Is it true that our L5 and L6 wattage is genetically pre-determined and one we can't really increase?
Your maximum attainable power may be genetically pre-determined, but you can increase your power across the entire power/duration spectrum and by a lot! As a rule of thumb, I would say one should target about 1.5-2x his or her untrained power at every duration. So, if one's untrained FTP is 150W, target 225-300. But, some adaptations happen more quickly than others. In general, I start earliest on aerobic power (e.g., FTP) and latest on neuromuscular power prior to a target event. In fact, if the target event doesn't require NM power, I never focus on it even though I typically throw in 2-3 5sec full power efforts at the end of most rides (just for the heck of it because I know I'll be in the shower in a few minutes).
If you have a nice base of L3 and L4 work then you can get a fairly big gain in L5 and L6 power. For me at least, the larger the base of threshold work, the longer the top end gains lasted and the more they'd increase. I'd give it at least 10 weeks for L5 and L6 to get really good gains and at least 4 weeks to start seeing some good gains. I've seen evidence that gains keep increasing upto 12 weeks but nothing to say that those gains stop after the 3 month mark - only because I haven't seen a study that went to 4 months.
Yeh, I think I'll focus on a nice base of L3 and L4 first. I'll treat L5 and L6 as the icing on the cake.
Yes, or another way of thinking about is that you take advantage of the opportunities the ride presents. If there's a long climb, ride it at L4. If you are limited to <5min pulls on front, ride them at L5/L6. Also, recognize that there is a ripple effect, especially from left to right on the power/duration curve. IOW, an L5 targets VO2MAX, but benefits aerobic power as well. Some have likened this effect to throwing a rock in a glassy calm body of water. The ripple is highest at the entry point, but radiates out with decreasing height.
Great questions. Some people do find it difficult to replicate their outdoor efforts on a trainer. Personally, I think it is more psychological than physiological, assuming that you have a good fan and don't overheat. And some people find it more difficult to produce the same wattage in a constant power ride than a variable power ride (e.g., group ride), especially if you are having to push yourself to stay with your group. As to FTP, I prefer to set mine with a 60min constant power trainer ride. Then I know it is rock solid because I know from experience that I can absolutely produce my trainer power on the road. But, for interim estimates it doesn't matter much because it is self-correcting. If you are estimating your FTP too high, your intervals will be too hard to complete (e.g., 2x20s). Likewise, if you are under-estimating your FTP, your training efforts will be too easy.
Yesterday, during my 2x20min intervals, my legs felt really tired after only about 15 minutes and yet my lungs and breathing was fine.
The leg fatigue is exactly what you want to be sensitive to. It is likely that the leg fatigue you feel is due to cumulative training fatigue. When I am training intensively, I have a good deal of cumulative fatigue on virtually every ride. In fact, it feels strange when my legs feel fresh. The fatigue and twitching you feel after a long group ride is simply training fatigue. It's normal and is the essence of training and adaptation. You might want to try some electrolyte tablets. I take two Hammer Endurolytes tablets before each ride and a couple per hour on hot days. Stress plus recovery equals adaptation equals increased power.
Going forward, you might want to consider replacing your chain more frequently. I hear riders talking all the time about checking their chain by measuring the gap between links. The problem with that approach is that by the time you can measure a stretch in the gap it's too late and you're already damaged your chainrings and/or sprockets. Those can be expensive parts. The alternative is to replace your chain on a mileage schedule. I replace my chain every 2500 miles regardless of whether I can measure any stretch. I go through a few chains a year but chains are cheaper than chainrings and sprockets.
Cheers for that.
