Ph.D Anna Gerke
email: agerke@audencia.com

Ph.D Julia Fehrer

Maureen Benson-Rea

Ph.D Brian P Mccullough

Ph.D Maureen Bensons-Rea

A Typology of Circular Sport Business Models: Enabling Sustainable Value Co-Creation in the Sport Industry

Keywords: Circular economy, sport business models, sustainability, sport ecology, pluralism, circular ecosystems

There is a continuing interest in the relationship between sport and nature. As a new field, sport ecology explores the impact sport has on the natural environment and how sport organizations and individuals can promote sustainability. However, a critical element is still missing in the sport ecology discourse -the link between organizations' sustainability efforts and their value co-creation processes. The circular economy can provide this link by decoupling the value co-creation of sport business models from their environmental impact and resource depletion. Based on an extensive literature review, this study provides a new theoretically derived typology of circular sport business models, including comprehensive reasoning about sustainable value co-creation processes in the sport industry. It explains how sport managers of all three sectors -for-profit, public, and non-profit, can transition toward more sustainable and circular business practices and offers integrative guidelines for future research.

Introduction

Sport ecology is a relatively new field focusing on the intersection of sport and environmental sustainability. It is centered on exploring the impact of sport on the natural environment and how sport organizations and individuals can reduce their negative impact and promote sustainability [START_REF] Mccullough | Sport Ecology: Conceptualizing an Emerging Subdiscipline Within Sport Management[END_REF]. This involves understanding how the organization of sport activities affects the natural environment [START_REF] Collins | Measuring the environmental sustainability of a major sporting event: a case study of the FA Cup Final[END_REF][START_REF] Mallen | The Assessment of the Environmental Performance of an International Multi-Sport Event[END_REF] and how nature and changes in the natural environment impact the practice of sport, sport events, and sport venues [START_REF] Kellison | Sport stadiums and environmental justice[END_REF][START_REF] Orr | Sport versus climate: Introducing the climate vulnerability of sport organizations framework[END_REF]. Current research highlights various aspects of environmental sustainability in sport, encompassing the environmental repercussions of events, motivations driving fans and athletes toward pro-environmental actions, and obstacles hindering such engagement [START_REF] Casper | Athletics Department Awareness and Action Regarding the Environment: A Study of NCAA Athletics Department Sustainability Practices[END_REF][START_REF] Cury | Environmental sustainability in sport: a systematic literature review[END_REF][START_REF] Mccullough | Advancing sport ecology research on sport and the natural environment[END_REF]. While this work is beginning to create awareness and education about environmental sustainability among athletes, fans, and other stakeholders in the sport industry, there is still an essential element missing in this discoursethe link between organizations' sustainability efforts and the value co-creation processes of sport business models and strategies. Organizational strategy in sport is an under-researched topic, especially for organizations from the nonprofit sector [START_REF] Gerke | Strategic processes in Australian golf clubs: a dynamic capabilities view[END_REF]. Moreover, those studies taking an organizational strategy approach tend to draw from theories like the resource-based view [START_REF] Amis | Achieving a Sustainable Competitive Advantage: A Resource-Based View of Sport Sponsorship[END_REF][START_REF] Gerrard | What does the resource-based view "bring to the table" in sport management research[END_REF] and dynamic capabilities [START_REF] Demir | Strategic sponsoring in professional sport: a review and conceptualization[END_REF][START_REF] Lefebvre | The deployment of professional football clubs' eSports strategies: a dynamic capabilities approach[END_REF]. Yet these frameworks fall short in accounting for the influential roles of the natural environment and stakeholders on the periphery of the sport sphere.

A useful framework to link organizational sustainability efforts and value co-creation is the circular economy (CE), specifically circular business models (CBMs) [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Geissdoerfer | Business models and supply chains for the circular economy[END_REF]. CE is emerging as a popular narrative for societal, institutional, and organizational change that offers guidance to decouple economic activity from resource depletion [START_REF] Fischer | Understanding the role of institutional intermediaries in the emergence of the circular economy[END_REF][START_REF] Gümüsay | Researching for Desirable Futures: From Real Utopias to Imagining Alternatives[END_REF][START_REF] Stahel | The circular economy[END_REF][START_REF] Stål | A decoupling perspective on circular business model implementation: Illustrations from Swedish apparel[END_REF]. Principles of CE include using renewable energies, eliminating toxic chemicals, and eradicating waste through maximizing reuse, repair, remake, and recycling [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Geissdoerfer | Business models and supply chains for the circular economy[END_REF][START_REF] Jackson | Prosperity without growth: Economics for a finite planet[END_REF][START_REF] Kirchherr | Conceptualizing the circular economy: An analysis of 114 definitions[END_REF].

