It’s my understanding that both intensity & duration are important in achieving desired adaptations for the higher zones. For example, 8+ minutes for Threshold, 3 to 8 minutes for VO2max, 30 seconds to 3 minutes for Anaerobic.
However, I’m not sure what the minimum length of an endurance ride (Coggan classic zone 2, or Polarized zone 1) needs to be. I have seen many opinions stated, such as “you need to ride at least 2 hours”, etc., but I have yet to see a single study on this topic.
I have a simple training philosophy - get 2 to 3 hard interval sessions in per week, and try and get the rest of my training below ventilatory threshold 1 (VT1) which is basically Coggan Zone 2 i.e. a Polarized training plan. It’s not always easy to carve out 2 to 4 hours for an endurance ride, so I’m wondering if accumulating multiple shorter rides may have a similar benefit. For example, are two 90-minute endurance rides about as beneficial as one 180-minute endurance ride?
Please resist the temptation to provide yet another opinion If anyone knows of a research study, or if you’ve done an experiment on yourself (i.e. an N=1 experiment), that would be great.