The placebo effect can be tricky to define and fathom. Some say it is a positive outcome from the belief in a treatment. Some say it is the mind helping the body. Some say it does not exist, on the logic that something inert (a placebo) can have no effect, or they argue that if the effect is mediated not physically but psychologically, this “psychotherapy” is not inert. And then, they throw in the notion of a nocebo. Believe me, it can get confusing (3). Fortunately, for something that may not exist, studies on it abound, so we can all try to keep learning about it. I cover recent studies in the following sections, and conclude with a caution.
Self-Talk: I Think I Can. I Think I Can. I Think I Can.
If the placebo effect in medicine is the mind helping the body heal, the placebo effect in sports is the mind helping the body perform. Self-talk may or may not be defined as a placebo, but according to a new study, it can enhance sports performance. This comes as no surprise to The Little Engine That Could, whose positive self-talk mantra was “I think I can” as it huffed and puffed and hauled the heavy train over the mountain. This new study may be the first to show that positive self-talk can significantly reduce rated perceived exertion (RPE) and enhance endurance cycling (2).
In the study, 24 recreationally trained young persons performed an incremental, high-intensity cycling time-to-exhaustion (TTE) test 3 times and were randomized into 2 groups of 12 after the second test. The first TTE was to gauge peak power output and maximal aerobic capacity. The second TTE was the baseline. Then, one group was taught self-talk (e.g., “drive forward,” “doing fine,” “feeling good,” “push through this”) and the other group was not. In the third TTE, the self-talk group, but not the control group, significantly reduced their RPE halfway through the test and increased their TTE by 18% (mean, 637 to 751 s).
That motivational self-talk seemed to increase TTE so markedly was taken as support for the hypothesis that the point of exhaustion is set not so much by muscle fatigue as by perception of effort. In other words, the athlete makes a conscious decision to “give up” (i.e., disengage from the endurance exercise trial) when the perceived effort becomes too great to continue (2,7). The authors call for more research on psychobiological interventions to reduce the perception of effort and so enhance endurance performance. The authors note that the lack of a familiarization trial was a limitation of their study and that their findings may reflect a placebo effect. I agree.
A similar study showed that psychological skills training (PST) can improve exercise performance in the heat. In a climate chamber, 18 men completed three maximal-effort, 90-min treadmill runs in the heat (30°C; 40% relative humidity). After the second run, matched subjects were randomized into a control group and a group that was taught PST, that is, goal setting, relaxation tips, mental imagery, and self-talk. In the third run, the PST group, but not the control group, ran significantly farther (8%; 1.15 km). No difference was seen in RPE. The authors conclude that performance in the heat has a psychological component that can be manipulated. They could not tell exactly how PST improves running in the heat. They admit it may be placebo effect, from greater contact with the experimenters who taught the PST (1). I agree.
Deception in Feedback During Performance
Deception also has been studied as a means of enhancing athletic performance. For example, cyclists pace themselves to delay fatigue and optimize performance. This is a conscious decision based on an estimate of the utmost physiological strain that can be maintained for the expected duration of the bout. In other words, as if to protect a “metabolic reserve,” self-paced exercise is performed at an intensity below top physiological capacity. It is proposed that gaining access to this metabolic reserve could benefit exercise performance (11).
In one deception study, 29 cyclists performed three 20-km time trials using their own bike on a Computrainer. The first two trials were performed either without feedback, with accurate feedback, or with false feedback, showing speed to be 5% faster than it really was. On the third trial, with accurate feedback, those who got the false feedback earlier believed they were capable of better performance, so they started harder and faster than usual. But later in the race, their power and speed fell off, and despite a final surge, their overall performance did not improve (8).
In another deception study, nine cyclists completed four 4-km time trials, viewing their progress via an onscreen avatar. Trial 1 was for habituation; trial 2 was for a baseline. On trials 3 and 4, which were counterbalanced, the avatar was set correctly, reflecting true baseline performance, or set deceptively, inflating baseline power output to 102%. The cyclists completed the “false avatar” trial 1.7% faster than the baseline trial and 1.0% faster than the “true avatar” trial. It was concluded that cyclists hold onto a metabolic reserve even during maximal time trials, and this reserve can be tapped after deception (11).
