Placebo in Sports
23 Jan 2016
For decades it was thought that the brain did not play a major role in determining athletic performances.
The original model of the factors limiting human performance proposed by Hill in 1924 suggested a decline of such when the oxygen demands exceeded the peripheral availability, resulting in triggering of anaerobic functions, lactic acid accumulation, homeostasis alteration and decrease in muscle contraction.
For over half a century this theory, however valid, influenced doctors and coaches and only recently, next to the concept of "peripheral fatigue", the belief of a "central fatigue" (cerebral) playing an important role too was developed.
The "Central Governor" model proposes the brain as a regulator of muscle performance and that fatigue intervenes in coincidence with changes in the concentration of neurotransmitters in the brain, particularly serotonin.
An indicator of the importance of the brain in determining athletic performances is represented by the Placebo Effect on them.
"Placebo" is an inert substance without any property or effect on performance; "Placebo Effect" is the consequence of its administration and is due to the symbolic meaning attributed to the placebo bringing forth a mental and/or organic change.
The effect is amplified by the psychosocial context, the charisma of the person (coach, physician) who suggested the "therapy" and the expectations of the subject.
Already in the 70's (Med Sci Sports 1972; 4: 124-126) it was possible to notice significant improvements (+ 4%) in the maximal strength of weight lifters who received placebo treatment, under the "guise" of anabolic steroids.
Subsequent studies have confirmed the Placebo Effect on athletic performances with a range of response ranging from -7.8% to +50.7% (Sports Medicine 2009;39:313-329).
The placebo acts not only by suggestion, but it evokes real changes in the brain and, with regards to pain tolerance, it has an effect on specific receptors responsible of activating opioid systems.
In fact, blocking the endogenous opioid substances produced by our brain with an opioid antagonist, naloxone, the placebo analgesia disappears (Journal of Neuroscience 2005;25:10390-10402).
The repeated administration of a drug (Sumatriptan) which increases the growth hormone (HGH) induces conditioned placebo responses, in which the very act of subcutaneous administration (without the presence of the drug) results in an increase of the hormone (Journal of Neuroscience 2003;23:4315-4322).
A placebo given to patients with Parkinson activates endogenous dopamine, the very same inhibited by the disease itself (Science 2001;293:1164-1166).
Placebo administered in order to evoke stimulation or sedation influence parameters such as Heart Rate and Blood Pressure (Lancet 1972;1:1279-1282) or respiratory functions in asthmatics (Psycol Br J Clin 1986;25:173-183).
Anxiety and stress can be reduced by taking a placebo (Science 1960;132:91-92).
Placebo's seem to be ideal candidates to improve the mental and physical performances of athletes, reducing or even preventing the use of performance-enhancing drugs, replacing them with an inert product unbeknown to the subject: "Cheating without cheating."
The more the athlete is cynically determined to cheat, the greater the Placebo Effect.
Those who received effective treatments in the past typically become good Placebo-Responders and some predisposed genotypes respond better than others thanks to a greater effect on their brain neurotransmitters.
The psychological component plays an essential role in physical performance: many substances considered to be ergogenic really only induce a Placebo Effect, in which the simple expectation of an increase in mental and physical performance has real effects on the brain and the motoric system.
NOCEBO EFFECT. The Placebo Effect can also go in the opposite direction: if the subject is expecting an increase in the symptom or a performance worsening, this can actually occur, particularly with regards to pain or motoric performance, with an inhibition of the production of dopamine (Arch Gen Psychiatry 2008; 65: 220-231).
The Nocebo Effect is increasingly present in our daily lives without us realizing it.
Media messages, often exaggerated or false, on the damage to health caused by this or that supposed danger, induce negative expectations in those receiving them, causing those very same symptoms that are evoked in the messages.