Anyway, the studies:
Twelve weeks of HIIE resulted in significant reductions in total, abdominal, trunk, and visceral fat and significant increases in fat free mass and aerobic power.
The actual protocol was quite tough by the look of it:
Subjects in the exercise group completed supervised exercise (8 s sprint, 12 s recovery) continuously throughout each 20-min session. The HIIE workload was set at 80–90% of each subject’s heart rate (HR) peak at a cadence between 120 and 130 r.p.m and recovery was set at the same amount of resistance but at a cadence of 40 r.p.m. Subjects were instructed to keep their exercise intensity at a level necessary to produce a HR between 80–90% of HR peak. As subjects adapted to HIIE training, workload was increased so HR stayed at the appropriate 80–90% HR peak level. HIIE was coordinated with a prerecorded compact disc counting down each sprint in a 3-2-1 manner. Subjects performed a 5-min warm-up and cool-down on the bike prior to and after each exercise session. All training cycling data included continuous recording of HR and r.p.m, whereas rating of perceived exertion  (RPE) was assessed at 5-min intervals.
High-intensity interval training and hypertension: maximizing the benefits of exercise?
Essential arterial hypertension is the most common risk factor for cardiovascular morbidity and mortality. Regular exercise is a well-established intervention for the prevention and treatment of hypertension. Continuous moderate-intensity exercise training (CMT) that can be sustained for 30 min or more has been traditionally recommended for hypertension prevention and treatment. On the other hand, several studies have shown that high-intensity interval training (HIT), which consists of several bouts of high-intensity exercise (~85% to 95% of HR(MAX) and/or VO(2MAX) lasting 1 to 4 min interspersed with intervals of rest or active recovery, is superior to CMT for improving cardiorespiratory fitness, endothelial function and its markers, insulin sensitivity, markers of sympathetic activity and arterial stiffness in hypertensive and normotensive at high familial risk for hypertension subjects. This compelling evidence suggesting larger beneficial effects of HIT for several factors involved in the pathophysiology of hypertension raises the hypothesis that HIT may be more effective for preventing and controlling hypertension.