By: Nicholas Soleyn, SSC

Barbell Logic Editor in Chief

There is something fun about the defining of terms. The deeper you go, the more problems you run into. Every word is just a stand-in for a concept or a collection of concepts. What follows is a thought experiment, following the concepts that make up strength and seeing what this investigation tells us about the meaning and measurement of strength.

The Problem With Strength

Out of the necessity for the economy of communication, we tend to take meaning in language for granted. Every coherent utterance that coincides with common use or a standardized definition is a signal for some concept. We know that when we use a word like strength we do so with a particular meaning in mind. But strength has many possible meanings, different connotations depending on the listener’s experience and bias. For the sake of understanding, you may have to clarify your meaning if you are trying to tell someone about your strength training program. While the picture in your mind is one of barbells, plates, and a squat rack, there’s a high chance that the picture in their mind of strength training looks something like yoga with dumbbells.

It’s worth taking a closer look at the meaning of strength, if for no better reason than understanding your own training. There’s also something fun about the defining of terms. The deeper you go, the more problems you run into. Remember, every word is just a stand-in for a concept or a collection of concepts. What follows is a thought experiment, following the concepts that make up strength and seeing what this investigation tells us about the meaning and measurement of strength.

The Concepts

Force is the most basic, fundamental quantity that produces movement in our physical space. Like distance, time, or space, it describes a concept, measurable with standardized systems, intuitively understood as it governs much of our physical existence, but a term whose meaning is more easily understood by pointing to examples and saying “this or that is force” than it is by description. Force is the thing that tends to cause movement. In a somewhat metaphysical sense, force exists to the extent that every object in our observable physical space is capable of movement. Giving a name to the quantity that causes movement and identifying various sources of force (gravitational force, electromagnetic force, strong nuclear, and weak nuclear) allows us to describe, measure, and explain the world around us.

If every object has the potential for movement due to force, then we can describe the transfer of energy that causes, or allows for, movement, with two basic concepts: force and distance. When a force causes movement or displacement of the point of force application in the direction of the force, we call that work. We might say that the existence of force is the description of the potential for movement in our physical space, and we can describe or measure actual movement by its work. The concept of work is, generally, backward-looking. Things that can create or direct force have the capacity to do work; when movement occurs (work is completed), we can measure the amount of work accomplished in the system.

This is important for barbell training where we move weights through a prescribed range of motion using specific models for each lift. Where we measure work against gravity, the models of the lifts standardize the distance part of the equation for any given lifter. When the lifter successfully completes a rep, we know that the lifter applied at least the minimum amount of force needed to move the barbell vertically against gravity. If we continue adding weight, we know that the minimum force necessary to accomplish the work goes up over time. It takes more force to move 305 lb. over a set distance than it does to move 300 lb. Work, then, becomes a proxy for measuring force (since in normal gym circumstances we cannot know exactly how much force you used to move the barbell, only that it exceeded the amount of force that would have normalized the gravitational pull on the bar), and, by extension, training stress.

The human body has the capacity for force production internally independent of the forces of the physical environment. Our cells convert energy into fuel for muscle contractions that pull on our skeletal systems, creating movement. When you lift a barbell, throw a ball, jump, run, or punch, you can measure the work you generate. This is as opposed to, say, sitting on a sled and letting gravity pull you down a hill. There, gravity is performing the work; it is outside the system, in that you are no different than a rock rolling down the hill. When combined with the physical environment, the human body can transfer energy from our cells to our physical space by applying force to external objects, generating force, or doing work.

What is Strength

This capacity for energy transfer is what we call strength or, more accurately, physical strength. Strength is a borrowed term, typically containing some connotation of resistance, aggressiveness, or measure of intrinsic capacities for motivation or force. In addition to physical strength, people often talk about strength as a component of virtues—strength of will or character, or moral distinction. In physics, strength describes resistance—the ability of something to withstand applied stresses without failure. These other uses of “strength” are linguistically valid, but not specific enough for an investigation into strength training.

