Can the add-on placebo effect augment the physical and mental health outcomes of exercise? A meta-analysis
Funding information: This research was supported by the Fundamental Research Funds for the Central Universities, Beijing Sport University, Grant/Award Number: Grant No.2020040
This study aimed to clarify whether the add-on placebo effect can augment the psychological and physiological benefits of exercise. The inclusion criteria were met by 18 studies with 1,221 participants. The add-on placebo effects promoted a more positive affect (g = 0.430), greater self-esteem (g = 0.454), improved cardiorespiratory fitness (g = 0.273), and decreased perceived exertion (g = 0.476) and blood pressure (g = 0.268). Improved affect benefits were moderated by placebo type (elaboration > external medium), self-selected exercise intensity (no > yes), and exercise type (running > nonspecific). The results support the proposal that the add-on placebo effect can provide significant positive benefits for exercisers, particularly in terms of psychological responses.
DATA AVAILABILITY STATEMENT
The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials.
|aphw12315-sup-0001-Appendix-1.xlsxExcel 2007 spreadsheet , 23.7 KB||
Appendix S1. Original Data Extraction database. (There are 3 sheets of original Excel data, including 3 tables. Hedge's g is calculated directly by the CMA software through the input of the sample size of the control group and the add-on placebo group, the mean and standard deviation of the pre- and post-test (sheet1-Table 1). If the pretest mean and standard deviation were missing, the post-test statistics were used (sheet2-Table 2); if both the pretest and post-test statistics were missing, the effect size or F value reported in the literature was used to calculate Hedge's g (sheet3-Table 3).
|aphw12315-sup-0002-Appendix-2.docxWord 2007 document , 29.4 KB||
Appendix S2. Characteristics of included studies (Table 1. All included studies, associated participants, add-on placebo group, control group, exercise characteristics, outcome measure and quality of the study; Search strategy included combinations of key terms).
|aphw12315-sup-0003-Appendix-3.docxWord 2007 document , 417.4 KB||
Appendix S3. Study Quality Evaluation. (Figure 1. Methodological Quality Evaluation Chart Included in Research Literature; Figure 2. Summarized risk of bias graph).
|aphw12315-sup-0004-Appendix-4.docxWord 2007 document , 283.7 KB||
Appendix S4. Publications bias evaluation. (Figure 1–5. Funnel plots for blood pressure, cardiovascular fitness, affect, self-esteem, RPE).
|aphw12315-sup-0005-Appendix-5.docxWord 2007 document , 378 KB||
Appendix S5. Forest plot for outcomes. (Figure 1–5. Forest Plot of Meta-analysis of add-on placebo effect on different outcomes).
|aphw12315-sup-0006-Appendix-6.docxWord 2007 document , 556.4 KB||
Appendix S6. Multilevel Meta-analysis of add-on placebo effect on affect (Figure 1. Forest plot on affect at multiple times (two-level models); Figure 2. Forest plot on affect at multiple times (three-level models)).
|aphw12315-sup-0007-Appendix-7.xlsxExcel 2007 spreadsheet , 813.6 KB||
Appendix S7. Original data for Multilevel Meta-analysis on affect (Table 1. Two-level models of add-on placebo effect on affect; Table 2. Three-level models of add-on placebo effect on affect).
Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
references marked with an asterisk indicate studies included in the meta-analysis.
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