It may seem counterintuitive to revert to base training every year after reaching new heights of performance, but this strategy pays dividends come race season.

What is Base Fitness?

Base fitness is synonymous with aerobic-base fitness, and this type of fitness is achieved via specific training that spurs particular physiological adaptations. Much like the name implies, this form of fitness is the very base upon which all further training is built.

But what exactly is it? I often see the same set of aerobic adaptation terms thrown around with little explanation of what each term actually means, so allow me:

Increased capillarization
– Translation: more of our tiniest blood vessels which deliver blood (oxygen & nutrients) to the muscle cells and also remove metabolic waste

Increased mitochondrial proliferation
– Translation: more of the muscle cell components that aerobically process fuel necessary for muscle contraction

Increased aerobic enzymes
– Translation: more of the catalysts necessary to aerobically produce energy from incoming fuel

Increased cardiac output
– Translation: more blood pumped out resulting in greater blood distribution per heartbeat

Increased fat metabolism
– Translation: more fat can be metabolized which reduces the amount of sugar necessary to fuel your muscles

All of these adaptations coalesce to achieve a shared outcome, which is more oxygen extraction at the muscle. The more O2 the muscle can utilize, the more work it can do–aerobically–and generate only water and CO2 as waste products.

Why Base Training is Important

Much like a pyramid, our fitness is built in a hierarchal fashion with the initial work serving as a critical foundation that will eventually support a higher peak. This foundation is achieved through effective base training in which a cyclist raises their fitness level. During this phase there are various transformations happening on different levels, but for the sake of simplicity, we’ll just focus on the efficiency of muscles to transform energy into speed on the bike.

As you focus your training on developing your aerobic capacity, you train your body to become more efficient at turning fuel into energy using oxygen. This transformation takes place within the mitochondria in your muscles. So, as you spend more time stressing your aerobic energy system, your body creates more mitochondria that are more efficient. The best news of all is that your mitochondria are involved in turning energy into speed at higher intensities as well as low intensities.

Are There Other Benefits of Base Training?

So those are many of the physiological and structural benefits achieved through base conditioning, but there are others. Of keen importance to endurance athletes is the heartiness of our connective tissue. This is often referred to as joint durability, and it’s something that occurs over a longer span of time than most of the more obvious fitness gains.

Rushing this slower adaptive process opens the door for frequent joint injuries. A lot of athletes will move into too much high-intensity work before their underlying support tissues can handle the stress. So if you’re new to endurance sports, coming back from a long layoff, or you’ve dealt with your fair share of joint injuries already, base training is where to start.

Also of merit is the act of gradually increasing your basic tolerance for work. It’s easy to compromise the effectiveness of high-quality, high-intensity workouts by failing to adequately prepare your mind and body for them. Base training does just that, regardless of whether you choose a Traditional or Sweet Spot approach.

What’s the Main Difference between Traditional Base and Sweet Spot Base?

Base training is most commonly accomplished via a traditional, longer, slower approach that imposes high amounts of low-intensity stress. But there is plenty of evidence to support lower overall training volume in exchange for more demanding levels of intensity. This is where Sweet Spot training enters the picture. But first, let’s explain the traditional approach to base training and why riders might choose to take it.

The Traditional Approach

The traditional approach to base training has athletes putting in long hours on the bike at lower intensities (less than 75% FTP) so that they are using as much of their aerobic energy system as possible. It’s a logical solution that has additional benefits that include an increased dependency on fat as a fuel source, and an opportunity to mentally reset from an arduous season of training and racing. It can be effective, but it is hindered by a number of factors that affect the large majority of cyclists.

Firstly, this type of easy riding requires a completely different mentality than a racer’s mentality. After a season of hard racing at high intensities, it can be extremely demotivating to spin easily for hours on end, turn down a friendly city limits sprint with your mates or avoid going for PRs on your favorite climbs. What this does is label base training as a period of necessary restraint during your training plan, hence the bad reputation base training has earned.

However deterring the mentality may be, it is nowhere near as restrictive as availability. While there are plenty of cyclists that have more than ten hours to train per week, they are a very small minority amongst cyclists around the world.

Most people are time-poor with greater family and professional responsibilities that limit their available training time. The reason this is so limiting in the context of traditional base training is due to the fact that the improvements you are chasing only come through a very large amount of volume. If a cyclist is training at these low intensities without high volume, then they are doing very little to build their aerobic capacity.

The Sweet-Spot Approach

Nearly all cyclists have schedules that don’t allow them to put in the necessary training volume to get the desired adaptations out of a traditional base training approach. But that doesn’t mean cyclists shouldn’t dedicate time to base training. The Sweet Spot approach foregoes the high volume/ low-intensity approach for one of low volume/higher intensity, allowing cyclists to build their endurance in less time while preparing for the intense demands of race season.

Sweet Spot training requires working at a fairly high percentage of your FTP without pushing things too high, too soon. And it does it in relatively very little training time. This allows riders to establish a high level of fatigue resistance which lends itself very well to harder and/or longer efforts down the road.

Sweet Spot training concurrently develops a sufficient base of aerobic fitness coupled with an ample amount of muscle endurance. This helps you achieve many of the benefits of longer, slower work while also increasing your moderate-intensity stamina in the process.

The way this is accomplished is through higher intensity intervals that fall inside or around the Sweet Spot power zone (88-94%). These are far from all-out efforts and although the anaerobic energy system is making an increased contribution, the aerobic system is still being relied upon to a large degree. With higher intensity efforts like this, the aerobic capabilities are being stressed in numerous muscle fibers, and groundwork is being laid to increase overall work capacity. It’s hard work, but it’s engaging and very effective at preparing cyclists for a successful season of racing.

Are There Cases Where Bypassing Base Makes Sense?

Yes. The most common case where riders can bypass a base training phase involves an athlete who has fairly recently undergone a base phase. If base conditioning has already been performed, its effects tend to last a long time assuming some form of maintenance training takes place. In that case, a single base phase can carry a rider an entire year in many situations.

This also applies to cyclists who have worked through an entire Base/Build/Specialty cycle and are entering into another season of competition. At this point, bypassing the Base phase and instead embarking on a repeat Build and/or Specialty phase makes good sense.

One final case for ditching base training revolves around highly experienced, well-conditioned athletes. However, this may not entail completely skipping base training but rather reducing its duration. Commonly, we’ll see athletes of this nature trim a 12-week base phase down to as little as 4-6 weeks.

These tend to be athletes with enough experience that they don’t rely on the recommendations of others. They know from vast amounts of experience just how much base conditioning they need.


For most of us, Base training will forever signify the start of another training year. We’ll use it annually to nail down the essential forms of fitness before we endeavor to get more specialized and event-specific with our training. And we’ll do it not because we’re supposed to, but because it’s scientific, time-proven, consistently beneficial and prudent.

If you’re ready to start your base training, check out the Base training plans TrainerRoad has available. 

Listen to the Discussion on Base Training

“Can I skip base training?” is a question we answered in one of our earliest episodes of the Ask a Cycling Coach. Listen to the episode’s full recording below to hear this and other questions from cyclists get answered.

Other Topics Covered in this Episode

For more answers to your cycling training questions, listen to our podcast Ask a Cycling Coach — the only podcast dedicated to making you a faster cyclist. New episodes are released weekly.

The information in this article was last updated on December 20, 2017.