base training

Busting the Myth of Winter Aerobic Base Training

By Jim Rutberg, CTS Pro Coach and co-author of “The Time-Crunched Cyclist”

Traditional aerobic base training needs to go the way of the dodo. Long, moderate intensity rides are fun and good to incorporate into training, but even if you’re a pro it is a fool’s errand to devote the winter to low-intensity training in the hopes of building a stronger aerobic base. For the rest of us who are time-crunched amateur racers and enthusiasts, traditional base training is a waste of time.

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The premise of aerobic base training is that accumulating a large volume of work at a low to moderate-intensity will result in increased capillary density (greater perfusion of oxygenated blood into muscles) and greater mitochondrial density. The latter is important because more and bigger mitochondria in muscle cells increase your capacity to break down carbohydrate and fat into usable energy more quickly. Processing more fat and carbohydrate per minute through mitochondria increases maximum sustainable power or pace. It also means you can operate at a lower percentage of your VO2 max at your “all day” pace, which may help you rely on a higher percentage of fat for energy and conserve stored carbohydrate. Those sound like the exact goals of endurance training, so what’s the problem?

Doing Less With More Doesn’t Work

As an endurance athlete you have already habituated to a certain volume of weekly training hours, likely because that’s all you have available. Training the same number of weekly hours (because you don’t have the time to add more) at lower intensities produces a lower total workload than you have already adapted to. As a result, it won’t stress your aerobic system enough to stimulate a positive adaptation.

When base training works, it only works because increased training volume contributes to greater total workload (or at least greater focused workload) despite reduced intensity. These longer rides are slower because of the inverse relationship between intensity and duration: you can go harder for shorter durations, but as rides get longer sustainable intensity naturally decreases. When volume is held basically constant by your training availability, reduced intensity only results in reduced workload, and therefore reduced training stimulus.

You Don’t Need a Huge Aerobic Base Anyway

While time-crunched athletes struggle to build a big aerobic base, the good news is that most amateur and masters racers simply don’t need one to win or be competitive in criteriums, road, cyclocross, and mountain bike races lasting 45 minutes to 3 hours. Your limiting factors are your power at lactate threshold, your power at VO2 max, and how long you can maintain those intensity levels. All three can be improved with a lower volume (8-10 hours a week)and higher intensity program that includes a mixture of 8-20 minute lactate threshold intervals and 1-4 minute maximum-intensity intervals, along with some endurance and recovery rides, of course. The reason pros still need to spend a lot of time combining high volume with high intensity is that they need to make race winning moves after 200km of racing. Aerobic endurance is a limiting factor for them because of the power demands required in the final hour of much longer elite-level events. You’re not a pro and you can be completely prepared for the demands of your shorter events without a huge pro-style aerobic base.

Even ultradistance competitors, like 100-mile mountain bike racers, 200-mile gravel racers, and Ironman triathletes, benefit more from training that elevates power/pace at LT and VO2 max compared to performing more volume at low-intensity. In a well-trained endurance athlete more volume at low-intensity will no longer result in greater mitochondrial density (they’ve already adapted to the intensity level required) (Dudley, 1982). To get faster they need to stimulate mitochondrial development with higher intensity efforts. (Burgomaster, 2005) Very long training sessions are still necessary, but more from an experiential standpoint than a physiological one.

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Going Slow Makes You Slow

Focusing your training on a particular intensity for a block of time is the basis for periodization, and there are benefits to focusing time at several different intensities. In that sense, base training is just a block of low-intensity endurance training, and the only real problem is that it’s typically too long. For amateur athletes, two- to three-week endurance blocks can and should be incorporated into training throughout the year. That’s different than a single 2-3 month block of low-intensity riding, during which you will see your power and pace at lactate threshold and VO2 max decline significantly.

The old premise of periodization was that you needed the big base of aerobic fitness before you could handle the stress of higher workloads. Hence, the schedule of base training first, followed by lactate threshold training, and then race-specific high-intensity speed work. The more modern view is that the pathways to producing energy are intertwined and you can improve performance in either direction. For instance, Helgerud showed that high-intensity efforts are more effective for improving power at VO2 max than moderate-intensity training (Helgerud, 2007). Researchers like Burgomaster, Gibala, and other have shown that these same short, high-intensity intervals improve oxidation of fat and carbohydrate by mitochondria to a similar degree as traditional, lower-intensity endurance training, but in a fraction of the training time. Practically what this means is that by working at the highest end of the intensity spectrum you can improve performance at all intensity levels below that, making it a very effective use of your limited training time. Similarly, lactate threshold workouts improve power at threshold and improve power for endurance intensities, too.

Base Training Was Never About Improving Fitness

There is some validity to the notion that too much intensity can lead to overtraining (better thought of as under-recovery) and increased risk of injury, so one school of thought is that a long period of lower intensity is safer than year-round structured training. There was a time when this was smart advice, but now that we have better tools for measuring and monitoring workload, fatigue, and recovery, the risks of pushing an athlete (or pushing yourself) over that edge is much lower. And for time-crunched cyclists, both the need for prolonged recuperation and the risk of overtraining are already reduced because your busy work and family schedules result in relatively low training volume and abundant time for recovery.