There are ostensive definitions of strength, acts or examples that we can point to and say “See? That’s strength.” There’s an implicit understanding of strength; like so many concepts, you know it when you see it. But this article is about the problem of precision, so let’s be precise.

I’ve outlined the concepts of force and work and the human ability for both. These are the essence of a thing that helps us describe an ability: Strength, or the ability to produce force against an external object. This is a definition that anyone familiar with Starting Strength should recognize. The greater the ability, the greater the capacity for work and the better able you are to transfer energy to your physical space.

There is a problem with defining strength as we do, however: You cannot measure the totality of one’s ability to produce force, either in all possible ways or by anticipating what may come tomorrow. There are almost countless ways that a person can exhibit strength. If strength is the ability to transfer energy, every human movement requires strength. This should make sense. We interact with our physical environment by moving either ourselves or things around us. Movement takes energy, translated into muscular contraction, into force. Not only can we flex, extend, abduct, adduct, pronate, supinate, and rotate the various joints of our bodies, we can do so in isolated or coordinated manners. We can accomplish innumerable tasks, from simply remaining standing upright to every conceivable skill in sports. So, even though our definition is precise, the possibilities to display strength are endless.

A person’s relative capacity for strength is also difficult to quantify. How “strong” you are depends on the measure. What “task” or state describes relative strength? Even then, if we can quantify actual force output, there are difficult or impossible-to-quantify factors that go into any display of strength. There are unmeasurable genetic components, practiced skills, or innate aptitude. If I perform a very heavy deadlift, am I stronger than someone who lifts less but is really tall with very short arms, who has to move the load through a much larger range of motion? If so, is it simply the force to cause movement that counts? Or is the actual range of motion of the lift relevant? If we wanted to compare deadlifts, would it make sense to allow each person to lift from a similar anatomical position (raising the bar for tall people, or making short people do deficit deadlifts)? Outside of competition, relative strength doesn’t really matter that much because any demonstration is inconsistent from one person to the next.

So, the goal is to be strong for you. A stronger you is better at all the things that might come your way.

This poses another problem. Of the near infinite demonstrations of strength that you might encounter, we don’t know what tomorrow will bring your way. Whether you are strong enough depends entirely on the task. And though we can make really good guesses as to your needs, we don’t even really know that the sun will rise tomorrow, let alone whether you will need to run a mile, carry another human being, push a car, or lift some stones. This means that the idea of definition and strength according to known tasks and the idea of preparedness is something of a fiction.

The Problem with Strength

The philosophical problem is that strength exists. It can be observed and tested. But it is not generally quantifiable. There is no summation of general strength that will hold completely true in all instances. If we cannot measure it, then strength is a term without definition, and relative terms must be quantified by a task. Strength, then, can only be demonstrated. There is no hypothetical measure of strength, only distinct methods of observation.

The quantification of strength, then, is only possible through a collection of observations and the rational conclusions you can draw from them. For example, Hafþór Björnsson (Thor) is a better deadlifter than I am, but we have no measure by which to quantify his strength relative to mine. Instead, we have overwhelming evidence: In all observable methods in which he and I have been tested, Thor has demonstrated a greater ability to produce force. This is strong evidence that, if we were able to quantify universal strength, such quantification would show that Thor is stronger than I am.

This is akin to saying the sun will rise tomorrow. Since the dawn of time, the sun has not failed to rise. This is strong evidence that the sun will rise tomorrow. But we cannot know that it will rise. We can only make an educated guess, wait, and watch. We cannot know that Thor is stronger than I am because we have no way of observing every possible way that we might test that, let alone a way to quantify the results. This is true even if the certainty of the statement is made with the same certainty that the sun will indeed rise tomorrow.

Admittedly, this leads to some of the absurdity of philosophy, because while we cannot know that Hafþór is stronger than me…everyone does know it. What can be shown is true. Thor deadlifts about twice what I do. The truth of that knowledge only lacks the formality of an impossible measuring device. His and my demonstrated abilities are so vastly disparate that any hypothetical measuring device could only show that he is, indeed, stronger than I am. Any other result would cause one to question whether said device had malfunctioned.

