Review of "Strength Training and Coordination: An Integrative Approach" by Frans Bosch

I recently finished the above-titled book by Frans Bosch.

It's one of the best books on movement I’ve read in a while so I decided to write a review and (rather lengthy) summary of the some of the ideas I found interesting. 

The book is about strength training and coordinated movement. If you are only interested in one of these topics, you should really read the book, because it makes a strong case that these subjects cannot be well-understood in isolation.

Before getting started I should point out that a lot of the muscle physiology and sports science is a bit over my head, so I am not in a position to offer any critical feedback there. With that in mind, here are some links to some articles by Pat WardCarl Valle and Mladen Jovanovic, three smart guys who work extensively with athletes, and have written a bit about Bosch from a more critical and informed perspective.

With that caveat in place, let's get started.

Reductionism versus complex systems theory

A major theoretical basis for this book is that a reductionistic approach to strength training has some serious problems, and that a complex systems approach might provide some useful correctives.

In general, a reductionist approach to science seeks to understand a whole by analyzing its parts. This is a tremendously successful way to explain the behavior of complicated systems, which are often the subject of study in fields like physics, chemistry, and engineering. But it has significant weaknesses when applied to complex systems, which are often studied in subjects like biology, psychology, economics and sport science. This is because in a complex system, perfect knowledge of the parts does not guarantee a very good understanding of the whole, because the whole is in some sense far greater than the sum of the parts.  

For example, in a human being, some of its most interesting qualities, such as its ability to learn motor control and adapt to physical stress, are invisible or non-existent when looking at the parts. These qualities only arise or "emerge" when those parts interact in a certain way.

Most sports and rehabilitation sciences have a very reductionistic approach. For example, sports science tends to reduce complex movement performance into categories like strength, power, flexibility, endurance and coordination. The idea is that each of these qualities can be assessed and corrected in isolation. Bosch argues that these divisions are often artificial and unhelpful. There is really no such thing as “strength" or “power" as a universal generalized ability. Both qualities depend on coordination for their expression, and coordination is a specific skill. Thus, a person can be strong in one area, but weak in another. 

So, although one can improve his or her performance in the bench press, squat or pull up, this does not necessarily mean that the athlete is any “stronger” in a general sense, or more importantly that the training will improve performance on the field. This is the problem of “transfer", and much of the book is devoted to solving it. Again, I am not expert enough to evaluate the merit of Bosch’s specific suggestions of how to optimize transfer, but I think he frames the issues very well, and also makes some very original and thought provoking arguments. 

I won’t get into to many of the specific exercises that Bosch recommends, except to say that he really likes one-legged cleans! 

Self organization and the role of the coach

Complex systems can be highly organized and adaptive even without any means of central control. The dynamic interactions between all the parts will cause the system to become attracted, in a statistical or probabilistic manner, to certain states that are advantageous under certain conditions. Thus, the system displays intelligent, adaptive behavior even without any single part of the system really “knowing” what it is doing. For example, termites build very sophisticated nests, even though there isn’t any one termite who knows the plan or even intends the overall result. We therefore say that the termite colony is “self-organizing", or that the design of the nest is “emergent”, or that the state of an organized nest is an “attractor” toward which the colony will tend to evolve under normal healthy conditions. 

Coaches and teachers should remember that their clients are self-organizing systems, that good movement will tend to just emerge under the right conditions, and that athletes will be attracted to the right movement patterns if they get the right kind of practice. They don’t need specific information about exactly how to move, only the right conditions to learn: 

No one can directly teach the learning system how to organize. All the coach, physical therapist or movement expert can do is create conditions that optimize the self-organizing system’s chances of finding generally valid principles of satisfactory solutions.

Thus, Bosch argues that coaches should view themselves as "gardeners not conductors.” 


What are the conditions that create better organization? Bosch refers to the constraints-based learning model by Newell, which identifies three basic constraints around which complex adaptive systems self-organize: (1) the task (e.g. squatting); (2) the current state of the organism (e.g. the length of the femurs, the health and condition of the knees, quads and glutes); (3) the environment (the presence of "affordances" such as a box to sit on).

