Introduction: The Physics of Fitness

Since the late 1800s, numerous resistance exercises have been used with the intention of strengthening and developing the body. The rudimentary barbell was invented in the early 1900s, followed by rudimentary dumbbells, then later by various types of resistance machines. From the beginning, there have been conflicting beliefs and much controversy, regarding which exercises are most productive for muscular development and those conflicts and controversies continue today.

Mechanically speaking, the human body is a fairly simple system of levers (bones), operated by muscles pulling on those levers. Any anatomical movement, combined with any form of resistance that is applied to the levers of the body, follows a very precise set  of physics principles. The analysis of anatomical movement, as it interacts with various forces, is called “biomechanics”. From a biomechanical perspective, it is actually quite clear which exercises load a given muscle more, and which ones load it less. When structural engineers analyze the physics of a bridge, they don’t disagree with each other, in terms of where the forces are greater or lesser. This type of physics (“Classical Mechanics”) is based on some very simple rules which are undisputed and universal. Many of those same rules apply when dealing with the mechanics of the human body.

Unfortunately, these principles are often overlooked, or not considered, in modern day exercise for muscular development. As mentioned above, the subject of “which exercises are best for muscular development” has been the focus of heated debate, almost as much as religion and politics. But, whereas religion and politics are based on faith or philosophy, the mechanics of resistance exercise is based on physics. The forces produced by various exercises are absolutely quantifiable.

Separate from biomechanical factors, there are also physiological factors, which are involved in the pursuit of muscular development. These include the type of muscle adaptations that is caused by high-repetition sets (with light weights) versus low repetition sets (with heavy-weight), the speed of the repetitions, the recovery time between workouts, etc. But these physiological factors are separate from the mechanical factors. So, although there could be some reasonable debate over physiological factors (how many sets, how many reps, how much recovery time, etc.), biomechanics is constant.

A longer lever (limb) always magnifies a load more than a shorter lever (all other factors being equal). A lever (limb) that is perpendicular with resistance always loads its target muscle more than that same lever would when it’s at a 45 degree angle to resistance (all other factors being equal). A muscle that is able to pull on its lever (bone) perpendicularly is always at more of an “advantage” (has less force requirement) than when that same muscle is forced to pull on its bone from a mostly parallel angle. These, as well as other mechanical factors, determine the “efficiency” (cost / benefit) of an exercise.

Determining which exercises are more efficient than others (i.e., load the target muscle more, with less weight), for the goal of muscular development, is simply a matter of mechanical calculations. Determining which exercises are safer than others, for the goal of muscular development and general fitness, is simply a matter of anatomical analysis combined with those mechanical calculations.

There should be no confusion about which exercises are better or worse, when the goal is physical well-being or muscular development. There should be no confusion about whether a person can “change the shape of a muscle” by using specific exercises. The question of whether an “isolation” exercise is as good as a “compound” should not be a matter of philosophical debate, if the goal is muscular development. These are all mechanical factors, and can easily be evaluated using biomechanical analysis.

The set of principles described in this book allows a person to evaluate any exercise, logically and mathematically, from the perspective of productivity, efficiency and safety. Of course, this narrows down the list of exercises which can legitimately be regarded as “very good”, and expands the list of exercises which can be regarded as “not very good” or as “very bad”.

Some people won’t like this. Some people prefer to believe that “all exercises are good”, and that more variety of exercises is always better. Marketers of programs that are mostly unproductive are likely to feel threatened by a system that allows consumers to evaluate any exercise. Commercializers of endless fitness trends may find themselves less able to fool an informed public once the principles that determine the value of an exercise are revealed.

The over-commercialization of the fitness industry, and the bias that has blurred the perspective of participants, has lead to an enormous amount of confusion about which exercises are good, what constitutes proper anatomical movement, and which goals are realistic. “What confusion”, you ask? The list is long.

For starters, there is no “lower abdominal”. It does not exist. It is not a separate muscle. Further, the appearance of the lower part of the midsection – the number of “notches” (four-pack versus six-pack) and the amount of body fat that is there – cannot be changed by way of targeted exercise. Yet, there are millions of references online which make recommendations for “how to work the lower abs”. This is nonsense.

Another example? Performing Incline Presses (with barbell or dumbbells) – with the belief that it works the “upper Pectorals” – is entirely misguided. Muscles always pull their operating lever, toward their origin. The Pectoral fibers pull the upper arm bone (the “humerus”) toward their origins, but those origins are all situated BELOW the arm line. There are NO Pectoral origins above the clavicle. Moving the arms in an Incline direction, moves them toward the chin or nose, but there are no Pectoral origins there. The Pectoral muscle fibers only move the upper arm bones straight forward, and downward (in various “Decline” angles). Yet, almost every gym in the world has one or more Incline Bench Press stations, and people use them regularly.

One more example? Parallel Bar Dips (using “bodyweight”) load the Triceps with about half as much load, as do Supine Dumbbell Triceps Extensions, using only a pair of 20 pound dumbbells (40 pounds, total). This is due to the angle of the forearm lever, during each of the two exercises.

Note: Parallel Bar Dips are compromised in other ways as well, which results in inefficient Pectoral stimulation and excessive loading of the Anterior Deltoids. So, the argument that “Dips is a good compound exercise even though it’s Triceps benefit is not great”, is not a reasonable argument.

