Often Discussed, Never Explained: Base Training, Part 2 of 3

Part 1 established what base training is, and for those who have the time to ride them, base miles are highly effective for a few reasons. Low intensity, high duration training provides a low muscular stress alongside a high aerobic stress, making athletes fitter while maintaining relative freshness in the legs, when compared with high intensity, lower time training. Base miles allow the body to adapt to relying on different energy systems, primarily fat, instead of precious, and much more limited, muscle glycogen. On top of that, base miles are just plain fun most of the time. Build a solid aerobic engine, with or without base miles, and you’re going to set yourself up for success. This is a great chart showing where the energy you use to ride bikes comes from, so here it is again.

Aerobic vs Anaerobic Chart jpeg (1)

Aerobic vs Anaerobic Chart

In spite of this, claims that cyclo-cross racers, mountain bikers, criterium racers, and even amateur road racers don’t need big aerobic engines are still found. Even in the individual pursuit on the track, a 4km event lasting just over 4 minutes, aerobic energy production contributes to approximately 70-85% of the power demands! Suggesting that an aerobic engine is not necessary for any bike racer is misleading, at best and improving aerobic power production should be the number one goal in training for bike racing. Besides increased sub-maximal power production, aerobic fitness allows faster recovery between anaerobic efforts. The major differences in training prescription between athletes should come from how the aerobic engine needs to be developed in relation to anaerobic efforts, available training time, and an athlete’s target events. Here’s an example of a 4km individual pursuit taken from Alex Simmons.

O2 Analysis 2011 IP (1)

O2 Analysis

Presenting the data from an individual race along with known Vo2max values, the chart shows that roughly 83% of the energy, for a 5-minute effort, comes from aerobic output. The rewards are obvious if you can develop this engine without over-stressing the rest of the system, which often requires hard hours of high intensity training that’s both mentally and physically draining. Base training allows you to get the same training load with relatively less damage to the muscle. Those hard efforts have different physical and physiological effects on muscles than base training, and maintaining a high volume with high intensity riding is very taxing, occasionally to the point that training becomes arduous and difficult to complete.
Another major benefit of base training is that it allows for a unique metabolic adaptation. While fat is used to replenish energy stores following high intensity anaerobic sessions, the aerobic metabolic pathway, aerobic glycolysis, is stressed differently during a long and slow ride than a short and intense one. With base training, fat becomes more available for energy during efforts under functional threshold power. When energy comes from fat, muscle glycogen is conserved and available later on in a race. Without stressing this system, which takes a lot of time in motion to tap into, this adaptation does not fully materialize to the same level.
This begs the question: why would any educated coach or mentor advise against traditional base training? Some logic goes that since the pros spend a large amount of time riding base miles, it must be the right thing for amateur racing too. The difference is that racing at the professional requires efforts deep into 5, 6, and even 7 hours of racing, which means anaerobic efforts after the 3000-5000kJ mark. Pros need to preserve their anaerobic reserves and muscle glycogen, deeper into a racing effort than amateurs. Rather than relying on the energy stored in muscles, or from eating during the race, they need to efficiently tap into fat stores for hours at a time. Base training is a highly effective way to develop that capacity to use fat and conserve the much more limited anaerobic energy. Amateurs don’t necessarily need this adaptation for a 40-minute criterium or a relatively short road race, which rarely last beyond 2 hours. Even elite races rarely last longer than 4 hours. Still, aerobic power development is ultimately the goal, and base training is valuable to those who are able to train with a high volume for multiple weeks. Pros have the luxury of time, so almost all of them enjoy long hours of base training to adapt to the unique demands of professional racing.

The average athlete doesn’t have the ability to train the aerobic engine the same way as a pro, but they can train the system regardless. Most Source Endurance athletes are not full time pros (although there are a few), they’re mothers, husbands, and working professionals. Regardless, aerobic training is important, so we work around it. Traditional base miles aren’t for most of us, but a big aerobic engine, is your best weapon against fatigue.
In the final part of the series, I’ll review some of the alternatives to building a solid aerobic foundation.

*Further reading: Guadette, Jeff. "A Historical Case For Aerobic Development - Competitor.com." Competitor.com. 4 Apr. 2014. Web. 29 Dec. 2015.
*Running is not cycling, but they’re both highly aerobic endurance sports and performance in running is often easier to analyze scientifically due to the great variability in cycling performance with factors like aerodynamics playing large roles. Even so, aerobic development in running shouldn’t be overlooked in terms of strategic application to cycling performance.

Laursen, P. B. "Training for Intense Exercise Performance: High-intensity or High-volume Training?" Scandinavian Journal of Medicine & Science in Sports 2010.20 (2010): 1-10. Web. Dec. 2015.
Foster C, Farland CV, Guidotti F, et al. The Effects of High Intensity Interval Training vs Steady State Training on Aerobic and Anaerobic Capacity. J Sports Sci Med. 2015;14(4):747-55.
Simmons, Alex. "Anaerobic Stuff." Alex's Cycle Blog. 16 Mar. 2011. Web. 30 Jan. 2016.
Coggan, Andrew. "Demands of the Individual Pursuit, Parts 1-3." Training and Racing with A Power Meter. 30 Apr. 2010. Web. Dec. 2015.
Craig NP, Norton KI, Bourdon PC, Woolford SM, Stanef T, Squires B, Olds TS, Conyers RAJ, Walsh CBV. Aerobic and anaerobic indices contributing to track endurance cycling performance. Eur J Appl Physiol 1993; 67:150-158.
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Seiler S, Jøranson K, Olesen BV, Hetlelid KJ. Adaptations to aerobic interval training: interactive effects of exercise intensity and total work duration. Scand J Med Sci Sports. 2013;23(1):74-83.


As an Exercise Science student at the University of Texas, Mitchell Sides assisted coaching the university cycling and triathlon teams. Since graduating, he raced professionally for Elevate Pro Cycling and started his coaching career at Source Endurance.  Mitchell has been using TrainingPeaks and WKO4 analytical software to help optimize workouts for each athlete. His athletes range from masters to college freshmen in cycling and triathlon. Learn more about Mitchell.