While we see an increasing push from organizations and governments to adopt the circular imperative (European Commission, 2020) and rising scholarly interest across disciplines as diverse as engineering [START_REF] Reh | Process engineering in circular economy[END_REF], environmental science [START_REF] Korhonen | Circular Economy: The Concept and its Limitations[END_REF], innovation, supply chain, and business model research [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Kirchherr | Conceptualizing the circular economy: An analysis of 114 definitions[END_REF], there is relatively little debate related to CE in sport [START_REF] Connolly | Social Entrepreneurship and Sport in Romania: How Can Former Athletes Contribute to Sustainable Social Change?[END_REF][START_REF] Fehrer | Circular Economy and Circular Business Models in Sports[END_REF]. Notable exceptions are recent studies in the context of sport events [START_REF] Bianchini | Design, implementation and assessment of a more sustainable model to manage plastic waste at sport events[END_REF], sport stadia [START_REF] Barry | Shadow Stadia and the Circular Economy[END_REF], and sport equipment [START_REF] Fuchs | Homogeneity or Heterogeneity: An Institutional Theory View on Circular Economy Practices in the Outdoor Sporting Goods Industry[END_REF], which utilize the CE framework to rethink traditional business practices. Arguably, sport equipment manufacturing, sport venue and infrastructure management, and the organization of sport training and competitions rely on vast quantities of exhaustible natural resources and non-renewable energy [START_REF] Fisher | Configuring a supply chain to reduce the cost of demand uncertainty[END_REF] and thus, require careful consideration of resource use decoupled from pollution, waste, and energy loss [START_REF] Gosalvez | Sport and the Environment: What is the Connection? Retrieved 31[END_REF].

The purpose of this study is to holistically discuss CE principles within the sport industry and provide an encompassing typology of circular sport business models and their value co-creation processes. We explore how organizations across for-profit, public, and non-profit sectors can leverage CE principles for sustainable transformations of their business models. We offer a synthesized view by systematically combining literature insights on business models within these sectors and value co-creation processes discussed in the circular business model literature [START_REF] Fehrer | A systemic logic for circular business models[END_REF][START_REF] Hoye | Sport Management Principles and Applications[END_REF]. The sport value framework [START_REF] Woratschek | The sport value frameworka new fundamental logic for analyses in sport management[END_REF], underscored by the guiding axiom of value co-creation [START_REF] Vargo | Evolving to a new dominant logic for marketing[END_REF], 2008, 2016), and its recent expansion into sport ecosystems [START_REF] Buser | Toward a Sport Ecosystem Logic[END_REF], provides the foundational perspective for our synthesis. To effectively map conceptual interrelationships, we adopt a typology-based style of theorizing [START_REF] Benson-Rea | The plurality of co-existing business models: Investigating the complexity of value drivers[END_REF][START_REF] Cornelissen | Editor's comments: developing propositions, a process model or a typology? Addressing the challenges of writing theory without a boilerplate[END_REF][START_REF] Jaakkola | Does one size fit all? New service development across different types of services[END_REF], which is particularly suitable for fields under development (Delbridge & Fiss, 2013, p. 329), since it allows for structuring complex relationships of concepts and theoretical assumptions [START_REF] Jaakkola | Does one size fit all? New service development across different types of services[END_REF].

Our research makes four important contributions. First, this study presents a typology of circular sport business models (CSBMs), including (1) circular for-profit SBMs, (2) circular public SBMs, (3) circular social purpose SBMs, and (4) circular platform SBMs.

These four archetypes highlight the potential for the sport industry to embrace the principles of CE and support a comprehensive reasoning about sustainable value co-creation processes in the sport industry. This typology can guide sport managers of all three sport industry sectors in transforming their organizations into more circular and sustainable ones. Our second contribution comes from introducing the circular platform SBM as a new archetype that overcomes traditional business model limitations by focusing on broader stakeholder engagement. It aligns with the interconnected dynamics of sport industries and promotes a collective, system-wide approach to sustainable transformation. Our third contribution underscores the sport industry's unique blend of economic and social value co-creation, spanning both for-profit and non-profit sectors. Our research illuminates how CSBMs across these sectors drive CE transformations, offering pioneering insights into circularity within social purpose and public organizations. Collectively, the CSBM framework encapsulates value pluralism and complexity, merging elements from both for-profit and non-profit sectors to realize business models that are economically sound, socially impactful, and environmentally conscious [START_REF] Castellas | Responding to Value Pluralism in Hybrid Organizations[END_REF]. More generally, it is one of the first studies that explains how circularity in social purpose and public organizations unfolds. Our last contribution includes a research agenda for sport management scholars to explore how the CE concept can advance sport management theory and strategy.