A coach could change any of these constraints to change the squat pattern: (1) the task (e.g. by holding a kettlebell in front); (2) the environment (e.g. by lowering or raising the box, or squatting on an unstable surface; (3) changing the body - through hypertrophy training, weight loss or pain reduction.

A change in any of these constraints would cause the system to reorganize automatically, without any specific instruction from the coach about how to squat. 

Cues and Feedback

In line with this thinking about self-organziation, there are better and worse ways to cue athletes and give them feedback.

There are two basic methods of providing feedback to assist learning: Knowledge of results (KR) and knowledge of performance (KP).  KR means letting the athlete know whether they accomplished their goal by showing them, for example, how fast they ran, how far they jumped, or whether they hit a target. Knowledge of performance is feedback about the specific techniques used to accomplish the result. For example: telling a sprinter to raise the knees higher, a thrower to turn the shoulders more, or a squatter to get the thighs to parallel.  

Substantial research indicates that knowledge of results is a far more effective and leads to faster motor learning. For example, one study showed that discus throwers perform better after being told how far they threw, compared to getting technical feedback from a highly qualified coach.  

The superiority of KP versus KR is analogous to the superiority of external over internal cues. An external cue asks the athlete to focus their attention on something external to the body during performance - such as a target when throwing, or touching an object when jumping. An internal cue has the athlete focus on the movement of the body during performance, such as the position of the arms during a throw, or powerful hip extension in a jump. Here again, there is significant research by Gabriel Wulff and others showing that external cues lead to far greater motor learning, and that internal cues may even be detrimental in some circumstances.

The intention-action model

Bosch explains these results in reference to the intention-action model, which hypothesizes that movements are primarily organized according to their intention, as opposed to the required combinations of joint movements and muscle activations.

People can write their names very well in many different circumstances - in small size on paper, in very large size on a blackboard, and in different orientations to gravity. Each task requires a completely different set of muscle activations. What they all have in common is an intention to create a certain result. So the system must think in terms of end results, not the processes to achieve them, which will always need to vary according to circumstance. 

The problem with many strength and rehab exercises is that they lack a clear intention about the end result the movement should achieve, and are instead designed to activate a certain set of muscles or move certain joints in sequence. This is not how the system thinks! It’s “library” of movement is organized by end result not patterns of muscle activity. It will learn a movement better if the movement is attached to an intention to create a meaningful result.  

Fortunately, most strength in rehab exercises can easily be improved by adding a specific intention, and/or directing the student’s attention to the results of the movement outside the body. 

Attractors and Fluctuators

One of the central concepts in the book is the difference between attractors and fluctuators. I mentioned before that an attractor is a state of organization to which a complex system will tend to gravitate. It’s basically a habitual pattern. 

A very good illustration of this idea involves a ball moving over a landscape of wells. The wider the well, the more often it will “attract” a ball, and the deeper the well, the harder for the ball to escape. 

An athlete will get “attracted" to certain movement patterns under certain constraints imposed by their body, the environment and the task they intend to perform. For example, if I smoothly increase my speed of locomotion toward a target, I will first walk, and then walk a bit faster, and then bit faster, and then I will suddenly shift into jogging, a totally different pattern of movement. This non-linear transition from one attractor to another is called a "phase shift.”   

According to Bosch, although humans can perform a near infinite number of movement tasks, there are relatively few basic movement patterns - e.g. running, jumping, squatting and throwing - that get the job done. These basic movement patterns become the building blocks for all movement. They are combined and varied and tweaked to generate a huge repertoire of complex movements. The attractors are the basic movements and the fluctuators are the movements that do the contextual adapting and tweaking. 

For example, Bosch claims that in an expert baseball swing, the movement of the arms is the proper attractor movement, and should be largely the same on each pitch. Movements of the lower body are the fluctuators, and always needs to adjust to bring the arms into the right position to hit the ball.

But a novice baseball player might use the opposite pattern, which would be ineffective. If the legs and lower body remain relatively motionless, then the arms have to move out of a powerful position to make contact. The novice baseball player makes progress by repeating swings over and over again, until they can start to figure out which aspects of the swing should remain the same, and which ones need to change. For Bosch, this means that a big part of improving performance is learning which movements should be the attractors and which should be fluctuators.

It's like learning which aspects of success are essential and which are incidental.

