This study does present some interesting results. But as will controlled studies that are designed to look at a narrow range of effects, I caution you to not read too much into them. I have no doubts about the validity of the tests or their results but other mitigating factors limit the usefulness of these studies for anyone other than other researchers.
FIRST) There were 7 untrained subjects in this test and while the standard deviation in the endurance test results definitely show significant improvements in time to exhaustion at both 65 and 80% of peak power, we have not control group of similarly untrained subjects doing another training intervention to see how they would respond. What would this intervention have looked like if applied to well endurance trained athletes?
SECOND) No athlete trains in 3 week isolated blocks. Athletes train all year of at least in season long blocks. What would this intervention look like if applied over a prolonged training block of months? Could it be sustained?
Third) The lactate levels dropped through out the 2 three week training blocks which is what we see with your ME workouts. This indicates that the aerobic metabolic system is contributing more of the ATP yet the researchers admit to finding some of their results contradictory and suggest that some of endurance improvement may be do do hypervolumea (increase in blood volume). This would especially pronounced in untrained subjects but much less so in well trained.
In short I suggest a heavy caution in trying to apply the results of lad studies to the real world. Instead, look at what the methods used by the best endurance athletes and coaches for guidance. The best laboratory in the world is the competitive arena. The best measurement is the stop watch. The pool of subjects numbers in the millions. The study lengths are measured in months and years. The natural evolutionary process of rejecting bad ideas and refining good ones using empirical methods naturally weeds out the field so that 100 years on we have very good consensus as to what works and what doesn’t.
Taking studies out of context is exactly what has given us the fitness fads like CrossFIt, PX90, Boot Camp, Orange Theory Fitness, Tabata intervals etc, etc, etc.
If these get fit quick schemes worked, the endurance athletes of the world would be flocking to them…….They’re not.