Aug 124 min read

Why You Might Be Hitting the Wall Too Soon—And How to Stop It.

Are You Struggling with Fatigue During Your Runs?

As a runner, there’s nothing more frustrating than feeling fatigued early into your long runs or noticing that your pace is slowing down despite all your hard work. You might be pushing yourself with intervals, hill sprints, and tempo runs, but instead of getting faster, you’re finding yourself hitting a wall much sooner than expected. If this sounds familiar, you could be dealing with something known as Aerobic Deficiency Syndrome (ADS).

Have heard the term "Aerobic Deficiency Syndrome" (ADS) thrown around in training discussions? While it might sound intimidating, understanding ADS and how it impacts your running performance is crucial for long-term success. ADS is more common than you might think, especially among those who focus heavily on high-intensity workouts while neglecting their aerobic base. Let's dive into what ADS is, its symptoms, and how to address it to improve your running performance.

What is Aerobic Deficiency Syndrome?

Aerobic Deficiency Syndrome (ADS) occurs when a runner's aerobic system is underdeveloped relative to their anaerobic system. This imbalance can lead to a reliance on the less efficient anaerobic energy system during longer runs or endurance activities, resulting in faster fatigue and a higher risk of injury.

According to Uphill Athlete, the aerobic system is responsible for sustaining prolonged, steady-state efforts by efficiently using oxygen to produce energy. When the aerobic base is weak, the body struggles to maintain endurance at lower intensities, forcing it to tap into anaerobic energy sources that are designed for short bursts of high-intensity effort.

Symptoms and Signs of ADS

Recognizing ADS in your training can be the first step toward correcting it. Here are some common signs that you might be suffering from Aerobic Deficiency Syndrome:

Inability to Maintain Easy Paces: If you find it difficult to sustain what should be an easy pace without feeling fatigued, it could be a sign of ADS. I have many of my athletes experience this in the end of their long runs.
Early Fatigue During Long Runs: Struggling with fatigue or needing to slow down significantly during long runs is another indicator. I see this when my athletes, when their heart rates increase while holding the same pace of the start of their long run. Or when they keep their heart rate level, but have a much slower pace by the end of the long run.
High Heart Rate During Easy Runs: An unusually high heart rate during what should be low-intensity workouts suggests that your aerobic system isn't as efficient as it should be.
Large Zone 3 in Lactate Testing: When you perform lactate threshold testing, an important indicator of ADS is finding that your Zone 3 (the zone where you are working moderately hard) is disproportionately larger than your Zone 2 (the aerobic zone). This indicates that your body is more reliant on anaerobic energy pathways, which are less sustainable for long-distance running. This imbalance is a hallmark of Aerobic Deficiency Syndrome.
Plateau in Performance: Despite training hard, you may notice a plateau in your race times or overall performance, which can result from an over-reliance on anaerobic conditioning without adequate aerobic development.

The team at Evoke Endurance emphasizes that runners with ADS often overtrain at intensities that are too high for their aerobic system, leading to burnout, injuries, and diminished returns from training.

The Importance of the Aerobic Threshold

To effectively combat ADS, it’s essential to understand and work within your aerobic threshold—the intensity at which your body primarily uses aerobic energy systems. According to Strength Matters, training at or just below your aerobic threshold is key to building a strong aerobic base. This level of intensity allows your body to adapt by improving its ability to use oxygen more efficiently, which in turn enhances endurance and stamina.

How to Overcome Aerobic Deficiency Syndrome

If you suspect you might be suffering from ADS, don't worry—there are effective strategies to rebuild your aerobic base:

Prioritize Low-Intensity Training: The foundation of overcoming ADS lies in spending more time training at low intensities. Running at a conversational pace (typically around 60-70% of your maximum heart rate) helps to build and strengthen your aerobic system. Lactate testing is the best way to truly find your intensities.
Increase Volume Gradually: Focus on gradually increasing your weekly mileage while keeping the intensity low. This approach helps to safely build endurance without overloading your body.
Incorporate Cross-Training: Activities like cycling, swimming, or hiking at low intensities can further enhance your aerobic base while giving your legs a break from running.
Perform Aerobic Threshold Testing: Regularly testing and monitoring your aerobic threshold can help you track improvements and ensure that your training is on the right track. This can be done through heart rate monitoring or more actuality with Lactate Acid testing.
Be Patient and Consistent: Rebuilding your aerobic base takes time, often requiring several months of dedicated low-intensity training. Patience and consistency are key to seeing long-term improvements.

Conclusion

Aerobic Deficiency Syndrome can be a significant barrier to achieving your running goals, but with the right approach, it’s entirely manageable. By focusing on low-intensity aerobic training, gradually increasing your mileage, and monitoring your progress, you can rebuild a strong aerobic base and unlock your full potential as a runner. Remember, endurance is built over time, and a well-developed aerobic system is the foundation upon which all successful running is built.

For more detailed insights on ADS and how to tailor your training to overcome it, check out the resources from Uphill Athlete, Evoke Endurance, and Strength Matters.

HAPPY RUNNING!!

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