And here is the potential benefit of strength training - we can use it to “deepen” the attractor wells for basic fundamental movements like squatting, lunging, jumping and running. For example, the triple extension coordination of the ankle/knee/hip during jumping is not much different from running, or a power clean. Thus, a power clean can teach the athlete something about how to optimize force production in this very fundamental attractor movement, and this will hopefully transfer in many different areas on the field.

Variability and adaptability

One of the key needs of the motor system is control that works in a wide variety of contexts. A method of control that works in only one particular environment is useless. Thus:

The precise movement corrections that, for example, physical therapists, golf teachers and coaches in Oriental martial arts are so fond of making serve little purpose. These are incidents that the learning system will not recognize as universally applicable and therefore also dismiss as incidents. In other words, the system will not want to learn much from them. The precisely taught lifting technique will not be remembered, for it is not universally applicable, if only because the objects that are listed in everyday life all differ in shape and weight.

This is part of the reason for Bosch’s preference for variability in lifting – it allows the system to determine which features of lifting are universal and which are incidental.

Muscle slack

Good athletes should be like kangaroos, taking full advantage of the elastic potential of their muscles and tendons. This requires an exquisite sense of timing and coordination in the activation of the muscles, particularly in their ability to co-contract around a joint, and create stiffness.

Reducing "muscle slack" is of crucial importance here, especially in bi-articular muscles like the hamstrings and gastrocs. Bosch believes these muscles should work almost isometrically in many powerful movements like running and jumping. Any change in joint angle at the knee, ankle and hip during the transition from landing to take-off should occur mostly by lengthening of passive elements in the muscle tendon complex. Muscles around these joints must co-contract to create the required stiffness.  

This improves power and efficiency through taking advantage of elastic recoil, and it also improves motor control. Muscles co-contracting on either side of the joint during a powerful movement act like shock absorbers in a car, automatically moving the joint back to neutral in response to perturbing forces without the need for motor commands from the nervous system.

Muscle slack refers to a lazy, uncoordinated pattern that fails to achieve the desired co-contraction and joint stiffness at the right time.

 Muscle slack and its relationship to co-contractions are among the most performance-determining factors in sport. . . .
The speed at which muscles can build up their tension overcoming muscle slack is therefore usually more important to performance than the amount of force they can eventually produce. . . .
The best sprinters display considerable stiffness in the ankle joint when accelerating and running at speed. In other words, the best athletes make smaller counter-movements during athletic movement. The management of muscle slack can account for this. . . .

What this means is that in sport specific strength training, all counter movements should be avoided.

Further, heavy barbell squats may have negative transfer, because they eliminate muscle slack for the athlete, so that he or she doesn't need to learn to eliminate it through co-contractions.

Central governors

Bosch states that limitations in strength, speed, power or endurance can be the result of the system trying to protect itself from perceived dangers associated with movement. Variability in training is one of the mechanisms to reset central governors in a beneficial direction.

Before coming into action, we make an estimate of the future state we wish to achieve and whether or not the environment and the body have the necessary properties to achieve it. Of course, this estimate is very much based on past experience, and stored in the memory. . . .
A number of important conclusions about the effect of strength training can be drawn from this probabilistic prognosis . . . Perhaps the most important of these is that the predictability of what happens in training (monotony) may act as a brake on the intended training results. Variation and  alternation in the types of training may keep the brain interested in adapting control yield better results.

Motivation and repetition

Emotional engagement and motivation is a critical aspect of learning.

Motivation  and motor learning is also strongly connected to lower mental aspects such as arousal or fear activation, and is fueled from the body bottom up. . . . Motivation is thus a state of the entire organism, can be seen as a thermostat in the learning process.

Repetition and practice is necessary to get better, but if it leads to monotony and reduces motivation, learning will suffer. Variation in training increases motivation and avoids monotony. 

If the load in strength training is kept low, more variation as possible.

Periodization probably works not because of the exact order in which work is done, but in the simple fact that it increases variability and thus motivation.


Well that's it. There's many other interesting points I didn't have time to cover. This is definitely one of those books where you do a lot of highlighting. It's also a book which leaves you with more good questions than firm answers. My kind of book, and highly recommended!