Mind into Muscle
By Dave Smith
Mental practice, the mental rehearsal of a task in the absence of overt move-ment, is a technique commonly employed by athletes, coaches and sport psychologists to enhance sporting performance. Several hundred research studies have examined this phenomenon during the last hundred years, and have generally concluded that mental practice can indeed improve the performance of sporting tasks, although it is not as effective as physical practice.
There is a great deal of anecdotal evidence suggesting that mental practice can also improve muscle strength, and many strength athletes and bodybuilders do believe in, and use, mental practice. For example, former Mr Universe Tom Platz attributes much of his bodybuilding success to this technique. Arthur Jones is also an advocate of mental practice, once claiming "I can add a quarter of an inch on my arms by just thinking about training my biceps and triceps". I have used this technique myself with individuals I have trained in the gym, as part of high-intensity training programs, with considerable success. Also, physiotherapists I have talked to report successfully using mental practice as part of rehabilitation following muscular injuries.
However, attempts by exercise science researchers to show this under controlled conditions that mental practice can improve strength have generally proved fruitless. Such researchers have mostly concluded that mental practice is ineffective in improving muscle strength. Thus, there is a large discrepancy between people's 'real world' experiences and what researchers have found.
So, who is right? Are the above anecdotal reports just hype, or can mental practice really improve muscle strength? The truth is that most of the research in this area has been so poorly conducted that it has not provided any meaningful information. For example, in most studies, subjects have only performed one or two mental practice sessions, which is clearly inadequate. Also, despite much evidence that mental practice is most effective when the individual attempts to feel himself perform the movement, rather than just seeing himself (like on a home movie), researchers have not generally instructed subjects to do this. Some of the methods used to assess strength in these studies, such as isokinetic peak torque, are also of somewhat questionable validity.
Therefore, researchers have not really given mental practice a fair test when it comes to assessing its effects on strength. However, myself and colleagues at Manchester Metropolitan University, England, are currently conducting a research programme to provide hard evidence as to whether mental practice can indeed increase muscle strength, and to examine the mechanisms through which this might occur.
In a study I recently presented at the annual British Psychological Society conference, we tested the isometric (static) strength of the abductor digiti minimi muscle (little finger abductor) in eighteen male subjects. The subjects were then divided into three groups: a physical practice group, a mental practice group and a control group. The physical practice group performed twenty maximum voluntary contractions of the little finger twice per week for four weeks, the mental practice group imagined performing the same number of contractions over the same time period, and the control group did nothing. At the end of the four-week period, the strength of the subjects was re-tested. The finger strength of the physical practice group subjects increased by an average of 33 per cent, the mental practice group increased by 16 per cent, and the control group showed no change.
Thus, in this study, mental practice did significantly enhance strength, although it was not as effective as actual performance. The rather obscure finger muscle was used as it is not used in any sport we could think of, or in everyday life. It was therefore unlikely that the results could be contaminated by anything the subjects were doing outside the laboratory. However, as all muscles work in essentially the same way, there is no reason why significant improvements would not also occur with other muscle groups.
This result may, at first, seem simply impossible. After all, how can merely thinking about training a muscle improve its strength ? Although we do not yet have all the answers, we are beginning to get an idea of how mental practice works.
Researchers have previously found, using a technique called electromyography (EMG), that when an individual vividly imagines performing a movement, tiny electrical signals occur in the muscles involved in the movement. Thus, the muscles contract even though there is no overt movement occurring. Some researchers, such as Ellington Darden, have suggested that this activity may cause adequate stimulation in the muscles for overcompensation to occur. In our study, we did find significant muscle activity occurring during mental practice. However, given the magnitude of this activity (many times smaller than that which occurs during actual performance), it is unlikely that this can explain such large increases in strength. Also, we found no relationship between the amount of this activity and the magnitude of the strength increases in our mental practice subjects.
A more likely explanation of how mental practice enhances muscle strength is related to what goes on in the brain when an individual imagines performing a movement. To understand this, it is important to know exactly what determines the strength of a muscle. This is dependent partly on structural factors within the muscle itself, such as the size of the muscle, and muscle fiber type and density. It is also partially dependent on neurological factors, specifically the ability of the brain to co-ordinate and to send neural signals to the muscle telling it to contract. This process is extremely complicated, involving many neural pathways in the brain, spinal cord and peripheral nervous system. It is well-documented that improvements in these neural pathways account for some of the strength gains which result from weight training.
Research currently ongoing in our laboratory indicates that it is very likely that it is this neurological ability which is being improved by the mental practice. This research involves the measurement of brain electrical activity patterns related to preparing for and carrying out movements, known as slow potentials. Using the finger strength task, we find that the slow potential shifts in movement-related areas of the brain, such as the primary motor cortex and supplementary motor area, are very similar during mental and physical practice. The motor areas of the brain, therefore, behave in much the same way when you imagine performing a movement as they do when you actually perform the movement. Thus, the neural pathways in the brain will be enhanced by mental practice in the same way as they will be by physical practice.
