International Journal of Applied Exercise Physiology 2322-3537 www.ijaep.com
Vol.8 No.1
Received: September 2018 , Accepted: December 2018 , Available online: March 2019
DOI: 10. 30472 /ijaep.v8i1.326
Analysis of the 2D:4D Ratios of National and Amateur Football Players Hakan ACAR 1, Erkut TUTKUN 2*
1 Zonguldak Bülent Ecevit University, School of Physical Education and Sports, Zonguldak, TURKEY, 2 Uludağ University,
Faculty of Sport Science, Bursa, TURKEY
ABSTRACT:
2D:4D has been identified as a biomarker for performance in various elite sports. The aim of the study is to analyze the relationship between league status and 2D:4D ratios of national and amateur football players. 38 football players participated to this study who deserved participation FCBEscola Antalya and İstanbul camps according to the scouting results. 19 of players were national football players who have taken place at least one time in U14 and U15 Turkish national football teams and 19 of them were amateur players. The height, body weight, body mass index and 2D:4D finger measurements of the participants were taken. For the differences in the measurements results of the groups, the independent t-test was carried out and the results were evaluated in the p˂0.05 significance level. In both groups a statistically significant difference was found between the right and left hand 2D:4D average values (p<0.05), and the right hand 2D:4D ratios were found to be lower than the left hand 2D:4D ratios. When compared the 2D:4D ratios of national and amateur players, it was determined that there was a statistically significant difference were found between the right hand 2D:4D ratios (p<0.05). Both right and left hand 2D:4D averages in national football players were found to be lower than the amateur football players. As a result of this study, it can be said that 2D:4D may discriminate between national and amateur footballers, and lower 2D:4D ratios could be linked to performance for football players. But for the healthier evaluation of the relationship between sportive performance and 2D:4D ratios, other determinative talent identification parameters should be taken together.
KEY WORDS Football, National Players, Amateur Players, 2D:4D
INTRODUCTION
Selecting or finding talented athletes has always been a multidisciplinary study area since
133 physiological parameters, performance
measurements, body compositions and physical profiles of athletes and continue doing research in terms of having a maximum advantage.
The 2D:4D ratio, is the ratio of the length of the 2nd finger which is the index finger (2D) to the length of the 4th finger, which is the ring finger (4D). Low 2D:4D ratio points out to being more exposed to the testosterone hormone in the prenatal period, while a high 2D:4D ratio points out to being more exposed to the estrogen hormone [1, 2, 3]. In a study, it is stated that prenatal testosterone has a negative relationship with 2D:4D and prenatal estrogen has a positive relationship with 2D:4D [4].
This relationship is proportional to sportive performance [5]. It is assumed that a negative relationship between 2D:4D and physical power affects 2D:4D and sports correlation [2]. There are studies which show that a low 2D:4D ratio is related to high performance in many sports branches [3, 5, 6, 7, 8, 9]. 2D:4D has been identified as a biomarker for performance in various elite sports [10]. Manning and Taylor (2001) determined that when the 2D:4D ratios of professional football players are compared with the control group, it is significantly low. In addition, they stated that football players in 1st team squads had lower 2D:4D than reserves or youth team players [5].
According to our knowledge, although there are studies in literature in different branches have been published in the recent years, there is just one study is about the relationship between the performance of the football players with 2D:4D [5]. A majority of the studies in this area have focused on subjects such as aggressive behavior, rather than the relationship with performance [11]. Therefore, it is not possible to make a healthy comment on whether there are differences between in particular the 2D:4D ratios of top level football players and lower level football players. In football, which is among the most popular sports branches in the world, it is extremely important to identify skill
in the early ages for the athletes to reach high performance levels. For these reasons, to understand whether 2D:4D is a decisive marker in the performances of elite football players, will contribute to the studies on talent identification in this field.
This study has been carried out with the purpose of analyzing the relationship between the league status and 2D:4D finger ratios of national and amateur football players.