Circular Business Models as Part of Sport Ecology

Evolving field of sport ecology

Although research on sport and environmental sustainability began in the 1990s [START_REF] Cachay | Sports and Environment Sports for Everyone -Room for Everyone[END_REF][START_REF] Lenskyj | Sport and Corporate Environmentalism: The Case of the Sydney 2000 Olympics[END_REF] with studies on the complex relationship between sport and the natural environment [START_REF] Mallen | A framework for debating the future of environmental sustainability in the sport academy[END_REF][START_REF] Mccullough | Sport Ecology: Conceptualizing an Emerging Subdiscipline Within Sport Management[END_REF], and despite its increasing relevance in sport management practice, there is relatively little scholarly focus on sustainable business practices. Only recently, sport management scholars started to unpack and discuss sport and the natural environment and framed sport ecology as a new field of sport management [START_REF] Mallen | A framework for debating the future of environmental sustainability in the sport academy[END_REF][START_REF] Mccullough | Sport Ecology: Conceptualizing an Emerging Subdiscipline Within Sport Management[END_REF]. [START_REF] Sartore-Baldwin | Equity-based sustainability and ecocentric management: Creating more ecologically just sport organization practices[END_REF], for example, argue that sport organizations are embedded in an anthropocentric society. Hence, their practices are determined by humancenteredness, production, domestication, violence, and policies (i.e., anthroparchic practices).

They propose an eco-centric and equity-based approach to sport organization practices that recognizes the "interdependent relationship and similarities between humans and the environment" (Sartore-Baldwin & McCullough, 2018, p. 397). They further emphasize that humans and non-human-beings as well as the environment, are all part of larger nested systems "in which the need[s] of all living entities must be met to ensure survival" (Sartore-Baldwin & McCullough, 2018, p. 396).

Sport ecology means understanding the bidirectional relationship of how the organization of sport activities affects the natural environment [START_REF] Collins | Measuring the environmental sustainability of a major sporting event: a case study of the FA Cup Final[END_REF][START_REF] Mallen | The Assessment of the Environmental Performance of an International Multi-Sport Event[END_REF] and how nature and changes in the natural environment impact the practice of sport, sport events, and sport venues [START_REF] Kellison | Sport stadiums and environmental justice[END_REF][START_REF] Orr | Sport versus climate: Introducing the climate vulnerability of sport organizations framework[END_REF]. Sport ecology discourse has recently focused on discussions of environmental sustainability in sport, including the (negative) impact sport has on the environment [START_REF] Thibault | Globalization of Sport: An Inconvenient Truth[END_REF][START_REF] Wall-Tweedie | Is the Grass Greener on the Other Side? A Review of the Asia-Pacific Sport Industry's Environmental Sustainability Practices[END_REF], how changes in the environment impact offers and demand in sport consumption [START_REF] Mccullough | Measuring Externalities: The Imperative Next Step to Sustainability Assessment in Sport[END_REF][START_REF] Orr | Sport versus climate: Introducing the climate vulnerability of sport organizations framework[END_REF], and how fans and athletes' can engage in pro-environmental behavior [START_REF] Cury | Environmental sustainability in sport: a systematic literature review[END_REF]. Parallel to these, academic inquiries have delved into how sport organizations strategically plan around sustainability, encapsulating aspects like staff perceptions of green practices [START_REF] Casper | Athletics Department Awareness and Action Regarding the Environment: A Study of NCAA Athletics Department Sustainability Practices[END_REF][START_REF] Kellison | Organisational perception management in sport: The use of corporate pro-environmental behaviour for desired facility referenda outcomes[END_REF][START_REF] Todaro | Stimulating the adoption of green practices by professional football organisations: a focus on stakeholders' pressures and expected benefits[END_REF] and decision-making anchored in sustainability [START_REF] Mallen | The Assessment of the Environmental Performance of an International Multi-Sport Event[END_REF][START_REF] Mccullough | Formation and Function of a Collegiate Athletics Sustainability Committee[END_REF][START_REF] Pfahl | Crossing Boundaries: An Examination of Sustainability Department and Athletics Department Collaboration Regarding Environmental Issues[END_REF]. Moreover, they have examined how fans perceive sustainability and how these views might guide strategic operations in communications [START_REF] Kellison | Marketing Pro-Environmental Venues in Professional Sport: Planting Seeds of Change Among Existing and Prospective Consumers[END_REF][START_REF] Mccullough | Assessing key performance indicators of corporate social responsibility initiatives in sport[END_REF].

