“…Due to its time-saving nature and the induced physiological adaptations similar to MICT, HIIT has been ranked first in 2018 [ 35 ] and third in 2019 in Worldwide Fitness Trends [ 36 ]. Growing evidence-based research, both original research and meta-analysis studies, shows that interval training programs ranging from 5 days to 12 months are effective in improving O 2max [ 37 ], endurance capacity [ 38 , 39 ], resting metabolic rate [ 40 ], substrate metabolism [ 41 , 42 ], body composition [ 43 ], insulin sensitivity [ 44 , 45 ], and cognitive functions [ 46 , 47 , 48 ]. Besides, interval training has been shown to decrease the risk for cardiovascular diseases [ 15 , 25 ], breast cancer [ 49 ], metabolic syndrome [ 50 ], osteoarthritis [ 51 , 52 ], and rheumatoid arthritis known to cause lower back pain [ 53 , 54 , 55 , 56 , 57 ] ( Figure 1 ).…”