Browsing by Author "Karakulak, Izzet"

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Citation - WoS: 2
Citation - Scopus: 2
Determination of Running Performance in Young Soccer Players
(Mattioli 1885, 2020) Karakulak, Izzet
Study Objectives: This study aimed to determine the relationship between running performances in young soccer players and various parameters. Methods: The study was conducted with 20 male athletes from the U-14 youth setup soccer team of a sports club playing in the Turkish Football Super League. Various measurements were made to determine athletes' height, body weight, leg, lower leg and upper leg length, leg force, active and squat jump heights, sprint times in 15, 20, 25, 30, 35, and 40 meters. The videos, on which athletes' two full stride lengths where they reached maximal speed were recorded, were analyzed on Ariel Performance Analysis System (APAS) package program the with below-waist analysis method, and their stride lengths on maximal speed were found. Thus, athletes' step frequencies were found by dividing their running times into their stride lengths. Data were evaluated on SPSS 22.0 package program with descriptive statistics and Spearman's rank correlation coefficient to determine the correlation between stride length and step frequency, and other parameters. Results: The results of statistical analyses showed that there was a negative medium level correlation between stride length and sprint time in 15m (r = -.484) while there was a negative strong correlation between stride length and step frequency (r = -.880). There was a positive strong correlation between step frequency and sprint time in 15m (r =.751), 20m (r =.691), 25m (r =.632) and 40m (r =.635) while a positive medium level correlation with sprint time in 35m (r =.460). Conclusion: Stride length is more determinative than step frequency especially in short distance races in terms of running performance in young soccer players.
The Effect of Low Dose Caffeine Powder Supplementation on Serve Speed, Spike Speed, and Speed-Endurance in Elite Sitting Volleyball Players: A Randomized Double-Blind Crossover Study
(BMC, 2025) Diedhiou, Azize Bingol; Erkan, Dilara; Guler, Melek; Sar, Halit; Karakulak, Izzet; Eyuboglu, Ender; Yildirim, Ulas Can
BackgroundSitting volleyball relies heavily on upper-body strength and anaerobic capacity. Serve, spike, and speed-endurance are decisive skills, yet the ergogenic potential of low-dose caffeine in this Paralympic sport remains unclear.PurposeTo examine the acute effects of low-dose caffeine (3 mg/kg) supplementation on serve speed, spike speed, and speed-endurance in elite sitting volleyball players.MethodsUsing a randomized, double-blind, crossover design, 13 elite male athletes from the Turkish National Sitting Volleyball Team completed serve speed, spike speed, and speed-endurance tests under caffeine (CAF) and placebo (PLA) conditions.ResultsCaffeine intake produced a moderate improvement in serve speed (p = 0.028, d = 0.460); however, this effect did not remain statistically significant after Bonferroni correction (adjusted p = 0.084). No significant effects were observed for spike speed (p = 0.547, d = 0.166) or speed-endurance performance (p = 0.709, d = 0.111). Perceived exertion during the speed-endurance test was similarly high in both conditions.ConclusionsLow-dose caffeine may offer a trend toward improved serve performance, but the effect was not robust after statistical adjustment, and no benefits were observed for spike speed or speed-endurance. These findings highlight that caffeine's ergogenic effects are context-dependent and shaped by task complexity and sport-specific motor demands. Further research with larger and more diverse samples, genotype-based subgroups, and varied dosing strategies is warranted to clarify caffeine's role in adaptive sports.Trial registrationThe randomized controlled trial was retrospectively registered on 21/06/2025 at ClinicalTrials.gov, under the registration number NCT07056231.
