The importance of building an aerobic engine (It's okay to go easy)
The term base training is one of those things that you hear a lot as a cyclist. In recent years, it seems as though many “time crunched” athletes have dismissed base training as an archaic, inefficient way of training that only professionals have time for. There are hundreds of articles out there claiming that a new interval session will give you twice the gains in half the time. With things like Zwift and TrainerRoad—many have started to believe that base training is useless, and that a quick set of intervals can give you the same gains in far less time. Let me dispel the myth for you: base training is essential.
Don’t get me wrong, intervals are just as important as base training. But without an aerobic base, you’ll never reap the full rewards of all those interval sessions. Base training is the bread—intervals are the butter, and no one just wants to eat butter. Let’s take a look at why base training is so vital.
The ATP Factory
The way your body creates energy to pedal your bike is through releasing the energy stored in the bonds of the ATP molecule. Your body holds a set amount of ATP at any one time; you can’t store more ATP through training. What you can train is your body’s ability to resupply these ATP stores. The quicker you’re able to resupply these ATP stores, the more energy your body can release and thus the more watts you can produce.
Your body can create ATP two different ways: aerobically and anaerobically (with or without oxygen). Your body will generate ATP aerobically in the mitochondria of the cell. ATP can be generated anaerobically in the inner membrane space known as the cytosol. The longer the effort, the more your body will rely on the mitochondria to supply ATP aerobically. How long of an effort are we talking? Well, any effort longer than 75 seconds will rely predominantly on the aerobic system for ATP. With this in mind it’s easy to see how even a 30 minute criterium will rely heavily on the aerobic system. Of course you will be also utilizing the anaerobic system in a criterium, but if you don’t have a solid aerobic base built, you will fatigue much faster. When you perform an intense “VO2 max” type effort of about 2-6 minutes long, your body will create 5% of its energy from stored glycogen anaerobically—this creates the byproduct lactate. That lactate is then converted to another molecule called pyruvate. The pyruvate then goes to the mitochondria to make the other 95% of energy aerobically. In order to improve your ability to perform even short VO2 efforts, aerobic training is essential. For longer threshold and tempo type efforts, an aerobic base is even more important.
If you go out for a zone 2 spin your body has adequate oxygen supply to generate all ATP aerobically in the mitochondria. In theory, you could hold this pace forever—neglecting the outside effects of glycogen depletion and dehydration. However, the moment you ride above your lactate threshold, things change very quickly. One of two things is happening, either your body does not have adequate oxygen to generate the ATP in order to sustain this pace OR the mitochondria are not able to generate ATP at a rate fast enough to meet these demands. The result is that you must draw upon your anaerobic system. Unfortunately this will cause your body to create negative byproducts that will cause you to fatigue, hence you can’t sustain this pace for very long. The longer you can generate ATP aerobically in a race, the slower you will fatigue. You’ll have much more left in the tank for the final climb or the race winning sprint. The aerobic system is a very efficient process. It utilizes predominantly the almost endless supply of stored fat to create ATP. This in turn will spare your very limited stored glycogen (stored carbohydrates in the muscle) for when it matters most. When the race heats up and the intensity increases, you will begin to transition from using fat to using glycogen. If you’ve already spent up that glycogen earlier in the race by going over your aerobic threshold, you will struggle to perform at the end.
In summary, a strong aerobic base will help with the following:
Improve performance for efforts lasting longer than 20 seconds
Delay fatigue by sparing muscle glycogen
Improve the ability to recover from hard efforts
Okay, so an aerobic base is really important. But how can you train it? While professional riders will put in 25-30 hour weeks on a regular basis, this isn’t realistic for those of us with jobs and families. The good news is that there are some simple changes you can make to your training that will make sure you’re training the aerobic system.
Since cycling is a mostly aerobic sport, it stands to reason that most of your time should be spent riding in zone 2 or below. A general rule of thumb is the “80/20” rule. During the season, this means that 80% of your rides should be “endurance paced”, and that only 20% should be high intensity (Lactate threshold or above). That means that you should only be doing about 2 days of high intensity per week. Make sure that the high intensity sessions prepare you specifically for your target events. There are exceptions to this rule during certain training phases, but this is a general rule during most of the season. This may not sound like a lot, but remember, riding in those aerobic zones is just as valuable as doing high intensity—you can’t have one without the other. Don’t be the guy who puts a whole stick of butter on his bread. This also means that the high intensity sessions can be a lot higher quality because you will be more rested going into them, so make them HARD- and then recover.
There are a lot of other things to talk about on this subject that I’ll save for later. Thanks for reading!