METHODS
Participants: 38 active licensed football
players from different clubs in Turkey with an age average of 13.59 ± 0.81 (years) participated to this study who deserved participation FCBEscola Antalya and İstanbul 2012-2013 camps according to the scouting. The participants were divided into two groups and the groups were determined as follows;
The national football players group; consisted of 19 football players selected to the U14 and U15 national teams in 2012-2013, while the amateur football players group; consisted of 19 football players who were taken into camp as a result of the selections carried out throughout Turkey and who are not a part of the national teams.
Measures: The body weight of the football
134 order to determine the ratio, the index finger
length was divided into the length of the ring finger.
Statistical analysis: The differences between
the measurement results obtained from the groups was analyzed with the Independent t-test
and the results were evaluated in the p<0.05 significance level.
STATISTICAL RESULTS
In the study, the measurements of the national and amateur football players were determined as follows;
Table 1: Comparison of some of the characteristics of national and amateur football players
n x ss p
Age (years) National athletes 19 13,57 ,51 ,802
Amateur athletes 19 13,61 ,49
Height (cm) National athletes 19 158,31 9,16 ,644
Amateur athletes 19 159,66 9,15
Body weight (kg) National athletes 19 45,84 4,95 ,099
Amateur athletes 19 49,14 7,08
BMI (kg/m2) National athletes 19 18.02 ,56 ,086
Amateur athletes 19 19.40 ,41
p<0.05
When we evaluated the study groups in terms of age, height, weight, BMI, it was determined that there were no statistically significance differences between the teams (p>0.05).
Table 2: Comparison of the right hand 2D:4D averages and left hand 2D:4D averages
n x ss p
National football players Right hand 2D:4D 19 0,889 6,013 ,000*
Left hand 2D:4D 0,936 5,057
Amateur football players Right hand 2D:4D 19 0.937 8,250 ,000*
Left hand 2D:4D 0.961 4,358
p<0.05
A statistically significant difference was found between the right and left hand 2D:4D average values of both national football players and amateur football players (p<0.05). It was determined that right hand 2D:4D ratios of both groups were lower compared to the left hand 2D:4D ratios.
Table 3: Comparison of finger ratios of national and amateur football players
p<0.05
A statistically significant difference was found between the right hand 2D:4D averages of national and amateur football players (p<0.05).
DISCUSSION In the study, the 2D:4D ratio results of national
and amateur football players discussed below.
n x ss t p
Right hand 2D:4D National football players 19 0,889 6,013 ,341 ,046
Amateur football players 19 0.937 8,250
Left hand 2D:4D National football players 19 0,936 5,057 ,116 ,131
135 A statistically significant difference was not
found between the variables of groups body weight (kg), height (cm) and BMI (kg/m2) which reflect the general physical structure of the participants’ body (p>0.05). The BMI (kg/m2) of the national and amateur football players were found as respectively 18.02±0,56 and 19.40±0,41. BMI (kg/m2) average values of both groups are of normal value according to the World Health Organization norms [12]. It is considered that the reason why BMI is low is that the age group is small and the difference in each group’s number of exercises and league matches allow these values to be acceptable.