This book is dedicated to the analysis and application of biomechanics – specifically in regard to resistance exercise, for the purpose of muscular development and general fitness. This book identifies the principles which provide maximum efficiency, in the pursuit of that goal. Efficient exercises allow us to get maximum muscle loading with the least amount of wasted effort, and the minimum risk of injury.

This book is intended for people seeking to maximize efficiency in their own resistance exercise programs, and also for those who teach resistance exercise to students and clients. This includes personal trainers, coaches and physical therapists.

It is important to understand that there is a difference between the use of weights (i.e., resistance) in pursuit of “muscular development” (bodybuilding and general fitness), and activities which also involve the use of weights, but are NOT intended for the purpose of muscular development or general fitness.

For example, “Powerlifting” and “Olympic Lifting” are sports that incorporate the use of weights, but are fundamentally different from the goals of physique development and general fitness. The goal of a Powerlifter and/or an Olympic Lifter, is to lift the maximum amount of weight in specific “Lifts”. The goal of a bodybuilder and/or a general fitness practitioner is to develop the physique, to gain a reasonable amount of useful strength, to improve one’s health and to remain injury-free. It is not to lift the maximum amount of weight.

Training for sports performance requires the use of resistance exercise (movements) that mimic the motions of a particular sport, even though those movements may be risky. Conversely, training for muscular development is best done by loading the skeletal muscles in ways that are most similar to natural anatomical movement.

Resistance exercise for physique development (and/or fitness) requires challenging target muscles with a “heavy” load. However, the amount of resistance with which a muscle is loaded is influenced by various mechanical factors, including the length of the lever (i.e., a limb), the angle at which resistance is acting on that limb, the angle at which the muscle is pulling on that bone, and a half dozen other factors.

A muscle that is working against resistance, does not “know” whether the load it is experiencing is produced by a lighter weight that is magnified more, or is more direct, versus a heavier weight that is magnified less, or is less direct. Either way, the net load on the muscle may be the same. However, the difference is the energy-cost required, the strain to non-target muscles and joints, and the degree of effectiveness that comes from issues related to range of motion and the resistance curve. Thus, it makes more sense to select exercises that provide a greater benefit for a lesser “cost”.

We sometimes hear people say, “this is a good exercise for the Lats” or “that exercise is a good exercise for the Triceps”. When that happens, we should ask two questions: 1) “compared to what other exercise?” and 2) “how are you evaluating that?”. Most of the time, people blurt out that sort of commentary without any legitimate method of analysis.

Citing that “Arnold Schwarzenegger did a particular exercise, and he looked good”, is not a valid method  of evaluation. Arnold (as one example) did many exercises – some of which were “good” and some of which were “bad” – mechanically speaking. Simply looking at his end result does not inform us of which exercises contributed more, which contributed less, and which posed a greater risk of injury. Only biomechanical analysis can tell us that.

“Biomechanics” is the only legitimate method by which an exercise can be evaluated. With this knowledge, we can evaluate any exercise by determining how many of the beneficial mechanical requirements an exercise meets, and how many it fails to meet. Then, we can make in informed decision of whether that exercise is “productive”, “efficient” or “safe”.

Here are some of the questions that need to be answered, when evaluating the efficiency, productivity and safety of an exercise:

Does the exercise move the limb of a target muscle, toward that muscle’s origin? Is the limb moving directly opposite the direction of resistance? Does that exercise provide more resistance at the beginning of the range of motion, or at the end of the range of movement? Is there alignment between the direction of movement, the direction of resistance, the origin and insertion of the target muscle? Does the exercise cause the joint(s) to move in a totally natural manner? These are just some of the factors that should be considered.

Some exercises meet all the qualifications. Naturally, those exercises would be far more productive and efficient than exercises which only meet some of the requirements. It would be unwise (inefficient) to select an exercise that rates a “3” or a “5” (on a scale 4 of 1 to 10), if one could just as easily select an exercise that rates a “9” or a “10”. Yet, it’s very common to see people performing exercises that rate a “3” or less, simply because they don’t understand the principles which make an exercise “good” (efficient, optimally productive and optimally safe) or “bad”.

Some people change their exercise routines with frequency, under the mistaken belief that “variety” is essential for continued progress. Some people call this “muscle confusion”. But, as will be fully explained in Chapter 17, this is simply not correct. Switching from an exercise that rates a “10” to an exercise that rates a “4”, will not benefit that muscle more, simply because it’s “new”. The target muscle will simply perceive that change as “inferior” stimulation.

Yes, it’s true that all exercises have some degree of benefit. Even an exercise that rates a “2” can produce muscular development results – if one compensates for the inferior rating by doing four or five times more sets, with a weight that is four or five times heavier than would otherwise be necessary. The question is whether or not an exercise is maximally productive, or if there is a more efficient way of benefitting the muscle. It’s a matter of “cost / benefit.”

If a person does not mind spending a given amount of time and effort, but only getting 40% of the benefit which COULD have been achieved with a “better” exercise – it’s fine. Or, if a person is willing to incur a 50% higher risk of injury – as compared with using a more efficient exercise – it’s fine. However, it’s likely that most people would prefer to spend their efforts wisely, and seek a higher (and safer) return on their investment of time, energy and effort.

The principles which determine exercise efficiency are described in this book. Along the way, we’ll also visit some long-standing myths about what is feasible, and what is not, in terms of changing the shape of a muscle or the dissipation of body fat. We’ll explore the ideal motion for each physique muscle, examine the ideal direction of resistance for each of those muscles, determine whether using barbells or dumbbells is best, evaluate which muscle groups are more prone to injury, and much more.