Comparison of Strength Values of Professional Footballers According to Their Positions before Football Season

The purpose of the present study was to compare the strength values of professional footballers according to their positions before the football season. The study group consisted of 27 professional footballers of Ş anlıurfaspor Football Club in the 2 nd League of Turkey. The mean height of the Study Group was 180.92±6.18 (cm), mean body weight was 80.18±1.5 (kg), and the mean age was 26.40±4.4 (years). The inclusion criteria for the study was being volunteers, and the necessary permissions were obtained from the players, club managers and coaches. The Precor-brand device was used to measure the differences of strengths according to the positions of the footballers. “1 RM” measurements were made from shoulder press, latt pully, leg curl, leg extension, and leg press machines in the footballers. The SPSS 24.00 Program was used in the statistical analysis of the study data. The descriptive statistics were given as mean, standard deviation, and minimum and maximum values. The normality test of the data was analyzed with the Shapiro-Wilk Test. One-Way Anova Test was used to identify the differences between the players and the positions. The significance level was determined as 0.05. According to the results obtained in the study, no significant differences were detected in strength values between goalkeeper, defender, midfielder, and striker positions (p > 0.05). As a result, among the biomotoric properties, strength is important, and quite necessary for a footballer to perform at a high level. These values obtained from 2 nd League football players are important for being taken as reference values, and it can be argued that these values obtained in the pre-season prepared the basis for the lack of qualitative differences. In future studies, data that will be obtained from different league levels and training stages will lead to research being considered differently.


Introduction
When players apply a technique, they perform with the help of a muscle system. By turning chemical energy into mechanical work, force is generated that acts on bodily action (Parpucu, 2009). When preparing training programs, strength and power-enhancing trainings are included in sports which require strength. The strength trainings being in line with the characteristics of the sports branch will play important roles in increasing the performance (Şahin, 2008).
Football involves highly violent actions and also the violence is intense and intermittent (Mohr et al., 2003;Rampin et al., 2010;Stolen et al., 2003). Players travel up to 10 km for 90 minutes in repetitive departure speeds, jumps and direction changes (Pettersan & Bren, 2019;Reilly et al., 1990;Stolen et al., 2003). The strength is an important factor during this time for the performance of players.
In football branch, there are preparation stages in and after the season. To keep the fitness of the players at a high level during the season, it is also necessary to maintain this level during the season when professional footballers have limited time for strength training. With the increase in competition, the importance of preparatory training become clear (Bangsbo et al., 2006;Hoff & Helgerud, 2004;Reilly & Gilbourne, 2003).
Maximum strength efficiency is a factor affecting strength, and the maximum increase in strength is usually in direct proportion with the development of strength. For this reason, maximum strength efficiency is an important factor potentially affecting football. It is important to maintain the strength achieved during the preparation period throughout the season (Derenne et al., 1996).
In the literature, many studies reported the importance of strength training in football. Strength is important in terms of being able to demonstrate the performance for a footballer at a high level. It is also important since it has a relation with other motoric features and applied techniques. In the light of this information, the purpose of the present study was to compare the strength values of professional footballers according to pre-season positions.

Study Group
The Study Group had a mean height of 180.92±6.18 (cm), mean body weight was 80.18±1.5 (kg), and mean age was 26.40±4.4 (years), and consisted of players in the 2 nd League of Turkey. The inclusion criteria for the study was being volunteers, and the necessary permissions were obtained from the players, club managers and coaches.

Body Weight Measurement
Body weight measurements were made bare foot with only tracksuits and t-shirts on the athletes with electronic scale with a sensitivity of 0.5 kg.

Height Measurement
The heights were measured by a metal scale, which had a 0.1 m sensitivity.

Strength Measurement
A Precor (USA)-brand device was used after 15-min warm-up to measure the differences of strength of the footballers according to the positions. 1 RM measurements were made in shoulder press, latt pully, leg curl, leg extension, leg press conditioning devices. After the players held the fitness device with appropriate seating and holding position, a pre-trial was done without weight, and after the maximum weight lifting level was determined, the weight at the maximum level was recorded.

