Don’t Get Dropped! The Importance of Aerobic Threshold Training

This is an article I wrote for ilovebicycling.com back in April when the relevant Northern Hemisphere race season was just getting started.

It never feels good to get dropped.

Those high intensity 1, 2, or 3 minute efforts always feel like the limiting factor. If you could just go a little bit harder you’d be able to stick with the rider in front as they attack up the road, or you’d be able to stick with the front group over the top of a climb.

But the limiting factor might be more with the 10, 20, or 30-minutes before you got dropped if you were riding too far above your Aerobic threshold. The counter-intuitive answer to being able to ride harder, can sometimes be to ride easier.

Balancing Energy Systems

We’re not talking Functional Threshold Power (FTP, or ANaerobic Threshold: AnT), but a threshold at lower intensity that is arguably just as important (training terms can be confusingly similar).

Your Aerobic Threshold (AeT) is the highest point at which you almost exclusively use your Aerobic energy system to produce power. Your Aerobic metabolism uses Oxygen to efficiently generate power without causing significant fatigue. At this low intensity you should feel like you can sustain the workload continuously for at least a few hours.

Higher intensity efforts such as short punchey climbs, sprints, and attacks require ANaerobic metabolism: high intensity, short duration power above your Aerobic threshold. The ANaerobic energy system fatigues quickly and needs to recover between repeated efforts.

You can think of your ANaerobic energy system as a battery that only has a few minutes of explosive energy contained within it. The battery drains as you ride above your Aerobic threshold, and replenishes as you ride below your Aerobic threshold.

The threshold between these two metabolic energy systems doesn’t act like a light switch: either on or off. Instead both energy systems work in coordination to meet the required power output at any given moment. So although you’ll always be using some amount of ANaerobic energy, if you can ride under your Aerobic threshold, you’ll be able to save your ANaerobic energy reserves for high intensity efforts when they are required.

Relative contribution of each energy system to power output over a given duration

The true limiter to performance during a race is often your aerobic endurance

If the pace of the group is above your Aerobic threshold, you’ll need to recruit more and more ANaerobic energy just to keep up. You might be able to keep in touch with the group for a while, until someone attacks or you hit a climb. Then you’ll try to reach deeper into your ANaerobic reserves, which will have been slowly depleting over time. You’ll feel like you’re dead in the water as you search for power that your legs just don’t have!

The limitation isn’t your high intensity power. If you were fresh you’d have no problem producing the short hard effort necessary. Rather, the limitation is actually how well you are able to conserve energy and recover between the high intensity efforts. So it’s the attacks, short punchey climbs, and other high intensity efforts where you feel the lack of fitness, but the true limiter to performance during a race is more often your Aerobic endurance.

Aerobic Threshold Training

  • Find your Aerobic Threshold – the maximum pace which you can sustain using primarily your Aerobic metabolism. This will be a moderate pace that just begins to feel uncomfortable, but that you can sustain for hours at a time. This should be around 4-6/10 on a scale of perceived exertion, or below 75% of your max heart rate (HRmax).
  • An easy way to determine this using Heart Rate is to go for a steady ride of at least 30 minutes at moderate intensity. Aim for around 5/10 relative effort, or 75% HRmax (pick up an HRM here). Observe when you just start to breath heavily above resting respiration rate and when your HR flattens at a steady level. This will indicate your approximate Aerobic threshold.
  • This informal test only provides an estimation of your Aerobic metabolism. Your target Aerobic threshold can change considerably day to day. Don’t be concerned if one day it feels way too high to maintain, but also be sure to enjoy the days where you float on the pedals and can seemingly ride forever well above your threshold! You can test Aerobic threshold with greater precision by having individual physiological testing done in a lab setting (which will be discussed in a future post!).
  • Knowing your Aerobic threshold, you can train to ride for longer periods of time just under this threshold without dipping into ANaerobic stores. At least 2 hours is ideal, but improvements can be gained even with rides shorter than an hour. Pros with far too much time to train will regularly ride at this steady intensity for 4-6 hours to further develop their Aerobic metabolism.
  • Note: if you only have an hour or less to train, that doesn’t mean you have to ride at a higher intensity to make up for less volume. Riding above your Aerobic threshold will start to use ANaerobic metabolism and actually provide less training benefit to your Aerobic system. Unless you have intervals or another workout prescribed for that day, you can still benefit from riding below your Aerobic threshold for shorter durations.
  • If you are already doing interval training and have extra time, add a sustained period (10-20+ minutes) of this Aerobic threshold training before and/or after the interval workout, to further develop your fatigue resistance and stamina at this moderate workload.

 

Set your Sights on the Long Term

It can feel counter-intuitive to focus more on your lower intensity Aerobic endurance if you’re getting dropped by high intensity ANaerobic efforts. However cycling is an endurance sport, and performance depends on endurance fitness and Aerobic metabolism.

Aerobic threshold is just as important as lactate threshold (FTP). Improving your Aerobic fitness is a long-term project and can initially feel slow, but when training adaptations begin to accumulate, the payoff is that you’ll have more energy left to win the sign-post sprint, attack the climb, or spend more time at the front working for your teammates!

2 thoughts on “Don’t Get Dropped! The Importance of Aerobic Threshold Training

  1. This sounds simple (it never is). I do 2 HIT, per week, then everything else at 75% of MHR? TrainerRoad divides training into Base, Build, Specialty. This sounds like Base…forever.

    What’s in the HIT sessions? Is that where variability comes in? Longer intervals during pre season Nov-Dec 4X8 or something like that? Then closer to race day maybe go with one of those 3X13’s?

    No more SST?

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    1. (it never is) is certainly the correct answer 🙂

      I’m writing up something on Physiological vs Performance training, which is how I look at Base vs Build: Physiological/Base is trying to build the engine, or even more fundamentally – the chassis. Performance/Build is expanding the engine with more race-specific efforts.

      I think Polarized training and all the Aerobic/VO2max protocol I’ve discussed belongs primarily in Physiological training. The literature suggests this is the best way to improve your (wait for it..) physiology. But racing is not all about physiology and having the highest VO2max won’t win races. That’s where Performance training comes in to expand or ‘shape’ the engine toward how it needs to perform on race-day. I think SST is a critical part of Performance training.

      Specific protocol I’ve intentionally left vague for now, mostly because once again there’s little consensus in the literature. But I’m working on a follow-up post to my last VO2max discussion that will suggest some workouts. Keep an eye out for that!

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