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A Scientific Approach to Fitness: Applying the Hierarchy of Knowledge

By August 17, 2011January 10th, 2014Guest Blogs, Training Philosophy

Today’s post was written by my good friend Brad Schoenfeld. I asked Brad to write this for my readers when the topic came up in conversation a couple of weeks ago. I really like what Brad wrote because it is very important that we make good decisions in our fitness programming. This article will help you get a better picture of the types of knowledge that can be used to help you formulate proper conclusions. One of my goals is to try to help strength coaches become better critical thinkers, and I think that this hierarchy should be memorized so you can start to analyze what type of evidence you’re utilizing in order to make decisions in programming.

A Scientific Approach to Fitness: Applying the Hierarchy of Knowledge

By Brad Schoenfeld

You’ve no doubt heard the phrase, “Knowledge is power!” On the surface, this statement seems like a no-brainer. After all, our knowledge base influences everything we do in life, including our approach to fitness.

But if you think about it, what actually constitutes knowledge? Is it experience? What we read in books? What we learn from others?

To answer these questions, we can look at knowledge as existing on a hierarchy (Portney and Watkins, 2007). The following is an overview of this hierarchy:

Tradition: Tradition constitutes the most basic form of knowledge. It can be defined as the acceptance of a given truth simply because it has always thought to be true. Although it is lowest on the hierarchal chain, tradition does have some value in our knowledge base. After all, tradition-derived knowledge is generally passed down based on what has been found to work for previous generations. You can make the argument that this type of knowledge has “stood the test of time.” However, if all we ever relied on was tradition, we’d still believe the world is flat and that the sun orbits the earth. The misguided use of tradition in the fitness field is rampant. For instance, a majority of those who lift weights perform the standard 3 sets of 10 reps for an exercise? Why? Invariably because “that’s the way it’s always been done.” The problem here is that such practices fail to consider whether there are better choices available and can suppress the quest for superior alternatives. Hence, knowledge from tradition should be viewed skeptically and employed only in the absence of other forms of knowledge.

Authority: Authority is the acceptance of a given truth because an “expert” says something is so. This is exemplified by the learning that takes place in the classroom, where knowledge is disseminated by the teacher and the student accepts the information as fact. It’s only logical to assume that the “expert” is knowledgeable about the topic of interest, right? Well, not necessarily. Problem is, experts are human and thus fallible. They form opinions based on various biases and sometimes cling to rigidly held beliefs even when there is evidence to the contrary. This is certainly the case in the fitness field. There are countless examples of fitness experts making unsupported claims that are blindly accepted by the general public. The late, great exercise scientist Mel Siff coined this “guruism” and it’s a primary cause for the numerous myths that exist as to exercise and nutrition. Bottom line: Simply because a fitness pro has an advanced degree does not necessarily mean he/she has all the answers and can’t be off base on a particular topic. Moreover, many so called “experts” achieve exalted status because they train celebrities and/or athletes, despite having little or no formal education in exercise science. So while expert opinion is a step above tradition, it must be taken in proper context. Listen and learn from the experts, but always defer to higher forms of knowledge when available.

Trial and error: Trial and error is a popular form of problem solving that involves trying out a given solution and evaluating its effectiveness. If the solution produces satisfactory results, it is adopted as a viable method; if not, it is discarded as useless. Intuition and creativity are essential here to develop alternative possibilities when a solution doesn’t work as desired. Fitness pros often use trial and error as the basis of their training. They’ll try out a routine or method (usually based on knowledge gleaned from tradition or authority) and decide whether or not it “works.” One little problem with the trial and error approach: It is highly unsystematic, failing to control for potential confounding variables and test alternative possibilities. Thus, you never know if the solution is applicable to a given situation. Moreover, you can’t be sure whether the “best” solution was found or if a better one potentially exists. The upshot: Trial and error can play a role in the acquisition of knowledge. In many cases it can help to spur future research. But it has significant limitations and therefore is best implemented only in the context of what we know from higher forms of knowledge.

Logical Reasoning: As the name implies, logical reasoning is a systematic process that combines personal experience, intellect, and formal systems of thought to acquire knowledge. Logical reasoning can be either deductive (where a theory is used to create hypotheses) or inductive (where generalizations are drawn from specific observations). Both inductive and deductive reasoning are essential aspects of research-oriented problem solving. That said, logical reasoning has limitations. Namely, just because something seems logical on the surface doesn’t mean that it is inherently true. There are numerous examples of this in the fitness field. Consider the concept of spot reduction. It may seem inherently logical that performing ab exercises would zap the fat in your midsection. Unfortunately, research has shown this isn’t the case. Despite the seeming logic, you can crunch until the cows come home but it won’t whittle away your spare tire. So while logical reasoning can and should be a valuable tool in acquiring knowledge, it ultimately needs to be validated by empirical testing.

