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2. 8. 2012.

Placebo effect

The phenomenon by which one’s expectations of a substance determine the body’s response to it it known as the placebo effect. This effect can seriously complicate the study of ergogenic qualities because researchers must be able to distinguish between the placebo effect and true responses to the substance being tested.
The placebo effect was clearly demonstrated in one of the earliest studies of anabolic steroids. Fifteen male athletes who had been involved in heavy weightlifting for the previous two years volunteered for a weight training experiment using anabolic steroids. They were told that those who made the greatest strength gains over a preliminary four-month weight training period would be selected for the second phase of the study, in which they would receive anabolic steroids.
Following the initial period, 8 of these 15 subjects were randomly selected to enter the treatment phase. Only six of these subjects passed all medical screening tests and were allowed to continue to the treatment phase. This phase consisted of a four-week period in which the subjects were told that they would receive 10 mg per day of Dianabol(an anabolic steroid), when in fact they received a placebo – an inactive substance typically provided in a form identical to the genuine drug.
Strength data were collected over the last seven weeks of the four-month pretreatment training period and over all four weeks of the treatment(placebo) period. Even through the subjects were experienced weightlifters, they continued to gain impressive amounts of strength during the pretreatment training period. However, strength gains while subjects were taking the placebo were substantially greater than during the pretreatment period! The group improved an average of 11kg(24lb) during the seven-week pretreatment period but improved 45kg(~100lb) during the four-week treatment(placebo) period. This represents an average gain in strength of 1.6kg(3.5lb) per week during the pretreatment training period and 11.3kg(25lb) per week during the placebo period – a more than seven times greater increase in the rate of strength gain during the placebo(supposed steroid) period over the pretreatment training period. Furthermore, placebos are inexpensive, risk free, and legal for use in sport. 

One of the coaches repeatedly witnessed the placebo effect while conducting a large series of studies investigating the effects of beta-blocking drugs on the ability to perform single bouts of exercise or to train aerobically. The Human Subjects Committee, a committee mandated by the federal government to oversee all research conducted with human subjects in the United States, requires that all human subjects receive a full disclosure of the risks associated with any experimental intervention so that they can provide informed consent before participating. Before the start of each study, a cardiologist presented a comprehensive background of beta-blocking drugs to each subject, including the drugs’ significance in treating various cardiovascular diseases and potential side effects associated with their use. It was amazing to note that over the course of six years of study, the most serious side effects almost always appeared in the subjects when taking the placebo.
When evaluating a substance for possible ergogenic qualities, researchers must remember that witnessing and ergogenic effect does not necessarily prove that a substance is truly ergogenic. All studies of potential ergogenic substances must include a placebo group so that researchers can compare actual responses resulting from the test substance with those resulting from a placebo. In many studies, a double-blind experimental design is used, in which neither the subject nor the experimenter knows who is getting the proposed ergogenic aid and who is getting the placebo. This is done to eliminate “experimenter bias”, whereby the experimenter’s beliefs might affect the outcome of the study. With this design, the substances are coded and only an independent person not associated with the project has access to the codes. See the introductory chapter for more information on the proper control of experiments.

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