute to increase postural asymmetries and physical development variations in adolescence. These findings underscore the necessity for monitoring body posture health in athletes during the early period of adolescence in an attempt to mitigate the potential negative long-term impacts on their life.

Keywords:

leg dominance; spinal asymmetries; angle trunk rotation; youth soccer players

1. Introduction

In developmental ages, abrupt biological maturation may result in spinal asymmetries, such as functional scoliosis [1,2], which is usually identified during school scoliosis screening [3]. In adolescent soccer players, these abrupt biological maturation-induced spinal asymmetries, in conjunction with increased usage of the dominant leg (DL) during daily practice, may signify risk factors for injury development [4] and a reduction in exercise performance [5]. Indeed, during growth and development, young athletes engage in more competitive sports, and specific training to improve skills may affect muscle balance and skeletal alignment [6,7].

Several studies have reported postural asymmetries, such as kyphosis, scoliosis and lordosis, and muscle imbalance, in young athletes due to poor posture and body malalignment [8,9,10]. Elite soccer players, for example, between the ages of 14 and 20 years, present substantial functional deficits, particularly in deep squat and trunk stability tasks, as well as asymmetry between the right and left sides of the body [11], which may subsequently affect soccer performance and the health of young soccer players [5,7,10]. Recently, it was found that overhead throwing sports increased muscle mass in the dominant arm, producing asymmetry in muscle mass between the arms due to repeated and frequent asymmetrical motions during daily practice [12]. Similarly, in children and in youth soccer players, it was observed that leg dominance may be a factor in causing truncal rotation on the contralateral side, which may progressively lead to functional scoliosis [7].

At all levels of soccer, most soccer players have a dominant leg, which has been found to potentially be a factor causing a distraction of symmetry in strength and flexibility of the lower extremities [13,14,15]. It has previously been suggested, for example, that laterality in certain sports is associated with asymmetrical adaptations in bones and muscle circumference, as well as with reduced flexibility and strength [16], and this may increase as a result of the laterality of sports training [17]. In a previous review, Bishop et al. (2018) concluded that there is a complication of inter-limb asymmetries, leading to postural asymmetry and inter-limb differences in muscle strength and dynamic balance, which both might result in a detrimental effect on physical performance [18]. The evidence is controversial, especially when considering asymmetries in jumping tasks and sport-specific activities like cycling and swimming. However, to the authors’ knowledge, no studies so far have examined the association between postural asymmetries and DL in children and youth soccer players. The aim of the present study was to therefore examine whether there is an association between the DL and the side of the angle trunk rotation (ATR) in youth soccer players between the ages of 11 and 14 years. It was hypothesized that there would be an association between the DL and the side of the ATR in young soccer players.

2. Materials and Methods

2.1. Participants

Five hundred and two (n = 502) male children (two hundred and ninety-one (n = 291) soccer players (age: 13 ± 2 years; height: 158 ± 17.5 cm; weight: 50.6 ± 12 kg) and two hundred eleven (n = 211) non-athletes (control group) (age: 13 ± 2 years; height: 158.3 ± 11 cm; weight: 50.5 ± 21 kg) voluntarily took part in the current study. The participants were further subcategorized into four groups according to their age, namely 11, 12, 13, and 14 years of age, in both soccer players (n = 63, 82, 68, and 78, respectively) and the control group (n = 15, 65, 71, and 60, respectively). For more details concerning the participants’ characteristics for each age category, see Table 1. After explaining the experimental methods and procedures, parental consent forms were obtained prior to scoliosis screening. No participant had any disease or musculoskeletal injury during the study. The study was approved by the National Bioethics Committee (ΕΕΒΚ/ΕP/2017/39 and EEBK/EP/2021.01.169), and the Code of Ethics of the World Medical Association (Declaration of Helsinki) was abided by.

2.2. Experimental Design

The height and the weight of all of the participants were measured and the DL was reported. Laterality refers to the preference for one side of the body in terms of usability, precision, and coordination [19]. Each participant reported their dominant leg as the one used to kick and control the ball [20]. Scoliosis screening was performed at the training facilities of soccer players and at the school of non-athletes. At all times, the coaches of athletes and the teachers of non-athletes were present during measurement. Parents were also allowed to be present at the measurements.