The Scientific Method: The scientific method is at the top of the knowledge hierarchy. The scientific method can be defined as the systematic, empirical, controlled, and critical examination of hypothetical propositions about the associations among natural phenomena” (Portney and Watkins, 2007). This is the process used in peer-reviewed research studies, where scientists set out to answer questions by empirical testing in a fashion that is as free from bias as possible. Now this in no way implies that research is without limitations. Far from it. For every study that says one thing, you can usually find one that shows the opposite. There are many factors that go into formulating and carrying out research, and all of these factors must be considered when developing evidence-based opinions. All things considered, however, the scientific method is the best method we have for knowledge acquisition, and should be employed whenever possible.

Okay, so now that we have an understanding of the hierarchy of knowledge, the bigger question is, How do we put it into practice? The answer is to start at the top. Seek out what research says on a topic. Consider the entire body of research available. If possible, find systematic reviews that consolidate information to maximize statistical power. The more research supporting a theory, the stronger the evidence that the theory has merit.

Once you have a firm grasp of the research, then utilize knowledge lower on the hierarchal chain to form an educated opinion on the topic. Realize that fitness is both a science and art. There is no pure scientific approach that overrides a person’s experience and creativity. Just remember, though, you can’t disassociate the art from the science that backs it up. To paraphrase an old saying: those who choose to ignore what is known from research are doomed to repeat the mistakes of the past. Provide you adhere to the hierarchy of knowledge, you won’t make such mistakes.


Portney LG & Watkins MP. (2007). Foundations of Clinical Research. Norwalk, CT:  Appleton & Lange; 3rd ed.


  • Ted says:

    For me, there is no knowledge hierarchy.
    Either you know, or you don’t.

  • Kathleen says:

    Re the scientific method: As you say, “For every study that says one thing, you can usually find one that shows the opposite.” This alone makes me VERY cautious when it comes to basing my choices on “science.” I look at who funded the study? Do the researchers have any particular (financial or otherwise) interest in the outcome? (It is not always possible to discern their interest!) How many subjects were enrolled in the study? Is the outcome applicable for me–a 56-year old, postmenopausal female, or only the 18-year-old male college students enrolled in the study? What were the study methods? Some methods give greater credence to the outcomes–eg, double-blind, placebo-controlled. What was the study length? I particularly appreciate the caveat at the end of some studies that says, “More studies are needed…”

    So, no. I don’t need some studies to tell me what to do. I DO use considerable past experience and personal judgment. I conduct my own study of 1 (yes, n=1) to see if something makes sense for ME.

  • Steve says:

    Nice try, but I don’t believe that that is a rational matter at all. If it was professors or philosophers would be able to tell us what to do re matters of strength, muscle gain and fat loss – they can’t. They can only measure the footprints of the giants who have disappeared over the horizon.

    Too much of the research is decidedly shonky. Not enough long-term work done on well-trained lifters. Take body-building – the average competitor is much more knowledgeable about lean mass gain than any research scientist who in any case can’t/won’t get ethics approval – or funding or recognition – to even back up what has been figured out in the field, never mind advance knowledge.

    Trial and error is better but the method has to be given a decent try: years, not weeks. How many people have properly even exhausted a linear progression of, say 5 X 5, for instance?

    Logical reasoning is over-rated too. When considering the work of authorities, say, rather than see what Abadjief or Broz have actually achieved, people start ‘thinking’ – which is to say trying to kill an elephant with a pea-shooter. They find someone else who does it differently, or contend that its all steroids, or genetic freaks, or its bad for your knees, or they thinker with the system till its unrecognizable and then say it doesn’t work, or state “I did Bulgarian for three months and was so tired and sore that I had to stop”. No shit.

    Its less a question of brain-power than one of will-power. The truth is that very few people are willing to train harder than they do; actually its probably more accurate to say no-one is willing to train harder than they do (otherwise they’d be doing so). I watched someone doing a 600lb full Olympic style squat recently and the effort was positively frightening, let me tell you.

  • Anoop says:

    If we relied on ‘considerable past experience and personal judgement’, we would be still cutting our jugular veins and vomiting to treat diseases. And we did that for over 3 centuries until one doctor thought it is time to test it with a scientific study! There are lot more examples where we blindly believed things to be true, but was shown to be outright false by scientific studies.

    And evidence based approach uses both scientific studies AND personal judgement and expertise.

    Nice article, Brad!

    • Kathleen says:

      I totally agree with your penultimate sentence, Anoop.

      Perhaps I was not as clear as I could have been. I read the studies, but I AM cautious. Studies, as you certainly know, can be conflicting. And it can take many studies over time to achieve a trustworthy conclusion.

    • Jared says:

      Well both are necessary.

  • Kathleen:

    Perhaps I wasn’t clear enough in my post. You should never rely on a research study to “tell you what to do.” Rather, you should defer to the research as an initial tool to assess what we know as evidence. As I stated, an evidence-based approach relies on a combination of empirical evidence, personal experience, and the needs and abilities of the individual.

    Yes, research has limitations. You noted some of them, and there are certainly others. This is why it’s important to read the studies–not just the abstracts–to get a sense of what limitations are inherent in the study. But it’s important to realize that the limitations of the lower hierarchical sources of knowledge are even greater than those in research.