This is partially a problem of language. What can be said (“He is stronger than I am”) is only a signal for something that is shown. Signals are inadequate necessities of communication comprising agreed upon (mostly) names to describe what one sees or experiences. To say that something is a dog, for example, does not capture the essence of it, but only signals that the thing about which you are talking meets certain definable criteria: Kingdom—Animalia, Phylum—Chordata, Class—Mammalia, Order—Carnivora, Family—Canidae, Genus—Canis, Species—C. lupus, Subspecies—C. l. Familiaris. Each taxonomic term describing a host of studies of animals including characteristics included in the dog definition and those excluded from it.

Unfortunately, we do not have such a taxonomic definition of strength. Colloquially, strength is used in so many different ways that we’ve retreated to our explicative definition (or term of art) of “The ability to produce force against an external resistance.” Even breaking down this definition may leave us wanting something more concrete:

Ability describes only a general hypothetical capacity that exists right now for all possible (but unknowable) circumstances.

Producing force includes the basic muscle contractions involved, but may also include more refined motor control as in the execution of powerful but skilled movements in sports. The forcefulness of a muscle contraction includes genetic considerations, innate and ingrained factors (like angles of attachment of muscles), as well as proprioceptive factors and even psychological factors. This is not to mention the external environment in any given demonstration of force production; the ambient temperature might affect the production of force at any given moment.

Strength Signals

This definition is still useful. It is the most useful definition that we have around which we can build a system for improving this physical trait. It allows us to communicate and measure strength. And, from this definition, whether we realize it or not, we have developed “strength signals” that help us describe strength to each other.

The most useful strength signals for our purposes are the squat, the bench press, the deadlift, and the overhead press. These also happen to be the lifts that we use to adapt and get stronger. They are general acts that, together, require a lifter to demonstrate strength in a big, coordinated manner, using a lot of muscle mass in ways consistent with most interactions with our environment. Performance in these lifts gives us a very good picture of one’s overall ability to produce force.

Measuring Strength Signals

Methods of quantification of “strength signals” can be real or fabricated. Lifts, reps and sets, and intensity give a demonstrable picture of what we can do and relate back to our definition of strength. An increase in your ability to produce force will allow you to demonstrate a deadlift at a higher weight than you previously could. It does not follow that because you demonstrated a heavier deadlift today than you did last week, month, or year that you are stronger. But enough demonstrations tend to satisfy this unknowable fact. While we might not know the sun will rise tomorrow, it has happened enough times that most people not named Wittgenstein are comfortable with the close-enough superstition that it will.

Fabricated quantification will include an added interpretation of this observable data. Some of these methods compare relative strength between individuals, such as a Wilks score in a powerlifting competition. Others attempt to unify demonstrations across different tasks. For example, a 1RM calculator will standardize different combinations of (weight)x(sets)x(reps) into a single value (a theoretical 1RM). Other attempts at quantification include a subjective component, such as a rate of perceived exertion (RPE). Perception is, by its definition, the bias of the observer. These types of quantification value the lifter’s perception of difficulty. Such measures give value to aspects of the lift that may be excluded in purely numerical measures—how the lift feels will increase or decrease the value of the weight on the bar.

Importantly, no calculated measure is predictive. These are attempts to add interpretation to existing data. Like the definition of work earlier, the quantification of strength can only be backward-looking. It is the force that did (or didn’t) cause movement. The only data that requires no interpretation is what you actually accomplished. (How much ya bench? is a more direct measure than How did that feel?)

What we care about is change: You want to be a stronger you. For this, you can pick whatever rational measure you prefer and pursue positive change in that measure over time. As a coach, I prefer the demonstrated PR, actual lifts performed at measurably heavier weights. There are a lot of assumptions that go into how we measure strength, rather than focus on force production, focus on demonstrated ability.

If you squat more today than you did last week, that is a demonstrable truth, an act that exceeds the limitations of language. The lift speaks for itself, and that should be enough.

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