To foster sustainable transformations, stakeholder buy-in is critical, especially among fans. Sustainable business practices will likely appeal to fans' values and can be communicated and leveraged to drive deeper commitments with the sport organization [START_REF] Trail | Marketing sustainability through sport: testing the sport sustainability campaign evaluation model[END_REF], 2021). Specifically, research by Casper and colleagues notes that as sport organizations communicate their environmental values, they can connect with fans across the political spectrum who may not otherwise be receptive to environmental messages [START_REF] Casper | Pro-Environmental Sustainability and Political Affiliation: An Examination of USA College Sport Sustainability Efforts[END_REF] and deepen the connection with lower commitment fans [START_REF] Casper | Examining environmental fan engagement initiatives through values and norms with intercollegiate sport fans[END_REF]. Trail andMcCullough (2020, 2021) found that these campaigns can have a positive influence at sporting events and in everyday life to the extent that some fans will advocate for change in other aspects of their community.

However, there is little debate related to sustainable value co-creation and transformative business models that enable and enforce sustainable business practices. As sport organizations embed environmental sustainability deeper into their strategic blueprint [START_REF] Mccullough | The green waves of environmental sustainability in sport[END_REF], there is an impending need to innovate business models, ensuring alignment with overarching sustainable values. This calls for sport ecology studies to embrace sustainable business model paradigms. In bridging this gap, CBMs emerge as a potent tool. CBMs transcend traditional sustainability practices to counter the three-pronged global challenges of climate change, biodiversity depletion, and pollution.

Circular economy and circular business models

CE promotes the idea that economic activity and economic viability can be decoupled from resource depletion. The concept builds on work by [START_REF] Pearce | Economics of natural resources and the environment[END_REF], who questioned the linearity at the core of the dominant industrial economic model. Linearity refers to the industrial process of firms taking resources and making goods and customers using and disposing of them at their end-of-life stage. This linear path, which guides many business models in the sport industry [START_REF] Gosalvez | Sport and the Environment: What is the Connection? Retrieved 31[END_REF], is viewed as problematic because it results in increasing waste and depletion of natural resources.

Originating from industrial ecology [START_REF] Graedel | Industrial Ecology[END_REF] and ecological economics [START_REF] Commoner | The closing circle. Nature, man, and technology[END_REF][START_REF] Commoner | The closing circle. Nature, man, and technology[END_REF]), CE promotes the idea of an economy that mirrors the regenerative and restorative cycles of nature [START_REF] Lyle | Regenerative Design for Sustainable Development[END_REF][START_REF] Morseletto | Restorative and regenerative: Exploring the concepts in the circular economy[END_REF]. Subsequently, academic discussions have positioned CE as a business case for sustainability [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Esposito | Introducing a Circular Economy: New Thinking with New Managerial and Policy Implications[END_REF][START_REF] Geissdoerfer | The Circular Economy -A new sustainability paradigm[END_REF]. Such discussions underscore CE's potential as an economically viable path towards sustainability, with businesses seeking economic benefits and environmental conservation. Amid critiques around its theoretical clarity [START_REF] Corvellec | Critiques of the circular economy[END_REF], lack of parsimony and distinctiveness [START_REF] Corvellec | Introduction to the special issue on the contested realities of the circular economy[END_REF][START_REF] Geissdoerfer | The Circular Economy -A new sustainability paradigm[END_REF], and oversight of social dimensions [START_REF] Geissdoerfer | Business models and supply chains for the circular economy[END_REF], CE continues to expand, drawing significant attention in contemporary management practice [START_REF] Fehrer | Shaping Circular Service Ecosystems[END_REF]. Definitions of CE span a spectrum: from specific focuses on recycling and reuse to expansive, systemic views [START_REF] Corvellec | Critiques of the circular economy[END_REF] that perceive CE as an "industrial economy that is restorative or regenerative by intention and design" (Ellen MacArthur Foundation, 2013, p. 7). While definitions vary, there is an emerging consensus around certain principles:

(1) Designing out waste and pollution through using renewable energy and products that are "made to be made again" with easily recyclable elements [START_REF] Webster | The Circular Economy. The Wealth of Flows[END_REF] (see also work on the cradle-to-cradle idea of minimizing environmental damage through closed material loops [START_REF] Braungart | Cradle to Cradle: Remaking the Way We Make Things[END_REF]);

(2) Maintaining and prolonging material and resource use [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Geissdoerfer | Business models and supply chains for the circular economy[END_REF][START_REF] Ghisellini | A review on circular economy: the expected transition to a balanced interplay of environmental and economic systems[END_REF][START_REF] Merli | How do scholars approach the circular economy? A systematic literature review[END_REF] enabled through service [START_REF] Tukker | Eight types of product-service system: eight ways to sustainability? Experiences from SusProNet[END_REF][START_REF] Tukker | Product services for a resource-efficient and circular economya review[END_REF]; and

(3) Regenerating natural systems through regenerative design [START_REF] Lyle | Regenerative Design for Sustainable Development[END_REF], biomimicry [START_REF] Benyus | Biomimicry: Innovation Inspired by Nature[END_REF], and (eco)systemic thinking [START_REF] Fehrer | Shaping Circular Service Ecosystems[END_REF][START_REF] Fehrer | A systemic logic for circular business models[END_REF][START_REF] Konietzko | Circular ecosystem innovation: An initial set of principles[END_REF].

