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Literature Review on the Placebo Effect on Enhancing Performance in Sport

BSc (Hons) Sport and Exercise Science Manchester Metropolitan University 2017

Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Abstract The placebo effect has been the central role in clinical trials for over 50 years and is acknowledged as a factor in sports medicine. Until recently little has been known of the prevalence of the effect in competitive sport, as only 1 intervention study had been conducted which was in 1972 and a further 11 intervention studies in sports performance which had been investigated between 2000-2008, all these 12 intervention studies examine the effects of placebo associated with the administration of an inert substance that is informed to participants to be an ergogenic aid. Within these various studies the magnitude of the placebo effect is reported in sport from weight lifting to endurance cycling. A review and analysis of the literature found suggestion that psychological variables such as motivation, conditioning and expectancy, the interaction of these variables combined with physiological variables, prove to be a significant factor in driving both positive and negative outcome.

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Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Contents Abstract: 1.

Introduction: 1.1

Placebo effect within medicine

2.

Method:

3.

Literature investigating the placebo effect in sport:

4.

Studies being reviewed: 4.1

Ariel and Saville (1972)12

4.2

Maganaris et al. (2000):

4.3

Clark et al. (2000):

4.4

Foster et al. (2004):

4.5

Porcari et al. (2006):

4.6

Beedie et al. (2006):

4.7

McClung and Colling (2007) and Foad et al. (2008):

4.8

Beedie et al. (2007):

4.9

Kalasountas et al. (2007):

4.10

Benedetti et al. (2007) and Pollo et al. (2008):

5.

6.

Summary and Conclusion: 5.1

Ethical issues: ……………………………………………………………………………………………………………………23

5.2

Specific areas that require further research: .…………………………………………………………………...23 References: ………………………………………………………………………………………………………………………….24

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Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Introduction A placebo effect is one in which an individual benefits from receiving false information which arises from the belief that beneficial treatment has been received (Clark et al., 2000), when in reality the treatment they have received is thought to be ineffective physiologically. The opposite effect of this is called the ‘nocebo effect’ which is a negative outcome which results from a person disbelieving that they have not received the desired treatment, or that the treatment they have received is harmful (Kong et al., 2008). It has been found that the psychological effect of placebo has an influence on physiological factors during performance such as improvements in participant’s strength or endurance (Hulston and Jeukendrup, 2009). A placebo is usually in the form of a substance but not always, it can be anything that has been falsified to enhance an athletes performance in some way, such as a tennis player being informed that the new tennis racket they have received will help improve their accuracy during a serve, when the tennis racket is just a similar racket to the one they have been using, this can be known as an imagery placebo (Guillot et al., 2012). In previous studies by (Bérdi et al., 2011) and (Ariel and Saville, 1972), it was seen that participants who believe to have received the placebo do improve on the task at hand, as believing that they have received a performance enhancing treatment optimises psychological variables such as confidence, motivation and arousal, subsequently enabling the athlete to perform to their full potential (Bérdi et al., 2011). The effectiveness of a placebo highly depends upon the information of the participant receives. This research study has been chosen to understand the effect of the placebo and if it can be considered as an ergogenic aid in sport, I will be gathering and reviewing previous literature that have used placebo interventions in sport and concluding weather the outcomes of these studies give the placebo significance as a ergogenic aid.

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Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Placebo effect within medicine The placebo effect has been used and acknowledged within medicine and has been controlled for in clinical trials for over 50 years (Napier, 2003). To understand whether a new medical treatment is safer and has more effect than no treatment at all placebos are used within clinical research, researchers have found that many of the volunteers that do improve is due to psychological reasons. In order to conclude if a new medical treatment is safe and effective, the impact of the placebo effect needs to be subtracted, this allow gathering of meaningful and useful information about how safe and effective a new therapy is in treating a specific medical condition (Goldfarb, 2008).

