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Scientific Muscle Building

Things Scientists Tell Me About Bodybuilding

As I often tell my girlfriend, Joy, ‘I’m just some guy.’ I’m not a messiah. I am of average intelligence. I am fallible, frequently making assumptions that later turn out to be wrong. So, when it comes to the science of building muscle, I figure the best people to ask are the scientists themselves.

And that’s what I do. I correspond with research scientists at universities around the globe’people who study muscle biology, neuromuscular physiology, biomechanics, nutritional biochemistry and endocrinology, among other disciplines. Sometimes they respond to my queries, and sometimes they don’t. When they do, occasionally I’m treated to fantastic bodybuilding secrets that are just too good to keep to myself.

Now, I don’t agree with everything the scientists tell me, and you shouldn’t either. You shouldn’t take what they say as gospel. As many of them will admit, their views are just that’views.

Some of my scientist friends have firsthand experience with bodybuilding. Some have coached athletes to international success. Others have never touched a barbell. Rarely do they agree 100 percent on anything. But if you ask them the right questions politely enough, you can learn cool things that you may not hear about anywhere else.

Secret 1: Hold On a Second (or Two)

Hold a grapefruit in your hand and straight out in front of you. Don’t let the grapefruit move. Just hold it steady. That’s an isometric contraction’your muscles generate force without shortening to any appreciable extent. Isometric is a loosely used term; however, that description will work for our purposes. Raise the grapefruit about a foot before lowering it back to the starting point. That’s a dynamic, or moving, contraction.

When you lift weights, you generally, well, lift them. In traditional bodybuilding you perform dynamic contractions. The thing is, some scientists believe that isometric contractions may offer an even more powerful way of increasing muscle size. Some suggest that it may not be necessary at all to move the weights up and down.

Thomas Burkholder, Ph.D., of the Georgia Institute of Technology, recently told me that ‘from a purely muscle point of view, it probably doesn’t make much difference whether the muscle moves during activation.’ Citing several references, he continued, ‘Similar results have been seen in humans.’

Robert Fitts, Ph.D., of Marquette University, goes a step further. He proposes that isometrics may be particularly useful for increasing the size of slow-twitch-muscle fibers. While his research seems to support that notion, the results are by no means conclusive. Indeed, some of his colleagues have told me that while Fitts may have a point, it may only be in theory. I tend to agree.

David Jones, Ph.D., of the University of Birmingham, is a longstanding proponent of isometric training. In a recent communication he said, ‘I think the short answer is that nobody knows for sure [whether isometrics are better for stimulating slow-twitch-fiber hypertrophy]. However, high force does seem to be the best stimulus [for increasing muscle size], and the maximum force is generated when a muscle is performing an isometric contraction’.

‘This probably holds true for both fast and slow fibers, and so it is a bit of a mystery to many muscle physiologists as to why people like yourself and power athletes insist on using fast contractions when training. In the case of power athletes it may have something to do with learning how to coordinate the rapid movements needed to jump or throw, but there is no obvious reason why bodybuilders should need to train with rapid shortening contractions. My suggestion would be to use slow or even isometric contractions, no matter what fiber type you are’.

‘Some people believe that eccentric contractions are the most effective way of training for muscle hypertrophy, possibly because higher forces can be generated and partly because some think that the muscle damage acts as a trigger for new growth. I have looked at this in two studies and found no such benefit, but there may be some benefits in some cases.’

I’ve discussed the muscle-building value of isometrics at some length with a number of scientists besides those mentioned above. Here are just a few excerpts from those discussions:

‘It has been shown that isometric contractions can cause massive increases in muscle size but that the strength increase is not proportional to the size and is relatively joint-angle specific.’
‘Dr. Philip Gardiner,
University of Manitoba

‘We have a paper that just came out in the Journal of Applied Physiology that argues for [the use of isometrics for increasing muscle mass], as we induced rodent muscles to first contract isometrically immediately followed by either shortening or lengthening actions or continued isometric actions. The results were that all three contraction modes induced the same amount of hypertrophy. Since the isometric mode was generated in all three modes, I think this is the essential stimulus.’
‘Dr. Kenneth Baldwin,
University of California, Irvine

‘Many dynamic resistance exercises include at least a momentary period of isometric activity. It may just be possible that this moment of very high force production before the load is put into motion may be an important stimulus to hypertrophy.’
‘Dr. Gregory Adams,
University of California, Irvine


The scientific jury is still out as to whether we should replace lifting weights with holding them in place. Take a look around any gym, and you’ll see that the great majority of bodybuilders favor dynamic over isometric contractions. As Richard Lieber, Ph.D., of the University of California, San Diego, admitted to me recently, the best answer is to ‘trust the wisdom of the gym. My experience is that those who actually do it’as opposed to those who just talk about it’are right, although they may not know why.’ Then he added, ‘And it may not matter!’

