Pain Psychology, Placebo, and the Nocebo Effect in Personal Training

The exercise experience extends beyond the physical realm and is deeply intertwined with psychology, such as the nocebo effect. Response expectancy theory, developed by Dr. Irving Kirsch, suggests that expectations shape people’s experiences. Understanding this concept is crucial for personal trainers as it helps explain why individuals may respond differently to the same exercise.

This article examines how the language trainers use and clients’ cumulative experiences shape their responses to exercise. Placebo and nocebo effects significantly influence exercise psychology. Research indicates that positive expectations of exercise can enhance cognitive benefits, while negative expectations can diminish them (Wang et al., 2023).

The Role of Expectation and Experience

Expectation and previous experience are key mediators of placebo and nocebo effects (Reicherts, 2017). Harnessing placebo effects is vital in medical and training settings, but preventing nocebo effects may be equally important. The biopsychosocial model asserts that biological, psychological, and social factors contribute to illness.

The nocebo response, particularly nocebo hyperalgesia, illustrates how negative psychological and social influences—such as unfavorable expectations and social interactions—can impact outcomes (Benedetti, 2020).

Nocebos are the negative counterparts of placebos. While placebo effects arise from positive expectations and verbal suggestions that encourage optimism, nocebo effects stem from negative expectations anticipating deterioration. The fear-avoidance model of pain exemplifies a nocebo-like effect where fear of pain leads to increased pain perception.

A meta-analysis found that placebo effects have a moderate to large impact (d = 0.67) on motor performance, but nocebo effects can be nearly twice as strong (d = 1.20) (Chhabra, 2024). This suggests that negative expectations can impair performance even more than positive expectations enhance it.

Placebo and Nocebo in Strength and Endurance Training

A placebo is an inert agent, event, or idea that produces effects through expectation or conditioned past experiences. The term “placebo” comes from Latin, meaning “I shall please,” while “nocebo” translates to “I will be harmful.”

Studies demonstrate the placebo effect in athletic performance. Participants who believed they had consumed an ergogenic carbohydrate (CHO) drink—when they had not—still showed performance improvements. Similarly, athletes who thought they had eaten energy-infused breakfasts performed better despite consuming a placebo meal.

Conversely, nocebo effects can impair performance. McLemore et al. (2020) showed that negative beliefs about a gluten-free cornstarch capsule led to declines in range of motion (ROM), perceived exertion (RPE), and total repetitions performed. They also found that negative suggestions led to a 7%-9% reduction in muscle strength.

Additionally, a study demonstrated that individuals with negative expectations about their physical capabilities experienced decreased neuromuscular efficiency, leading to lower overall performance (Cormack et al., 2023). These findings emphasize the importance of positive communication in coaching.

The Impact of Language and Communication

Athlete support personnel should strive to maximize placebo effects by fostering positive beliefs in legitimate training methods (Hurst, 2020). Placebo effects were strongest when athletes believed an aid was banned for its ergogenic properties, reinforcing their belief in its effectiveness.

The nocebo effect arises under three primary conditions (Raglin, 2020):

• Explicit negative instructions, e.g., “This will cause pain.”
• Pre-existing negative expectations based on past experience.
• Negative side effects from treatment or medication.

Nocebo effects can significantly influence motor performance. A review by Horvath (2021) found a mean effect size of 0.60, indicating a medium-to-large nocebo effect on performance. Negative verbal information can be more impactful than positive reinforcement. Coaches should avoid language that induces fear or anxiety, such as saying:

• The session will make you really sore for at least a week
• The session will be extremely hard
• This exercise might hurt
• This is a really hard exercise
• We might have to regress the exercise if you can’t do it

Nocebo Effects in Rehabilitation and Exercise Adherence

Personal trainers face challenges motivating clients to exercise. Negative expectations can diminish the benefits of exercise. Research shows that many patients with musculoskeletal (MSK) pain struggle to follow exercise prescriptions due to fear of movement or unfavorable past experiences (McLeod et al., 2023). Catastrophizing beliefs, in particular, are linked to poorer outcomes and increased pain sensitivity (Sullivan et al., 2001).

Exercise is a fundamental treatment for MSK pain (Cormack et al., 2023), yet personal trainers sometimes do not effectively communicate its benefits. When exercise is presented negatively, clients may view it as ineffective or even harmful. This is similar to serving a gourmet meal in an unattractive manner—its worth is diminished, which may discourage future participation.

Clinicians and trainers must ensure their messaging aligns with patient expectations and perceptions. Providing evidence-based information alone is not always enough; trainers must communicate in a way that resonates with the client’s values and beliefs (Raglin et al., 2021).

Fostering a Positive Relationship with Exercise

The positive relationship between trainer and client is crucial for mitigating nocebo effects. A strong relationship fosters engagement and enhances outcome expectations. Trainers should:

• Use positive language when prescribing exercise.
• Involve clients in decision-making.
• Align exercise prescriptions with clients’ goals and preferences.
• Build a strong rapport through effective communication and active listening.

A study in Cormack et al.’s review (2023) found that trust in a healthcare provider significantly influenced treatment outcomes in chronic pain patients. Trainers who create an environment of trust and empowerment can enhance clients’ belief in their ability to improve, reinforcing positive outcomes. The integration of graded exposure, where clients gradually increase intensity while receiving positive reinforcement, has reduced fear-avoidance behaviors (Bendetti et al., 2023).

Creating a Positive Exercise Experience

Negative experiences with exercise can lead to nocebo effects, fear of reinjury, and lower adherence. Hope and fear shape outcome expectations (Cormack, 2023). Trainers should:

• Use positive messaging to reinforce resilience and strength.
• Provide success-oriented feedback rather than focusing solely on corrections.
• Avoid over-medicalizing exercise, which can shift focus away from the individual’s experience.

Movement can reinforce positive messages, emphasizing that the body is strong and capable (Cormack et al., 2023). Trainers should remember that their words and attitudes shape their clients’ exercise experience and adherence.

Conclusion

Nocebo effects can impact exercise perception, adherence, and general fitness and rehabilitation outcomes. This article underscores the significance of communication and expectation management in personal training. While the optimal exercise dosage for MSK conditions remains uncertain, researchers should explore the role of nocebo effects in different training environments. Future studies should examine:

• How patients and clinicians perceive negative elements in exercise prescription.
• Barriers to exercise adherence related to nocebo effects.
• The impact of different coaching styles on exercise perception and performance.

From a practical standpoint, trainers should:

• Frame exercise positively rather than emphasizing its difficulty.
• Ensure clients feel in control of their training program.
• Focus on small, achievable goals to build confidence and engagement.
• Involve clients in the decision-making process of exercise programming.
• When selecting exercises, consider the client’s beliefs, values, experiences, expectations, and preferences.

Trainers should not only concentrate on the exercises they prescribe but also on the messaging and psychological context in which these are delivered. By creating a positive training environment, trainers can amplify placebo effects, lessen nocebo effects, and enhance client outcomes.

References

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