Introduction

The technique of somatotyping is used to assess the body shape and composition or the physique. Currently, the most commonly used method for estimating physiques is the Heath-Carter anthropometric somatotype (Heath and Carter 1967; Liiv et al. 2013; Reis et al. 2007). A somatotype is expressed in a three-number rating, representing the endomorphic, mesomorphic and ectomorphic components, respectively, always in the same order. Endomorphy is the relative body fatness, mesomorphy is the relative musculoskeletal development, and ectomorphy is the relative linearity or slenderness of a physique.

Heath-Carter somatotyping is not only significant in research on body shapes and physiological functions, but also in some diseases and prediction of potential movements of young people, etc. It was recommended as a comprehensive evaluation method of the human body by the “International Biological Development Planning” (Carter and Heath 1990).

Some somatotype studies have been carried out to examine the relationships between physiques and sports (Battista et al. 2007; Bale et al. 1994; Kawashima et al. 2003; Hopper 1997) and to predict the potential movement of adolescents (Monsma and Malina 2005; Duncan et al. 2006; Nikolaidis and Vassilios Karydis 2011). The findings indicated that the somatotype and its components are related to disease risk factors and cardiovascular disease (Baltadjiev et al. 2009; Eiben et al. 2004; Valkov et al. 1996; Mensah et al. 1999; Baltadjiev 2012). Other results showed that physical stress not only causes retardation of linear growth, but also produces changes in the human physique during the growth period (Ozener and Duyar 2008).

Xi’an is one of the main places of origin of the Han population. Xi’an is the most populous city in China, with 53 ethnic groups. The largest ethnic group, the Han, accounts for more than 98.9 % of the Xi’an population. Therefore, the evolution and development of the Xi’an Han somatotype could represent the somatotype of the Han nationality. This study could be significant for protecting against disease and improving the Chinese nation’s database.

The aim of this study was to explore the somatotype characteristics and compare the somatotypes of people of Han nationality in Xi’an with those of other nationalities or districts.

Methods

Subjects

The study sample consisted of 429 people of Han nationality (207 males, 222 females) from Xi’an, China, aged ≥20 years old, obtained in 2010. Informed consent was given by all participants. The subjects were divided into five groups based on their ages (20–29, 30–39, 40–49, 50–59, ≥60 years old). Each group had two subgroups: male and female. There were more than 40 people in each subgroup. All the subjects were in good health and came from unrelated families. Each subject was traced back for more than three generations of family history in Xi’an to ensure that they were national representatives of the Xi’an Han population (He et al. 2012). All anthropometric measurements were taken by the same well-trained anthropometrist, according to standard techniques (Xi and Chen 2010).

Anthropometry and somatotyping

The subjects were somatotyped with the Heath-Carter anthropometric method (Heath and Carter 1967), which defines an individual’s somatotype as a composite of the contributions of three components: endomorphy, mesomorphy and ectomorphy. Anthropometric measurements, including body weight, height, skinfold thicknesses (triceps, subscapular, supra-ilium and medial calf), bi-epicondylar breadths of the humerus and femur, and contracted arm girth and calf girth, were taken from each subject.

The subjects’ body weight was measured with a body weight and fat measurement device (Omron HBF-358, Powerlogics Co., Ltd., Korea). The height was measured with a Martin altimeter (Nanchang Measuring Instrument Factory, China). The skinfold thicknesses were assessed by a skinfold thickness meter (Nantong Hyatt Fitness Measuring Equipment Co., Ltd., China), girths with a tape measure and skeletal breadths with a small sliding caliper (Chengdu Jingbo Diameter Precision Measurement Research Institute, China).

The three somatotype components were computed according to the Heath-Carter Anthropometric Somatotype Instruction Manual (Carter and Heath 1990).

All examinations were approved by the Ethics Committee of Xi’an Jiaotong University Health Science Center.

Statistical analysis

All statistical analyses were performed using the SPSS 17.0 software for Windows (SPSS Inc., Chicago, IL, USA). Somatotype components were analyzed with one-way ANOVA to determine whether there were statistically significant differences among the somatotype means of different ages. Student’s t-test was applied to compare the variations of somatotype components between females and males at different ages. Somatotype attitudinal mean (SAM) values were obtained to get an estimate of the dispersion of somatopoints in each age/sex group. The comparison of somatotypes between the Han and other nationalities was made by U test. All data are expressed as mean ± standard deviation (X ± SD), and the level of significance was set at p < 0.05.

