Simone@Italy said:... it seems that the limiter is now muscular rather than cardiovascular (VO2Max?)...
After the first five or six weeks of training the limiter is almost always muscular. Heart stroke volume and increased red blood cell count are both very early adaptations to training. Long term adaptations include increased mitochondrial density, increased capillary density, and recruitment of additional muscle fibers. These changes all take place in and around the working muscles. IOW, the really important adaptations that lead to long term power increases aren't centralized to the heart and lungs, they include those systems but have a lot more to do with what's going on in the muscles of interest(your legs).
Quoted post said:- train @ lower cadences to raise muscular power? maybe some hill training?..
Train hills if you want/need to improve on hills. For instance if your races/rides will include a lot of climbing. But there's no magic in hills that will encourage the appropriate training adaptations better than flat riding at appropriate intensities.
Quoted post said:- try some 5 x 5' @ 110% FTP?...
Perhaps some focused VO2 Max work might help. That represents a "pull up" approach to raising sustainable power. Personally I hold off on VO2 Max work until I'm within 6 to 8 weeks of important races. I simply can't do as much total work at that level, the workouts themselves are mentally and physically harder and I tend to need more recovery before I'm ready to train hard again. So moving to L5 work too soon costs me over all training load.
Quoted post said:- stick with the 2x20' @ FTP?...
Well from your description I'd stick with SST and L4 work. That might be 2x20s if that's your preferred way to train SST and L4. Personally I've moved away from pure 2x20 work. I do some efforts for that duration from time to time but I prefer longer SST efforts in the half hour to hour plus range. I might do straight 20 minute efforts on my hardest L4 day but then follow it with a day backed off a bit but with the intervals stretched to 45 minutes or more and then back off on the third day of a block to high Tempo work and hold it for an hour to an hour and a half. I've just found I seem to build power better and get more total training load with longer efforts. The 2x20s are still good to press the limits of L4 power but I've found my overall progress is better if I don't do that too often.
Remember, it's not about pure muscle strength. That point often gets lost when our legs hurt so badly during a high power effort. But even Lance in his prime only pedaled up big climbs with 50 to 60 pounds per pedal stroke peak force. But he did it at 90-110 times per minute continuously for as long as it took. Can you walk up a flight of stairs? If you can and you're an average adult male you're lifting a lot more than 50 to 60 pounds with each step.
The reason we can't put out TDF winning power isn't our strength, it's our ability to rapidly convert fuels to power so that our muscles can keep putting out that submaximal force 90-110 times per minute for an hour or more at a shot. That translates to metabolic fitness, not pure strength. You'll develop that metabolic fitness with hard but not necessarily maximal intervals that make you work, get you breathing deeply and that you sustain for at least 10 minutes per effort.
Don't get hung up in the strength myths and start pedaling at 10 rpm up big hills or hang up your bike for the weight room. If you want to get more powerful then ride your bike with focused submaximal efforts, the longer the sustained individual efforts the better as long as they get you breathing deeply and steadily for the duration. Exchanging a lot of O2 during these efforts is a really good sign that you're stressing your metabolic fitness. Oh yeah, don't worry about HR. I know you said you pace on your PT, but some days HR will be low for the effort, some days higher it gets influenced by a lot of factors but doesn't necessarily mean you are more or less fit on a given day.
Good luck,
-Dave
