Couldn’t find a search topic that hit the points…
Basics. Looking to target a 75 mile MTB event that should be in the 7 hour range.
Is it possible to train for something like that without absolutely destroying decent results in those 1’ish hour MTB (XCST) “B” events?
Will TR just adapt to it if I change up the calendar, or is one style of event going to suffer?
Is there a way to bounce the body out of the Endurance phase and back into Pop world?
Hey there,
You could still certainly do both! If your A event is a Marathon MTB race, the training may not be ideal for XC/ST races, but you should still have some solid fitness to carry you through those shorter races. You might not have as much punch as you might want if you were to specialize in those types of races, but you should have plenty of aerobic fitness to get you through them.
One style of racing will have to suffer a bit depending on what your top priority is – but I wouldn’t say your results in the “backseat” discipline would be “absolutely destroyed,” either. While XCM races are longer than XC/ST races, there will still be some crossover between those event types. Your longer, sustained power will probably be stronger than your shorter, punchier power, but that should be expected with the type of training you’d be doing for Marathon races.
TR won’t adapt or change anything unless you change your A race/the focus of your plan to XC racing from Marathon in terms of what kinds of workouts you’ll see. Red Light Green Light will propose adaptations if your races are more intense than your plan calls for by advising you to rest up more if needed. On the whole, though, your plan will remain focused on the efforts needed to train for Marathon MTB racing if that’s what you have selected as your A event.
I think you should still be plenty prepared for your XC races, though! Again, while your prep for those B races may not be ideal, you’ll still have enough fitness to go and do those races. Plus, keep in mind that they’ll be sharpening up your fitness for your A event later on in the season. 
Hope that helps clear things up – feel free to let us know if you have any additional questions!
That certainly makes sense. Would there be any benefit in adding certain VO2 Max efforts or a few different Anaerobic workouts to keep that explosiveness around?
I don’t think it would hurt, especially if it were during the weeks of those B races. Just make sure to replace one of your other hard workouts for that week so you can keep your intensity days capped at 2-3 sessions per week so as to avoid excess fatigue. That should help you “open up” a bit before those shorter races without throwing the rest of your plan off track. Using TrainNow or browsing our Workout Library and using the appropriate search filters would give you some good options for workouts to pick in those instances.