    And while n=1 is actually the optimal source of evidence for an individual, the protocol used should be based on the evidence and then adjusted as needed–otherwise you are “walking in the dark.”



    • Kathleen says:

      Hey Brad,

      As I commented to Anoop, I DO read the studies. I don’t always abide by them. For example, aspartame. Studies show it is safe, but with AD and cancer in my family, I choose not to take a chance; I avoid products containing aspartame.

      With regard to optimal rep ranges for building muscle, I know that different things work on different people. We are all biochemically different. I’ve interviewed so many bodybuilders over the years who have reported success with so many different training methods. Low reps, high reps, once a week bodypart training, multiple times a week training the same bodypart, supersets, straight sets. I see that you have to find what works for YOU. So a study of 12 18-year-old men on that subject means little to me. I’ll read it, yes. Consider it. Maybe even try the protocol. But I am not shocked if it doesn’t work for ME.

      And let’s look at Vitamin D. For years, nutrition experts were saying we were getting enough Vitamin D. Now they say we are not. The experts who made their recommendations 20 years ago were going by “evidence,” no? And so are the experts today–but with wildly different recommendations.

      These are just a few reasons why I say you need to be cautious when applying study results. I do think we are on the same page there.

      On a side note, I found it funny that a muscle magazine that loves to run studies can run a study on one page and two pages later run a study concluding the exact opposite. Without putting the studies into context, the magazine leaves readers flummoxed. I understand why researchers get annoyed with media interpretations. It can be dangerous.

  • Steve:

    Please explain how trial and error is a better source of knowledge than controlled research? Are you familiar with how research is conducted? Before you dismiss science, you should have a firm understanding of its underlying principles.


  • Anoop:

    Well stated. There are still bodybuilders who do thousands of crunches in an attempt to whittle away their abdominal fat (see Arnold Schwarzenegger’s training book!) or performing cable crossovers to get a “line down the center of their pecs.”

    As you correctly note, an evidence-based approach employs both scientific evidence as well as personal experience. The hierarchy in no way dismisses the importance of fieldwork. The knowledgeable fitness professional employs all sources of knowledge to arrive at a best solution.


  • Risto Uuk says:

    I really like this post, which is why I feel obliged to write my comment here.

    I like the hierarchy, but there are so many different ways to use each component. If it’s possible, maybe you could highlight shortly what to focus on when using each method. In other words, how to take the most of studies, how to think logically, how to use trial and error as well as possible, etc?

    • Bret says:


      I love this post too and want to do a follow up post where I show how the model can be used to form decisions. I think this would be a very good idea to do with something controversial like spinal flexion exercise, training for vert or horiz forces in sprinting, etc.

      If only I wasn’t trying to get a PhD, writing a book, and conducting workshops I’d have so much more time to post blogs.


  • Sam Leahey says:

    Thanks for posting this, Bret.

    Your blog is becoming more and more “sciency” and research glazed. I’m enjoying every minute of it man. Keep up the good work. You and I are certainly developing a much larger appreciate for formal education then we once had. Good stuff!

    All the best,

  • Wow, what a conversation! More about the sources of our decision making than it is about training. Very cool.

    I’ll weigh in … Who wouldn’t listen to evidence that an unbiased piece of research shows us? Good research is fun to read. I won’t comment on anyone in this discussion but I will make a statement because it is vital to our quest for Truth.

    Ultimately, what we are all seeking is truth. Science is a tool, as is reason, and experience. It is sadly not science at work, but arrogance, when some of the disciples of the centuries old religion that we call Science, fail to see the limitations of science.

    Unfortunately, science is highly limited. If we had unlimited money, nerds, honesty, intelligence and fairness then perhaps science would unlock all of the secrets of the universe. But we don’t. I personally marvel at what we Don’t understand yet, and it makes me snicker.

    As an example that is only partially tongue in cheek, we can’t even prove beyond a doubt whether OJ was guilty or whether there were WMD in Iraq. But science is hard to apply in real world situations isn’t it? This is the original reason for remembering the proposed Research-Clinical Gap. There is so much that we don’t know, yet our clients rely upon us to bring them truth – and that’s the truest truth of all.

  • mia says:

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  • Daniël Niks says:

    Great article Brad!

    At 30 years of age I’m recollecting memories of me moving through the hierarchy in my quest for a stronger body. When I started I trusted that what everybody did was the right thing for me to do. It worked for a little while, but than no more. Then I started listening to the big guys and applied their theories. Worked for a while, but… you know. Than I read an article about High Intensity Training and worked with different programs using trial and error. It turned out that what everybody did wasn’t what I personally needed, less turned out to be better. I started wondering why, read more about the subject and gained better understanding of the mechanics involved. The more I read, the better I learned to reason about what was actually going on in practice. Questions arose from better understanding and peaked interest in related research. Now, in my daily practice of working with clients all this helps me tremendously in assessing and communicating their needs.

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