These principles have inspired novel CBMs, emphasizing closing, slowing, and narrowing material loops [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Esposito | Introducing a Circular Economy: New Thinking with New Managerial and Policy Implications[END_REF][START_REF] Geissdoerfer | Business models and supply chains for the circular economy[END_REF]. Closing material loops focus on recycling and collection to enhance material and energy efficiency [START_REF] Bocken | A literature and practice review to develop sustainable business model archetypes[END_REF]. This can include take-back schemes and the reuse of resources. Slowing loops accentuate the extended product lifecycle via repair, refill, and refurbishment methods [START_REF] Khan | Review on upgradability -A product lifetime extension strategy in the context of product service systems[END_REF]. This is bolstered by service business models that underscore prolonged product use, highlighting leasing, upgrading, and pay-per-use strategies [START_REF] Khan | Review on upgradability -A product lifetime extension strategy in the context of product service systems[END_REF][START_REF] Peronard | Broadening the understanding of the role of consumer services in the circular economy: Toward a conceptualization of value creation processes[END_REF]. Lastly, narrowing material loops prioritizes diminished resource intake across the value chain, fostering eco-efficiency [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Stewart | Circular economy in corporate sustainability strategies: A review of corporate sustainability reports in the fast-moving consumer goods sector[END_REF]. It promotes the adoption of renewable, biobased, or biodegradable resources.

Recent CBM studies transcend the confines of focal organizations and explore organizations in their capacity as interconnected ecosystems [START_REF] Fehrer | Shaping Circular Service Ecosystems[END_REF][START_REF] Konietzko | Circular ecosystem innovation: An initial set of principles[END_REF]. The overarching sentiment highlights the importance of inter-organizational relationships [START_REF] Gerke | An exploratory analysis of interorganisational relationships towards circular economy and their motives: insights from smaller players in the sporting goods industry[END_REF], collaboration, cooperation, and coordination [START_REF] Castaner | Collaboration, Coordination, and Cooperation Among Organizations: Establishing the Distinctive Meanings of These Terms Through a Systematic Literature Review[END_REF]. This perspective captures the complexity of multi-stakeholder settings. It recognizes that economic and societal transitions are grounded in institutional change processes and expand beyond narrow value creation by a focal organization. It allows for zooming in and out to consider value co-creation processes within and between nested and interconnected circular ecosystems [START_REF] Fehrer | Shaping Circular Service Ecosystems[END_REF][START_REF] Vargo | Institutions and axioms: an extension and update of service-dominant logic[END_REF].

While the CE narrative rapidly evolves, its spread into sport business models remains relatively unexplored [START_REF] Connolly | Social Entrepreneurship and Sport in Romania: How Can Former Athletes Contribute to Sustainable Social Change?[END_REF][START_REF] Fehrer | Circular Economy and Circular Business Models in Sports[END_REF]. By merging insights from CBMs and sport business models as they present themselves in for-profit, public, and nonprofit sectors, we aim to elucidate how CE can drive sustainable value co-creation within the sport domain.

Methodological Approach to Theorizing

Step 1: Identifying and grouping relevant research

We followed a structured process of a narrative literature review [START_REF] Greenhalgh | Storylines of research in diffusion of innovation: a meta-narrative approach to systematic review[END_REF][START_REF] Montori | Methodologic Issues in Systematic Reviews and Meta-Analyses[END_REF] of prior sport management research that considers environmental sustainability aspects combined with circular business model research. The publication search process was initially exploratory and became more focused as we became more knowledgeable on the topic [START_REF] Tod | Conducting Systematic Reviews in Sport, Exercise, and Physical Activity[END_REF]. All authors participated in the theorizing process throughout the review process through regular meetings and discussions about the reviewed material and collaborative writing.

