For intermediate and advanced riders, when you’re planning out your preparation for key events for the season, it’s good to include a ride or ride block that is tougher than your event. If your expected race completion time is less than about 5 hours, you can do a single ride that is either about the same time and tougher (more climbing), or a ride that is longer (6 hours), or a ride that is some combination of both - tougher and longer.
If your race will take you over 5 hours to complete, I like to break the tough session into two days. Put the highest intensity in the first day – and more intensity than you plan to do on race day. On the second day, ride at an accumulated intensity that totals about what you plan to do on race day. How you split the hours, (i.e. three hours on day one and two hours on day two, or three hours each day) depends on your athletic specifics.
This type of training, of course, boosts your physical fitness - but - only if you’ve done the preparation work to fully absorb the training.
Secondly, a really tough ride or ride block will give you a mental edge. On race day, knowing you’ve completed training that is more difficult than the race, you can ride with more confidence - and if you’ve planned correctly, more speed.
You’ll be tough.