The placebo effect and exercise: An investigation into the manipulation of expectations of benefits from exercise

Abstract

The placebo effect is a fascinating phenomenon that has advanced beyond the medical field into the field of sport and exercise psychology. The goal of the present study was to expand this literature by investigating the effects of expectation manipulation on perceived physical, affective, and cognitive benefits following exercise. To address this aim, 77 young adults (M_age = 29.84, SD = 9.83) were asked to rate the expected cognitive, affective, and physical benefits of a stretching program, and to elaborate on their ratings via an online survey. Participants were randomly allocated to three expectation conditions: expectation-benefit, expectation-no benefit, or no expectation control. All participants were evaluating the same stretching program, but read fictitious testimonies and watched videos that were aimed at manipulating their expectations. Analyses revealed that the expectation-benefit group expected higher cognitive and affective benefits from the stretching program than the expectation-no benefits group (ps < 0.001). No significant differences emerged on the expectation to receive physical benefits among all three groups. The thematic analysis of participants’ rationale for their ratings revealed that beliefs about benefits were modified through the testimonies and videos provided. Participants also relied on their previous knowledge or experience about stretching to inform their predictions about the expected benefits of the stretching program. Results from this study expand the knowledge on expectations manipulation in exercise settings, and provide exercise professionals with strategies to maximize the benefits participants can receive from exercise.