“I am open to self-belief”: A study examining the impact of open-label effects on postexercise affect and postintervention exercise behaviour

The contribution of placebo effects can be measured by manipulating psychological factors, such as positive expectations for exercise outcomes, without the need for traditional placebos (such as inert substances). While placebo effects are well known, research has revealed intriguing findings suggesting that placebos can have beneficial effects even when studies are performed without deception. Open-label placebo (OLP) interventions (prescribed honestly), which harness the power of belief, may represent another effective method for enhancing the benefits of exercise effects. This study compared the efficacy of a conventional placebo intervention, an OLP intervention, and a control group among 89 individuals. Participants' levels of affective response after exercise and exercise behaviour were assessed during the intervention period (4 weeks) and at follow-up (4 weeks). The results revealed similar levels of improvement in all outcomes across the three conditions. Both the conventional placebo and OLP intervention groups exhibited greater enhancements in postexercise enjoyment. OLP interventions demonstrated distinct advantages in terms of remembered affect and expectation fulfilment. Nonetheless, neither intervention directly stimulated postintervention exercise behaviour. Future studies should continue to explore the impact of OLP interventions on adherence to exercise behaviour.