sustainability Article Conditions under Which Trickle-Down Effects Occur: A Realist Synthesis Approach Luke R. Potwarka 1 and Pamela Wicker 2, *   Citation: Potwarka, L.R.; Wicker, P. Conditions under Which Trickle-Down Effects Occur: A Realist Synthesis Approach. Sustainability 2021, 13, 69. https://dx.doi.org/10.3390/su1301 0069 Received: 26 November 2020 Accepted: 18 December 2020 Published: 23 December 2020 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2020 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/). 1 Department of Recreation and Leisure Studies, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada; lrpotwarka@uwaterloo.ca 2 Department of Sports Science, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany * Correspondence: pamela.wicker@uni-bielefeld.de; Tel.: +49-521-106-12994 Abstract: Policy makers often legitimize bids for major sport events and public funding of elite sports by trickle-down effects, suggesting that hosting events, sporting success, and athlete role models inspire the population to participate themselves in sport and physical activity. According to previous review articles, empirical evidence of trickle-down effects are mixed, with several studies citing marginal or no effect. The purpose of this study is to apply a realist synthesis approach to evaluate under which conditions trickle-down effects occur (i.e., what works for whom under which circum- stances?). Using rapid evidence assessment methodology, 58 empirical articles were identified in the search process and critically analyzed through the lens of realist synthesis evaluation. The analysis identified six conditions under which trickle-down effects have occurred: Event leveraging initiatives, capacity of community sport to cater for new participants, live spectating experiences, consumption possibilities on television or other media, and communities housing event venues. The findings have implications for the sustainability of sport policy decisions and public finance, as the likelihood of trickle-down effects increases with integrated planning and sustainable spending related to the above six conditions. Keywords: demonstration effect; sport participation legacy; sport event; evaluation 1. Introduction Bids to host elite international sport events often point to trickle-down effects (TDE) as one of the benefits associated with staging the event [1]. These effects refer to the inspiring role of elite sport including an event’s capacity to increase sport and/or physical activity (PA) levels within host populations [2]. TDE are often employed as one argument to legitimize the spending of public money to support these events ex ante or to finance elite sport programs. To this end, claims of TDE can be used by event and elite sport stakeholders (e.g., governments and policymakers) to position events and elite sports as having positive and sustainable social impacts in host communities [3]. For instance, examples of TDE rhetoric from the London 2012 Olympic Games bid include: “ ... the Olympics will be the catalyst that inspires people of all ages and all talents to lead more active lives” [4] (n.p.); and “ ... [if London hosts the Olympics] grassroots participation will be boosted. An already sports-mad nation would get fitter and healthier” [5] (p. 2). Outcomes of TDE can be measured in terms of new participants in a sport or PA, an increase in participation frequency, participants returning to a sport after a long hiatus, or participants switching from one sport/activity to another [2]. To date, empirical evidence of TDE is mixed, with several studies reporting minimal or no changes in post-event participation [6]. These findings have led some researchers to dismiss claims of TDE, arguing that there is no reliable evidence to support their existence. Weed [2], for example, stated that there is “no reliable evidence to indicate that any Games staged to date had raised participation in the host community” (p. 7). Indeed, sport researchers are beginning to critique this area of inquiry in terms of both theory Sustainability 2021, 13, 69. https://dx.doi.org/10.3390/su13010069 https://www.mdpi.com/journal/sustainability