Why Triathletes Need to Stop Talking About Base Training

The traditional aerobic base training needs to step aside. Long, moderate-intensity training may be enjoyable and beneficial to incorporate into training, but even if you're a professional, dedicating winter to low-intensity training in the hopes of building a stronger aerobic base is foolish. For the rest of us, amateur athletes and enthusiasts with little time to spare for training, traditional base training is a waste of time.

The traditional aerobic base training needs to step aside. Long, moderate-intensity training may be enjoyable and beneficial to incorporate into training, but even if you're a professional, dedicating winter to low-intensity training in the hopes of building a stronger aerobic base is foolish. For the rest of us, amateur athletes and enthusiasts with little time to spare for training, traditional base training is a waste of time.

The premise of aerobic base training is that accumulating a large volume of training at low to moderate intensity will result in greater capillary density (improved blood flow to muscles) and higher mitochondrial density. 

The latter is crucial because more and larger mitochondria in muscle cells increase their ability to break down carbohydrates and fats into usable energy more rapidly. Processing more fat and carbohydrate per minute through mitochondria enhances sustainable power or pace. It also means you can train at a lower percentage of your VO2 max at your "all-day" pace, which can help you rely on a higher percentage of fat for energy and conserve stored carbohydrates. These seem to be exactly the goals of endurance training, so what's the issue?

Doing Less With More Doesn't Work

As an endurance athlete, you're accustomed to a certain volume of training hours per week, likely because it's all you have available. Training the same number of weekly hours (because you don't have time to add more) at lower intensities results in a lower total volume than you've already adapted to. As a result, this won't stress your aerobic system enough to stimulate positive adaptation.

When base training works, it's only because the increased training volume contributes to a higher total load (or at least a concentrated higher load) despite reduced intensity. These longer workouts are slower due to the inverse relationship between intensity and duration: you can go harder for shorter periods, but as workouts get longer, the sustainable intensity naturally decreases. 

When volume is essentially constant due to training availability, reduced intensity only results in reduced load and, therefore, reduced training stimulus.

You Don't Need a Huge Aerobic Base Anyway

While time-constrained athletes struggle to build a large aerobic base, the good news is that most amateur and masters athletes simply don't need one to excel or be competitive in races lasting from 45 minutes to 3 hours. Your limiting factors are your lactate threshold power, your VO2 max power, and how long you can sustain those intensity levels. All three can be improved with a lower volume program (8-10 hours per week) and higher intensity, including a mix of lactate threshold intervals of 8-20 minutes and maximal intensity intervals of 1-4 minutes, along with some endurance and recovery training, of course. 

The reason professionals still need to spend a lot of time combining high volume with high intensity is that they need to make attacks after 7 hours of racing. Aerobic endurance is a limiting factor for them due to the power demands required in the last hour of much longer elite events. You're not a pro and can be completely prepared for the demands of your shorter events without a huge professional-style aerobic base.

Even Ironman competitors benefit more from training that elevates lactate threshold power and VO2 max power compared to doing more volume at low intensity. In a well-trained endurance athlete, more volume at low intensity won't result in greater mitochondrial density (they've already adapted to the necessary intensity level). To get faster, they need to stimulate mitochondrial development with higher-intensity efforts. Long workouts are still necessary, but more from an experiential standpoint than a physiological one.

Going Slow Makes You Slow

Focusing your training at a specific intensity for a period of time is the foundation of periodization, and there are benefits to spending time at various different intensities. 

In this sense, base training is just a block of low-intensity endurance training, and the only real issue is that it's usually too long. For amateur athletes, resistance blocks of two to three weeks can and should be incorporated into training throughout the year. This is different from a single block of 2 to 3 months of low-intensity training, during which you'll see your lactate threshold power and VO2 max power decline significantly.

The old premise of periodization was that you needed the big aerobic fitness base before you could handle the stress of higher workloads. Hence, the base training schedule first, followed by lactate threshold training and then specific high-intensity race work. The modern view is that energy pathways are intertwined, and you can improve performance in both directions. 

For example, high-intensity efforts are more effective at improving VO2 max power than moderate-intensity training. Researchers like Burgomaster, Gibala, and others have shown that these same short, high-intensity intervals improve fat and carbohydrate oxidation by mitochondria to a similar degree as traditional low-intensity endurance training, but in a fraction of the training time. In practice, this means that by working at the higher end of the intensity spectrum, you can improve performance at all intensity levels below that, making it a very efficient use of your limited training time. Similarly, lactate threshold workouts improve threshold power and power for endurance intensities.

Base Training Was Never About Improving Fitness

There's some validity to the idea that too much intensity can lead to overtraining (better thought of as under-recovery) and increase the risk of injury, so one school of thought is that a long period of lower intensity is safer than structured training year-round. There was a time when this was sound advice, but now that we have better tools to measure and monitor workload, fatigue, and recovery, the risks of pushing an athlete (or yourself) to the edge are much lower. And for time-constrained athletes, both the need for prolonged recovery and the risk of overtraining are already reduced, as their busy work and family schedules result in relatively low training volume and ample recovery time.

But perhaps the most insidious reason why the idea of base training still persists is that it has always been the refuge for athletes who simply want to train. 

Base training is largely unstructured, a low-intensity cruise. In an attempt to escape structure after a season of interval training, athletes turn to the comfortable, outdated notion of base training. 

However, there's a difference between desiring less structure and needing less workload. If you want a break from intervals, that's okay. Let your mood, the terrain, the wind, or the group you're riding with dictate the intensity; 

just make sure there's some intensity!