I know the threshold/tempo/aerobic threshold/anaerobic threshold are all different things to different people. But back in my college running days “threshold” was defined as the pace you could hold for one hour. Is that true for cycling as well?
And that’s an interesting point about MTB. When I first went from runner to MTBer the constant up, down, left, right reminded me more of interval training or weight room than going out for a run. I guess threshold training can work that speed endurance when it comes to racing but I’m guessing that needs to be done on the roads or trainer. No way can you get a smooth threshold on my local trails. As you said it’s either up or down.