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Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Method The method I have chosen to use to carry out this research study is a literature review which is a form of a research report, this is where I will be looking at the effect size as well as psychological and physiological mechanisms involved with the effect of the placebo, this will be done from the data taken from different journals and articles and gaining analytic insight within the results of the chosen studies. This relies on the appropriate selection of previous research studies, and requires a thorough and systematic literature search. The use of MMU library, google scholar and PubMed will be used to identify the various journals, also reviewing reference lists within retrieved articles. Reviewing literature requires the ability to juggle multiple tasks, from finding and evaluating relevant material to understanding information from a different number of sources, from critical thinking to paraphrasing, evaluating, and citation skills. (kitchenham et al., 2009).

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Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Literature investigating placebo effect in sport The approach I had used to gather significant and relevant literature to include within my research included using a chronological and thematically approach. In order to organise the research studies, to allow me to review and analyse them all critically while comparing and contrasting with other studies, I constructed a list which included all the papers I will be using for my research, the title of the study with authors names, the sample size used within the study, sample characteristics, the design of the study, performance measures, the intervention that was informed, what the participant received and finally the change that occurred from the intervention and if it was of significance or not, I had done this for all of my studies. The empirical evidence to make assumptions of the effect the placebo has on sport performance has only come alight recently, as prior to the year 2000 only one study by (Ariel and Saville, 1972) had been published. An additional 11 studies have been added from the years between 2000 and 2008 by (Maganaris et al., 2000; Clark et al., 2000; Foster et al., 2004; Porcari et al., 2006; Beedie et al., 2006; McClung and Collins, 2007; Beedie et al., 2007; kalasountas et al., 2007; Benedetti et al., 2007; Pollo et al., 2008; Foad et al., 2008). This suggests that the placebo effect is more known and can be implicated within sports to be used as an ergogenic aid.

Ariel and Saville (1972) - Anabolic steroids: the physiological effects of placebos 

6 participants



Which consisted of sub elite weight lifters



Used within subjects design



Performance measure was strength which included (bench press, military press, seated press and squat).



Intervention informed was an anabolic steroid



Received - placebo which showed a 9.5 change.



2 four week periods

7

Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Maganaris et al. (2000) – Expectancy effects and strength training: do steroids make a difference? 

11 participants



National level powerlifters



Within subjects design



Strength exercises, bench press, dead lifts and squat



Intervention informed was an anabolic steroid, anabolic steroid and then placebo



Received - placebo both times



Change was 3.8% and 1.7%

Clarke et al. (2000) – Placebo effect of carbohydrate feeding during a 40-km cycling time trial 

43 participants



Sub-elite endurance cyclists



Between subjects Latin-design (6 cell)



Performance measure – endurance (40km cycling power)



Intervention informed carbohydrate, placebo, 50/50 chance of receiving carbohydrate or placebo



Received – carbohydrate - Placebo (50% of participants), carbohydrate (50% of participants) change was 4.3 change



Received – placebo - placebo (50% of participants) carbohydrate (50% of participants) change was 0.5%



Received – 50/50 chance of receiving carbohydrate or placebo - placebo (50% of participants). Carbohydrate (50% of participants) change was -1.1



Overall placebo effect change was 3.8.

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Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Foster et al. (2004) – The placebo effect on exercise performance 

16 participants



Sub-elite runners



Within-subjects design



Performance measure – endurance (5 km running time)



intervention informed new ergogenic aid



Received - placebo



Change was 1.1

Porcari et al. (2006) – The placebo effect on exercise performance 

32 participants



Sub-elite runners



Between-subjects design



Performance measure endurance (5km running time)



Intervention informed super – oxygenated water



Received – placebo



Change was 8.0

Beedie et al. (2006) – Placebo effect of caffeine in cycling performance 

7 participants



Sub-elite cyclists



Within-subjects design



Endurance (10km cycling power)



Intervention informed 0mg/kg caffeine, 4.5 mg/kg caffeine, 9.0 mg/kg caffeine



Received – 0 mg/kg caffeine – placebo, change was -1.4%



Received – 4.5 mg/kg caffeine – placebo, change was 1.3%



Received – 9.0 mg/kg caffeine – placebo, change was 3.1%



Overall placebo effect was 2.2%

9

Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

McClung and Collins (2007) – Placebo effects of an ergogenic aid on athletic performance 