Citation - WoS: 12
Citation - Scopus: 10
Impact of Detraining Process Experienced During the Covid-19 Pandemic on the Selected Physical and Motor Features of Football Players
(Mattioli 1885, 2020) Korkmaz, Sezgin; Aslan, Cem Sinan; Eyuboglu, Ender; Celebi, Murat; Kir, Ridvan; Karakulak, Izzet; Geri, Serdar
Study Objectives: The purpose of this study was to examine the changes in the selected physical and physiological properties of football players in the long-term detraining stage during the pandemic period. Methods: In this study, 14 semi-professional football players (mean age: 22.21 +/- 3.29 years old and mean height: 177.86 +/- 5.35 cm) took part voluntarily. The participants had remained in detraining in the home environment for 89 days until the final measurements, following the decision of cessation of the leagues made by the Turkish Football Federation, except soft and irregular exercises they did with theirbody weight. The participants' body composition characteristics, anaerobic performance, flexibility, and speed performance were measured. The descriptive statistics for numeric variables were expressed as mean standard deviation. Since parametric test assumptions were provided as a result of examining the data acquired from the experimental subjects via the Shapiro-Wilk test, the repetitive measurements were evaluated using the "Paired-Sample t-test". In addition, the mathematical differences between the two measurements were indicated with percentage. The results were evaluated at the confidence interval of 95% and the value p <0.05 was accepted to be significant. Results: Comparing the pretest-posttest results of the participants; the difference between the two measurements was statistically insignificant in terms of body weight, BMI, 30 m speed, and fatigue index properties, while the difference in terms of body muscle mass, fat mass, fat ratio, waist-hip ratio, peak power, average power, minimum power and flexibility properties was significant. Conclusion: A long-term detraining process significantly damages the physical and motor performance of football players.
Citation - WoS: 6
Citation - Scopus: 9
Is There Any Effect of Non-Suitable Pull Technique in Back & Leg Dynamometers on the Leg Strength Test Results
(Carbone Editore, 2019) Aslan, Cem Sinan; Karakulak, Izzet; Sahin, Fatma Nese; Eyuboglu, Ender
Introduction: Dynamometers are valid and reliable test instruments that have been used for many years to measure strength. However, there are excessive differences in leg strength scores in different studies with similar groups. This situation suggests a non-conformity to testing procedures occurred during the practice of the tests. The purpose of this study was to determine the effect of non-suitable pulling technique on the leg strength test results. Materials and methods: A total of 127 healthy subjects (24 female athletes and 41 male athletes, 22 sedentary females and 40 sedentary males) were included in the study. A back & leg Dynamometer was used to determine the leg strength of the participants. The participants pulled up the dynamometer's grab handle with and without contact with their upper leg. Results: The results showed that there was a significant difference (p=0.000) between contacted and non-contact pulling trials of all participants. The percentage difference of leg strength between contacted and non-contact pull was 51.69% (43.25 kg) for female athletes, 54.78 (73.46 kg) for male athletes, 5631% (37.52 kg) for sedentary females, and 50.69% (65.55 kg) for sedentary males. Conclusion: There were significant differences between contacted and non-contact pull trials. It was determined that during the pulling phase if the dynamometer's grab-handle contacted the upper leg of a subject, the strength measurement's score increased considerably. In this case, it can be said that non-suitable pulling technique in the "back & leg dynamometers" affects the leg strength test scores.
Mental and Physical Outcomes of Yoga Participation in Women with Spinal Disorders: A Qualitative Study
(Frontiers Media S.A., 2025) Akyol, Gamze; Ermis, Sermin Agrali; Karakullukcu, Omur Fatih; Guler, Ozkan; Karakulak, Izzet; Arslanoglu, Cansel; Kucuk, Hamza
Yoga, a holistic practice supporting both physical and mental integrity, has gained increasing attention in recent years as a public health-promoting activity. Particularly among women with spinal disorders (e.g., hernia, lordosis, scoliosis, kyphosis), yoga is recognized not only for improving physical functionality but also for contributing significantly to psychosocial parameters such as stress management, self-awareness, and life satisfaction. In this context, the present study aimed to explore the mental and physical outcomes of regular yoga practice in women diagnosed with spinal disorders, using qualitative methods. This study was conducted using a phenomenological design, as the participants had experienced the situation under investigation. It included semi-structured, in-depth interviews with 15 adult participants diagnosed with spinal disorders and with at least 3 months of yoga experience. In line with the nature of qualitative research, the number of participants was deemed sufficient, and it was accepted that data saturation was reached through the interviews conducted with 15 participants. The findings revealed multidimensional benefits, including mental and physical relaxation, improved stress management, postural enhancement, better quality of life, and increased self-compassion. Participants also highlighted the positive influence of yoga on body-mind balance, awareness of personal limits, and a deeper understanding of their condition. These results suggest that yoga functions both as a physical intervention and a psychological support mechanism for women with spinal disorders, promoting active engagement in their treatment process and enhancing public health outcomes. In conclusion, yoga practice was found to provide significant and sustainable contributions to spinal health and overall psychosocial well-being.