Step 2: Evaluation of guiding theoretical framework

To identify the categories for a CSBM typology, we linked previously unconnected sport business models and CBM literature in a novel way by examining it through a lens of value co-creation [START_REF] Vargo | Evolving to a new dominant logic for marketing[END_REF], 2008, 2016). This lens offers a counterpoint to traditional sport management frameworks [START_REF] Woratschek | The sport value frameworka new fundamental logic for analyses in sport management[END_REF], in which one actor (usually the firm) creates, delivers, and captures value. Instead, [START_REF] Vargo | Evolving to a new dominant logic for marketing[END_REF] suggest that value is always co-created through a wide range of stakeholders (firms, nongovernment organizations, fans, sponsors, athletes, customers, communities, governments, and others). Importantly, all these stakeholders, when they integrate their resources (for instance, sport event managers through providing recycling stations and fans through recycling their waste), are both providers and beneficiaries of sustainable service. Integration with the sport value framework [START_REF] Buser | Toward a Sport Ecosystem Logic[END_REF][START_REF] Woratschek | The sport value frameworka new fundamental logic for analyses in sport management[END_REF] enabled us to see established business model types in a new way through a novel higher-order perspective [START_REF] Macinnis | A framework for conceptual contributions in marketing[END_REF].

Step 3: Defining four CSBM archetypes

We develop four CSBM archetypes by iterating between Steps 1 and 2 [START_REF] Benson-Rea | The plurality of co-existing business models: Investigating the complexity of value drivers[END_REF]. Following [START_REF] Doty | Typologies as a unique form of theory building: toward improved understanding and modeling[END_REF], we refer to archetypes as ideal types of business models in the sport industry. Typologies are particularly suitable for fields under development [START_REF] Delbridge | Editors' comments: styles of theorizing and the social organization of knowledge [Article][END_REF] since they allow for structuring complex relationships of concepts and theoretical assumptions [START_REF] Jaakkola | Does one size fit all? New service development across different types of services[END_REF]. According to [START_REF] Doty | Typologies as a unique form of theory building: toward improved understanding and modeling[END_REF], archetypes should be conceptually derived with explicitly defined constructs, and the relationships between constructs should be set out to enable predictions for further research and testing. In this study, we define CSBM archetypes in terms of their salient features [START_REF] Helkkula | Archetypes of Service Innovation: Implications for Value Cocreation[END_REF], comprising different configurations of stakeholders, value co-creation mechanisms, structure, and governance that enable circularity.

A typology can "reduce complexity to manageable levels, both conceptually and methodologically," hence, a typology is useful in the early stages of a research stream's development "because the systematic ordering of a phenomenon's core elements provides the initial building blocks for theory development." (Snow & Ketchen, 2014, p. 231). These building blocks offer opportunities to construct and test evolving and extend existing theory [START_REF] Snow | Typology-Driven Theorizing: A Response to Delbridge and Fiss[END_REF]. This CSBM typology draws from business models established in for-profit, public, and non-profit sport industry sectors [START_REF] Moore | Managing for Value: Organizational Strategy in for-Profit, Nonprofit, and Governmental Organizations[END_REF]. It extends them by [START_REF] Thomas | Architectural leverage: Putting platforms in context[END_REF] adding a new archetypecircular platform SBMs that transcend traditional sector boundaries and (2) (re-)defining sustainable value co-creation processes aligned with CE principles.

Typology of Circular Sport Business Models

Archetype 1: Circular For-Profit SBMs

For-profit sport organizations follow predominantly economic goals, with business models centered on manufacturing and distributing sport fashion, gear, and merchandise or providing service through professional sport leagues, sport media, sponsorship, tourism, events, facilities, and infrastructure management, as well as sport education and university college sport [START_REF] Babiak | Mapping Research on Interorganizational Relationships in Sport Management: Current Landscape and Future Research Prospects[END_REF]. Independently from the specific context, sport business models often have one central aim in common -creating experiential value for their stakeholders, including their fans, athletes, and customers [START_REF] Perić | Conceptualising innovative business models for sustainable sport tourism[END_REF][START_REF] Perić | Understanding the delivery of experience: Conceptualising business models and sports tourism, assessing two case studies in Istria, Croatia[END_REF][START_REF] Perić | Suggesting a service research agenda in sports tourism: working experience(s) into business models[END_REF].

