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Don't Underestimate the Power of Suggestion
Author:
Stan Reents, PharmD
Original Posting:
02/04/2008 08:36 AM
How many of you know what the "placebo effect" is?
The mind is very powerful, but it can be easily misled. It turns out that we are all affected by marketing and advertising a
lot more than we think. Even physicians are susceptible. Studies show
that hospital use of a specific antibiotic increases in response to
pharmaceutical sales reps "detailing" those physicians on that drug.
In this review, I will summarize some examples that illustrate how easily perceptions can be influenced.
THE POWER OF SUGGESTION IN COLLEGE STUDENTS
Even very intelligent people can be fooled, as evidenced in this study of medical students from way back in 1959:
Researchers performed a variety of hoaxes on medical students to measure how stress affected heart rate and blood flow. In order to
create a realistic stress response, the psychological scenarios were extreme and bizarre. These included:
- administering a grueling oral exam in the area of physiology and then severely criticizing the students with each response, whether or not it was correct
- convincing the students that, after inserting a needle into their arms, something had gone wrong and they were losing a large amount of blood
- dissecting open the stomach of a rabbit and then telling the student he had to consume the contents
In most of the trials, these medical students believed the stories and panicked, which
was the whole point of the study in the first place: to examine the
effects of the autonomic nervous system during stress. In one student, resting heart rate increased from 80 bpm to 140 bpm after he believed he was experiencing severe blood loss. (Blair DA,
et al. 1959).
THE POWER OF SUGGESTION IN FOOD MARKETING
In a recent study from Stanford University, researchers had subjects rate the taste of food from McDonald's. In some cases, it was served in the original wrapper (thus, making it clear that the food was McDonald's), and, in other cases, the original wrapper was replaced with an unmarked wrapper.
In every case, the subjects rated the "McDonald's-wrapped" food as tasting better even though all of the food was from McDonald's. Even the McDonald's-wrapped carrots were rated as tasting better!
Now, here is the punch in the gut: all of the study subjects were.....pre-schoolers!
Further, the preference of the McDonald's brand was higher in children from households that had more television sets and ate at McDonald's more often (Robinson T, et al. 2007).
This study shows how food-branding and marketing can begin to affect our psyche at a very early age.
But, perhaps you may be saying, "it's not relevant....those were children....I'm not that gullible." If so, think again:
One of the national TV networks recruited young professionals from New York City to participate in a taste-test of various vodkas. Before the test, each subject was asked what their favorite vodka was. Then, they were asked to sample several vodkas, including their personal favorite, without knowing the brands they were tasting. In several cases, the subjects rated their supposed "favorite" poorly during the test. Premium brands such as Belvedere and Grey Goose were not rated better than more economical brands such as Smirnoff.
THE POWER OF SUGGESTION IN CLINICAL RESEARCH
To avoid obtaining misleading results when doing research in humans, the use of a placebo (ie., a control group) is often necessary.
Here's an example:
A researcher recruited people to participate in an analysis of a drug used to promote and improve sleep. The researcher told the subjects that some would receive the active drug and others would receive a placebo. (This is exactly how a placebo is used in scientific study, and, it is customary to inform subjects that a placebo is being used, but not tell them which one they receive.)
At the end of the sleep study, the researcher asked his subjects about their sleep quality. Many subjects stated that they slept much better and were certain that they had received the active drug, even though they didn't know what they had been given. In fact, some subjects liked the "drug" so much, that they wanted to continue taking it.
Now, here's the catch: BOTH groups received a placebo. Not one subject received any active drug!
This illustrates how the power of suggestion can influence research results. This is called "the placebo effect."
ATHLETES CAN ALSO BE FOOLED
So what does all this have to do with exercise, fitness, and/or sports nutrition, which, of course, are the topics we focus on here at AthleteInMe.com®?
It turns out that the placebo effect can fool athletes into thinking a supplement works when, in fact, it doesn't.
 • Study #1: In 2006, researchers in the UK recruited well-trained cyclists for a study of the effects of caffeine on cycling performance. The cyclists were told to perform three 10-km time trials. Before each one, they were told they would receive either placebo, caffeine 4.5 mg/kg, or caffeine 9.0 mg/kg, in random order. (caffeine and placebo were administered as capsules in this study)
Performance improved as expected: performance after low-dose caffeine was better than performance after taking the placebo, and, performance after taking high-dose caffeine was better than both of the other trials (Beedie CJ, et al. 2006).
Now, here is the kicker: no caffeine was ever administered! During all 3 time-trials, the athletes received placebo. In fact, the power of suggestion was so strong that all of the cyclists stated that they experienced caffeine-related side effects (despite not receiving any caffeine)!
What happened here was that the athletes performed better solely on the basis that they believed they would.