2.3. Scoliosis Screening

The ATR was measured with a scoliometer (Mizuho Osi^®, Mizuho OSI Inc., Tokyo, Japan) by a qualified kinesiologist. Initially, the participant performed Adam’s forward bending test with extended arms touching their knees for thoracic and thoracolumbar measurements and closed their feet together. Afterward, the participant bent forward with extended arms pointing down for the lumbar measurements and closed their feet together [21]. During Adam’s bending forward test, the researcher observed whether there was asymmetry at any level of the spine, and the scoliometer was placed at that level to obtain the measurement [21]. The researcher recorded the scoliometer measurement, the spine level, and the convexity side of scoliosis. In cases where there were asymmetries at two different levels, the researcher recorded both, indicating the higher measurement as primary and the lower as secondary. The primary ATR was recorded as ATR (A) and the secondary ATR was recorded as ATR (B). The participants were categorized into three subgroups: 0–2 degrees, 3–5 degrees, and ≥6 degrees [22].

2.4. Statistical Analysis

Following the normality of the distribution test (Kolmogorov–Smirnov), most of the data were reported as the median and interquartile range (IQR). Most of the values are described with the median and IQR, except the weight of the soccer players and the height of the non-athletes since these variables did not violate normality assumptions for parametric analysis. A non-parametric examination was performed using the Chi-square test (χ²) to determine whether the tested variables were associated with primary and secondary ATR, in both groups. The Cramer’s V value was also requested in order to identify the strength of the effect size of the tested association. For unpaired evaluations between the soccer players and the control group, for each parameter per age group, the Mann–Whitney U-test was employed. The effect sizes (ESs) were estimated using the Rosenthal (1991) equation (r = Z/√N) [23]. The ESs were interpreted according to Cohen’s criteria. A value of r = 0.1 was considered a small effect size, 0.3 represented a medium effect size, and 0.5 represented a large effect size. Statistical significance was declared at p < 0.05 [24]. All of the statistical analyses were performed using SPSS software (version 20 for Windows; IBM SPSS Inc., Chicago, IL, USA).

3. Results

3.1. Descriptive

The descriptive characteristics of each age category are presented in Table 1 for the soccer players and the control group.

The ATR-A and ATR-B were categorized according to the severity of ATR and by age. The frequency and percentage of each category are presented in Table 2 for soccer players and Table 3 for non-athletes. There were no participants with ≥6 degrees with ATR-B in the non-athletes group.

3.2. Chi-Square

In soccer players, there was a small-to-medium association between the DL and the ATR-A side, χ² (Table 4) = 32.06, p = 0.001, V = 0.235. However, there was no significant association between the DL and the ATR (B) side. In non-athletes, there was no association between the DL and the ATR-A side (Table 5). However, there was a small-to-medium association between the DL and the ATR-B side in the control group, χ²(2) = 7.22, p = 0.027, V = 0.185.

3.3. Mann–Whitney U Test

The Mann–Whitney U test was conducted to compare the soccer players and control groups per age subgroup to identify whether there were any differences.

11 years of age

There was no statistically significant difference in height (U = 421.5, z = −0.647, p = 0.518, r = −0.07), weight (U = 444, z = −0.361, p = 0.718, r = −0.04), BMI (U = 469, z = −0.044, p = 0.965, r = −0.01), ATR-A (Side) (U = 438.5, z = −0.479, p = 0.632, r = −0.05), ATR-A (Region) (U = 468, z = −0.061, p = 0.952, r = −0.01), ATR A (Degrees) (U = 418.5, z = −0.696, p = 0.486, r = −0.08), ATR B (Side) (U = 423, z = −1.002, p = 0.317, r = −0.11), ATR-B (Region) (U = 426.5, z = −0.931, p = 0.352, r = −0.11), or ATR-B (Degrees) (U = 416, z = −1.142, p = 0.253, r = −0.13) between the soccer players and non-athletes of 11 years of age (Figure 1).

12 years of age

There was no statistically significant difference in height (U = 2335, z = −1.287, p = 0.198, r = −0.11), weight (U = 2607.5, z = −0.224, p = 0.823, r = −0.02), BMI (U = 2575, z = −0.351, p = 0.726, r = −0.03), ATR-A (Side) (U = 2325, z = −1.464, p = 0.143, r = −0.12), ATR-A (Degrees) (2548.5, z = −0.465, p = 0.642, r = −0.04), ATR B (Side) (U = 2435, z = −1.660, p = 0.097, r = −0.14), ATR-B (Region) (U = 2447, z = −1.574, p = 0.115, r = −0.13), or ATR-B (Degrees) (U = 2435.5, z = −1.656, p = 0.098, r = −0.14) between the soccer players and control subjects of 12 years of age. There was, however, a statistically significant difference in ATR-A (Region) (U = 2030.5, z = −2.636, p = 0.008, r = −0.22) between the soccer players and control subjects of 12 years of age (Figure 2).

