Body Proportions of Football Players and the Untrained Population, and the Impact on the fit of the Trousers

The aim of this research was to identify the differences in body proportions between football players and the untrained population, and their influence on trouser fit. By identifying the differences in body measurements, and comparing the empirical and constructional values of body measurements required for the construction of men’s trousers, an attempt was made to prove the need for a change in the existing cut of trousers. A total of 324 men aged 15 to 26 years participated in the research. The survey involved 162 football players with an average playing experience of 10.7 years and 162 untrained subjects from the general population. A total of 19 variables were analysed relating to the study of the fit of men’s trousers. The SPSS software package was used for statistical data processing. The results showed that the football players were slightly but not significantly, taller, that their chest girth was almost the same as untrained subjects, and that their hip girth was slightly smaller. The greatest and most significant statistical difference was in the mid-thigh girth, which is greater in football players, and the waist girth, which is smaller in football players. Due to the identified value of a statistically significant increase of the mean thigh girth in football players, the modelling of trousers in this area was performed. The performed modelling of men’s trousers met the criterion of garment fit, and opens the possibility of cooperation with industry in terms of improving the making of cuts for the surveyed sport population.


Introduction
People are increasingly interested in the fit and comfort of garments, but such garments are very difficult to find on the market. Garment cuts were made according to the standard. However, such clothing does not fit the entire population. In the trained population, there are deviations in some body measurements in relation to the standard system of clothing sizes, causing garments not to fit. In the production of fashion and sportswear, anthropometric measurements are applied in the field of design and modelling, and are obtained using anthropometric measurements on a sample of a given population [1]. By applying the conventional method using anthropometric instruments on the basis of the ISO 3635 (2008), ISO 8559 (2012) and ISO 9407 (2008) standards, the basics of a unique definition of human body measurements for the clothing and footwear industry were obtained, and for the implementation of anthropometric measurements (HRN EN 13402 (1−3) 2008) [2−3]. Proportions or relationships can establish the correct interrelationship between individual body parts or individual measurements. Many authors are engaged in research on garment fit. The use of hand measurements is recommended to determine glove size so that the user can easily find the proper glove size [4]. The purpose of a sizing system is to fit the majority of a given population whose body proportions fall within predetermined standard dimensions. A sizing system can be defined as a method or system used to create a set of clothing for a variety of people on the target market [5]. Based on anthropometric measurements, the development of a new Chinese bra sizing system was based on anthropometric breast measurement. Factor analysis is often employed to determine key dimensions from the statistical aspect of anthropometric dimensions that are influential to major factors explaining the total sample variance, with a high percentage selected as key dimensions [6−8]. The authors Paal and McCulloch et al. [9,10] proposed an optimisation approach to construct an apparel sizing system based on a mathematical model. They determined that the proposed method for establishing a sizing system could satisfy three aspects: 1. increase the accommodation of the population; 2. reduce the number of sizes in the system; and 3. improve overall fit in accommodated individuals. To obtain more comprehensive measurement variables, 3D body scanning is generally regarded as more complete. It would be ideal for measuring the entire population before defining the size range and body shape categorization of people. However, this is unrealistic in any sizing system development [11]. It is important to identify a representative sample of the population [12]. Based on the influence of sporting activities, there are changes in the morphological structure and relief surface of the body of persons who are actively involved in sports in relation to persons not active in sports. Through training, certain physical changes are achieved, which lead to changes in morphological structure, an increase in muscle mass and a decrease in fat tissue in certain body parts. With years of training, muscle mass can increase by between 30-60% [13]. Differences in body measurements and in body shape between basketball players and the untrained group of the general population of test subjects have been proven. Because of the shape differences, it is necessary to modify front and back block pattern parts, as well as the sleeves, in order to ensure additional ease allowance on increased areas and optimal garment fit [14]. According to research on the anthropometric characteristics of football players, other researchers obtained similar results with regard to body height, i.e. they concluded that the body height of football players does not differ significantly from the average height of the male population of the same age [15]. Differences were also found between the trained and untrained population, such as increased thigh circumference. Previous research on the anthropometric characteristics of football players relates to the study of anthropometric variables according to the instructions and regulations of the International Biological Programme (IBP). Anthropometric characteristics of the sport population have not been investigated from the aspect of the clothing industry. The aim of this research is anthropometric measurements of the sport population in accordance with the ISO 3635 and ISO 8559 standards, and the study of differences in relation to the untrained population and the impact of the identified effects on the fit of the trousers of football players. delu izvedeno modeliranje hlač. Modelirane moške hlače so ustrezale kriteriju pravilnega prileganja oblačila in s tem se odpira možnost za sodelovanje z industrijo v smislu izboljšanja krojev za anketirano športno populacijo. Ključne besede: merjenje telesa, prileganje oblačila, konstrukcija oblačila, nogometaši, hlače 2 Test subjects and research methods A total of 324 men aged 15 to 26 years participated in the research. For the purposes of this research, the conventional method of anthropometric measurement was used to determine anthropometric sizes for young men (football players and the untrained population) in accordance with the ISO 3636 and ISO 8559 standards [8]. The survey involved 162 football players with an average playing experience of 10.7 years and 162 untrained subjects of the general population. The statistical analysis of the measured research variables was used to determine the main and design measurements for the two surveyed groups. Differences in body proportions between the two groups were defined. In order to meet the criteria of garment fit, the modelling of the front part of the trousers is shown for a group of football players ( Figure 1). The results of anthropometric measurements were processed using descriptive statistics, including an estimate of central tendency parameters (arithmetic mean and median) and dispersion (standard deviation, coefficient of variation, 95% confidence interval and data range). The correlation of individual body measurements and the suitability of standard procedures (mathematical expressions) for estimating body measurements depending on one and two predictors (basic body measurements) was verified using linear regression models with one and two predictors, respectively [16]. The modelling of computer body models for football players and the untrained population was carried out using the Optitex 3D software package, intended for construction preparation in the clothing industry. Body models were defined on the basis of the results of conventional anthropometric measurements, i.e. on the basis of average values of body measurements. Computer body models facilitated a clear visualisation of the bodies of the studied samples [1]. A total of 19 variables were studied: body height (1), chest girth (2), waist girth (3), hip girth (4), trouser length (5), crotch length (6), seat depth (7), waist height (8), hip height (9), knee height (10), ankle joint height (11), hip depth (12), total seat length (13), inside upper leg length (14), upper leg girth (15), middle leg girth (16), knee girth (17), girth under the knee (18) and lower leg girth (19). These are variables relating to the examination of the fit of men's trousers ( Figure 2).

