One of now quite a few studies on high intensity interval training, all showing the same thing whether is interval vs continuous or high intensity interval vs lower intensity interval.
High intensity yields same results with half the training.
“We compared the effects of submaximal and supramaximal cycling interval training on determinants of exercise performance in moderately endurance-trained men.”
— “6 weeks (3 sessions/week) of submaximal (85% maximal aerobic power, High Intensity Interval Training 85 [HIIT85])”
— “supramaximal (115% maximal aerobic power, High Intensity Interval Training 115 [HIIT115])”
“High-intensity training volume was 47% lower in HIIT-115 vs HIIT-85 (304 minutes vs 571 minutes).”
“6 weeks of submaximal and supramaximal interval training performed to exhaustion seems to equally improve VO2 max and anaerobic power in endurance-trained men, despite half the accumulated time spent at the target intensity.”
Effects of submaximal and supramaximal interval training on determinants of endurance performance in endurance athletes
Scandinavian Journal Of Medicine & Science In Sport — Volume 27 #3 — March 2017