While the majority of studies on for-profit sport organizations do not refer to the business model concept explicitly, they implicitly link their work to some form of revenuecost models [START_REF] Borges | Soccer Clubs as Media Organizations: A Case Study of Benfica TV and PSG TV[END_REF][START_REF] Buzzelli | Poaching the News Producers: The Athletic's Effect on Sports in Hometown Newspapers[END_REF][START_REF] Vera | The eSports ecosystem: Stakeholders and trends in a new show business[END_REF][START_REF] Dilys | Structural Business Model Based on Cooperation between Sports Organizations and Sponsors [Article][END_REF][START_REF] Hutchins | It's Fantasy Football Made Real": Networked Media Sport, the Internet, and the Hybrid Reality of MyFootballClub[END_REF]. A few sport management studies refer explicitly to business models as devices that firms use to mediate technology development and economic value creation [START_REF] Chesbrough | The role of the business model in capturing value from innovation: evidence from Xerox Corporation's technology spin-off companies[END_REF] or blueprints that map relationships among firms' customers, allies, and suppliers to enable product, information, and money flows [START_REF] Chelladurai | A personal journey in theorizing in sport management[END_REF][START_REF] Osterwalder | Business model generation: a handbook for visionaries, game changers, and challengers[END_REF][START_REF] Weill | What IT infrastructure capabilities are needed to implement ebusiness models[END_REF]. [START_REF] Aversa | Business model configurations and performance: A qualitative comparative analysis in Formula One racing, 2005-2013[END_REF], for instance, in the context of professional sport, conclude that Formula 1 race teams build on two complementary business models: one focused on selling technology, the other on selling well-trained human resources to competitors.

Interestingly, much of the sport management literature concerned with business models takes a broader understanding of value creation into account, including not only economic but also sport performance [START_REF] Di Minin | Udinese Calcio soccer club as a talents factory: Strategic agility, diverging objectives, and resource constraints[END_REF][START_REF] Mcnamara | Competing Business Models, Value Creation and Appropriation in English Football[END_REF] and social value creation [START_REF] Pittz | Sport business models: a stakeholder optimization approach[END_REF]. For example, Di Minin et al. ( 2014) investigated a medium-sized Italian soccer club's strategic agility [START_REF] Doz | Embedding Strategic Agility: A Leadership Agenda for Accelerating Business Model Renewal[END_REF] to understand the business model's balance of economic and sport performance. [START_REF] Pittz | Sport business models: a stakeholder optimization approach[END_REF], in their study on business models of professional sport leagues in North America, explore stakeholder relationships and ownership structures and specifically refer to social value creation. Recent studies, particularly in sport tourism, consider the natural environment as the central value driver of sport business models [START_REF] Perić | Conceptualising innovative business models for sustainable sport tourism[END_REF][START_REF] Perić | Suggesting a service research agenda in sports tourism: working experience(s) into business models[END_REF]. This provides a starting point to discuss sustainable value co-creation of circular for-profit SBMs [START_REF] Girard | From linear to circular tourism[END_REF][START_REF] Manniche | The circular economy in tourism: transition perspectives for business and research[END_REF][START_REF] Manniche | Destination: A circular tourism economy. A handbook for transitioning toward a circular economy within the tourism and hospitality sectors in the South Baltic region[END_REF][START_REF] Margaryan | Sustainable by nature? The case of (non)adoption of eco-certification among the nature-based tourism companies in Scandinavia[END_REF][START_REF] Sorin | Exploring Circular economy in the hospitality industry: empirical evidence from Scandinavian hotel operators[END_REF].

According to CE principles, circular for-profit SBMs need to be designed to achieve efficient material and information flows directed toward zero waste by closing, slowing, and narrowing biological and technical lifecycles [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Stewart | Circular economy in corporate sustainability strategies: A review of corporate sustainability reports in the fast-moving consumer goods sector[END_REF].

Material efficiency can be increased through reusing material and resources through recycling, collecting, and take-back schemes [START_REF] Bocken | A literature and practice review to develop sustainable business model archetypes[END_REF]). Adidas, for example, is exploring closed-loop manufacturing processes for its products, in which materials from used products are recycled and used to create new products. This includes local sourcing and shortening transportation [START_REF] Sorin | Exploring Circular economy in the hospitality industry: empirical evidence from Scandinavian hotel operators[END_REF]. To achieve this, Adidas has released a sneaker made with materials and technology that enables the shoes to be returned to Adidas at the end of their life cycle [START_REF] Tiernan | Adidas Releases Recyclable Sneaker for The Circular Economy[END_REF].

Furthermore, the effective reduction of material throughput (i.e., dematerialization through service) supports circular closed-loop processes [START_REF] Kasulaitis | Dematerialization and the Circular Economy: Comparing Strategies to Reduce Material Impacts of the Consumer Electronic Product Ecosystem[END_REF][START_REF] Tukker | Product services for a resource-efficient and circular economya review[END_REF]. For example, Spinlister and other peer-to-peer sport equipment rentals enable the sharing sport equipment, such as bikes, skis, or surfboards, with others in their community.

