Olympic cross-country mountain bike racing as a lot to do with high intensity efforts above FTP followed by recovery at endurance, tempo or close to FTP intensity and/or coasting on descents. Courses often feature short, 1 to 3 minutes climbs with multiple shorter, punchy, steep climbs. You're also forced to accelerate out of corners or put out more power to clear technical obstacle. And let's not even talk about the start of the race, please. Only thinking about it hurts! The overall effort patern sounds much like overloading your system with lactate, then trying to recover and clear that lactate production at a lower pace in order to be able to overload your system again once you reach the next course feature that will require a high power output.
First race of the season was brutal and an eye opener. After analysing my race file, I tweaked some of my workouts to target more specific MTB racing requirements. I have come up with 2-3 workout that I will experiment and/or have been experimenting in the past few weeks. These workouts are some type of micro-intervals workout with moderate to high intensity rest intervals. There are several goals behind each workouts which are adressing specific MTB physiological demands:
1- work at a general critical lactate ''management'' intensity, i-e. arround FTP. The average power for each efforts is generally arround 90% to 110% of FTP depending on effort duration. The ''recovery'' part is done arround 85% to 95% of FTP to force lactate clearance under significant stress.
2- include some short bursts at higher intensity to induce significant lactate production. Bursts are generally done at 120% to 150% of FTP. The bursts average power being more arround 120% to 130% of FTP and the effort spiking arround 150% of FTP.
3- it targets MTB racing neuro-muscular demand with high intensity bursts targeting specific motor unit recruitment and muscle fiber type.
The workouts description:
workout 1: 4 x 5min (20'' @ 90% FTP / 20'' @ 130% FTP) 5min easy
Some tweaked vo2max workout with the average power for the 5 minutes blocks falling arround 110% of FTP. They are 5 minutes blocks where you ride for 20 seconds at 90% of FTP alternated with 20 seconds at 130% of FTP. Mentally very different from an iso power effort. I'd do no more then 4 blocks during racing season and maybe 5 blocks during winter/pre season preparation.
workout 2: 2 x 20min (2' @ 90% FTP / 20'' @ 120%-130% FTP) 5min easy
Nothing new here, only some 2x20 variation. Average power falls arround 90% of FTP depending on how you manage it. A little harder then a regular iso power 20 minutes effort at 90% of FTP.
workout 3: 2 x 8 x (30'' @ 90% FTP / 30'' @ 120% FTP) 5min easy
This one I have not tested just yet and will do tonight. It should be interesting. The relatively low total volume is for the same reason as above, i-e. to match racing season load. Maybe I'd do 3 sets during pre racing preparation.
These workouts could also be well suited to criterium racers or cyclocross racers. Basically any intermittent discipline which results in a high average power output while including a lot of bursts above your FTP could benefit these workouts.
Try them, love them!