Another study, also from the UK, went like this:
• Study #2: Forty-two "team sport" athletes were recruited to perform a series of 30-meter sprints. After collecting baseline times, the athletes were given 200 mg of cornstarch in a gelatin capsule, but, they were told that it was an ergogenic substance and would likely improve their sprint times. Twenty minutes after taking the capsule, the athletes repeated the sprints. Performance was indeed better after the athletes ingested the cornstarch placebo (Beedie CJ, et al. 2007).
Here is another one, with an even more unique design (I just love this kind of research):
• Study #3: Researchers in Scotland recruited elite runners to complete a series of 1000-meter time trials. In this study, the effects of sodium bicarbonate and placebo were compared. (Sodium bicarbonate is known to provide ergogenic effects during high-intensity, short-duration physical effort.)
When the athletes believed that they had been given sodium bicarbonate (even though they had actually received placebo), their performance was improved. Conversely, when they were given sodium bicarbonate but were not told, their performance did not improve (McClung M, et al. 2007). Again, this shows that what you believe can influence your performance.
GUIDELINES TO CONSIDER WHEN EVALUATING SUPPLEMENTS
The point of this discussion is to get you to question what you read, hear, and think about supplements. In doing so, there are 2 major issues to always keep in mind:
Testimonials are no substitute for evidence / proof / data
 It is important that you realize that, in the US, supplements do not
undergo extensive and rigorous scientific evaluation for efficacy
before they are placed into the marketplace. They don't have to.
Why? Because the 1994 DSHEA law allows manufacturers to market
supplements (in the US) without proof of efficacy as long as they do
not make specific claims.
You should never believe that a
supplement works just because (a) you think it does or (b) someone
tells you it does. Even if you take it for a week or 2, and, even if
you are absolutely certain that it is making a difference, it could
simply be the placebo effect that you are perceiving....just like the various studies I described above. You should be even more skeptical if the person trying to convince you to buy a supplement receives a commission on sales of that product.
Research conducted without a placebo control group may not be valid
Even when research on the efficacy of a supplement has been conducted, look to see if a "placebo control group" was used. If it wasn't, then it will be very difficult to prove that whatever results were observed were truly due to the supplement being studied.
SUMMARY
In the US, supplements do not undergo extensive and rigorous scientific evaluation for efficacy before they are placed into the marketplace. Even when research has been conducted on the performance-enhancing effects of supplements, that research may not be valid if a placebo-control group was not used. The observed results may be due to the power of suggestion.
QUESTIONS
Q: What is a "placebo"?
ANSWER: In very simplistic terms, a "placebo" is simply a "fake" drug....ie., a
sugar pill. In scientific study, it is very important to plan for the
possibility that the placebo effect can influence the results. The
reason for this is because when humans expect a response will occur, a
physiologic (ie., measurable) response can actually occur...even when
they receive the sugar pill. Human beings are known to change their behavior when they know they are being studied; this is called the "Hawthorne Effect." The use of a placebo helps to make research findings more reliable.
FOR MORE INFORMATION
Readers may also be interested in this review:
PERSONALIZED FITNESS and WELLNESS COUNSELING
If you'd like some help designing your personal fitness program, or
have questions regarding exercise, or simply want some regular
motivation, sign-up for our Fitness Counseling Service. It may be the best investment in your health that you'll ever make. REFERENCES
Beedie CJ, Stuart EM, Coleman DA, et al. Placebo effects of caffeine on cycling performance. Med Sci Sports Exerc 2006;38:2159-2164. Abstract
Beedie CJ, Coleman DA, Foad AJ. Positive and negative placebo effects resulting from the deceptive administration of an ergogenic aid. Int J Sport Nutr Exerc Metab 2007;17:259-269. Abstract
Blair DA, Gover WE, Greenfield AD, et al. Excitation of cholinergic vasodilator nerves to human skeletal muscles during emotional stress. J Physiol 1959;148:633-647. Abstract
McClung M, Collins D. "Because I know it will!": placebo effects of an ergogenic aid on athletic performance. J Sport Exerc Psychol 2007;29:382-394. Abstract
Robinson TN, Borzekowski DL, Matheson DM, et al. Effects of fast food branding on young children's taste preferences. Arch Ped Adolesc Med 2007;161:792-797. Abstract
ABOUT THE AUTHOR
Stan Reents, PharmD, is a former healthcare professional. He holds
Personal Trainer and Fitness Counselor certifications from the American
Council on Exercise. He has been certified as a tennis coach by USTA.
He is the author of Sport and Exercise Pharmacology (published by Human Kinetics). He can be reached at: Editor@athleteinme.com.
Last Revision: 03/27/2010 10:46 AM
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