Results and discussion
The correlation of individual body measurements and the suitability of standard procedures (mathematical expressions) for estimating body measurements depending on a predictor were verified using linear re-gression models. The differences between the groups were tested using variance analysis. Table 1 shows the indicators for the distribution of body measurements of football players and untrained groups of the general population measured using the traditional method of anthropometric measurement.  The results showed that the football players were slightly but not significantly taller, that their chest girth was almost the same as untrained subjects and that their hip girth was slightly smaller. The greatest and most significant statistical difference was in the middle leg girth, which is greater in footballers, and in the waist girth, which is smaller in football players. The scatter plots of pairs of the main body measurements of football players and the untrained group of the general population are shown in Figure 3 and confirm that these variables are linearly related to each other in both samples. According to the presented relations, there are no significant deviations between the main body measurements. These also do not result in changes in the construction of trousers. Figure 4 shows the empirical distribution of the statistically most significant differences in middle leg girth. On the basis of the results of statistical data processing, computer-aided 3D body models were created, separately for the group of football players and separately for the untrained group. Each 3D model shown was designed according to the mean values of body measurements. Figure 5 shows the body models of a football player and an untrained subject, showing their significant differences in body shape (e.g. in the middle leg girth, upper leg girth), which affect the cut of a football player's trousers. Table 2 presents the main, proportional and structural body measurements required for the construction of men's jeans. The main body measurements (body height, chest, waist and hip girth) were obtained on the basis of anthropometric measurements. The values of the main body measurements were used to calculate the construction measurements (trouser length, crotch length, seat depth, front trouser width, back trouser width, front seat width and back seat width). Mathematical expressions were used to calculate them. Based on the ratio between measured and calculated proportional body measurements (trouser length, crotch length and seat depth), the deviations of the body from the standard body shape were determined, and changes or adjustments to existing structures were necessary. The other previously mentioned proportional body measurements were difficult to measure accurately, so their values were determined solely based on mathematical formulas.

