Base building versus High Intensity

Base Building vs. High Intensity

A research study

One of the most enduring and intriguing ideas in endurance training lore is the concept of base building.  Runners are frequently advised to ”build a base” or to return to base building because their base has eroded.  By building or re-building a base runners believe that their performance will be enhanced as compared to training that does not include a base building phase.  What is base building and is it truly as effective as suggested by many?  These were the questions that researchers from the University of Montana, the University of Minnesota, and St. Cloud State University teamed up to answer (1).  Let’s examine their study and its results.

What is Base Building?

At its essence, base building is a phase of training where the endurance athlete concentrates on steadily increasing weekly training volume via steady state, easy to moderate paced training (generally known as “aerobic” paced training).  This type of training is referred to as high volume, low intensity training.  The proposed advantage to the athlete for steadily increasing training volume through aerobic training is an increase in the aerobic capacity of the athlete – an increase in the aerobic “base”, hence the name base building.  Endurance athletes are typically advised to remain in the base building phase for as long as possible in order to build their aerobic base as large as possible.  Upon completion of the base building phase, the athlete then incorporates higher intensity training into the training schedule.  Proponents of base building believe that the larger the base built during the base building phase that the greater will be the improvements in the following phases.

The base building idea is not limited to just runners though.  It is a widely promoted idea amongst endurance athletes from many sports, including triathlon, swimming, cycling and cross country skiing.

As noted above, base building is generally a phase of training.  Base building is not a complete training program unto itself – it merely comprises a phase of a complete training program.  This larger training program typically consists of several different training phases each with a particular training goal.  Dividing training into distinct phases is typically known as periodization.  The training phases are generally organized similar to the following phases:

1 – base building phase

2 – pre-competition phase

3 – competition phase

4 – rest or recovery phase. 

Different coaches and authors may prescribe variations in the overall organization of the periodized training program and in the description of the training phases (2,3,4).  However, the differences are relatively minor and the overall training methods generally correspond to the goals of the phases listed above.

Base building research

Does a period of base building result in greater improvement to the endurance athlete during the competition phase as is suggested by its advocates?  What if, instead of a period of base building, an athlete substituted high intensity training?  Would the high intensity training athletes perform better, the same as, or worse than athletes who spent training time base building?  That is exactly what our team of researchers set out to determine. 

A two year project was designed to study a group of 14 cross-country skiers, all working for the same club and willing to have their training manipulated and monitored for the two years of the study.  The subjects were hard training, competitive cross country skiers, consisting of 6 males and 8 females with an average age of 23.  The men averaged 11 years of serious training and the women averaged 8 years.  All subjects had previously competed in the U.S. National Championships and the competitive goal of these athletes during the study was optimal performance during competition.  In addition to testing the physiological indices of performance of these athletes (i.e. VO2max, lactate levels, HR, etc.), the training and competitive history of the subjects was also assessed by the researchers at the start of the study.

The first training year

During the first training year all 14 athletes basically followed the same periodized training plan.  Each athlete had their training plan individualized based on their particular needs, but they still remained within the basic training structure.  They averaged 660 hrs of training the first year, with 16% of the training at high intensity (lactate threshold or above).

Training data was recorded by each athlete using a five level intensity scale.  Low intensity training included zones 1-3.  High intensity training includes zones 4-5 and speed training.

Table 1: Training zones (data drawn from Table 2 of the research study)




HR Rangea

Sample HRb


Endurance 1

Very easy

LT-60 to LT-35



Endurance 2


LT-35 to LT-20



Speed endurance


LT-20 to LT-5



Race zone


LT-5 to LT+10




Very hard

LT+10 to max


a – Heart rate below or above lactate threshold (LT)

b – Based on maximum heart rate of 190 and LT heart rate of 165

Training data was divided into three training periods for each year. 

1)     Basic endurance period – this period consisted of 23 weeks from May through October during which the aerobic base was developed via high volume, low intensity training (this was the base building phase).

