Mike, I'm having a real hard time following your line of thinking, but I'll take a cut at answering your questions:
Mike Jacobs said:
...First, if I'm doing a nice level 16 mph charity century without wind or elevation, am I ever going to go beyond 50% vmax (what's an example of 50% for an average joe)? If not, then why should I be concerned about restoring glycogen?
First, you burn some glygocen even at rest and a progressively higher percentage relative to fat stores as you increase intensity. IOW if you ride long enough even at a pace that keeps you below 50% of MAP (Maximum Aerobic Power which is what I guess you mean by vmax or power at VO2max pace) you'll still need to replace glycogen. The concept that you entirely burn fat at sufficiently low workloads is a bit overstated, you burn some glycogen all the time and even if you're predominantly burning fat, you'll still burn glycogen which you should replenish during and after your rides.
You imply a 16 mph charity event is pretty easy for you (50% of vmax) but unless you're pretty darn fit (doesn't sound like it if you're only contemplating structured training) holding a 16 mph average speed is moving along at a pretty decent clip. Holding 16mph for short sections of flat road isn't too tough, but a 16 mph average is a pretty good pace for most weekend warriors and a lot of century riders. I'd be surprised if a 16 mph average pace didn't push you harder than your 50% estimate. I've done an awful lot of planned and impromptu century rides both during periods when I was racing and perhaps even more during years when I just rode for the fun of it. A 7 hour century ride (~16 mph) requires a fair amount of effort and burns an awful lot of calories, including a lot of glycogen that has to be replaced.
I rode a solo hundred miler last fall just after getting my first power meter. I finished in 6 and a half hours and burned over 5000 calories according to my power data. I definitely needed to fuel up before, during and especially after the ride and although I didn't bonk (a sure sign of glycogen depletion) I'm sure I would have if I hadn't consciously refueled along the way and kept the carbs coming. Maybe your charity ride is a lot shorter, but unless 16 mph is completely rest pace for you, you'd better think in terms of replenishing glycogen if it's a long event.
On the other hand, if I really push myself on a 40 mile ride, I can expect to run through zones, right? Can we feel the transition? I feel one about 10 miles (I can fly!) and then again at 25 (hmmm are we there yet?). Are those shifts between metabolisms?
I'm not sure whose training zones you're referring to, but all that I'm familiar with (Coggan's, Friel's, etc.) are based on intensity not when they happen in a long ride. If your output is steady you won't be passing through different workout zones at different points in your ride. You might feel different as you exhaust one energy source or as you warm up or for other reasons, but training zones are keyed on output intensity.
So if you start your 40 mile ride at a casual warmup pace (a good idea) say L1/L2 in Coggan's power based schema, you'll be burning a blend of fat and glycogen with modest amounts of O2 that you can get via steady, relaxed breathing. You should feel like you can go all day at this pace and you should find it easy to hold a conversation. Bump the intensity up a bit into L3 and you'll burn a higher percentage of glycogen, need a bit more O2 and your breathing will deepen and probably speed up a bit. Conversation gets a bit tougher but you should still feel like you could hold this pace for quite a while without undue discomfort. It should take some concentration to stay at this level but shouldn't be too tough if you stay focused.
Bump the output up again and now your burning a lot more glycogen, breathing deeper and faster and conversation becomes tough and limited to a word or two at a time. You still shouldn't be dying or out of control with breathing but you're working hard now and need to hold your focus or you'll slip back to easier levels.
Harder yet and breathing gets maxed out along with glycogen consumption and conversation is basically impossible. Any harder than this and you're tapping other energy systems and fueling your muscles anaerobically.
Anyway, I'm not sure what you're feeling in terms of passing through zones at different points of your rides but training levels are related to intensity (and duration but that's a bigger discussion) so on any ride you should feel the difference between zones by how much effort you have to put out. From your flying at 10 miles to looking for the finish at 25 quote it sounds like you're going out a bit too hard and need to work on pacing. If you're going out at an L4 pace you should feel o.k. for 10 or more miles but you'll run out of steam after half an hour to 45 minutes unless you're well rested and highly motivated. Even then you'll run out of steam after an hour since L4 is basically your best one hour pace. Back off the first part a bit and the second half should feel better.
It looks as though the SERIOUS rider/racer trains to ride in the anerobic zone?
It depends upon the rider's goals and the kind of events they're targeting. But a serious road racer needs a lot of aerobic work (L4, VO2max) to hold the pace for the duration to climb longer hills and to time trial effectively. They need anaerobic work to respond to surges in the pace, cover attacks, bridge to breakaway groups and to stay up front in the closing kilometers of a fast race. They need top end neuromuscular work (also fueled anaerobically) to sprint and to handle rapid acelerations throughout the ride (like jumping hard out of crit corners). So they need the complete package, but a time trial specialist doesn't really need the anaerobic work and will dedicate more training time to aerobic workouts. Track specialists might turn that around but they still need a lot of aerobic fitness.
I thought I read that you train to be efficient on a fat-burning metabolism, but if 50% vmax is fat burning, how does this work? What did I miss?
It's not like 50% (still don't understand what you're taking 50% of) is a magic number. You burn a higher percentage of fat at lower intensities but still burn quite a bit as the intensity increases. In fact, even though the fat/glycogen ratios change with intensities if you compute the total number of fat calories burned at different intensities you'll see you burn more total fat if you work harder(but stay aerobic). Sure you'll need to replenish more glycogen but in the end you'll burn off more fat which is the goal of many folks.
I guess one way to restate your quote is that racers train to have efficient and powerful aerobic metabolisms. This allows them to ride awfully fast while still burning a higher percentage of fat than untrained folks that have to ride at higher intensities to maintain the same speed but the racers aren't artificially capping their workouts at 50% of MAP. They still train all their energy delivery systems and in particular train all aspects of their aerobic metabolism including their ability to work at VO2max (the top end of the aerobic range) which burns a very high percentage of glycogen.
Finally, I get the idea that there is a whole 'nother world out there for the VERY SERIOUS trainer. What is this level about? Is the world class competitor able to do something that "normal" serious trainers can't as far as metabolism goes?
I'm no exercise physiologist, but I don't think there are any magical transformations as someone hits the elite ranks. The energy delivery mechanisms are the same but the more serious folks train (and rest) in ways that maximize their time efficiency. They may train harder and longer because they've worked up to it but barring banned substances, they don't have any magic or special powers regarding the way they burn fat, glycogen or phosphocreatine. Their heart volumes may be larger due to training, their muscles may be more efficient with better blood delivery and higher mitochondrial densities again as a result of their training but I don't think there are any sudden changes to the way the elite athletes process fuels or the kinds of stress relative to their fitness levels that induces positive adapations.
Hope this helps,
Dave