Results

Somatotype and anthropometric characteristics of male and female Han subjects in Xi’an

All ten descriptive statistics measurements used to compute the three somatotype components are presented in the supplementary data (supplementary Tables 1 and 2). Anthropometric characteristics of males and females are presented in Tables 1 (endomorphy-mesomorph-ectomorphy, X and Y and SAM), 2 and 3. When classifying the people according to the somatotype categories (13 categories) established by Carter (Carter and Heath 1990), the male somatotype focused on Meso.Endo (61.4 %), Endo-Meso (12.1 %) and Balanced Endo (7.7 %); that of females focused on Meso.Endo (74.3 %), Balanced Endo (7.2 %) and Ecto.Endo (5.4 %). Both the male and female samples belonged to a mesomorphic endomorphy (endomorphy is dominant and the mesomorph is greater than ectomorphy) profile. The SAM indices indicate that, in both sexes and all age groups, the sample presents a high degree of homogeneity of the somatopoints. The mean somatotypes of various sex/age groups are plotted on the somato-charts for the Han nationality in Xi’an (Fig. 1a, b).

Table 1 Anthropometric characteristics of males and females of Han nationality in Xi’an
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Table 2 Somatotype distribution of Han males in Xi’an (%)
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Table 3 Somatotype distribution of Han females in Xi’an (%)
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Fig. 1
figure 1

Distribution of the mean somatopoints for the Han nationality in Xi’an. a Mean somatotype for age/gender groups. b Distribution of the mean somatotype by gender

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Differences in somatotype components in each age group for gender

The somatotype components of males and females were compred. The results are shown in Table 4. All somatotype components in males remained virtually unchanged after 29 years of age, but except for ectomorphy the somatotype components kept increasing up to ≥60 years in females. The ectomorphy in females appeared to decrease down to ≥60 years. The endomorphy showed statistically significant differences between sexes in all age groups (P < 0.01). The mean value of endomorphy was significantly higher than those of mesomorphy and ectomorphy in males and females. There were prominent differences between males and females in mesomorphy and ectomorphy in the age groups 50–59 and ≥60 years. However, there were no significant differences in mesomorphy and ectomorphy between males and females in the age groups 20–29, 30–39 and 40–49 years.

Table 4 Sex differences in the somatotype components of the Han population in the five age groups in Xi’an
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Difference in somatotype components by age

The comparisons of somatotype components in each age group for both genders are shown in Table 5. In females, there were significant differences in somatotype components between the 20–29-year and all other age groups, the 30–39-year and all other age groups, and the 40–49-year and all other age groups (P < 0.01 or P < 0.05), except for between the 40–49- and ≥60-year old age groups for endomorphy. Furthermore, there were no statistically significant differences among the three somatotype components between the 50–59- and ≥60-year-old females. However, in males, there were prominent differences in somatotype components between the 20–29-year and other all age groups (P < 0.01 or P < 0.05), except for between those 20–29 and ≥60 years old for endomorphy. Otherwise, in males, there were dominant differences in endomorphy among those 30–39 and ≥60, 40–49 and ≥60, and 50–59 and ≥60 years old (P < 0.01 or P < 0.05).

Table 5 Age differences of somatotype components in the Han population in Xi’an (one-way ANOVA)
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Comparison of somatotypes between the Han and other nationalities in China

Tables 6 and 7 show the comparison of somatotype components between the Han and five other nationalities in China (U test) (Zheng et al. 1996; Zhu et al. 2000a, b; Zhu et al. 1997; Huang et al. 2002). There were prominent differences in the endomorphy of males and females between the Han and five other nationalities in China, respectively (P < 0.01). There were significant differences in the mesomorph of males between the Han and five other nationalities except the Mongoloid and Hui, respectively. There were marked differences in the ectomorphy of males between the Han and other five nationalities, except for the Ewenki, respectively. Otherwise, there were significant differences in the mesomorphy and ectomorphy of females between the Han and Hui, as well as Zhuang, respectively (P < 0.01). However, there were no statistically significant differences in the mesomorphy and ectomorphy of females between the Han and Mongoloid, Ewenki and Oroqen populations, respectively.

Table 6 Comparison of somatotype components between the Han and five other nationalities in China (males) (U test)
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Table 7 Comparison of somatotype components between the Han and five other populations in China (Females) (U test)
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Discussion

Somatotype of the Han nationality adults in Xi’an

The mean somatotype of the Han population is 5.6-4.2-1.8 in males and 6.7-4.2-1.6 in females. Both the male and female samples feature a mesomorphic endomorphy (endomorphy is dominant, and mesomorphy is greater than ectomorphy) profile. The three somatotype components of all ages are dominated by endomorphy.

