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30/30 intervals, which consist of alternating 30 seconds of intense effort followed by 30 seconds of light pedaling, are a classic cycling training method to improve VO₂max, i.e., the body’s maximum capacity to use oxygen during exercise. But not all cyclists benefit equally from this method. Depending on the type of rider, the effectiveness of 30/30s can vary. Here’s why and how to adapt this training to optimize its effects.
By Guillaume Judas – Photos: depositphotos.com
According to most common training plans, 30/30s are programmed at an intensity of 125 to 145% of FTP (Functional Threshold Power), alternating 30 seconds of effort in the target zone with 30 seconds of active recovery. The goal of this type of exercise is to create a high oxygen demand, to force the heart to work at a flow rate close to its maximum, in order to stimulate the cardiovascular adaptations necessary to increase VO₂max. According to a study published in the Journal of Sports Sciences (2020), short, high-intensity intervals like 30/30s are effective in improving aerobic capacity, especially in athletes with a lower aerobic base.
For very endurance-focused riders who lack a bit of punch, those who excel in long efforts but struggle with sprints or short accelerations, 30/30s at 125-145% of FTP are intense enough to push them to their limit. These cyclists often finish these intervals out of breath, a sign that the aerobic stimulus has been achieved.
However, for riders who benefit from strong anaerobic power, these same intervals may seem too easy. An intensity of 125-145% of FTP is not enough to make them gasp, which limits the impact on their VO₂max. Why? Because their physiology allows them to bypass the perceived difficulty of these efforts, relying on anaerobic rather than aerobic mechanisms.
Why 30/30s are easier for some
Riders with strong anaerobic capacities benefit from three physiological advantages that reduce the effectiveness of traditional 30/30s in stimulating their VO₂max:
- Rapid phosphocreatine (PCr) regeneration: their muscles rapidly regenerate ATP-PCr stores during the 30 seconds of recovery. This allows them to produce energy without fully engaging their aerobic system during effort intervals. A Sports Medicine study (2017) shows that athletes with high anaerobic capacity recover up to 50% of their PCr stores in 30 seconds, thus reducing oxygen demand.
- Better glycolytic buffering capacity: Type II muscle fibers, predominant in these riders, have a superior capacity (approximately 50%) to neutralize lactate and H⁺ ions. This delays acidosis, preventing the effort from pushing the aerobic system to its maximum, as explained in a Frontiers in Physiology analysis (2019).
- Neuromuscular efficiency: they preferentially recruit fast-twitch fibers, which consume less oxygen per watt produced. Result: they can maintain the target power without reaching the heart rate associated with VO₂max, according to research published in the European Journal of Applied Physiology (2018).
In summary, if you finish your 30/30s feeling easy or enjoying the exercise, chances are you are this type of rider. These intervals don’t push you enough to generate the expected VO₂max stimulus, unlike a sustained 5-minute effort at the limit of your aerobic capacity.
How to adapt 30/30s
For riders with high anaerobic capacity, it is crucial to adjust 30/30s so that they truly engage their VO₂max. To optimize them, increase the intensity to 150-170% of FTP, or even more, to maximize aerobic demand and fully engage the cardiovascular system. Reduce recovery periods to 15-20 seconds to limit phosphocreatine regeneration, and thus maintain a strong aerobic demand, as recommended in HIIT protocols. Extend interval blocks to 8-12 repetitions per set, with multiple sets, to accumulate fatigue and force the aerobic system to activate. Finally, supplement your training with sustained efforts of 3 to 5 minutes at 95-100% of VO₂max (approximately 110-120% of FTP) to maximize aerobic gains.
Test your profile and adjust your training
To find out if you are a diesel or a punchy rider, observe how you feel during 30/30s. If you find them relatively easy and recover quickly, increase the intensity or modify the interval structure. If, on the contrary, you are out of breath after each effort, the classic protocol is probably suitable for your profile.
A simple test recommended by many coaches is to compare your power on a 30-second sprint to that of a 5-minute effort. If your 30-second power is significantly higher (e.g., 50% more), you are likely a punchy rider (Friel, J. (2021). The Cyclist’s Training Bible. VeloPress).
Personalize your 30/30s for optimal gains
30/30 intervals are a powerful tool, but their effectiveness depends on your physiological profile. For diesels, the standard protocol at 125-145% of FTP is ideal. For more dynamic cyclists, efforts must be intensified and recoveries adjusted to truly stimulate VO₂max. By adapting these intervals to your physiology, you will optimize your progress, whether you are an explosive sprinter or an endurance climber.
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