Placebo Power by Injection
Paavo Nurmi, the “Flying Finn,” dominated distance running in the early 20th century. He won nine Olympic gold medals. A taciturn champion, Nurmi emphasized psychological strength. He said muscles are just pieces of rubber and “mind is everything.” A new study on the power of placebo fits the Nurmi hypothesis: Runners who believed they were injecting themselves with erythropoietin (Epo) ran faster, even though they were injecting placebo (10).
The study was based on the premise that any benefit of any placebo is best gauged in a “real-world” race, because head-to-head competition alone can enhance performance. To this end, 15 well-trained, club-level male runners completed the randomized crossover design of 3-km races before and after 7-d “control” versus “placebo” phases. There was no intervention during the control phase. During the placebo phase, participants injected themselves subcutaneously with saline every day, believing it to be a new drug that mimicked Epo.
Result? Race time was significantly faster (mean, about 10 s or 1.2% faster) in response to the placebo intervention, but not so (<2 s faster) in response to the control condition. When the men believed they were injecting an Epo-like drug, they ran faster. The authors note that the men were not elite athletes and that the 1.2% benefit, while of “clear sporting relevance,” is smaller than the performance improvement from Epo itself (10). They do not mention, however, that up to 25 or 30 elite cyclists have died from abusing Epo (4).
These intriguing studies on self-talk, deceptive feedback, and placebo power offer insight into key psychobiological aspects of top athletic performance. Let us not forget, however, that athletes or soldiers determined to “give 110%” in a setting where coaches or drill instructors “demand 110%” can end up dead. Self-talk may enable you to go longer in the heat, but combined with “coach talk” may push you into fatal exertional heat stroke. The same caution applies in the face of sickle cell trait, as reflected by the increasing reports of fatal exertional sickling from extraordinary and sustained exercise intensity not only in certain athletes but also in the U.S. Army, the Air Force, and even the U.S. Naval Academy (5,6,9). Self-talk and coach talk can help you go, but it can be wiser to stop — and live to fight another day.
1. Barwood MJ, Thelwell RC, Tipton MJ. Psychological skills training improves exercise performance in the heat. Med. Sci. Sports Exerc.
2008; 40: 387–96.
2. Blanchfield AW, Hardy J, De Morree HM, et al. Talking yourself out of exhaustion: the effects of self-talk on endurance performance. Med. Sci. Sports Exerc.
2014; 46: 998–1007.
3. Eichner ER. Placebos for athletes: do they exist? If not, do they work anyway? Curr. Sports Med. Rep.
2013; 12: 134–5.
4. Eichner ER. Top marathon performance: interesting debate and troubling trends. Curr. Sports Med. Rep.
2015; 14: 2–3.
5. Fajardo KA, Tchandja J. Exercise-induced cardiac arrest in a sickle cell trait-positive Air Force recruit: a case report. Mil. Med.
2015; 180: e372–4.
6. Ferster K, Eichner ER. Exertional sickling deaths in Army recruits with sickle cell trait. Mil. Med.
2012; 177: 56–9.
7. Marcora SM, Staiano W. The limit to exercise tolerance in humans: mind over muscle? Eur. J. Appl. Physiol.
2010; 109: 763–70.
8. Micklewright D, Papadopoulou E, Swart J, Noakes T. Previous experience influences pacing during 20-km time trial cycling. Br. J. Sports Med.
2010; 44: 952–60.
9. Quattrone RD, Eichner ER, Beutler A, et al. Exercise collapse associated with sickle cell trait (ECAST): case report and literature review. Curr. Sports Med. Rep.
2015; 14: 110–6.
10. Ross R, Gray CM, Gill JM. The effect of an injected placebo on endurance running performance. Med. Sci. Sports Exerc.
2015. [Epub ahead of print].
11. Stone MR, Thomas K, Wilkinson M, et al. Effects of deception on exercise performance: implications for determinants of fatigue in humans. Med. Sci. Sports Exerc.
2012; 44: 534–41.