Efficacy of reduced exertion high intensity interval training to modify cardiovascular disease-related risk factors—a narrative review

Despite advances in medical imaging and treatment, cardiovascular disease (CVD) remains the primary cause of premature mortality in adults. Lifestyle modification including regular physical activity (PA) is a well recognized strategy to prevent onset of CVD, although the number of adults who attain recommended guidelines for PA is low, partially due to a perceived lack of time. Recent data show the efficacy of sprint interval training (SIT), brief, repeated “all-out” efforts performed at supramaximal intensities, to increase cardiorespiratory fitness (VO 2 max) in diverse groups of adults. This adaptation is important due to the known association between VO 2 max and all-cause mortality as well as mortality from CVD. A unique iteration of SIT is reduced exertion high intensity interval training (REHIT), which typically requires no more than 1 min of vigorous exercise consisting of two to three 20 s sprints within a 10 min exercise session. This review will define what REHIT is, explore its various health- and fitness-related benefits, and demonstrate its potential feasibility to modify cardiovascular disease-related risk factors in adults.