Figure 5: 3D computer body models created according to the mean values of body measurements: a) untrained population, b) football players
A constant of 40 cm was determined for measuring the circumference of the trouser leg [17]. As shown in Table 3, the group of football players is different from the untrained group of subjects of the general population. The body measurements are described using arithmetic mean (), standard deviation (s), coefficient of variation (CV), reliability confidence interval (95%) and data range (minimum and maximum values) ( Table 3). Proportional and structural measurements vary equally for both groups of test persons and range between 3% and 7.2%, with the exception of the seat depth, which varies between 17% and 18% for both methods of determination (manual or computational) (Table 3). Structurally, the trouser length was calculated as 5/8 of the body height minus 4 to 5 cm. Statistically, this ratio can be estimated by linear regression with body height as a predictor. Table 4 lists the parameters of such an assessment, showing that trouser length can be predicted based on body height (p < 0,001) and that this explains 37.3% of the variability in trouser length. The obtained regression coefficient with body height is 0.659 cm, which is almost indistinguishable from the construction coefficient 0.625, i.e. 5/8. The regression constant (-7.5 cm) exceeds the construction constant (-4.5 cm) by about 3 cm. However, it is not statistically significant, which means that it is adjustable as needed. Structurally, the crotch length is determined as half of the body height reduced by 4.5 cm. Statistically, similar to the case of trouser length, this relationship can be estimated using linear regression with body height as a predictor. Table 4 lists the parameters of this estimate, showing that trouser length can be predicted based on body height (p < 0,001) and that 38.5% of crotch length variability was explained. The regression constant (-6.5 cm) exceeded the construction constant (-4.5 cm) by 2 cm, but was not statistically significant, i.e. it can be adjusted if necessary. Structurally, the seat depth was determined as trouser   The empirical values determined for football players and the untrained group, as well as construction values, have no statistically significant influence on the construction of the trouser cut. However, due to the determined value of a statistically significant increase of the middle and upper thigh girth in football players, it is necessary to model the trousers in this area. In order to meet the criteria of the fit of the trousers as a garment, there are also very influential and additional body measurements, in addition to the construction and main body measurements. One of those measurements is mid-thigh girth.
Based on the analysis of body measurements and the determination of differences, Figure 6 shows the modelling of a pair of trousers for a group of football players to improve the trouser fit. The modelling of trousers is based on previously conducted analyses and differences in body measurements between these two groups of subjects. The analysis of the measurement results showed that the mid-thigh girth was on average 5 cm larger than in the untrained group of test subjects, and the necessary redesign of the basic cut of men's trousers in this area was carried out accordingly.
The construction of trousers according to the standard (for the untrained population) is drawn in blue, and the modelling of trousers for football players is drawn in red. The trousers were modelled in the area of the mid-thigh girth in such a way that, on the line representing the middle of the front of the trousers from the hip depth to the knee height, widening was performed by 3 cm and the trousers were widened at the side seams by 1 cm on each side. The difference in the middle leg circumference is 5 cm, and for this reason the pants are widened by that amount.

Conclusion
Differences in body proportions between the trained and the untrained group of test subjects were presented in this research. The largest statistically significant difference was found in the area of the mid-thigh girth. This variable has a significantly higher value among the surveyed football players and affects trouser fit. With this in mind, modelling and changes were made to the standard construction of the trouser cut to achieve a better fit. The garment fit criterion is defined by the parameters relating to the construction of the garment, which implies the correct joining of the garment in the sense that the garment has the appropriate size without being tightened anywhere on the body. The performed modelling of men's trousers met the criterion of garment fit, and opens the possibility of cooperation with the industry in terms of improving the making of cuts for the surveyed sport population.