Does interval duration or intensity during high-intensityinterval training affect adherence and enjoyment inoverweight and obese adults?Huei-Jhen Wen1 and Boon Suen Ang21Physical and Health Education Center, Tzu Chi University2Exercise & Sports Science Programme, School of Health Sciences, Universiti Sains MalaysiaAbstractOverweight and obesity have been associated with a variety of chronic diseases andimpairment in executive function of all age groups. Both continuous aerobic exercise training andintermittent/ interval training were reported to be beneficial for overall health and cardiovascularfitness. In recent years, high-intensity interval training (HIIT) had been shown to be moreeffective and time-efficient as compared to moderate-intensity continuous training (MICT).Short-term moderate- to high-intensity interval training intervention had also induced modestbody composition improvements in overweight and obese individuals. Although many studiesreported HIIT to be more superior than MICT, with effective intensity ranging from moderate- tohigh-intensity intermittent or all-out. However, an effective and practical approach for managingoverweight required a long-term strategy. This paper reviewed the adherence to HIIT in relationto its intensity, interval, and its applications in real world for overweight or obese adults. Reportson levels of affective response and enjoyment in MICT and HIIT are inconsistent, and could bedue to discrepancies of the protocols and stages of training, as well as participants’ fitness levelsand competencies. Some studies indicated that lower intensity and/ or shorter interval in HIITimproved pleasure and enjoyment during exercise. Among inactive and overweight adults,increased in exercise intensity above the ventilatory threshold appeared to have a negative effecton the affective response. Exercise competency could also be a critical factor contributing to theenjoyment of HIIT. High enjoyment for variations of interval style training could be achieved ifthe intensity was reduced and duration of the interval was lengthened beyond the traditional 30-sall-out bouts, which ultimately improved a weight management program. For the enhancement ofoverall quality of the study on effectiveness and exercise adherence, a longer period ofintervention should be considered. In future studies, other factors such as session attendance,adherence rate and adverse events should be included to ascertain their potential roles.