THE DEFINITION OF STRENGTH

In a famous U.S. Supreme Court decision, Justice Potter Stewart argued that he could not define pornography; however, he wrote, “I know it when I see it.” I’m sure you do, your honor.

The concept of strength is also hard to define, but for a different reason: because there are many forms of strength, each specific to a particular function. For our purposes, we can define human physical strength simply as the capacity to move a load against resistance. The load can be one’s own body, a shovel full of snow, a weighted barbell, or many other things. The resistance is usually the force of gravity, which is inseparable from the load, because the weight of a load is defined as the amount of force that is required to move that load away from the center of the earth. But there are also other, gravity-independent forms of resistance, such as the elastic resistance that must be overcome to stretch a resistance band and the frictional resistance that must be overcome to push a tackling sled.

Many factors contribute to human physical strength, and not all of them have to do with muscles. For example, having short limbs makes certain strength tasks easier to perform by reducing the distance a load has to travel. I have long arms and legs for my height, which put me at a disadvantage when I bench-press and squat (but help when I deadlift).

The two major muscular properties that affect strength are the muscle’s cross-sectional area and neuromuscular efficiency. Muscle cross-sectional area refers to the thickness of a muscle. As a general rule, the thicker a given muscle becomes, the more forcefully it can contract. This is the case, in part, because thicker muscles have thicker muscle fibers, and thicker muscle fibers usually contain a larger number of contractile proteins, which are the fundamental mechanisms of muscle contraction. Adding contractile proteins to your muscle fibers is sort of like adding pullers to your side of the rope in a tug-of-war.

Neuromuscular efficiency is a broad concept that refers to the contribution of brainmuscle communications to strength performance. Every muscle contraction starts in the brain. A part of your brain called the motor center sends an electrical signal through your spine and motor nerves into your muscle fibers, causing them to shorten. Training produces changes in this system that enable you to contract your muscles faster, more forcefully, and more efficiently. If you think of the brain’s role in muscle contractions as being like that of a drill sergeant commanding a platoon of muscle fibers to contract, then this increase in neural drive is like turning up the volume of the command from a whisper to a shout.

Gains in neuromuscular efficiency happen independently of muscle growth. That’s why you can’t always predict how strong someone is from the size of his muscles. A person with relatively small muscles and a high level of neuromuscular efficiency often can outlift a person with larger muscles and a lower level of neuromuscular efficiency.

The ideal type of training to increase a muscle’s cross-sectional area is different from the ideal type of training to increase neuromuscular efficiency. When you’re a beginner, pretty much any kind of training will increase both your muscle size and your neuromuscular efficiency. As you increase the volume of weightlifting you do or the amount of weight you lift, or both, you will continue to increase the cross-sectional area of your muscles and your neuromuscular efficiency. However, as you become more experienced, you come to a point where it simply isn’t possible to train to maximize both the size and the strength of your muscles simultaneously. The reason is that you cannot truly maximize the volume of weightlifting you do and the amount of weight you lift simultaneously. If you want to maximize your training volume, you have to limit the amount of weight you lift, so your muscles don’t become exhausted too quickly. But if you want to maximize the amount of weight you lift, you have to limit your training volume, because lifting very heavy weights will fatigue your muscles faster.

For reasons that I will explain below, doing a high volume of weightlifting with moderately heavy weights is the most effective way to increase muscles’ cross-sectional area. Lifting very heavy weights is the best way to increase neuromuscular efficiency. So if you choose to emphasize volume over weight in your training, you will eventually reach a point where the volume of training you do for size gains actually comes at the expense of neuromuscular efficiency, causing your strength to plateau. Therefore, if your goal is to increase your maximal strength as much as possible, you need to train in a way that balances muscle growth with gains in neuromuscular efficiency—and that’s where I come in!

WHAT MAKES MUSCLES GROW?