If you think that isometric training is worth trying, here are three ways you can do it:

1) Get a copy of the October ’04 IRON MAN, and read my article ‘Optimum-Length (OL) Training.’ The routine I outline is a good way to begin experimenting with isometrics.

2) Try Steve Holman’s Positions-of-Flexion (POF) training method, but include isometric contractions. Dr. Jones said, ‘The only advantage I can see to using shortening [concentric] contractions is that they do use the muscle over the full range of movement and do stop the muscle from becoming shorter, as it will do if used only in one position. However, I would still recommend that for optimum results you train with maximal isometric contractions but repeat them with the muscle in different positions over the full range of movement.’

You can put Jones’ suggestions to use by incorporating isometric contractions, or iHolds, into POF workouts: For each POF exercise you perform, pause at the sticking point and hold the weight for one to five seconds before finishing the rep. Do that on every rep of a six-to-eight-rep set. Dr. Fitts recommended that I try a five-second hold, but iHolds of shorter duration may also work. Experiment to see what works best for you.

By the way, the sticking point is where the muscle fibers recruited for the exercise at hand have to generate the most force. Thus, it is there that the muscle-building signal should be greatest’or so the theory goes.

[Note: Jonathan Lawson and Steve Holman, who write the ‘Train, Eat, Grow’ series for IM, recently got phenomenal gains in only one month using a similar technique at the end of POF sets. For more information and before and after photos, visit www]

Recently I created a workout routine for a client that incorporates the iHold technique on every exercise. He continues to build muscle and says it’s the best he’s used in his entire bodybuilding career. His biceps have responded particularly well.

3) Perform iHolds at the sticking point of each exercise at the end of a regular set. Perform dynamic contractions as you normally would, and when you can’t do another full rep, pause for a one-to-five-second iHold at the sticking point before ending the set.

Secret 2: Jump-Start Your Muscle-Building Engines

All day long your muscle fibers make protein and break it down. The process is called protein turnover. If your muscle fibers synthesize more protein than they break down, they will get bigger over time.

Leucine is one of the branched-chain amino acids. It’s also a potent stimulator of muscle protein synthesis’perhaps the most potent amino acid of all in that regard. Tracy Anthony, Ph.D., of the Indiana University School of Medicine, shared with me her thoughts on leucine supplementation for the bodybuilder:

‘I have published quite a bit on both leucine supplementation and exercise, so I can offer some data from my lab and my opinions, for what they’re worth. In general, we need more testing of the clinical uses of leucine supplementation. My opinions are based on my work with rodents. Certainly, rats are not humans, and endurance exercise is very different from resistance exercise. But the following, I believe, are true:

‘1) Leucine behaves as a signaling molecule to jump-start the translational machinery to make protein.

‘2) Leucine’s effects are transient, lasting about two hours after intake. This is certainly because balanced substrate (the other aminos) becomes limiting without subsequent food intake.

‘3) Leucine’s effects are most prominent in muscle. The liver does not respond similarly to oral intake of leucine.

‘4) Leucine alone does not a protein make. While leucine can turn on the translation machinery, there still must be an adequate supply of amino acids available to continue to make protein. In our case, we fasted our rats overnight before giving leucine. [We believe that] the overnight fast likely results in increased protein breakdown, essentially providing balanced substrate to support the short-term effect of leucine. We do not see stimulation of protein synthesis by leucine in freely fed rats.

‘5) It remains to be tested whether leucine is of clinical benefit as a supplement or alone.

‘Do I think it’s possible that dietary supplementation with branched-chain amino acids may enhance muscle mass in healthy resistance-exercising persons such as yourself? Possibly, yes. Probable? Depends on the person and developing the right situation. I think the BCAAs are very important for muscle’for both synthesis and energy. My feeling is that leucine and the other BCAAs will be of greatest benefit under conditions of muscle catabolism. Resistance exercise is generally anabolic; protein synthesis is increased 12 to 15 hours after a bout of resistance exercise independent of nutrition. So, whether leucine can further boost an already anabolic situation is unclear. Certainly, having enough is important, but supplementing very high amounts may be of no additional benefit.’

