Ronnestad and company post new study comparing effort matched short vs. long intervals

Highly trained athletes
3 week intervention period, 3 interval sessions per week,
Short intervals = 3x (13x 30 sec work / 15 sec recovery) and 3 min recovery between sets
Long intervals = 4x (5 min work intervals with 2.5 min recovery)

The relative power outputs were different, but the perceived intensity of each workout was a 9/10

Short intervals achieved a larger (p<0.05) relative improvement in peak aerobic power output than Long intervals (3.7±4.3% vs. -0.3±2.8%, respectively), fractional utilization of V̇O2max at 4 mmol∙L-1 [La- ] (3.0±5.8 percent points vs. -3.5±2.7 percent points, respectively) and larger relative increase in power output at 4 mmol∙L

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Here’s the link from Alex Hutchison Outside Magazine article about the study - https://www.outsideonline.com/2408756/cycling-sprints-workout-study?

In terms of why the short intervals worked, there was no improvement in VO2 max. But tellingly, average lactate levels during the 20-minute time trial increased from 5.4 to 7.5 mmol/L in the short-interval group; there was no change in the long-interval group. Doing all those short intervals with tiny snippets of rest seems to have improved their ability to tolerate high levels of lactate, perhaps by improving the capacity of the muscles themselves to buffer lactate. In contrast, a long interval with no rest forces you to start more slowly and spend less time overall in that high-lactate zone.

So should we all be doing short 30-second intervals instead of the more common 3- to 5-minute VO2 max intervals? Not quite. As I suggested at the top, I think the benefits of any given workout depend heavily on the context. These cyclists were already super-fit, and had just completed a training block that emphasized high volume and low intensity. They were already strong on VO2 max and weak on lactate—so it makes sense that they responded to the shorter intervals.

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