Scientists are still trying to figure out the mechanisms of muscle growth, that is, precisely how hormones, genes, immune cells, and other factors cooperate in response to training to increase the size of existing muscle fibers and to cause new muscle fibers to develop. We’ve learned a lot within the past few years, but many aspects of the process are still shrouded in mystery. What we know much more about is the types of training that promote muscle growth most effectively. Fortunately for those who are seeking maximal muscle growth, it is possible to know what works without having the foggiest notion of why the hell it works!

The two training factors that have the greatest impact on muscle growth are load and sets/reps. To put it in terms any kindergartner can understand: If you want big muscles, you have to lift heavy weights and you have to lift them many times. This training approach is known as the repetition method. Lifting heavy loads is required to stimulate muscle growth because heavy loads cause far more muscle tissue disruption than lighter loads, and muscle tissue disruption is a key initiator of the adaptive processes that make muscles grow. Of course, lifting a heavy weight six times will cause more tissue disruption than lifting it three times, and completing two sets of six heavy lifts will cause more tissue disruption than completing one set—and that’s why volume is important for muscle growth, as well.

The catch is that load and reps are inversely related. The more weight you lift, the fewer times you can lift it. Likewise, the more times you plan to lift a weight, the lighter that weight must be. You can work around this issue in various ways: by performing multiple sets with rest breaks between them, by pairing relatively unrelated exercises to avoid overlap, and by training frequently—but the fact remains that you can achieve only so much volume without sacrificing the load.

Now, by definition, you can lift your one-repetition maximum (1RM) load for any given movement only one time. Sure, you might be able to lift it again after a few minutes of rest, but at most you can complete only a handful of 1RM lifts separated by full recoveries before you’re exhausted. The cause of exhaustion in such cases is nervous system fatigue, which essentially means your brain, spinal cord, and peripheral nerves refuse to “tell” your muscles to continue working at maximum capacity. When you lift maximal loads, nervous system fatigue sets in before muscle tissue disruption reaches the levels it reaches when you lift somewhat lighter loads more times. This is one reason why you have to find a middle ground between load and volume if you want to maximize muscle growth.

Muscles contain two basic types of muscle fibers: type I fibers, which are endurance specialists, and type II fibers, which are strength specialists. Bodybuilding-type training presents the muscles with a greater endurance challenge than maximum strength training does, because maximum strength training involves lifting lighter weights more times. In other words, bodybuilding-type training challenges the type I muscle fibers a little more than maximum strength training does, while maximum strength training challenges the type II fibers more. Interestingly, research has shown that bodybuilding-type training causes the type I muscle fibers to grow more than maximum strength training does. This may be another reason bodybuilders have found that high-volume training with moderately heavy loads is most effective for muscle growth.

Bodybuilders certainly are not endurance athletes in the sense that distance runners and cyclists are. However, the primary reason bodybuilders tend to have larger muscles than powerlifters and Olympic weightlifters is that bodybuilding-type training stimulates structural adaptations in the muscles that increase both strength and short-term endurance, whereas maximal strength training tends to increase strength alone. The only structural adaptation that’s really needed to increase maximal strength is an increase in the number and concentration of contractile proteins in the muscles. However, to increase their endurance—even relatively short-term, anaerobic endurance—the muscles also need to store more fuel, acid buffers, fluid, and other things that help them resist fatigue. And this is exactly what we see when we look inside the muscles of bodybuilders. For example, studies have shown that bodybuilding-type training increases the amount of muscle glycogen (the primary fuel for sustained high-intensity exercise) stored in the muscles almost as much as marathon training does. Since the muscles store nearly three grams of water for every gram of glycogen they store, this adaptation tends to increase the size of muscle cells.

When we look inside the muscles of powerlifters and Olympic weightlifters (especially lightweight competitors), we see a greater concentration of contractile proteins than we do in bodybuilders, but smaller amounts of all the other “junk” that increases endurance and cell volume. Since contractile proteins are much denser than the other junk, the muscles of strength athletes take on a dense look, while those of bodybuilders look puffier. The fact that the contractile proteins are more closely connected to maximal strength than the other junk explains why I wouldn’t hesitate to put my money on a denser Brad to bench-press, deadlift, and squat more than his bigger twin brother, Chad.

