I mean, the 7 to 14 mile one Running’s impact on HDL LDL (running 7 to 14 miles a week) has been legit. You see what I mean? I saw that directly impact my LDL. Like a medication almost.

Another famous one for VO2 max is the Norwegien.

VO2 max is a cardio fitness meaning heart strength. So you can isolate the workout to that system.

Any kind of HIIT execution will work. Bike could be it.

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Norwegian 4×4 Protocol: What the Research Actually Shows

Four 4-minute intervals at 90-95% of max heart rate, three days a week. Helgerud 2007 found it raised VO2 max about 7% in eight weeks, beating moderate cardio at the same total workload.

By Domenic Angelino, MS, MPH, CSCS, CPT · Published May 28, 2026 · Updated July 19, 2026 · 11 min read

Key Takeaways

• The protocol is simple. Four work intervals of 4 minutes at 90 to 95% of max heart rate, each followed by 3 minutes of active recovery, bookended by a 10-minute warm-up and cool-down. Total session: about 38 minutes.
• Helgerud 2007 is the foundation study. Forty moderately-trained men did 4×4 three times a week for eight weeks. VO2 max rose about 7%, and the gains beat moderate continuous training of the same total workload.
• It works in clinical populations too. Wisloff et al. (Circulation, 2007) ran the protocol in heart-failure patients and saw a 35% rise in ejection fraction and 46% rise in VO2 peak, with no excess adverse events.
• And in older adults. The five-year Generation 100 trial showed high-intensity intervals were safe and effective for adults aged 70 to 77.
• The dose matters less than people think. Two sessions a week, layered on a base of easy aerobic work, captures most of the benefit with much lower dropout than three.