13 years of age

There was no statistically significant difference in weight (U = 2248.50, z = −0.697, p = 0.49, r = −0.06), BMI (U = 2034, z = −1.601, p = 0.11, r = −0.14), or ATR-A (Side) (U = 2335.50, z = −0.380, p = 0.70, r = −0.03) between the soccer players and non-athletes of 13 years of age. There was a statistically significant difference in height (U = 1951.50, z = −1.949, p = 0.05, r = −0.17), ATR-A (Region) (U = 1338.50, z = −4.903, p = 0.00, r = −0.42), ATR-A (Degrees) (U = 1798, z = −2.645, p = 0.01, r = −0.22), ATR B (Side) (U = 1637, z = −4.827, p = 0.00, r = −0.41), ATR-B (Region) (U = 1654, z = −4.734, p = 0.00, r = −0.40), and ATR B (Degrees) (U = 1631.50, z = −4.854, p = 0.00, r = −0.41) between the soccer players and non-athletes of 13 years of age (Figure 3).

14 years of age

There was no statistically significant difference in height (U = 2330, z = −0.043, p = 0.97, r = 0.00), weight (U = 2130.5, z = −0.900, p = 0.37, r = −0.08), BMI (U = 2081.5, z = −1.110, p = 0.27, r = −0.09), ATR-A (Side) (U = 2115, z = −1.086, p = 0.28, r = −0.09), or ATR-A (Degrees) (U = 2177.5, z = −0.709, p = 0.48, r = −0.06) between the soccer players and non-athletes of 14 years of age. There was a statistically significant difference in ATR-A (Region) (U = 1493.5, z = −3.893, p = 0.00, r = −0.33), ATR-B (Side) (U = 1801, z = −3.266, p = 0.00, r = −0.28), ATR-B (Region) (U = 1858, z = −2.920, p = 0.00, r = −0.25), and ATR-B (Degrees) (U = 1824, z = −3.116, p = 0.00, r = −0.27) between the soccer players and non-athletes of 14 years of age (Figure 4).

4. Discussion

The aims of the present study were to examine (a) whether there is an association between the DL on the side of ATR in soccer players and (b) whether there were differences in anthropometric characteristics between soccer players and non-athletes in four different age subgroups (11, 12, 13, and 14 years old).

4.1. Laterality

Several factors including hereditary, environmental, hormonal, metabolic, biochemical, neurological, and asymmetric growth are considered scoliosis causes [25]. It was well documented that incorrect body posture results in severe deterioration with age [26,27], while rapid musculoskeletal growth in puberty may alter the biomechanical condition [27,28]. Regarding spinal growth in adolescents, any of the above-mentioned factors may cause scoliosis and progression of the scoliotic curve [25]. Therefore, unilateral overload may also result in deviations and functional changes in the spine and joints [29]. Theodorou et al. (2024) investigated the relationship between dominant limbs (hand and leg) and the side angle of trunk rotation (ATR) in adolescents, focusing on gender differences. In boys, significant associations were observed between both the dominant hand and leg with the side of primary ATR, indicating cross laterality (where right dominance correlated with left-sided trunk rotation). Interestingly, these associations were not present in girls. The sample was mixed though in regard to sports training [3]. In another study, Theodorou et al. (2024) found a significant association between leg dominance and the contralateral side of ATR, in soccer players, with them showing higher contralateral ATR compared to their dominant leg [7].

The results of the present study suggest that a unilateral overload may be associated with ATR in young soccer players since in this group, a significant contralateral association was found between the DL and the side of ATR-A but not with the ATR-B. On the contrary, in the control group, a significant association was found between the DL and the side of ATR-B but not with ATR-A. The contralateral association possibly indicates that soccer players develop primary ATR due to leg dominance overuse as a result of regular specific soccer training. The control non-athletes, who have already developed a primary ATR due to mechanisms or factors related to scoliosis, had also developed a secondary ATR associated with leg dominancy, possibly as compensatory of primary ATR. Across the age categories, the results revealed that there were higher percentages for soccer players with 3–5 degrees of ATR-A at the age of 13 and 14 years old compared to the control. Furthermore, soccer players seem to be more prone to developing secondary ATR-B than their non-athlete peers, across all four age groups. These results may signify that DL in soccer may be a causative factor in ATR development. In addition, the findings further support the hypothesis that the DL may play a significant role in causing spinal asymmetries in young soccer players since across all ages, soccer players developed contralateral ATR with significant association.

