An Investigation of the Leptin Levels of Footballers and Wrestlers in Terms of Aerobic Capacity

The purpose of the present study is to investigate the association among the leptin levels and aerobic capacities of footballers, wrestlers and sedentary group. The study included a total of 130 volunteers (43 footballers, 41 wrestlers and 46 sedentary). The results showed a statistically significant difference between footballers and the sedentary group in terms of leptin levels both male and female. Leptin levels of the females were significantly higher than the males for all groups while MaxVO2 levels of the males were significantly higher than the males for all groups. The correlations between serum leptin levels and MaxVO2 levels of both males and females were no significant in all groups. Besides, as the aerobic capacity of the groups who did sports increased, their serum leptin levels decreased. Consequently, it can be ascertained that serum leptin levels of footballers and wrestlers are lower than those of the sedentary group and this difference is caused by the athletes’ aerobic capacities. Address for correspondence: Dr. Mehmet Yalcin Tasmektepligil Associate Professor Ondokuz Mayis University, Yasar Dogu Faculty of Sports Sciences, Kurupelit 55139, Samsun, Turkey Telephone: +90 542 2318264 E-mail: [email protected] INTRODUCTION Leptin and the regulation or synthesis of oscillation of leptin is an important public health issue (Durstine et al. 2011). At the same time, leptin can be assessed as a fitness or performance variable for athletes. As a matter of fact, studies on leptin have reported an association between leptin levels and body fat mass (Kowalska et al. 1999). In addition, volumes of the exercise and energy amount spent during exercise are reported to be important factors affecting serum leptin levels (Unal et al. 2005). Thus, the strong effects of exercise on energy balance and body fat mass change the oscillation of leptin (Ucok and Gokbel 2004). Leptin is a hormone secreted from adipocytes, which suppresses the food intake by acting on the hypothalamus through negative feedback mechanisms and increases energy expenditure (Alp et al. 2011). Within this context, it is known that exercise reduces obesity effectively. Long term, moderate exercise has been observed to suppress serum leptin levels based on the decrease in body fat percentage represented by BMI (body mass index) (Sutken et al. 2006). Indeed, a large number of studies have been reported that short-term training sessions (<12 weeks) do not have an impact on leptin levels so long as they do not reduce fat mass (Kohrt et al. 1996; Gutin et al. 1999; Okazaki et al. 1999), while long-term training sessions (>12 weeks) decrease leptin levels (Torjman et al. 1999; Weltman et al. 2000; Kraemer and Castracane 2007). Within this framework, a significant relationship is thought existing between serum leptin level and type of exercise. Further, the characteristics of a sport affect the serum leptin levels of an athlete who does that sport. Football is a team sport that requires sportive performance such as high level endurance, strength, flexibility, speed, agility, strategy and control (Bloomfield Bouassida 1994). High levels of aerobic endurance and anaerobic strength is important for footballers (Reilly et al. 2000). The studies on Professional footballers have shown that footballers have a high aerobic capacity (Reilly et al. 2000; Helgerud et al. 2001; Hoff et al. 2002; Reilly and 2003). Besides, wrestling is a sport in which anaerobic energy system is used predominantly and in which factors such as speed, strength, agility, flexibility, balance, muscular and cardiovascular endurance and coordination affect performance (Macdougal et al. 1991). In fact, the Success in wrestling depends on power, endurance, maximum strength, short term muscle endurance and flexibility as well as technical and tactical skills. Wrestling is a periodic sport characterized as a 356 EROL DOGAN, MEHMET YALCIN TASMEKTEPLIGIL AND SONER CANKAYA short term and high level explosive activity. It required anaerobic aptitude and it works in the medium level of aerobic system (Bompa and Carrea 2005). Within this context, a difference may be expected between the leptin values of the athletes that is compared in this study, since, they are doing different sports. In addition, the sedentary group’s profile is seen as a problem that should be presented. Purpose of the Study The purpose of the present study is to determine whether there is an obvious difference between the leptin levels of footballers and wrestlers in terms of aerobic capacity parameters and to determine how these differences are reflected in the performance. MATERIAL AND METHODS The study included a total of 130 young volunteer participants, 43 of them were active footballers (21 female-23 male), 40 of them were active wrestlers (20 female-20 male) and 46 of them were sedentary (20 female-26 male). The participants were between the ages of 18-25. Body mass index (BMI), aerobic capacity (MaxVO2) and serum leptin levels of the participants were determined. BMI was measured by using GAIA 359 PLUS Body Composition Analyzer (individuals whose BMIs were close were included in the study) with a frequency analysis of 5, 50, 250 kHz; aerobic capacity (MaxVO2) was determined by 20 meter shuttle run test in Power timer PC 1.9.5 Version New test protocol (MaxVO2 values were measured by the device) and blood leptin levels were found by ELISA method. 4 ml blood was taken from the participants (at 09:00) and after they were put in biochemistry tubes with normal gel, they were centrifuged for 5 minutes at 3000 g, their serums were taken to eppendorf tubes and they were kept at -40oC till the end of the working day. At the end of the working day, they were melted in room temperature and worked on with ELISA method. Ethical Considerations Before the study, the required ethics committee approval by Ondokuz Mayis University was obtained (2012/12). The aim of the study was explained to the athletes during the data collection phase, and thus the “informed consent principle” was fulfilled. Statistical Analysis First, the Shapiro-Wilk test was used to assess assumption of normality of the obtained data before the use of parametric tests. Since the data presented an asymmetrical distribution, logarithmic transformation was used to normalize the data distribution. Secondly, One-way ANOVA was used to determine the differences between branches. Then Tukey multiple comparison test was applied to determine any further differences among the groups. Thirdly, Student t-test was used to present the differences between the measurement values of the participants in terms of their genders. Finally, Pearson correlation coefficient was used to determine the relationship between the parameters. Significance was evaluated at P < 0.05 for all tests. All the computational work was performed by means of SPSS 21.0 V.