INTRODUCTION
Kosovo is a democratic, multi-ethnic and secular republic which administratively is subdivided into seven districts (Ferizaj, Gjakova, Gjilan, Mitrovica, Peja, Pristina and Prizren) and five regions (Eastern, Western, Northern, Southern and Central). This study analyzes the standing height and its estimation utilizing tibia length measurements in adolescents in western region which contains two districts (Peja & Djakova) and seven municipalities (Deçan, Gjakova, Junik, Rahovec, Pejë, Istok & Klina). This region (Fig. 1) covers the area of 2,494 square kilometers and has population of 368,907 inhabitants, while average density per square kilometer is 150 inhabitants. Although Kosovo does not cover a large territory, it has a varied relief that is mostly part of the Dinarides mountain range and the author assumed this fact might influence the main objective of this study, because of the type of the soil as well as other socio-economic and geographical characteristics as a potential influencing factors (Arifi et al., 2017).
There are many scientific findings which confirm that the measurement of standing height is a vitally important variable when assessing nutritional status (Datta Banik, 2011; Arifi et al.), as well as when assessing the growth of children, evaluating the basic energy requirements, adjusting the measures of physical capacity and predicting the drug dosage and setting standards of physiological variables such as muscle strength, metabolic rate, lung volumes and glomerular filtration (Mohanty et al., 2001; Golshan et al., 2003, 2007; Ter Goon et al., 2011). However, according to Quanjer et al. (2014), the exact standing height cannot always be identified and resolved in the usual way (e.g. paralysis, fractures, amputation, scoliosis and pain). Because of these factors, an estimate of standing height has to be acquired from other reliable anthropometric indicators such as hand and foot lengths, tibia lengths, knee height, length of the forearm, length of the sternum, vertebral column length, sitting height, length of scapula, arm span as well as cranial sutures, skull, facial measurements et cetera (Gardasevic et al., 2017; Popovic, 2017; Masanovic et al., 2018). Therefore, all these anthropometric indicators, which are used as an alternative to estimate standing height, are very important in predicting loss in standing height connected with aging. Also, to diagnose individuals with disproportionate growth abnormalities and skeletal dysplasia or standing height loss during surgical procedures on the spine (Mohanty et al.), as well as to anticipate standing height in many older people as it is very difficult to measure it precisely, and sometimes impossible because of mobility problems and kyphosis (Hickson & Frost, 2003). Lastly, it is important to state that this knowledge finds its importance in sport since the standing height represents a significant factor which influences the success in various sport disciplines (Popovic).
Several researches have reported the benefit of using various body parameters in predicting standing height, and arm span happened to be one of the most reliable ones in adults (Hickson & Frost; Jalzem & Gledhill, 1993; Mohanty et al.; Ter Goon et al.), while some authors (Singh et al., 2012) believe that foot length measurement is the most reliable predictor during adolescent age, due to the fact that ossification and maturation occurs earlier in the foot than the long bones and standing height could be more accurately predicted from foot measurement as compared to long bones during adolescent age. In addition, the relationship of long bones and standing height was found to vary in different ethnic and racial groups (Steele & Chenier, 1990; Reeves et al., 1996; Brown et al., 2002; Bjelica et al., 2012; Popovic et al., 2013, 2016) as well as various regions (Arifi et al.). Hence, researchers have derived a specific formula for calculating standing height from long bones for each ethnic/race group. The mentioned variations might be the case with tibia length predictions too, mostly due to the fact that the Dinaric Alps population has specific body composition than national as well as regional point of view (Popovic). Even though many studies with this essence are available on neighboring countries as well as worldwide population, only narrow data is available on Kosovan subjects, just one conducted by Popovic et al. (2013, 2016, 2017) that has covered whole Kosovan population, and one regional analyses that confirmed Western-Kosovans have specific standing height/foot length ratio, comparing to general population in Kosovo. Considering rather sparse recent scientific literature, the purpose of this research was to examine the standing height in both Western-Kosovan sexes and its association with tibia length.
MATERIAL AND METHOD
The nature of this research gave extension to the 664 high-school students last year (338 male and 326 female) from Western Region of Kosovo to be subjects. Two reasons which qualified the selected individuals are: the first is related to the fact that the growth of an individual ceases by this age, while the second is related to the fact that there is no age-related loss in standing height at this age. The average age of the male subject was 18.24±0.43 years old (range 1820 years), while the average age of the female subject was 18.25±0.45 years old (range 18-20 years). It is important to underline that the researchers have excluded from the data analysis of the individuals with physical deformities as well as those without informed consent. The exclusion criterion was also being non-Western Kosovan.
The anthropometric measurements, including standing height and tibia length, were taken according to the protocol of the International Society for the Advancement of Kinanthropometry (Marfell-Jones et al., 2006). The trained measurers have measured selected anthropometric indicators (same measurer for each indicator), while the quality of their performance was evaluated against the prescribed “ISAK Manual”. Lastly, the age of the each subject was obtained directly from their birth record.