4.2. Differences Between Soccer Players and Non-Athletes per Age Group

For the 11-year-old and 12-year-old participants, the analysis revealed no statistically significant differences between soccer players and non-athletes regarding height, weight, BMI, or any of the ATR metrics. Nevertheless, the results show a trend of soccer players being taller than non-athletes, from 11 to 13 years old, possibly because taller boys are selected more often than shorter boys. In 14 years age group, there was no difference in height. There was a significant difference in ATR-A (Region), suggesting that more soccer players in the 12 years age group had ATR in at least one region of the spine, compared to non-athletes. For 13-year-olds, the analysis revealed statistically significant differences in height, ATR-A (Region), and ATR-B (Side Region, Degrees) measurements. The results indicate that soccer players were significantly taller and had a higher incidence of ATR-A (Region) and ATR-B (Side Region, Degrees) compared to non-athletes. There were no statistically significant differences in height, weight, or BMI, although non-athletes had slightly higher values in weight and BMI. Similarly, among 14-year-olds, the analysis revealed statistically significant differences in several ATR measures, indicating that soccer players had a higher incidence of ATR-A (Region) and ATR-B (Side Region, Degrees) compared to non-athletes. There were no statistically significant differences in height, weight, or BMI. However, non-athletes were heavier with a higher BMI.

Certain sports, particularly basketball and volleyball, may negatively affect body posture, leading to increased deviations over time [30]. Conversely, gymnastics training promotes symmetrical posture but raises concerns about spinal changes in the sagittal plane [30]. Several studies have explored the effects of sports, particularly soccer, on postural alignment and body symmetry in youth athletes. Postural deviations, including the ATR, are crucial indicators of spinal asymmetry and scoliosis, which may develop or worsen with age, especially in youth athletes who engage in unilateral or asymmetric sports. The current study indicates that while no significant differences in ATR metrics were observed in younger participants (11 and 12 years old), there were statistically significant differences in older age groups (13 and 14 years old). Soccer players exhibited higher instances of ATR in both measured regions (ATR-A and ATR-B), compared to non-athletes, especially as they grew older. This trend aligns with broader findings from existing studies [9,31].

In our study, no significant differences were found in ATR-A and ATR-B measures between soccer players and non-athletes for 11- and 12-year-old participants. A significant difference was observed in ATR-A (Region), showing that more soccer players in this age group had primary ATR in at least one region of the spine compared to non-athletes. However, a slight trend towards higher ATR measures in soccer players was observed, which, even though it is shown as not statistically significant, should be considered and not be underestimated. This is consistent with previous findings which did not identify significant postural deviations in younger soccer players either; however, a study pointed out that the effects of asymmetric loading patterns become more pronounced as athletes age [31]. Similarly, Grabara (2012) found that early adolescent soccer players exhibited relatively symmetrical pelvic alignment, although some deviations in shoulder blade symmetry were observed [9].

In contrast, for older participants (13 and 14 years old), the current study revealed statistically significant differences in ATR measures between soccer players and non-athletes. Soccer players were more likely to exhibit higher ATR incidence in one or more regions of the spine (ATR-A), as well as higher degrees of truncal rotation (ATR-B). This aligns with the findings from a previous study which demonstrated that as soccer players age, they are more likely to develop postural asymmetries, particularly scoliotic and kyphotic postures, leading to a decline in flexibility and neuromuscular performance [5]. Similarly, Lourenço et al. (2021) observed significant postural deviations in older soccer players, particularly in shoulder and pelvic alignment. The researchers noted that, over time, the asymmetric loading of the body inherent in soccer could result in greater postural asymmetry, and the current findings also corroborate this effect for older soccer players [31].

The increasing differences between soccer players in ATR metrics observed in our study, among 13- and 14-year-olds, could be partially explained by the physical changes associated with puberty and growth spurts characterized by this particular age group [1]. These changes tend to occur more rapidly during early adolescence and could exacerbate any underlying asymmetries [1]. Rapid changes in height and body composition during growth spurts are linked to an increased risk of postural deviations, particularly in sports that demand rapid, asymmetric movements like soccer [32]. Our findings of significantly higher ATR measures in older soccer players (13 and 14 years old) may reflect the fact that as they grow taller, the asymmetries caused by repetitive soccer movements become more pronounced. This corresponds with the increased incidence of scoliosis and kyphosis, deteriorating neuromuscular explosiveness performance and diminishing the lower limbs’ flexibility in young international-level soccer players, as previously observed [5].