To provide more concrete evidence that this is the case, we are currently comparing the changes in slow potential activity which occur over time as a result of physically or mentally practicing a strength task. While all the results are not yet in, the early results are encouraging and once again support my above hypothesis.
Therefore, we now have solid evidence that mental practice does improve strength, and some understanding of the mechanisms through which this occurs. However, this still leaves the question of how to actually perform mental practice for optimal strength gains. In the next issue, I will present guidelines for mental practice which, if you follow them as directed, should significantly improve the results you achieve from your high-intensity training program.
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In my last article, I presented evidence showing that mental practice (the mental rehearsal of a task in the absence of overt move-ment) can significantly increase muscle strength. I also noted that our research suggests that such improvements are probably due to improvements in neurological efficiency (the ability of the brain to coordinate and send neural signals to the muscle telling it to contract), rather than changes in the actual structure of the muscle.
The information we have gained in these and other studies has not only given us a good idea as to how mental practice works, but has also helped us to understand how mental practice should be performed for optimal results. The aim of this article is to present guidelines which, if followed as directed, should improve the strength gains you achieve from high-intensity training. It is important to point out, however, that these guidelines refer to the use of mental practice in addition to your physical workouts, not instead of them (except in cases such as physical injury, where you are unable to train). Mental practice is not an adequate substitute for training in the gym!
The main questions which need to be addressed here are: How often should you do it, how long should you do it for, and how should you do it? I will address the latter question first.
Probably the most important piece of advice I can give you on mental practice is that it should be as realistic as possible. I pointed out in Part 1 that the electrical activity in the motor-related areas of the brain is very similar during physical and mental practice. However, this will only be the case if what you are imagining is realistic. To make mental practice as realistic as possible, it should be done in the first person. That is, you should see what you would see, and feel what you would feel if you actually performed the movement. You should not simply visualise yourself doing the movement, like on a home movie. Instead, you should mentally simulate it, feeling the muscle shortening and lengthening, the lactic acid buildup, the pump, the sweat pouring down your face, the pounding of your heart, and so on. In other words, proper mental practice is not just forming a mental picture your workout, it is recreating the whole experience in your mind. Thus, all of the senses, not just vision, should be involved.
Anything which makes your mental practice more realistic is a step in the right direction. Many people find that imagining the smell of the gym, for example, can help them to really believe that they are in the gym lifting the weights. Some people may even benefit from changing into their gym clothes to perform their mental practice. This may sound ridiculous, but the point is that these things can help make the experience more similar to actually performing the workout.
A good mental practice session will have immediate physical effects. Your heart rate will increase, your muscles will contract, and you may even start to sweat! These are all good signs, as they are valid indicators that the motor cortex is behaving in much the same way as it would if you were actually performing your workout.
Now to frequency and duration. At first sight, it may appear that mental practice can be performed much more frequently than your actual workouts, as mental practice does not make the same inroad into your recovery ability. This is true up to a point, but caution should still be exercised. Mental practice may not be very demanding on the muscles, but it will fatigue the central nervous system, as it demands a great deal of mental effort. In my own research, I have found significant increases in muscle strength from two mental pratice sessions per week. However, as with your actual workouts, it is impossible to give a sure-fire prescription that will work optimally for everybody.
It is probably unwise, however, to perform your mental practice session on the same day as your workout. If you perform mental practice prior to your actual workout, this may adversely affect the workout, due to the high degree of mental effort involved. However, if you perform you mental practice session following your workout, you will probably be too tired to put maximum effort into your mental practice. Giving 100% effort is as important with mental practice as it is with actually lifting weights.
Your mental workout should last the same amount of time as your physical workout, involving the same exercises performed in the same manner and in the same order. Mentally simulating your workout in slow motion, or rushing through it, is unlikely to yield the same results as imagining it in 'real time'. This is because the latter strategy helps ensure that the neuronal activity in the movement-related areas of the cerebral cortex is similar to that which occurs during physical performance.
You should imagine using heavier weights than you are capable of using in your actual workouts, as imagining lifting these heavier weights will help you believe that you can actually do it in practice. Some people find that imagining lifting huge weights, far in excess of those they are actually capable of lifting, helps to inspire them, giving them a psychological boost which enhances their performance. However, others find that they cannot imagine this realistically, and thus it may not be of great benefit to these people. Individuals who fall into this category would be well advised to imagine using weights which are slightly (but realistically) heavier than those they are actually using at present.
As with actual weight training, the magnitude of the strength increases achieved through mental practice vary considerably from person to person. It would therefore be a futile exercise for me to try to predict the gains you will make from using this technique. However, I can tell you, based on my research and personal experience, that the use of these guidelines should result in significantly greater gains than you would achieve by physical training alone.
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Dave Smith has a first class BSc degree in Sports Studies from Staffordshire University, England. He is currently a researcher and lecturer in sport psychology at Manchester Metropolitan University, England, where he is completing his PhD in the psychophysiology of mental practice. Dave has coached many individuals in strength training, and is a strong advocate of Heavy Duty training principles.
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