Creatine is an ergogenic aid with positive effects on muscle and performance. The aim of the study was to determine whether there is a difference between the effects of creatine supplementation taken together with Wingate-based HIIT on anaerobic power, leg strength, heart rate variability and body composition. In the study, Wingate-based HIIT program was applied three days a week for six weeks. Anaerobic power (Wingate anaerobic power test), heart rate variability (Polar H10 chest band), leg strength (back and leg dynamometer) and body composition (PlusAvis 333) measurements of the participants were made 1 week before the training program started and the week after the training program ended. Twenty physically active adult men aged 18-30 were voluntarily included for the study. Participants were divided into two groups: Wingate-based HIIT with creatine supplementation (K-HIIT) and Wingate-based HIIT only (HIIT). As a result of the analysis, it was seen that creatine supplementation taken together with wingate-based HIIT had an effect and increased on the anaerobic power parameters, peak power, average power and minimum power values, and leg strength. In addition, it was determined that heart rate variability parameters improved heart rate (HR, beat/min) and low frequency (LF, ms2) values, but did not cause any change in body composition. Comparing and investigating the effects of different HIIT methods on anaerobic power, leg strength, heart rate variability and body composition will increase the generalizability of the study.

Despite the time-efficiency of HIIT in inducing chronic physiological adaptation, it depleted phosphocreatine stores in the muscle and decrease power output. It has been observed that high-intensity exercise performance increases with the increase of intramuscular phosphocreatine. It is thought that with creatine supplementation, the rate of phosphocreatine resynthesis and mitochondrial transfer of ATP to the cytoplasm may increase. This suggests that performing HIIT with creatine supplementation will provide further improvement. Therefore, the purpose of this study to compare the effectiveness of HIIT with creatine supplement compared to HIIT only. We hypothesized that creatine supplementation intake with wingate-based HIIT will positively affect power capacity and performance-related parameters.

The research will be carried out using experimental research design, one of the quantitative research methods, to measure the variables and determine the relationship between dependent and independent variables. Anaerobic power, heart rate variability, leg strength, and body composition measurements of the participants will be made 1 week before the training program started and the week after the training program ended.

The G*power software was utilized in order to determine the appropriate sample size. It has been reported that a minimum of 12 participants, 6 in each group, should be included in the study (alpha value = 0.05, 1-beta value = 0.80, and effect size = 1.6). Measurement of tests and the Wingate-based HIIT program will be conducted in the Performance Laboratory of the Faculty of Sports Sciences of Ankara University. Twenty physically active adult men aged 18-30 years, who had no history of medical and did not use drugs or ergogenic aids, will be recruited voluntarily. The ethics committee approval for the study methodology was obtained from the Ethics Committee of Ankara University Rectorate (Number: E-56786525-050.04.04/378028 Decision Number: 2022/02) and it will be carried out in compliance with the Declaration of Helsinki's principles. Written inform consents which explain the study to the participant and any right and risk will be obtained prior to data collection. Permission for the research to be carried out in the Performance Laboratory of the Faculty of Sport Sciences of Ankara University will be obtained from the Deanery of the Faculty of Sport Sciences of Ankara University. Participants will be divided into two groups as those who will perform Wingate-based HIIT with creatine (C-HIIT) (age: 21,78 ± 1,79 years; height: 179.56 ± 8.26 cm; weight: 76.86 ± 10.66 kg) and those who will perform only Wingate-based HIIT (HIIT) (age: 20.167 ± 0,98 years; height: 172.33 ± 9,88 cm ; weight: 66.53 ± 9.51kg ). Out of twenty potential participants, only 15 participants agreed to participate in the study (HIIT=6, C-HIIT=9) and 5 dropped out because of sport injuries that occured before the study process.

IBM SPSS 24.0 program (SPSS Inc., Chicago, IL, USA) will be used to statistically analyze the data obtained in the study. First of all, the distribution of the data will be evaluated to determine the test used to compare the data as parametric or non-parametric. This normality distribution assessment will be tested with Shapiro Wilk, as both groups had less than 50 participants. Determination of the mean difference in within-group statistics will be performed with Paired Sample t-Test in data with normal distribution and with Wilcoxon test in data where it is not normal. Groups will be expressed as mean ± standard error. American Psychological Association (APA) 6.0 style will be used to report statistical differences. The alpha value will be accepted as 0.05 in all statistical analysis.

This study aimed to determine whether there was a difference in the effects of taking creatine supplementation with Wingate-based HIIT on anaerobic power, leg strength, heart rate variability and body composition.

The limitation of the current research is that the study will be carried out with a single gender. In future studies on the subject, the number of participants can be increased, female participants can be included in the research and it can be examined whether there is a difference between genders and to increase the generalizability of the study, the effects of different HIIT methods on anaerobic power, leg strength, heart rate variability and body composition can be compared by investigating. In addition, the trial period may be extended as longer periods are needed to see clearer changes in HRV.

Inclusion Criteria:

• having no health and communication problem
• using no drugs or ergogenic aids
• being physically active adult men aged 18-30 years

Exclusion Criteria:

• using any drugs or ergogenic aids
• having any musculoskeletal problem