Book Review Body by Science by Doug McGuff and John Little

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This article was edited and updated on December 23, 2021.

Body by Science presents some seemingly radical ideas — but maybe not so new after all

Body by Science by Doug McGuff and John Little is a short but very intense look at “strength training, body building and complete fitness in 12 minutes a week.” During my first reading, I was overwhelmed by the science (which gets pretty technical) and thought that maybe everything I had ever learned about training and fitness was wrong. Or I had at least misunderstood...or been misled.

But, a second reading changed my mind. The book is intended for those who are very serious about fitness — and the authors’ training ideas are backed up by science and research. I could not ignore what they had to say and keep doing everything in my fitness classes precisely the same as I had always done them. At the same time, most of their suggestions involve using machines (not free weights) and working with one individual at a time, not a group. It was tough to reconcile the differences and decide what to do.

I asked myself how I could adapt their excellent ideas to what I do four times a week in my fitness classes, often with people who are older than 55. I had to skim the book a third time to answer that question. In the end, I found four concepts that I can use in my own life and with my fitness class participants. I do not include here all the science that is discussed to back up their assertions, merely the conclusions. If you want to know the detailed science and the research, please read the book!

Health, Fitness and Metabolism

An early statement in the book, after defining health, fitness, and exercise is: “In reality, fitness and health are not extrinsically linked; as one goes up, the other does not necessarily go up with it.”

The authors go on to say: “It should be acknowledged that longevity, as with fitness, is not necessarily linked to health. It can be, but the important thing to remember is that health is ultimately linked to DNA — the self-replicating molecule that creates our bodies. The purpose of the body from the DNA”s standpoint is merely to function as a vehicle to carry it forward into the future.”

No fitness instructor can promise a fitness participant that if they attend their class, they will lose weight or get healthier. It just doesn’t necessarily go together.

In addition, the fitness industry in general has centred our drive for fitness and health on the cardiorespiratory system. But McGuff and Little state that “the center of metabolic not the heart and cardiovascular system; it is the muscular system. ...It’s in the muscle where all the ‘gold’ that can be panned from exercise is found. The fitness world’s misplaced focus on the cardiovascular system needs to be redirected to the muscular system, because that’s where everything that results in positive adaptive change happens.”

If you are a runner, you will not like this book! (Although they don’t discuss it much, I doubt they have much good to say about step classes either.) A combination of some aerobic intensity (see below) combined with strength training (see below) is the most likely path to metabolic health.

Aerobic Intensity

Research shows that aerobic effects need not be long. How long does that mean? Would you believe as little as seven minutes once a week? “How could so little time spent exercising produce the same aerobic effects as more conventional workouts in only about 2 percent of the time?” the authors ask rhetorically. They reply, quite simply: “high-intensity muscular effort.”

Research shows that seven minutes of moderate-to-high intensity aerobic effort once a week is enough to keep the cardiovascular system working well. I’m pleased to say that we accomplish that in my fitness class, as we begin with mobilizations and range-of-motion activities and then move on to slightly higher levels of intensity, ending with about a seven-to-ten minute section of moderate-to-high intensity movement. It’s one of the reasons I call my class Light Fit. McGuff and Little might very well feel that I have chosen the wrong name.

Effective Strength Training

So how do McGuff and Little approach strength training and make it effective? “[Effective strength training] an aggressive recruitment and momentary weakening of muscle fibers. If you are able to recruit, fatigue, and weaken muscle fibers within a defined time frame, then you are going to recruit all of the different muscle fiber types aggressively and therefore get the most mechanical and metabolic effect for producing an adaptation. If the exercises are performed properly — that is, in accord with muscle and joint function — you can do so in a way that eliminates all of the other extraneous components, such as excessive force and excessive wear and tear on the joints, which are completely unnecessary for the delivery of the stimulus.”

It really doesn’t matter, say the authors, how many reps and sets you do. What matters is whether or not you push the muscle to fatigue. And you only have to do that once a week with each exercise!

“This is one of the unique advantages of strength training,” the authors continue. The forces are low to begin with: If you start with a weight of 100 pounds, it stays at 100 pounds, requiring the same amount of force to move it at the end of the set as it does at the beginning, even as your fiber recruitment and rate of fatigue increase.”

As a fitness instructor, I will teach this concept to my participants. If you want strength training to be effective, you need to use the right weight and proper form. And, most important of all, you shouldn't quit until you know that your muscle is fatigued. Otherwise, you may well be wasting your time. In a group fitness class, this is not always possible to achieve, but each person should be able to choose a weight that is appropriate to the task.

See also: Why Lift Weights?

Rest or Recovery of Muscle Fibers

“Two different aspects of recovery need to be distinguished. One is the temporary recovery of the [various fibers of the muscle]. The other is the recovery of the energy and resources that are expended during a workout. What we’re referring to in this context is [the] recovery..involved to the point where they are capable of contracting again.”

How long might this be? It partly depends on the fibres which you tap into. If you are making use of the fibers we use when fleeing from a man-eating lion, these fibers, “once tapped, can take four to ten days (or longer) to fully recover.” If, however, you are aiming for “momentary muscular failure,” then those fibers would be available for recruitment after three days of rest. Your slowest-twitch motor unit, by contrast, would be available for recruitment again after a rest of ninety seconds.”

Resting between exercise sessions is vital for muscle growth, development, and maintenance. Over-training can happen all too easily if we convince ourselves that going to the gym every day is essential. See also Over-training.

Final Thoughts

The research has been there — coming in by dribs and drabs — for quite a while: we don’t have to “do” fitness every day for even an hour. Two clear messages of the book, and well worth considering when planning your own schedule: how and how often do you exercise? And do you rest in between? You can be fit without sacrificing hours and hours of your time every single day.

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I am a BCRPA-certified fitness instructor in Vancouver, BC. I teach four classes at the West End Community Centre in Vancouver, BC, mostly designed for the older adult. The Inevitable Disclaimer: Everything published here expresses only my opinion, based on my training and research. What you do with the information is entirely your own responsibility. I am not liable for any injury you suffer that seems to be related to anything you read here. Always consult your doctor before beginning an exercise program. For other articles, return to the table of contents.

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