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Base training, fatigue vs fuelling and anaerobic capacity

MishMash95MishMash95 Posts: 104
After completing RideLondon yesterday, I found that I really started to suffer on sustaining a higher power over a longer duration. This mostly made sense to me because I don't really do many long rides, at least not very hard ones, all that frequently.

I did a bit of research and while it's by no means a new topic, I wanted to check to see if my understanding and analysis was reasonable. As it stands, I've never had a dedicated period where I have done "base" training, nor have I done many rides to specifically target it outside of riding.

As it stands, my FTP is 270-275w though I have a higher power over shorter durations, my best 4-min power is 400w and my best 5-min 385w. What I concluded from this is that from all the training I have done so far, and thus I feel that I have a rather good anaerobic capacity or "tank", but consequently quite a lower fat burning base, meaning that even when riding at threshold, the aerobic power is heavily supplemented by anaerobic energy systems.

What this seemed to mean in the case of long rides however was that even after riding at a relatively modest power, it seemed that I really needed to drop the watts back in order to be able to recover and consequently also needed to eat a tonne to keep the energy up. There were quite a few other people in the ride who didn't seem to eat much at all, but were able to power on, and I felt like I was shovelling in carbs every few minutes just to keep on top but perhaps reached a cap for how fast it could even digest.
In the end I was quite disappointed with my avg power (194w weighted avg over just under 5 hours) despite what felt like a really tough effort (still a fair bit of time riding tempo and above but was very weak on the climbs, averaging a measly 220w up Leith despite climbing normally being a strength. I'd normally expect to at least push 300w+ on the shorter climbs that are part of a longer ride), I was mostly aiming for a high speed and consistent power.

My take on this was that my "base" must be quite low, but all the other training I've been doing has booped up the capacity on top of that, which has what enables me to ride hard, improve and push out higher efforts when fresh, but equally my ability to recover from an intense effort while still riding at a decent pace (e.g. in a race or CG) is rather weak given that having a lower aerobic base could imply that you need to drop the power lower before your glycogen stores can refill faster than you use it up?

Is this a reasonable conclusion to make and does this seem like a weakness that would be resolved with base training, or are there better means of training that would address this? In my head all of this makes sense, e.g. the fading despite seemingly eating enough to fuel however never sure if it's even worth getting this in depth.

I'd also like to understand where fatigue falls into play, i.e. what actually causes the main onset for fatigue and what caps you from being able to repeatedly put out efforts below threshold even if you are fully fuelled and allow time for digestion etc;

My main takeaway is to just gain a better understanding of where i'm at and also design a training plan for next year that will help me yield the best overall improvement. As I understand, periodisation fits into this by the base period improving your base, which sets a potential for how far you could go? then the build/peak phase would target increasing the capacity above that (which seems like the only style of training I've mostly been doing up until now).

Equally, are there any expectations from how a base period could set you up? i.e. any quantifiable way of measuring where your performance cap for the season may then lie? I now feel i've potentially been wasting time building and peaking but only squeezing out marginal gains with VO2max and threshold work which have massively pushed up those zones, but haven't seemed to have sustainably improved my practical performance outside of fixed length efforts.

Any suggestions appreciated :)


  • cougiecougie Posts: 22,512
    That's a lot of words.

    If you don't do a lot of 100 mile rides you'll never get good at riding them.
  • N0bodyOfTheGoatN0bodyOfTheGoat Posts: 5,782
    If your normal power interval training rides are short, your body will adapt to cope with short, power-rich rides.

    If you then throw in a "random" longer duration ride, your body won't be prepared for it and your normalised power for the ride could be much lower, especially once the duration goes past your "normal" ride length.

    It's something I'm guilty of, my power interval training rides tend to be less than 40 miles and ~3 hours, I've used the heatwave to try and do longer duration/distance rides with lower max power, because trying to power up cat3/4 hills at ~300W meant I was going through my 2l of water at a rapid rate.
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  • bobmcstuffbobmcstuff Posts: 11,178
    edited July 2018
    I would suggest you went out at too high a % of your FTP and suffered as a result. Typical intensity factor for a 100 mile ride will be 0.7-0.8 (NP/FTP). If you go out too hard you will have problems at the end.

    It sounds like you are riding with power, I would bet quite a lot that if you look at the power for the different parts of the ride you will find that the intensity factor was much higher towards the start and therefore you will struggle to maintain that at the end.

    Doing longer rides more often is obviously going to help but once you can ride for 3 or 4 hours it is more of a mental exercise. Pacing is key.
  • Honestly, we can really only talk in general about training here. Attempting to specifically assess an individual isn't reasonably feasible without more detailed personal analysis.

    Fatigue is multifactoral. Glycogen levels will always decline during such bouts of exercise - replenishment will never match metabolism and attempts to do so will result in feeling ill.

    Efforts above threshold are exceptionally costly on your sparse glycogen stores. Anaerobic metabolism uses glycogen at a rate nearly 20 times that of aerobic glycolysis meaning watts above threshold deplete your stores very quickly and during very long exercise bouts such supra-threshold forays are to be avoided wherever possible. 5-min spent at 50W over threshold could instead readily fuel another 30-40 minutes tapping out at 200W without issue.

    One glycogen levels get very low, you will have little choice but to slow down and rely on fat metabolism (lipolysis). For all intents and purposes there's a limitless supply of this fuel however it is a rate limited supply meaning power output will be somewhat under threshold.

    An indicator is what proportion of your VO2 at threshold is of your VO2max. A simple power proxy would be ratio of threshold power (FTP) to maximal aerobic power (MAP, mean maximal 1-min power from an incremental test to exhaustion with power demand increasing at 25W/min). Typically it's 72-77% but if you are somewhat lower then lifting that ratio will help you. What training does that is also mutlifactoral - no one type of training or session solves it, it's an integral of all that you do, e.g. the manner of your training load progression as well as the mix of intensity and duration.
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