No, The “Norwegian protocol” is not special. Or even something many novices should do. It’s not even what Ingebritsen does…And it is definitely NOT “sprinting” Please do not reduce interval training into a "best" workout. This is marketing. But it’s nonsense. There is no single best interval workout to improve cardiovascular fitness. Science does NOT show this. It is NOT the NORWEGIAN 4x4min as many health people claim. It's just not... The best interval training is varied. Change the stimulus (speed, rest period, rest type, rep distance). Especially if you are after general fitness. Focusing on a single best interval workout is what we did in the 1940s and 50s when Zatopek ran endless 400s, and Bannister ran 10x400 most days. We've evolved since then. (And even Zatopek ran some 200s every now and then.) Let's bring hard workouts into the 21st century. My preference for general fitness is to rotate your hard workouts between: 1. Short and fast, but smooth 2. Medium length at 5k pace 3. Longer and steady Examples: 1. 10 to 15 x 200m at mile pace with 200m jog recovery (or a pace you can sustain for 5-8min) 2. 5x 3min @ 3k-5k pace (pace you can sustain for 10-18min) with 3 minutes rest 3. 3x8min @ tempo/steady effort (pace you can sustain for ~hour) with 2min rest These aren't magic either. Vary them up and alter the stimulus. You can do option #2 (medium intervals) as short intervals if you make the rest really short (i.e. 400s with 25sec rest @ 10k pace). Or option #3 tempo, you could do in short intervals with really short rest at not too fast of a pace (10x2min on/30sec off at 15k pace) Why? Because you manipulated the speed/rest to get the same aerobic stimulus as doing longer intervals, with longer rest, at a touch slower. The basic idea is do something that is manageably hard (7/8 out of 10, not max). Do a hard workout once, maybe twice per week. And lots of easy surrounding that. The magic is in the manipulation of the variables. Not in a single special workout. For more: thegrowtheq.com/an-exercise-… *On the research on intervals: It's not that the research is bad. It's that you can't test interval training as it's done in the real world. So what happens is researchers isolate intervals for ~ 6 weeks and see what does "best" in improvement of a parameter. So you take a bunch of people doing easy mileage, then put them through 6 weeks where everyone does X, Y, or Z workout 2-3x a week. It's not a reflection of what occurs in the real world. Often, studies on interval training are just a demonstration of what helps people peak for a "race" (or in many cases some physiological test). It's why interval training almost always appears better in studies than it actually works in the real world. Why? Because we aren't constantly peaking...we're training for months on end, not 6-8 weeks. It’s a false comparison. And often the workout that is most specific to the task demands ends up “best” surprise surprise. I break down the Norwegian 4x4 claim here in full: youtube.com/watch?v=7YkY8TZh…