But perhaps the most pernicious reason the idea of base training is still around is that it has long been the refuge for athletes who just want to ride their bikes. Base training is largely unstructured, low-intensity cruising. In an effort to escape structure after a season of interval training, athletes fall back to the comfortable and antiquated idea of base training. There’s a difference, however, between desiring less structure and needing less workload. If you want a break from intervals, that’s fine. Let your mood, the terrain, the wind, or the group you’re with dictate the intensity; just make sure there’s some intensity!

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Burgomaster, Kirsten A., Scott C. Hughes, George J.F. Heigenhauser, Suzanne N. Bradwell, and Martin J. Gibala. (2005) Six Sessions of Sprint Interval Training Increases Muscle Oxidative Potential and Cycle Endurance Capacity in Humans. J Appl Physiol. Jun; 98 (6): 1985-90.

Burgomaster, K. A., Howarth, K. R., Phillips, S. M., Rakobowchuk, M., MacDonald, M. J., McGee, S. L., & Gibala, M. J. (2008). Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans. The Journal of Physiology586(Pt 1), 151–160.

Dudley, G. A., W.M. Abraham, and R. L. Terjung. (1982) Influence of exercise intensity and duration on biochemical adaptations in skeletal muscle. J Appl Physiol. Oct; 53 (4):844-50.

Helgerud J, Høydal K, Wang E, Karlsen T, Berg P, Bjerkaas M, Simonsen T, Helgesen C, Hjorth N, Bach R, Hoff J. (2007) Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc. 2007 Apr;39(4):665-71.

Stöggl, T. L., & Sperlich, B. (2015). The training intensity distribution among well-trained and elite endurance athletes. Frontiers in Physiology6, 295.

Comments 10

  1. Thanks for the thoughtful article, I appreciate the work you guys do. There was one phrase that I take a little issue with: “And for time-crunched cyclists, both the need for prolonged recuperation and the risk of overtraining are already reduced because your busy work and family schedules result in relatively low training volume and abundant time for recovery.” I think it’s dangerous to assume that because someone is training lower volume they’re at a lesser risk for overtraining. Psychological and emotional stressors (otherwise known as life happening) can and do contribute to the total stress on an individual. I would argue that driven amateur athletes are MORE likely to experience overtraining than competitive athletes because of conflicting priorities stretching them thin despite the relatively lower training volume.

    I see the winter base training as an opportunity for recovery, be it physical or psychological, for these athletes. Could they benefit from some intensity mixed in? Probably. But not at the cost of their longer term health if they’re in need of a break.

  2. All I know is this. The fastest I’ve ever been was a month after a 3000 mile bike tour. To only do high intensity rides I couldn’t ride 2 days in a row. And the weight, trying to drop weight is so hard for me which means riding as much as I can, with dead legs, in bad weather etc. and I want to ride year round. You can’t stay fast forever. You need to slow down and accept those valleys, rest with base rides then turn it up when it gets warm and get fast again. Right?

  3. As a Physiologist, Physician, and active Masters road and MTB racer I have to agree with the main points in the article. Races less than 2 hours can be trained for with shorter intense rides. Races up to 3 hours need a portion of your training to come from longer endurance (sub threshold) rides.
    However, as the leader of my team’s yearly Winter Training Camp (4-6 days of high mile, lower intensity paced rides) the biggest gain we get out of this is the social aspect and team building. As Masters racers we pay to race and ride, so we have to get our enjoyment from the riding itself. Do not downplay the psychological effects of going out for a long ride in beautiful country with like minded friends. All work and no play makes Johnny a dull cyclist.

  4. There are some valid points made,. A person will make rapid improvement with high intensity training, but will never reach their full potential without a solid aerobic base created at 60-70% MHR. Not only will the starting point for speedwork be higher, but an athlete will be able to maintain VO2 max/AT gains longer before the inevitable decline associated with peaking. Trying to keep all seasonal gains year round will lead to burnout and injury. Minimal High intensity work during the off season is needed to avoid losing all of the previous season’s gains. the lack of oxidative stress associated with hard efforts also promotes health, not just fitness!

  5. Fantastic read! Thank you for posting. I had followed the “base season” mentality for years and felt like it took all race season to get back to the fitness/form that I typically enjoy. Hallelujah! I no longer need to have a phobia of “going to hard” during the winter base season. Feeling great doing it too

  6. I’m going through the book
    The Ultimate Ride, The Foundation period sounds as if it is the “base period” with strength work. Are the pricipals in this book now obsolete? What do you recommend for someone that trains about 12-14hrs a week?

    1. With 12-14 hours per week, you’re not time crunched. Base training can be effective for you. Don’t give it up completely based on one article .

  7. I guess I’m an “athlete” who just wants to ride his bike. Without a racing schedule to fill, it’s a skill in itself keeping motivated to maintain a regimen of any sort, be it intervals, long hills, endurance, etc. Keep the advice coming, please, cuz even without racing it’s still fun to pretend, and be ready for friendly rides with steep hills and sprints included. Thanks

  8. Any thoughts on the concept — forget the name — whereby 80%of your training is lower intensity (upper recovery/lower endurance zones) and 20% is high intensity (at/above AT), with little in between? Would this work well for recreational/time-crushed non-racers?

    1. Polarized training, see Seiler for the research. The % is sessions, not time, be aware of that. It’s a tool that can be utilized by any athlete.

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