Soccer, like other unilateral sports, imposes a significant asymmetric load on the body, particularly in the lower limbs and trunk. This unilateral loading is a likely contributor to the higher ATR values observed in soccer players. Kalata et al. (2020) found that asymmetrical sports like soccer are associated with greater bilateral strength asymmetry, which may contribute to the development of postural deviations over time [33]. In the current findings, soccer players at ages 13 and 14 showed a higher incidence of ATR-A (in specific regions of the spine), likely reflecting the cumulative effects of these unilateral stresses. In younger players (11 and 12 years old), the absence of significant differences suggests that the body’s growing capacity to adapt to asymmetric loads is not yet overwhelmed. However, as the children grow, these asymmetries become more difficult to be corrected without specific interventions [10].

The strength of the current study is the observation that older adolescent (13–14 years of age) soccer players exhibited higher ATR tendency compared to non-athletes, suggesting that regular usage of the DL during daily soccer training may increase postural asymmetry incidences and produce physical development variations in adolescence. Consequently, this observation underscores the necessity for monitoring body posture health during the early period of adolescence in athletes in an attempt to mitigate the potential negative long-term impacts on their lives. The key limitation of the study is the relatively small sample size for each age category and subcategory (i.e., ATR A and B; left and right leg groups) particularly, which may limit the generalizability of the results.

5. Conclusions

The current results indicate that older adolescent soccer players (13 and 14 years of age) exhibited higher ATR tendency compared to non-athletes. This suggests that daily soccer training and DL usage contribute to increased postural asymmetries and physical development variations in adolescence. These findings underscore the necessity for monitoring body posture health during the early period of adolescence in athletes in an attempt to mitigate potential negative long-term impacts on their lives. Future training interventions aimed at correcting or mitigating these asymmetries should focus on the introduction of balanced, bilateral exercises to offset the asymmetric nature of soccer as a sport. Despite the initial cause of functional scoliosis, correction should target all possible coexisting causes to ensure correct growth development and injury prevention and preserve performance in young male soccer players between the ages of 11 and 14 years old.

Author Contributions

Conceptualization, E.T. and M.H.; methodology, E.T. and M.H.; validation, E.T., M.H. and E.C.; formal analysis, E.T., M.H. and E.C.; investigation, E.T.; data curation, E.T.; writing—original draft preparation, E.T. and M.H.; writing—review and editing, E.T., M.H. and E.C.; supervision, M.H.; project administration, E.T. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study was conducted according to the ethical principles stated in the Declaration of Helsinki and approved by the National Bioethics Committee (ΕΕΒΚ/ΕP/2017/39, EEBK/EP/2021.01.169).

Informed Consent Statement

Informed consent for participation was obtained from all subjects involved in the study.

Data Availability Statement

The data presented in the current study are available from the corresponding author upon request.

Acknowledgments

The authors express their gratitude to the athletes for their voluntary involvement in this study, to their parents, and to the coaching staff of the soccer academies.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Differences between soccer players and non-athletes (11 years old). ATR A = Primary Angle Trunk Rotation and ATR B = Secondary Angle Trunk Rotation.

Figure 2. Differences between soccer players and non-athletes (12 years old). ATR A = Primary Angle Trunk Rotation, ATR B = Secondary Angle Trunk Rotation, and * = statistically significant.

Figure 3. Differences between soccer players and non-athletes (13 years old). ATR A = Primary Angle Trunk Rotation, ATR B = Secondary Angle Trunk Rotation, and * = statistically significant.

Figure 4. Differences between soccer players and non-athletes (14 years old). ATR A = Primary Angle Trunk Rotation, ATR B = Secondary Angle Trunk Rotation, and * = statistically significant.

Table 1. Soccer players and non-athletes’ characteristics per age category.

	Sub-Groups	Height (cm)	Weight (kg)	ATR-A (°)	ATR-B (°)
Soccer Players (n = 291)	11 yrs (n = 63)	147 ± 6	41.5 ± 7.8	2 ± 3	0 ± 0
	12 yrs (n = 82)	153 ± 11	47.1 ± 9.6	2 ± 1	0 ± 0
	13 yrs (n = 68)	163 ± 15	54.1 ± 11.8	3 ± 2	0 ± 3
	14 yrs (n = 78)	168 ± 12	58.5 ± 11.2	3 ± 2	0 ± 2
Non-Athletes (n = 211)	11 yrs (n = 15)	146 ± 7	40.7 ± 10.7	2 ± 2	0 ± 0
	12 yrs (n = 65)	152 ± 8	44.4 ± 14.4	2 ± 3	0 ± 0
	13 yrs (n = 71)	159 ± 10	53.9 ± 20.9	2 ± 2	0 ± 0
	14 yrs (n = 60)	168 ± 7	59.2 ± 55.6	3 ± 2	0 ± 0