2)     Precompetition period – this period consisted of 10 weeks from November through mid-January.  It started at the end of the basic endurance period and ran to the start of the major competitions and included the early season preliminary competitions.  Training during this period focused on maintaining training volume with increasing intensity through greater emphasis on LT intervals and race simulations.  Volume of training was initially held high and then slowly reduced near the end of this period.

3)     Competition period – this period consisted of 10 weeks from mid-January through March.  This period consisted of reduced volume, high intensity intervals and racing with planned rest periods between races.

The primary performance ranking criteria used to evaluate performance was first, the United States Ski Association (USSA) Points list and second, the highest place achieved by each athlete at the United States Senior National Cross Country Championships.

The second year

At the end of the first year the athletes were separated into two groups – control and treatment.  The control group (7 subjects) consisted of those athletes that had increased VO2max by 7% or more, increased VO2threshold by 10% or more, and increased their USSA points by 10% or more.  The control group followed the same periodized program the second year with the addition of an overall 6% increase in volume.  The 6% increase in training volume is consistent with annual volume increases seen in elite athletic programs of the top cross-country ski countries.

The treatment group (7 subjects) consisted of those athletes that did not meet the achievement criteria.  Of note is that in addition to not meeting the achievement criteria for the first year of the study, the treatment group had not seen any improvements in performance during the three years prior to this study.  The researchers noted that based on their race data from the previous three years that the treatment group’s performance had apparently plateaued.  So, it seems that a four year diet of ever increasing training volume (i.e. base building) failed to cause any performance improvements for this group.  The treatment group was then given a modified training program to follow the second year of the study, which consisted of a 36% reduction in low volume training, a 136% increase in high intensity training, and a slight (but non-significant) reduction in total training hours.

Table 2:  Training summary for the treatment group showing the hours trained during each training period (data drawn from table 4 of the research study)

Training period (average hours training in each zone during the training period)

First Year Data

Second Year Data

Treatment Group

Basic Endurance



Year 1 totals

Basic endurance



Year 2 totals

Low Intensity









High intensity




























Table 3:  Training summary for the control group showing the hours trained during each training period (data drawn from table 4 of the research study)

Training period (average hours training in each zone during the training period)

First Year Data

Second Year Data

Control Group

Basic Endurance



Year 1 totals

Basic endurance



Year 2 totals

Low Intensity









High intensity



























Low intensity includes zones 1-3

High intensity includes zones 4-5

Strength – strength training

* – significant difference between control and treatment group


The sum of all the above data simply says that for two years the control group followed a traditional periodized training program that included a significant period of high volume, low intensity base building each year.  The treatment group followed the same periodized plan the first year and then replaced much of their low intensity training with high intensity training the following year.

What were the results?  The high intensity treatment group significantly improved performance and all physiological indices of performance.  The control group had no significant changes in performance or physiological indices of performance during the two years of this study.

Table 4:  Competitive results as determined by season long USSA ski points and by best finish at the US National Championships (low scores are better for both performance measures) – data drawn from Table 7 in the research study


1st competitive season

2nd competitive season

USSA points    







US National Championships









* – significant change from previous year


There are several interesting things to be learned from this study.  In the first year of the study half of the subjects improved performance following the traditional periodization plan that included a 23 week base building period.  This would seem to be an indication that base building is at least somewhat effective for some athletes.  But why would only half of the subjects improve following base building?  A rephrasing of the question may shed some light on the difference in results during the first year of the study.