Maximal strength training has its place in the training programs of bodybuilders and others seeking maximum muscle growth. For that matter, corrective strength training, high-repetition low-load “foundation” training, and other types of training also have their place in such programs. You can’t take any type of fitness very far—be it muscle size, maximal strength, speed, endurance, or anything else—without variation in your training methods. Clearly, though, the specific type of training that is most effective for increasing muscle size is, again, high volume with moderately heavy loads (e.g., multiple sets of 6 to 12 repetitions with 6 to 12RM loads). Other standard bodybuilding methods that serve to maximize the training volume with such loads include selecting exercises that attempt to “isolate” individual muscle groups, performing multiple exercises for a given muscle group within a workout, training only a few muscle groups per training session, and training each muscle group frequently.

WHAT MAKES MUSCLES STRONG?

As I mentioned above, two factors contribute to gains in muscle strength: increasing muscle cross-sectional area (that is, increasing muscle size) and improved neuromuscular efficiency. The most important factor in muscle strength gains is improved neuromuscular efficiency. Beginning weightlifters always become stronger before their muscles become measurably larger because of improvements in neuromuscular efficiency. Specifically, the brain quickly learns to send stronger contraction signals to the muscles in response to the challenges imposed by strength protocols.

There is evidence that, beyond the beginner level, further improvements in neuromuscular efficiency are largely responsible for further strength gains, all the way to the point where an individual reaches his genetic limit for strength. There are three specific adaptations to training that enhance neuromuscular efficiency:

1. MORE MUSCLE INVOLVEMENT: When you contract a muscle, you might assume that all of the tissue in that muscle is actively involved in the contraction. But it’s not. In fact, the average beginning weightlifter is able to activate only half the tissue in a given muscle when contracting it with maximum force. Training quickly increases the amount of muscle tissue your brain can activate.

2. FASTER MUSCLE ACTIVATION: Training also increases the speed at which electrical signals travel from the brain’s motor center to the muscles, enabling the muscles to contract more powerfully.

3. BETTER COORDINATION: The brain learns to use “co-contraction”—or the activation of muscles other than the prime movers in a given lift—to stabilize joints better and improve the efficiency of joint movements. It also learns to relax antagonist muscles that inhibit force production in the desired direction of movement.

While beginners can improve their strength using virtually any type of resistance training involving loads greater than 40 percent of 1RM, continued strength gains require further increases in training load to 70 percent of 1RM and above (all the way to 90 to 100 percent in more advanced lifters). In other words, to truly maximize your muscle strength, you must use your maximal muscle strength in training. Only maximal-effort lifts are capable of stimulating the primarily neural adaptations that serve to increase maximal strength beyond a certain point. This approach to developing muscle tension to increase maximal strength is known as—drum roll, please—the maximal effort method.

In addition to the repetition and maximal effort methods, there is a third and rather different training method of developing muscle tension that is also effective in increasing maximal strength. It’s called the dynamic effort method. Unlike the maximal effort method, which entails lifting heavy loads of 85 to 100 percent of 1RM, the dynamic effort method entails lifting lighter loads, typically ranging between 35 and 75 percent of 1RM, at a rapid speed. How does the dynamic effort method contribute to building maximal strength? The answer has to do with time—and speed.

In order to lift the maximum load you are capable of lifting in any given movement, you must attempt to lift (or more precisely, accelerate) the load as quickly as possible; this phenomenon is known as compensatory acceleration. The reason is that a neural command from the brain’s motor centers telling the muscles to contract (shorten) as fast as possible is required to activate the largest number of muscle fibers simultaneously, and this rapid activation is in turn required to produce maximal force. However, there is a difference between the intent to lift a load quickly—which is essential for maximal strength performance—and the ability to actually contract the muscles quickly based on that intent. It all depends on the size of the load you’re attempting to lift and the specific nature of the strength task you’re performing.

