In spring I advocated training concept built around implementing intensive workouts at LT level (or MLSS level as some name it). I also believed that all interval workouts should be done until the burn in legs starts regardless how long they are. If the burn starts I must stop and recover anyhow.
My goal was to particiate in 100km MTB marathon in the middle of September.
Off-season I went completely out of shape. I spent more than 3 months off the bike. New season started at Jan 1, 2004. For the first 2.5 months I've been spinning on trainer with weekly volume about 5hrs and doing a lot of 3-4 min intervals based on previously mentioned criterion. In January my legs burnt at 160 bpm (82% of MHR). After 2.5 months this threshold moved up to 180-185 bpm (92-95% of MHR)!
Then I moved on the road and mixed endurance work with 30 sec intervals, 3-4 intervals, prolonged workouts at 160-170 bpm. Weekly volume was about 6.5-7 hrs with 4 training sessions.
By the middle of April I started to ride off-road still sticking to my rule - "don't let legs burn a lot!". I just alternated my workouts doing endurance work on one day and intense off-road workouts on another with weekly volume about 7-7.5 hrs with 4-5 training sessions.
I maintained this schedule up to my major race and I did this race great. I was faster than I was a year before in spite of off-season lay-off. And it was really easy to be faster! And I found out some interesting thing. By the end of the season I could climb steadily at 175-180 bpm with no problem but I died at once if my HR had gone over 180. It became much harder to reach my max HR. I believe I've developed very good aerobic power but sticking to my rule I have developed no anaeropic power at all.
One more conclusion. Muscle endurance requires just 6-8 weeks to build even with such low volume. I did this work on my trainer! Cardiovascular endurance requires much more time with this volume. It almost didn't improve on trainer with 5 hrs/week and it took 4 months to discover any noticeable results with 6.5-7.5 hrs/week.
This season I will stick to the same rule and the same volume and maybe I would add some workouts to develop anaerobic power.