The Impact of High-Intensity Interval Exercise Including Acceleration/Deceleration Patterns on Redox Status of Healthy Male Adults  
[PERSON]  
1 Department of Sport and Physical Education, Faculty of Health Sciences, Aegean College, 105 64 Athens, Greece, [EMAIL_ADDRESS]  
2 Department of Sport Health and Exercise Science, Faculty of Health Sciences, School of Life Sciences, University of Hull, Hull HU6 7 RX, UK  
3 School of Pharmaceutical Sciences, Faculty of Life Sciences, University of Bradford, Bradford BD7 1 DP, UK; [EMAIL_ADDRESS]  
4 Human Performance Laboratory, Department of Life Sciences, School of Life and Health Sciences, University of Nicosia, Nicosia 1700, Cyprus  
5 Leeds Trinity University, Leeds LS18 5 HD, UK; [EMAIL_ADDRESS]  
[PERSON]  
3 School of Pharmaceutical Sciences, Faculty of Life Sciences, University of Bradford, Bradford BD7 1 DP, UK; [EMAIL_ADDRESS]  
[PERSON]  
4 Human Performance Laboratory, Department of Life Sciences, School of Life and Health Sciences, University of Nicosia, Nicosia 1700, Cyprus  
4 Department of Sport and Physical Education, Faculty of Health Sciences, Aegean College, 105 64 Athens, Greece, e.  
showed that a running exercise may not produce a response to specific biomarkers of oxidative stress; instead, oxidative damage to the biomarkers of lipids, proteins, and various enzymatic and non-enzymatic antioxidants is expressed according to the training level of each individual [4]. Indeed, studies have shown that higher physical fitness levels are associated with decreased oxidative stress [19], and regular endurance physical exercise appears to improve antioxidant capacity [3; 8].  
The difficulty, perhaps, of determining oxidative stress levels during exercise may be due to the diversity of the different exercise components that potentially affect the overall result, since there is no single \"universal exercise protocol\" to be implemented for such studies, resulting in contradictions in the literature [4; 20]. A widely used exercise protocol applied in the active population is high-intensity interval training (HIIT) [21; 22]. This type of activity involves brief intervals of high-intensity exercise interspersed with periods of low-volume exercise or rest [23]. The use of intermittent exercise has been shown to be an effective approach for physiological adaptations and an efficient exercise approach that promotes benefits in healthy [24; 25] and diseased individuals [21]. However, the manipulation of HIIT variables and the diversity of HIIT regimes that exists may directly affect physiological responses [26].  
Although HIIT has mainly been utilized in the literature for training studies, the acute responses or the effect of intermittency and/or the rate of acceleration and deceleration phases during HIIT-induced oxidative stress have not been documented yet [27; 28; 29]. It is also not currently clear what, if any, impact the degree of intermittency (how often intensity is changing during exercise) and rate of acceleration may have on the generation of oxidative stress [4]. Understanding the contributions of these parameters to exercise-induced oxidative stress could provide an important insight and context for the design of future HIIT protocols, particularly in the context of use in diseased populations, such as patients with cardiovascular or metabolic health complications [30; 31; 32]. Consequently, the aim of the current study was to examine the impact of intermittency and acceleration/deceleration phases during HIIT-induced oxidative stress. It was hypothesized that different HIIE levels and acceleration/deceleration phases during running would produce different oxidative stress responses in healthy, physically active males.