Table 5:  High intensity training, annual hourly total (data drawn from Table 5 in the research study)


Control Group

Treatment Group

First year

112 hours

100 hours

Second year

111 hours

236 hours

From the data in table 5 note that in the first year of training there was a small difference (though not enough difference to reach a level of significance) in the total number of high intensity training hours between the two groups – the control group conducted 12 additional hours of high intensity training.  A review of tables 2 & 3 shows two hours more in the basic endurance phase, two hours more in the precompetition phase, and an eight hour difference in the competition phase.  The competition phase lasted 10 weeks, equaling 45 minutes additional high intensity training per week for the control group during this phase.  Why did only half of the athletes improve the first year?  We can’t say definitively, but it’s possible that the overall additional 12 hours of high intensity training and especially the additional 8 hours in the competition phase are responsible for the difference in results.  Considering what we know about the influence of intensity on performance, the additional intensity could be a likely explanation for the difference in results of these two groups in the first year.

Examining intensity and performance in the second year provides some additional insight.  In the second year, the control group increased overall training volume from 649 hours to 688 hours, a 6% increase.  However, high intensity training hours did not change – 112 hours the first year, 111 hours the second year.  The control group increased volume of training, but did not increase intensity of training – and their performance didn’t change either.

Conversely, when the treatment group replaced a large portion of their low intensity training with high intensity training and conducted that high intensity training for the entire training year, their performance improved dramatically.  The conclusion that high intensity training is responsible for the changes in the treatment group adds credence to the idea that the additional 12 hours of high intensity training by the control group in the first year could explain their improved performance.

You could make the argument that the control group contained high responders while the treatment group contained low responders.  This would be a possible explanation for the results of the first year of the study, but would be an inadequate explanation for the lack of improvement in the control group in the second year.

You might also advance the argument that since the overall training volume was similar for the two groups in the second year, while the volume of high intensity training was very different, that this study only re-affirms that high intensity training works.  Essentially the argument would be that both groups had the same base, so naturally those who train with higher intensity will outperform those who train with lesser intensity. 

There are two problems with this argument.  First, recall the reason given for the need to build a base in the first place – building a base is supposed to enable a better performance when high intensity training is added later in the training season.  This is clearly not the case with this study.  The control group built a larger base the second year (39 additional hours of base building, and 163 hours more of base building training than the treatment group), but failed to improve performance at all.  Second, recall that not only did the treatment group not improve during the first year of this study, they also hadn’t improved in the three years prior to the start of this study.  We know that in accordance with their periodized training plan that training volume was increased each year.  However, despite four years of steadily increasing training volume the treatment group failed to improve performance.  If base building truly lays the groundwork for improved performance later in the training year, we should have seen some improvement in the treatment group’s performance during the previous four years.  This was not the case though.  It was only the addition of high intensity training that allowed the treatment group to once again enjoy an improvement in performance.

In any case, the lack of improvement in four years by the treatment group and the lack of improvement in the second year by the control group presents a serious challenge to the belief that base building provides additional benefits to athletes as compared to high intensity training.


The results of this study show that a strong case could be made that, despite its popularity, base building confers less benefits than does a program that contains significantly more high intensity training.  At a minimum, this study demonstrates that base building is less effective for some athletes than is high intensity training.


1.       Gaskill, S., Serfass, R., Bacharach, D., Kelly, J., Responses to training in cross-country skiers, Med Sci Sports Exerc, 1999, 31(8), 1211-1217

2.        Pfitzinger, P., Douglas, S., Advanced Marathoning, Human Kinetics, 2001, 35

3.        Friel, Joel, The Triathlete’s Training Bible, Velo Press, 1998, 33

4.        Friel, Joel, The Cyclist’s Training Bible, Velo Press, 1996, 79


Base building versus High Intensity — 9 Comments

  1. Pingback: Base building versus High intensity – a research study | Training Science

  2. Hi Richard!

    You’ve milked another sacred cow here! And I’ve always believed that speed is not something you “add” as the final component at the top of the traditional training pyramid. However, the arguments in favor of basebuilding will continue to remain strong because the system many coaches employ follows Jack Daniel’s “block” approach for distance running, and that first block is “basebulding.” The irony is that other protocols are used during the basebuilding block, and since the time or goal projections for those protocols are based on athletes’ current vVDOT levels, I’ve often wondered if the confusion over a basebuilding block is really more a matter of semantics.

