Do placebo expectations influence perceived exertion during physical exercise?

Abstract

This study investigates the role of placebo expectations in individuals’ perception of exertion during acute physical exercise. Building upon findings from placebo and marketing research, we examined how perceived exertion is affected by expectations regarding a) the effects of exercise and b) the effects of the exercise product worn during the exercise. We also investigated whether these effects are moderated by physical self-concept. Seventy-eight participants conducted a moderate 30 min cycling exercise on an ergometer, with perceived exertion (RPE) measured every 5 minutes. Beforehand, each participant was randomly assigned to 1 of 4 conditions and watched a corresponding film clip presenting “scientific evidence” that the exercise would or would not result in health benefits and that the exercise product they were wearing (compression garment) would additionally enhance exercise benefits or would only be worn for control purposes. Participants’ physical self-concept was assessed via questionnaire. Results partially demonstrated that participants with more positive expectations experienced reduced perceived exertion during the exercise. Furthermore, our results indicate a moderator effect of physical self-concept: Individuals with a high physical self-concept benefited (in terms of reduced perceived exertion levels) in particular from an induction of generally positive expectations. In contrast, individuals with a low physical self-concept benefited when positive expectations were related to the exercise product they were wearing. In sum, these results suggest that placebo expectations may be a further, previously neglected class of psychological factors that influence the perception of exertion.

A below-knee compression garment reduces fatigue-induced strength loss but not knee joint position sense errors

“…Future studies need to solve the inconsistencies by separating the effects of compression from placebo (Mothes et al 2017) through the detection of the physiological mechanisms underlying the effect of compression on targetmatching behaviour. Using kinesthetic movement reproduction task rather than a proprioceptive identification of joint position is more favorable because this setup excludes the possibility that an increase in the ROM increases the cognitive difficulty of the task, resulting in greater JPS errors in more extended knee joint positions.…”

An above-knee compression garment does not improve passive knee joint position sense in healthy adults

“…Although applying compression/ischemia resulted in a less accurate joint position sense by impairing afferents [ 10 ], many other studies reported that CGs could improve physical performance [ 36 , 37 ] or proprioception [ 5 , 6 , 14 ]. Perhaps much of the favourable motor outcomes is nothing more than a placebo effect [ 38 ].…”

Can the add‐on placebo effect augment the physical and mental health outcomes of exercise? A meta‐analysis

“…Numerous studies have investigated the positive effects of acute and long‐term exercise on affect, cognition, and fitness (Arbinaga et al, 2018; Lindheimer et al, 2017; Martland et al, 2020). The specific direction and magnitude of these responses vary from one individual to another, depending on the expectation of the exercise (Lindheimer et al, 2019; Mothes, Leukel, Jo, et al, 2017; Mothes, Leuke, Seelig, et al, 2017; Stanforth et al, 2011); in other words, the specific outcome, characterized by self‐confirmation and stability, is based on previous experience that a future event will occur (Beedie et al, 2018). There is also a link between expectations and exercise benefits.…”