Consider the example of a vertical jump versus a heavy barbell squat. In both movements, maximum performance requires the intent to exert as much force from the feet into the ground as quickly as possible. In the case of the vertical jump, because the load is mere body weight, the muscles can, in fact, contract very quickly, allowing force to be sent into the ground very quickly and returned just as fast, sending the athlete skyward. But in the case of the heavy squat, the large load prevents the muscles from contracting quickly, even though they are trying to contract just as fast as in the vertical jump.

Research has shown that somewhat different neural and muscular adaptations result from dynamic effort training than from maximal effort training. (By the way, you can perform almost any lift as a dynamic effort lift by selecting an appropriate load and cranking up the speed of movement. For example, the barbell squat becomes a dynamic effort lift when a 50 percent of 1RM load is lifted two to four times at a rapid tempo.) If you want to optimize your performance in strength tests that allow fast muscle contractions, it is essential that you incorporate dynamic effort training into your program. The set of strength tests with which the Maximum Strength Program culminates on Moving Day includes one such test: a broad jump, making dynamic effort training a requirement within the program. Still, dynamic effort training can also contribute to performance in other strength tests, such as the maximal squat, as long as it is combined with maximal effort training in a complementary way. For this reason, the dynamic effort component of the Maximum Strength Program is not limited to exercises that are specifically designed to enhance broad-jump performance.

In addition to its greater emphasis on the maximal effort method and the dynamic effort method versus the repetition method, training for maximal strength also differs from bodybuilding-type training in its greater emphasis on whole-body movements. Most of the traditional tests of strength are whole-body exercises. Naturally, in order to increase your performance in such tests as much as possible, you need to emphasize whole-body movements over isolation movements in training. For example, machine hamstring curls will do very little to improve your deadlift performance, even though the hamstrings act as prime movers in the deadlift, because unlike machine hamstring curls, the deadlift requires the hamstrings to work in coordination with many other muscle groups.

This is not to say that isolation movements cannot serve a purpose in maximal strength training. Just as there is a place for maximal strength lifts in bodybuilding-type training, there is also a place for isolation movements here and there in maximal strength training. Specifically, certain isolation movements are beneficial in correcting muscle imbalances and strengthening stabilizing muscles to create a sound frame that can better handle the heavy loads and whole-body movements emphasized later in the training process.

Fatigue occurs faster in sessions emphasizing whole-body movements than it does in workouts emphasizing isolation movements for various muscle groups. This is the second reason powerlifters and Olympic weightlifters, who emphasize whole-body movements, typically don’t spend as much time in the gym as bodybuilders, who emphasize isolation exercises. The first reason, you will recall, is that training with very heavy loads causes nervous system fatigue fairly quickly. (To be perfectly accurate, many Olympic weightlifters and powerlifters actually perform longer training sessions than bodybuilders, but more of that training time is necessarily spent resting between lifts and performing ancillary training, such as dynamic flexibility work.)

THE RECIPE FOR STRENGTH

Taking into account these two important fatigue factors, the Maximum Strength Program entails only 4 (ball-busting) resistance-training sessions per week—far fewer than the 6 to 12 weekly resistance workouts that serious bodybuilders do. The loads are mostly heavier than those used in bodybuilding workouts, and there is also more dynamic effort work and a greater emphasis on whole-body movements than in the typical bodybuilding program. These features make the Maximum Strength Program ideally suited to increase your maximal strength—which, as you now understand, is rather different from maximum muscle size—as much as possible in 16 weeks. That said, let me reiterate that the methods on which the Maximum Strength Program is based still build appreciable muscle mass, just like the bodybuilding-type training you’re probably used to, which means you will very likely gain some muscle mass on the program to go along with the excellent performance gains you experience. The next chapter provides a detailed overview of the program.