A statistically significant difference was found between the right hand 2D:4D and left hand 2D:4D ratios of both national and amateur football players (p<0.05). In both groups, the right hand 2D:4D ratios are lower compared to the left hand 2D:4D ratios. In national football players, the right hand 2D:4D ratio was determined as 0.889 and the left hand 2D:4D ratio was determined as 0.936, whereas these averages in amateur football players were determined respectively as 0.937 and 0.961. In their study, Keshavarz et al., (2017), found the right hand 2D:4D average as 0.93, left hand 2D:4D average 0.93 in elite Greco-Roman wrestlers; the right hand 2D:4D average as 0.97 and left hand 2D:4D average as 0.98 in wrestlers who are not elite and the right hand 2D:4D average as 0.98 and the left hand 2D:4D average as 0.99 in the control group [13]. Kilduff et al. (2011) determined the right hand 2D:4D average as 0.944 and left hand 2D:4D average as 0.976 of male surfers in their study which involved 46 competitors in the Men's 5-star Professional World Qualifying Series surfing competition in Newquay, United Kingdom, in 2009 [14]. Acar and Eler (2018) determined the right hand 2D:4D ratio as 0.935 and left hand 2D:4D ratio as 0.960 of elite male swimmers (n=41) and that there is a statistically significant difference between the 2D:4D ratios of both hands (p<0.05) [15]. The result of our study in terms of the existence of a significant difference between the right hand averages of both national and amateur
football players and the right hand averages in all studies being lower than the left hand averages can support the results of several studies suggesting that right digit ratio is more sensitive to prenatal sex steroids than left digit ratio [4, 16]. In addition, the finger ratios of the national team football players in our study are lower compared to the finger ratios of elite athlete groups in other studies. This can be associated with the fact that there were elite athletes from different ethnic backgrounds in the study groups and that the studies involved different sports branches.
136 2D:4D ratio compared to athletes in lower
categories. These results verify Manning et al.’s (2001) result that low 2D:4D ratio is related to high performance level in many sports branches. When studies in the literature in which groups involving elite athletes and non-athletes are compared, Sudhakar et al. (2013) have determined the right hand 2D:4D average of male swimmers as 0.957, the left hand 2D:4D average as 0.961 and the right hand 2D:4D average as 0.974 and the left hand 2D:4D average as 0,979. In their study, swimmers in the age group of 18-25 years who have been practicing regularly for 30 hours/week for at least 5 years (Average duration of training was 9±1.7 years) and have participated in national level swimming competitions formed the study group. Among male swimmers, a significant difference was found in 2D:4D ratios of both of the hands, with swimmers having a lower ratio compared to their controls. Male swimmers had a significantly reduced 2D:4D ratio compared to their controls [19]. Manning and Taylor (2001), determined that 304 male elite (professional) soccer players had a lower mean 2D:4D of the right and left hands than those of the population of 533 non-athlete controls (5). Panda et. al. (2014) determined a difference in the ratio of 2nd to 4th digit between volleyball players and controls both in the right and left hands in national and international level elite male volleyball players. A highly significant difference was found in 2D:4D ratios of both of the hands with volleyball players having a lower ratio compared to their controls. They have determined the right hand 2D:4D average of volleyball players as 0.936, the left hand 2D:4D averages as 0.952 and these averages in the control group successively as 0.974 and 0.978 [20]. Giffin et.al. (2012) have determined the 2D:4D ratios of athletes who play in university teams as 0.97 and the 2D:4D ratios of non-varsity athletes as 0.99 and concluded that varsity athletes had significantly lower ratios than their non-varsity peers [21]. Bennett et.al. (2010) have determined the right hand 2D:4D ratio of male elite rugby players as 0.963 and the
left hand 2D:4D ratio as 0.956, whereas they have determined the right hand 2D:4D ratio as 0.985 and the left hand 2D:4D ratio as 0.975 for the control group which consisted of non-athletes. They found that the players had lower 2D:4D than the controls. However, there was no significant difference in the right − left 2D:4D difference between the players and the controls [3].
As a result of this study, it can be said that 2D:4D may discriminate between national and amateur footballers. the fact that the national footballers have lower 2D:4D ratios than the amateur footballers, could be associated with a determinant factor for the sportive performance, however 2D:4D averages should not be taken as a determinant for sportive success and performance alone.
In addition, according to literature, it is not possible to talk about a standard average in terms of the 2D:4D finger ratios of elite athletes; therefore, it might be guiding to identify in which intervals the 2D:4D averages of elite athletes. However, differences in the 2D:4D averages in different ethnic backgrounds [22, 23] brings forward the thought that necessity of evaluating athletes from different races in the same sports branch together.
For future studies if 2D:4D is measured with other performance markers, and also is compared players from different ethnic backgrounds in football it may provide more valuable information.
ACKNOWLEDGEMENT
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