This means that the body fat content is high, the body linearity decreases, and the musculature is not very developed. This result indicates that the problem of overweight and obesity in Han nationality adults represents a serious public health issue, mainly due to the changes in the population’s lifestyle (Koletzko et al. 2012; van Avendonk et al. 2012), such as a high-calorie diet and reduction of physical activity (Campbell et al. 2011), leading to a drop in the mesomorphic component and tendency to an increase in the endomorphic component, mainly in older females and males. This high adiposity-type profile contributes to increasing the probability for the population to suffer from diabetes and cardiovascular issues (Feng et al. 2015; Henagan et al. 2014).

Gender differences in Han adults

As shown in Table 4, we investigated the gender differences in the somatotype components of the Han population in Xi’an in this study. Females tended to have significantly higher endomorphic values. There were distinct endomorphic differences between males and females in all age groups. The previous studies agreed that the mesomorphy is higher in males and endomorphy in females in younger American individuals (Malina et al. 2005; Arce et al. 2012). The main reason is that boys may be more involved in recreational games associated with high levels of physical activity. Vigorous activity tends to favor musculoskeletal development. The studies by Kalichman and Kobyliansky (2006) reported that sex differences in somatotypes appear to be the strongest for endomorphy, with generally higher values in females (Kalichman and Kobyliansky 2006). Our results are consistent with these findings (Table 4). However, interestingly, our data suggested that the differences in mesomorphy or ectomorphy were prominent between males and females in the 50–59- and ≥60-year age groups, but the studies by Kalichman and Kobyliansky (2006) noted no differences in mesomorphy and a very small difference in ectomorphy between males and females aged 18–30 years. This may be the result of multiple factors, such as differences in region, ethnicity and livestyle.

Adult Han somatotypes change with age

We also noted age-related patterns of somatotype change. There were marked differences between the 20–29-year and all other age groups in both sexes except for between the 40–49- and ≥60-year-old groups in the endomorphy of males. There were no significant differences in somatotype components between the 50–59- and ≥60-year-old groups in females. These findings are almost consistent with studies of Kalichman and Kobyliansky (2006). Furthermore, we observed a decrease in the mean values of endomorphy in both sexes for those ≥60 years and in the mean values of ectomorphy in males ≥60. These findings are in accord with those of Buffa et al. (2005) and Kalichman et al. Otherwise, our results showed that after 30 years of age, the male somatotype had hardly changed. These are not quite consistent with previous results (Katzmarzyk and Malina 1999), but consistent with Kalichman and Kobyliansky (2006). We would increase the sample size for further research in the future.

Interestingly, our data indicated that mesomorphy and ectomorphy displayed opposite age-related tendencies. Mesomorphy increased with age in both sexes, whereas ectomorphy tended to decrease with age in both sexes. The previous studies of somatotype components have shown results parallel to ours in various elderly populations (Kalichman and Kobyliansky 2006; Buffa et al. 2005). This finding indicated that the metabolism of the body and declined with age in males. The detailed reasons also need more meticulous research in the future.

Comparison of somatotype components between the Han and other nationalities

The somatotype differences appear to be the strongest for endomorphy between the Han and other five nationalities in both sexes in China. The mean endomorphic value of the Han was higher than those of the other five nationalities in China (Zheng et al. 1996; Zhu et al. 2000a, b; Zhu et al. 1997; Huang et al. 2002). This result indicated that the subcutaneous fat was thick in Han males. This kind of characteristic might be related to dietary components. For example, the Mongoloid, Ewenki and Oroqen populations are predominantly carnivorous, but the Xi’an Han prefer pasta. Otherwise, the mean ectomorphic value of the Han population was smaller than those of other nationalities except for the Ewenki in males as well as females, except for the Ewenki and Mongoloid populations. Moreover, the results dramatically showed that for mesomorphy there is an opposite gender trend. The mean mesomorphic value of the Han population is lower than those of other nationalities except for the Ewenki and Oroqen in males; the mean mesomorphic value of the Han population is higher than those of other nationalities except for the Ewenki in females. These findings indicate remarkable differences in the somatotype components between the Xi’an Han and other five nationalities in China in males and females. These findings demonstrated that the subcutaneous fat of Xi’an Han males and females was thicker than that of other nationalities. The Han population’s skeletal and muscular systems were generally developed; the bodily linearity was lower in males but moderate in females. This characteristic, in addition to genetic and race-related differences, may also be factors associated with their respective economic and cultural level, the geography and climate, lifestyle and eating habits, etc.

In conclusion, our data demonstrated that the somatotype of the Han population in Xi’an, China, has a predominantly mesomorphic endomorph profile. The endomorphic component showed distinct differences between ages/genders, respectively.

There were remarkable differences in the somatotype components between the Xi’an Han and five other nationalities in China in males and females.