  3. Hello,
    I do cycling at a national elite level in Holland. Since I am now working 40 hours a week, I am looking for different training methodes so I will still be able to perform at this level. My races go 4 to 5 hours, so doing the miles is important. But mostly during the workweek I will not be able to do those miles.

    In the past 6 years I was also a strong believer of building a foundation, then doing some hard training weeks and then go into racing season. Mostly I would build in 2 peaks a season.

    My question:
    Cycling is a real endurance sport, as I said, my races are over 4 to 5 hours, so I got to have in them my legs. But do you think that high intensity training even during build up phase, could also be effective with cycling? Could I replace some of the training of doing long hours by more shorter but more intensive training sessions
    The subjects in this article where cross-country skiers, there races are far less then the races I do.

    With kind regards,

    • Hi, Joost.

      Yes, I believe that some high intensity training during your build up phase would be effective. You will still need to do your long rides on the weekends since your races are 4-5 hours long but some shorter high intensity stuff during the week will likely serve you well.


  4. I’m not understanding how this relates to base building. Base building involves increasing training volume by considerable amounts (think in terms of %50-%100 and higher) over a significant period of time, The control group here wasn’t base building, just maintaining the same training.

  5. Im no expert but I think their definition of base building is different from yours. As opposed to training volume, base building would be seen as maintaining the same aerobic heart rate, which over time is reduced (by the training) resulting in increased times to maintain said heartrate zone.

  6. Maybe I missed something in the reading, but I have some concerns about the research:

    1. Testing elite athletes has drawbacks, in particular many of them are already very close to their genetic ceiling. That can serve as an explanation as to why they weren’t/didn’t improve.

    2. The athletes had had at least 11 years of “base building” – are we to assume that those years played no part in the results of this study?

    3. The athletes had been doing the same programming for at least 3 years (albeit, with a 6% increase per season). Is it any surprise that they’d plateued? In fact, I’m surprised the athletes’ programming increased in volume over the years. Many times runners will decrease volume come an Olympic year to maximize speed in periodization.

    4. Since when is speed endurance considered “moderate” effort?

    5. What does “hard training” mean?

    6. What does “high intensity” mean; seeing as they’ve considered speed endurance training as a moderate effort.

    I understand that this isn’t a conclusive study, but I’d argue that it’s hardly worthy of supporting any claims whatosever because the language is vague, the programming is suspect, and the test subjects are far from ideal.

  7. There is far more to this than aerobic capacity, ‘base’ building, etc etc. The sporting world in general has a general misunderstanding of the function of our muscles at the cellular level.
    Read Dr. Rushall’s work on swimming and rowing. I am an amateur rower. 5000m is my race of choice. During my last training cycle I had rowed over 300,000m and achieved a personal best. All of the rowing was 5000m or greater in training. I then started to stagnate. Then slip off of my times. I found Rushalls work and changed my training to intervals. 250m at race pace with 20 seconds rest. Repeat. Failure to hold my desired pace three times and I actively recovered for 15 minutes. Then started another set.
    After a very short period of time, I raced again w/o much prep. I knocked 31 seconds off my PB and was angry because I had more to give!
    Here’s my laymens take on the research I’ve read, boiled down to a level I or excellent understand. Imagine your cardiovascular and muscular system as a ‘Walmart’. All the long distance training represents your average Tuesday sales volume. Good volume, but not the best. The store is restocked “energy moved in to replace expended energy” at Tuesday’s volume. Now change that to Black Friday. All of the energy expended has to be replaced at a greater rate. This is what rushall refers to as adaptation. We work the one side without working the other. I’m sure my example falls far short of the science behind it.
    The works he has written are worth the read. If your mind is open to science then this is for you. If you are a firm. Believer in anecdotal evidence, then keep pounding away.

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