The analysis was performed by using the Statistical Package for Social Sciences (SPSS) version 23.0. Means and standard deviations (SD) were obtained for both anthropometric variables. A comparison of means of standing height and tibia length between genders was performed using a t-test. The relationships between standing height and tibia length were determined using simple correlation coefficients at ninety-five percent confidence interval. Then a linear regression analysis were carried out to examine the extent to which the tibia length can reliably predict standing height. Statistical significance was set at p<0.05.
RESULTS
A summary of the anthropometric measurements in both genders is shown in Table I. The mean of the standing height for male was 179.71±5.99 cm and tibia length was 41.35±3.01 cm, while for female the standing height was 166.26±5.23 cm and tibia length was 37.60±2.52 cm. The sex difference between standing height and tibia length measurements was statistically significant (standing height: t=30.759; p<.000; and tibia length: t=17.359; p<.000).
In Table II. the simple correlation coefficients and their ninety-five percent confidence interval analysis between the anthropometric measurements are displayed. The associations between standing height and tibia length were significant (p<0.000) and high in this sample, regardless of sex (male: 0.538; female: 0.559).
The results of the linear regression analysis are shown in Table III. The first of all models were extracted by including age as a covariate. However, it was found that the contribution of age was insignificant and therefore the age was dropped and estimations were derived as a univariate analysis. The high values of the regression coefficient (male: 0.538; female: 0.559) signify that tibia length notably predicts standing height in both Western-Kosovan sexes (male: t=11.709, p<0.000; female: t=13.465, p<0.000), which confirms the R-square (%) for the male (29.9) as well as for the female (35.9).
Table III Results of Linear Regression Analysis Where the Tibia Length Predicts the Standing Height.

The associations between tibia length measurements and standing height among the above models is sketched as a scatter diagrams (Fig. 2).
DISCUSSION
The assessment of standing height using various anthropometric measures is very typical from the past centuries and it has been attempted to be studied by many researchers. However, it is important to underline that the arm span has been obtained as the most reliable body indicator for predicting the standing height of an individual (Mohanty et al.; Ter Goon et al.), while tibia length is was very close (Agnihotri et al., 2009; Kaore et al., 2012; Khatun et al., 2016). In parallel, it is important to emphasize that the individual and ethnic variations referring to standing height and its association with tibia length might vary from ethnic group to ethnic group as well as race to race, because the racial and ethnic differences are affective on these measures and reduce the possibility of generalizing (Bjelica et al.). This fact confirms the study conducted by authors (Agnihotri et al.) who confirmed a very high linear correlation between standing height and tibia length in both genders, while the research study conducted by Khatun et al. shows significant correlation between standing height and tibia length in both genders of Indian population. The highest correlation coefficient in this population was found for tibia length in males (r=0.67) as well as in females (r=0.58).
All above-mentioned have confirmed the necessity for developing separate standing height models for each population on account of ethnic differences and the recent study conducted by Popovic et al. (2013, 2016, 2017) who have analyzed the entire Kosovan population and have found specific correlation coefficient standing height and foot length in Kosovan male (r=0.669) and female (r=0.625) population; however, some recent studies have also confirmed the regional differences between the same ethnic groups too (Arifi et al.), which caused the need for additional caution. Therefore, the main goal of this research was to test the hypothesis if above-mentioned facts are true for the Western-Kosovans, that is, for the one of five Kosovan regions. As the correlation between foot length and standing height was significant in both Western-Kosovan sexes, the tibia length measure therefore seems to be a reliable indirect anthropometric indicator for estimating standing height in both genders of Western-Kosovan population.
The results of the study conducted by Popovic et al. (2013, 2016, 2017) confirm the necessity for developing separate standing height models for both sexes in Kosovo but the authors of the same study have recommended that further studies should consider dividing the population of this country to regional subsamples and analyze it separately, just to be sure there are no geographical differences (such as type of the soil) influencing the average standing height in both Kosovan sexes as well as its association with tibia length. This concern was based on the fact that entire Kosovo does not fall into Dinaric Alps racial classification. In parallel, this study confirms the assumption mentioned above and also confirms that it is necessary to develop separate standing height models for each population on account of regional variations in Kosovo.
Next to highlighted issue, the obvious constraint of this research might also be the composition of the measured sample that consisted of high school students. This limitation is based on the fact there are some studies which assumed the growth of an individual doesn’t cease by this age. This assumption might be supported by the fact that universityeducated individuals have been founded to be taller than the high school population in Bosnia and Herzegovina (Grasgruber et al., 2017; Gardasevic et al.), Poland (Wronka & Pawliñska-Chmara, 2009) and Hungary (Szollosi, 1998). On the other hand, this was not true for Montenegro (Popovic) and comparing the average standing height measures of this study to the results of some study sampled by university students might give the science much precise conclusions. One more obvious limitation of this study is also the fact that both sexes of Kosovo did not reach their full genetic potential yet, since various environmental factors controlled their development. Further continuous monitoring is necessary, mostly due to the reason it is expected the secular changes influencing standing height will ascend in the following two or three decades.