16 Participants



Sub-elite endurance athletes



Within-subjects Latin square/ balanced placebo design (4-cell)



Endurance (1000m running time)



Intervention informed sodium bicarbonate, sodium bicarbonate -0.3, no treatment, no treatment



Received - sodium bicarbonate – sodium bicarbonate, change was 1.7%



Received – sodium bicarbonate – placebo, change was 1.5%



Received – no treatment – sodium bicarbonate, change was -0.3%



Received – no treatment – no treatment, change was 0.0%



Overall placebo effect was 1.8%

Beedie et al. (2007) – Positive and negative placebo effects resulting from the deceptive administration of an ergogenic aid 

43 participants



Sub-elite athletes



Between-subjects design



Anaerobic (30m running speed)



Intervention informed positive ergogenic aid and negative ergogenic aid



Received – positive ergogenic aid – placebo, change was 0.0



Received – negative ergogenic aid – placebo, change was -1.6

Kalasountas et al. (2007) – The effect of placebo-induced changes in expectancies on maximal force production college students. 

42 participants



Untrained students



Between-subjects design



Strength measures (bench press, seated leg press) and strength (bench press, seated leg press)



Intervention informed amino acids and amino acids then placebo



Received - Amino acids – placebo, change was 19.6 10

Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971  Received – Amino acids then placebo – placebo, change was 6.3

Benedetti et al. (2007) – Opioid-mediated placebo responses boost pain endurance and physical performance; is it doping in sport competition?         

40 participants Sub-elite athletes Mixed design Pain tolerance Intervention informed – no treatment, morphine, morphine (after conditioning procedure), and morphine (after conditioning procedure). Received – No treatment – no treatment, change was 7.5 Received – morphine – placebo, change was 17.6 Received – morphine (after conditioning procedure) – placebo, change was 50.7 Received – morphine (after conditioning procedure) – naloxone, change was 6.2

Pollo et al. (2008) – The top-down influence of ergogenic placebos on muscle work and fatigue 

44 participants



Sub-elite athletes



Mixed design



Strength (leg extension), perceived fatigue



Intervention informed caffeine, caffeine (after conditioning procedure), perceived fatigue, caffeine, caffeine (after conditioning procedure)



Received – caffeine – placebo, change was 11.8



Received – caffeine (after conditioning procedure) – placebo, change was 22.1



Received – perceived fatigue – Caffeine – placebo, change was -0.3



Received – perceived fatigue – Caffeine (after conditioning procedure) – placebo, change was -7.8

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Jahad Ali

Literature Review on the Placebo Effect on Enhancing Performance in Sport

13153971

Foad et al. (2008) – Pharmacological and psychological effects of caffeine ingestion in 40km cycling performance 

14 Participants



Sub-elite cyclists



Within-subjects Latin square/balanced placebo design (4 cell)



Endurance (40 km cycling power)



Intervention informed, caffeine, caffeine, no treatment and again no treatment



Received – caffeine – caffeine, change was 2.3



Received – caffeine – placebo, change was 0.1



Received – no treatment – caffeine, change was 2.9



Received – no treatment – no treatment, change was -1.9



Overall placebo effect 0.7

Ariel and Saville (1972) The oldest and first study found to have investigated the placebo effect in sport is dated back to 1972 by Ariel and Saville, this study investigated the placebo effect of anabolic steroids. In this study the researchers reported substantial strength gains exhibited by the participants who were deceptively informed that they would be ingesting oral anabolic steroid methandrostenolone, instead these participants were given a placebo. The participants included 15 experienced weight lifters, in which 6 of these participants received a placebo throughout the study. Strength data was collected over two 4 week periods, the ’pre-placebo period’ where there was no intervention administered, and the ‘placebo period’ in which a placebo capsule was administered. The participants showed an improvement in their overall strength within the components measured which succeeded baseline measure with statistical significance at p...