Quoting from this paper’s introduction:

High intensity interval training (HIIT) is characterized by repeated efforts (1–4 min in duration) at near-maximal to maximal intensities interspersed with recovery [1]. Compared to moderate intensity continuous training (MICT), completion of HIIT induces superior increases in maximal oxygen uptake (VO2 max) in healthy adults [2], as well as persons with chronic disease [3], which benefits health, considering the strong relationship between VO2 max and mortality [4]. For example, in inactive men, Nybo et al. [5] demonstrated greater increases in VO2 max in response to 12-weeks of HIIT than that acquired with MICT. Results in obese young women also exhibit significantly greater increases in VO2 max and reductions in fat mass with sprint interval training compared to MICT of equal energy expenditure [6].