Anaerobic Work Capacity and Its Importance

In a previous article, we discussed the Critical Power model, which consists of two components. While the previous article focused on the aerobic component, this article will delve into the anaerobic work capacity component. The anaerobic work capacity plays a crucial role in short, intensive efforts such as a steep climb or a late-race attack.

Anaerobic Energy Tank

Anaerobic work capacity, also known as AWC or W', can be visualized as an energy tank representing the size of your anaerobic energy system. The larger this tank is, the more power you can release above your Critical Power level. This means you'll have more power for short efforts lasting a few minutes, as well as increased power for longer durations, like the 20-minute test discussed in the previous article. To calculate the amount of 'anaerobic' energy you can release, we need to determine the exact size of your AWC tank, measured in kilojoules (kJ). When your AWC tank is empty, you won't be able to ride above your threshold point until you recover. The body recovers from anaerobic efforts through the aerobic system, which can burn lactate aerobically and refill the tank.

The Bigger the Better?

One might assume that a larger AWC tank is always better. While this is partially true, the body's adaptability means that increasing AWC may come at the expense of your Functional Threshold Power (FTP). As the body becomes more anaerobic, lactate production accelerates, resulting in more and faster lactate at lower intensities.

The decision to increase AWC depends entirely on your goal. If you're training for a long cyclo, it's wiser to prioritize aerobic fitness rather than AWC. However, if you're preparing for a short criterium lasting an hour, anaerobic energy becomes paramount.

For instance, let's consider a 20-minute test (1200 seconds). Someone with a low AWC (12000 kJ) can release 10W 'anaerobically' over 20 minutes (12000 kJ / 1200 sec = 10W). On the other hand, an individual with a high anaerobic capacity (36000 kJ) can release 30W over the same duration (36000 kJ / 1200 = 30W). If both individuals can maintain an average power of 300W over 20 minutes, it implies a Critical Power of 290W for one and 270W for the other, showcasing a significant aerobic difference.

Training AWC

Due to the intensity of these efforts, it's crucial to start these training sessions when you're well-rested and fresh. Additionally, ensure you're fully recovered before beginning the next repetition, allowing for longer rest periods between blocks. Consider incorporating blocks of 30 seconds to 2 minutes of full-throttle effort, followed by 5-10 minutes of low-intensity cycling to flush out lactic acid from your muscles. Strength training in the gym can also enhance your anaerobic work capacity.

The anaerobic system has the advantage of responding quickly to training, with noticeable improvements within a few weeks. Conversely, developing the aerobic system requires much more time.

Conclusion

The significance of anaerobic energy depends on your goals. Increasing the anaerobic system may come at the expense of the aerobic system, so it's crucial to carefully plan your training regimen. Consider the appropriate phase to schedule anaerobic workouts and ensure you approach them when you're fresh and well-rested. Additionally, it's important to critically evaluate your data before drawing any conclusions, as performance and energy system calculations rely heavily on the quality of input.