World Journal of Sport Sciences 2 (1): 27-30, 2009 ISSN 2078-4724 © IDOSI Publications, 2009 Corresponding Author: Dr. N. Rahnama, Faculty of Physical Education and Sport Sciences, Department of Physical Education, University of Isfahan, Isfahan, Iran 27 Diurnal Variation on the Performance of Soccer-Specific Skills N. Rahnama, N. Sajjadi, E. Bambaeichi, 1 1 1 H.R. Sadeghipour, H. Daneshjoo and B. Nazary 2 2 2 Faculty of Physical Education and Sport Sciences, 1 Department of Physical Education, University of Isfahan, Isfahan, Iran Department of Physical Education, University of Payamenur Kazerun, Iran 2 Abstract: The purpose of this study was to investigate diurnal variation in some specific skills performance and some physical fitness and physiological factors in soccer players. Twelve male soccer players (mean±SD; age 22.6±3 years; height 1.76±4.4 m; body mass 66.5±4.6 kg) participated in the study. Subjects performed some specific soccer skills and some physical fitness factors in one day. One test was carried out in the morning, between 7.00 and 9.00 and another one in the evening, between 19.00 and 21.00. A significant main effect of time of day was observed for oral temperature: the temperature in the evening was higher than morning (T= 2.83, P= 0.01). No significant time of day effect was found for hear rate (T= 1.72, P=0.11), systolic pressure (T=-0.67, P= 0.51) and diastolic pressure (T= 0.34, P= 73). A significant main effect of diurnal variation was found for sergeant jump (T= 4.98, P= 0.000), sit and reach (T= 4.1, P= 0.002), flexibility of right hip (T= 4.15, P= 0.002) and 20-m running (T=-4.27, P= 0.001): the values of these factors were better in the evening. A significant diurnal variation was found for dribbling (T= 3.55, P= 0.004), wall volley (T=2.83, P= 0.01), soccer chipping (T= 5.04, P=0.000) and Yeagley soccer test (T=-4.09, P= 0.02). No significant difference was found in penalty kick (P = 0.18). It can be concluded that there was a circadian rhythm in performance of soccer players. Key words: Diurnal variation %Soccer skills %Time of day INTRODUCTION Furthermore, body temperature has been a classic Biologic rhythms are defined as cyclic changes that fundamental variable in diurnal variation of human recur regularly over a given time and circadian rhythms performance [1, 4, 7]. Souissi et al. [8] studied the time of refer to variations recurring periodicity of 24 hours [1, 2]. day effect on anaerobic performance and oral temperature Numerous studies have demonstrated the existence of using force-velocity test and Wingate test and reported circadian rhythms in human physical performance that body temperature, maximal power, peak power and especially for athletes in training and competition [3]. mean power varied concomitantly during the day [8]. For Also it is well established that most of physiological endurance performance [9], hamstring flexibility [10] and functions are affected by circadian rhythms [4]. Studies isometric strength of quadriceps and handgrip [11] time of showed that most of these circadian rhythms originate day effect were observed. Kline et al. (2007) examined the from an endogenous pacemaker located in the chiasmatic circadian rhythm in swim performance across 8 times of nucleus (SCN) of the anterior hypothalamus [5]. Diurnal day independent of environmental and behavioral variations in athletic performance have been reported in masking effects such as sleep, ambient temperature and numerous studies. Most of studies showed that peak energy intake. They reported a significant pattern in swim athletic performance has been found to occur in the early performance relative to both environmental and circadian evening and this time is contemporaneous with peak of times of day [12]. the body temperature rhythm, while worst performance There are some studies which have different results has been found in the morning [2,6]. when compared to the above-mentioned reports. For marker of circadian rhythms and is described as a