While there is no conclusive evidence that supplementing with leucine will help you build muscle any faster, it probably won’t hurt to give it a try. Anthony states that leucine jump-starts the muscles’ protein-building machinery. To take advantage of that, you need to supply all of the other amino acids used to build muscle protein. Leucine’s effects last perhaps two hours. Based on those and other observations, I came up with the following method of leucine supplementation:

Before and after your workout take two grams of leucine immediately followed by one scoop of protein powder mixed with water. Note that the two-gram dose is just a guess. Nobody really knows what dose is best. It will probably vary according to your muscle mass, among other factors. Nor is my proposed method of leucine supplementation by any means proven. Far from it. You’ll just have to give it the old college try for three to four weeks and see what happens. Let the mirror be your judge.

Secret 3: Never Drive With Your Tank Half Empty

Henning Wackerhage, Ph.D., is a lecturer in molecular exercise physiology at the University of Dundee in Scotland. He studies the cellular mechanisms by which muscles grow in response to exercise. Wackerhage mentored Dr. Mike Rennie, now at the University of Nottingham, whom some readers may recognize as one of the leading authorities on muscle protein metabolism and the anabolic properties of the amino acid glutamine.

Wackerhage and his colleagues have studied a protein known as AMP kinase, which is believed to serve as a fuel sensor of sorts. There is evidence to suggest that as muscle glycogen stores are reduced, AMPK becomes more active, which causes protein synthesis to slow down. That’s why Wackerhage suggests that bodybuilders always train with full muscle glycogen stores, something best achieved by eating ample carbohydrates before and after your workouts.

Wackerhage has given me many other muscle-building tips. Here’s an excerpt from one of our discussions. In response to my question about the cellular mechanisms of exercise-induced muscle hypertrophy, he said, ‘You have identified the biggest problem in our field, which is, What is the upstream signal and upstream-signal-transduction pathway that will activate the known regulators of protein synthesis (and satellite cell proliferation)? The known regulators of protein synthesis are the PKB-TSC2-mTOR, which is activated by IGF-1 splice variants but possibly also other mechanisms, and Smad2/3 signalling, which is activated by myostatin, a muscle-growth inhibitor that might decrease acutely after resistance training. Mechanosensing is currently unknown, and we have started research in order to try to find an answer. It will probably be a long time before we identify the key growth-inducing signal, the sensor for that signal and the upstream pathway that links it to IGF-1/myostatin expression or directly to PKB and Smad2/3.

‘The current signal-transduction research has only resulted in two findings that have practical implications:

‘A) Minimize energy stress before, during and after resistance training. Energy stress’induced by more prolonged exercise’will activate AMPK, which in turn will reduce protein synthesis. Special cells switch off energy-consuming protein synthesis when there is a high energy turnover. Thus, if you train legs, don’t cycle for at least 20 minutes afterward so you can cool down. In addition, it might be worth trying to do sets in which you lift, rest for a count of three, lift again, count to three and so on. The break is likely to prevent AMPK activation.

‘Another point is that you should always try to train on high glycogen. AMPK has a glycogen-binding domain and is activated when glycogen is low. Those claims have not yet been experimentally verified’and, unfortunately, not many funding bodies will give money for this type of research’but they seem likely.

‘B) Activate mTOR additionally by taking in protein, clearly directly after but possibly also during the workout. mTOR is the master regulator of protein synthesis, and it responds to high-intensity exercise and essential amino acids. You might drink some protein 15 minutes before your workout, have a few sips during it and have some more at the end, but that is well known to bodybuilders. Sorry, that’s all we know at the moment, but we will try to crack the problem that you have identified.’

In simpler terms, Wackerhage advises that you avoid doing cardio right after you train legs. That’s intended to minimize any suppression of protein synthesis caused by reduced muscle glycogen and ATP stores, a.k.a. energy stress. If you want to do cardio on the same day, try doing it later in the day. Ideally, you would do it on another day entirely. And, of course, make sure you get adequate carbohydrate so that you can keep your muscle glycogen stores as close to full as possible.

Wackerhage also says that there may be some value in sipping a protein drink before as well as during your workouts.

A number of researchers suggest that muscle fatigue is not necessary to stimulate muscle growth. They feel that the generation of force per se is of prime importance. I believe they may be underestimating the importance of fatigue, but that’s just my amateurish opinion, based on 18-plus years of trial and error.

Wackerage advises resting for a count of three between reps in order to prevent energy stress. If you’re a little frightened of trying that on every muscle group, then do it on just one or two; say, thighs and biceps. Give it a whirl for three to four weeks and see what happens. It’s impossible to fail, as you’re bound to learn something from your experiments!

Editor’s note: For more of the kind of information revealed in this article, check out the new Real and Original Bodybuilding (ROB) club, an online discussion forum at Rob Thoburn’s Web site. Each week Thoburn shares muscle-building and fat-losing secrets provided by some of the world’s top research scientists in the field. You won’t find this stuff anywhere else. For details on how to join the ROB club, visit IM

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