Analysis of Data
The SPSS 24.00 Program was used in the statistical analysis of the study data. The descriptive statistics were given as mean, standard deviation, minimum, and maximum values. The normality test of the data was done with the Shapiro-Wilk Test. The One-Way Anova Test was applied to identify the differences between the athletes and the positions. The significance level was determined as 0.05.

Findings
As seen in Table 1, the mean height of the footballers was 180.92±6.18 (cm), mean body weight was 80.18±1.5 (kg), and the mean age was 26.40±4.4 (years). As seen in Table 2, no significant differences were detected between the shoulder press strength values according to the positions of the players (p > 0.05).  ISSN 2377-22632020 As seen in Table 3, no significant differences were detected between the latt pully strength values of the footballers according to their positions (p > 0.05). As seen in Table 4, no significant differences were detected between the leg curl strength values of the footballers according to their positions (p > 0.05). As seen in Table 5, no significant differences were detected between the leg extension strength values of the footballers according to their positions (p > 0.05). As seen in Table 6, no significant differences were detected between the leg press strength values of the footballers according to their positions (p > 0.05). ISSN 2377-22632020

Discussion
The purpose of the present study was to compare the strength values of professional footballers according to pre-season positions. The study group consisted of 27 professional footballers of Şanlıurfaspor Football Club in the 2 nd League of Turkey. The mean height of the study group was 180.92±6.18 (cm), mean body weight was 80.18±1.5 (kg), and the mean age was 26.40±4.4 (year).
At the end of the study, the mean shoulder press values of the players were as follows; 71.6±2.8 (kg) in goalkeeper, 75.0±6.5 (kg) in defense, 80.0±5.9 (kg) in midfield, 72.5±6.5 According to the data obtained in the present study, no significant differences were detected between shoulder press force values according to the positions of the footballers (p > 0.05). There were no significant differences between the latt pully force values according to the positions of the footballers (p > 0.05). No significant differences were determined between the leg curl force values according to the positions of the footballers (p > 0.05). There were no significant differences between the leg extension force values according to the positions of the footballers (p > 0.05). There were no significant differences between the leg press force values according to the positions of the footballers (p > 0.05).
Bağış and Akın conducted a study in 2019, and found that the strength parameters of athletes, and found that the mean shoulder press value before training was 21.4±5.6 (kg), mean leg extension was 60.0±10.3 (kg), mean leg curl was 41.1±6.6 (kg), mean leg press was 68.3±8.8 (kg).
In their study conducted on strength values of team sports players in 2011, Özer and Kılınç found that the mean leg press value was 136.9±25 (kg), mean shoulder press value was 77.9±15.5 (kg), mean leg extension was 102.6±13 (kg), mean latt pully was 67.3±10 (kg), mean leg curl was 69.5±15.2 (kg).
Yıldız and Bağış (2019) conducted a study in 2019, and found that the mean pre-test total technique of the research group was 254±38.4 (kg), the average of the breakout technique was 113.8±17.7 (kg), the average of the shake technique was 140.6±20, It has been determined as (kg). Eystein et al. (2013) conducted a study in 2013, and found that the mean leg press pre-test value was 237.2±54.8 (kg) and the mean post-test value was 276.7±57.9 (kg).
In their study conducted among footballers who played in different positions, Köklü et al. reported that there were no statistically significant differences in terms of biomotoric characteristics. Joe Dunbar and Treasure (2005) found that there were no significant differences among positions in their study conducted on English Premier League footballers.
As a result, strength, which is among biomotoric properties, is very important and quite necessary for a footballer to perform at a high level. These values obtained from 2 nd League football players before the season are important in terms of being reference values, and it can be argued that these values obtained in the pre-season prepared the basis for the lack of qualitative differences. In future studies, data that will be obtained from different league levels and training stages will lead to research being considered differently.