This model encourages the sharing of resources and reduces the need for individuals to purchase their equipment. In this case, value co-creation means the mutualization of assets with low utilization ratios [START_REF] Fehrer | A systemic logic for platform business models[END_REF]. This can also be seen with sport facilities or stadiums that are (re-)designed for shared purposes, to use under-utilized assets. Slowing loops prolong the use phase and end-of-life cycle through designing long-life products, repairing, sharing, refurbishing, and upgrading [START_REF] Khan | Review on upgradability -A product lifetime extension strategy in the context of product service systems[END_REF]. For instance, companies like REI (2020) and [START_REF] Patagonia | Patagonia Wins Circular Economy Multinational Award at World Economic Forum Annual Meeting in Davos[END_REF] have established programs to refurbish and resell used sport equipment and clothing, thus extending the life of products and reducing waste. Finally, narrowing loops use fewer resources (e.g., water, energy) throughout production, resulting in efficiency enhancements [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Stewart | Circular economy in corporate sustainability strategies: A review of corporate sustainability reports in the fast-moving consumer goods sector[END_REF]. CSBMs view natural resources, such as clean water, electricity, construction materials, and facilities, as investments (not costs) [START_REF] Sorin | Exploring Circular economy in the hospitality industry: empirical evidence from Scandinavian hotel operators[END_REF] and focus on repetitive recovering and reuse of resources [START_REF] Manniche | The circular economy in tourism: transition perspectives for business and research[END_REF].

At each stage of the sustainable value co-creation process, customers and other stakeholders are seen as active participants in creating sustainable experiences [START_REF] Jernsand | Tourism Experience Innovation Through Design[END_REF]. [START_REF] Breiby | Exploring sustainable experiences in tourism[END_REF], for instance, suggest that spectators at sport events can be introduced to resource monitoring systems to learn about the material and other resource flows involved in the event. Once they accumulate, experiences like this can have a broader societal effect and shape new cultural values built on pro-environmental behavior [START_REF] Huguenin | Creating change through pilot and demonstration projects: Towards a valuation policy approach[END_REF][START_REF] Manniche | The circular economy in tourism: transition perspectives for business and research[END_REF].

Archetype 2: Public CSBMs

Public sport organizations have the status of governmental organizations with the purpose of delivering public services related to a sport at a national, regional, or local level. A national sport governing body represents a sport (e.g., athletics and its disciplines) at a national level. It is responsible for governing, administering, financing, and developing it if the state provides it [START_REF] Kennelly | Strategic alliances in sport tourism: National sport organisations and sport tour operators[END_REF]. A sport federation's tasks include maintaining rules and the code of a sport, developing elite sport, and working with regional and local associations and clubs to develop grassroots sport opportunities [START_REF] Ferkins | Developing board strategic capability in sport organisations: The national-regional governing relationship[END_REF][START_REF] Henry | European Models of Sport: Governance, Organisational Change and Sports Policy in the EU[END_REF] 1 .

Public sport organizations have a social purpose [START_REF] Moore | Managing for Value: Organizational Strategy in for-Profit, Nonprofit, and Governmental Organizations[END_REF]. Indeed, from a traditional business model perspective, public sport organizations arguably have no 'business.' However, public sport organizations increasingly professionalize their activities towards more business-like functioning and management [START_REF] Nagel | Professionalisation of sport federationsa multi-level framework for analysing forms, causes and consequences[END_REF] and develop internal revenue streams through the professionalization and commercialization of a range of activities (e.g., sport competitions, merchandising) [START_REF] Dowling | Understanding the concept of professionalisation in sport management research[END_REF][START_REF] Nagel | Professionalisation of sport federationsa multi-level framework for analysing forms, causes and consequences[END_REF][START_REF] Shilbury | Professionalisation, sport governance and strategic capability[END_REF]. For example, sport federations have diversified their revenues from public subsidies to sponsorship revenues [START_REF] Bailleul | Des revenus records à venir pour la Fédération Française de Football grâce au sponsoring, droits TV et billetterie[END_REF]. Sport federations are increasingly exposed to competitive pressures; thus, they align their business practices to those of for-profit organizations [START_REF] Garcia-Fernandez | Exploring fitness centre consumer loyalty: differences of non-profit and low-cost business models in Spain[END_REF][START_REF] Hautbois | From monopoly to competition. The new strategic challenges facing public sport organizations[END_REF][START_REF] Santacruz Lozano | Spanish sport facilities: differences between public and private, and according to their business model[END_REF][START_REF] Yu | Verifying the Effectiveness of Sports Event Policies for a City's Sustainable Growth: Focusing on the Multiple Effects[END_REF].

There is limited discussion related to sustainable business practices of public sport organizations in the existing literature. This is surprising because the public sector is a major contributor to sustainable value co-creation, not only through policymaking but also through green procurement, waste management, and green infrastructure management [START_REF] Klein | Circular Economy Practices and Strategies in Public Sector Organizations: An Integrative Review[END_REF][START_REF] Kristensen | Circular public procurement practices in Danish municipalities[END_REF][START_REF] Wijayasundara | Green procurement for a circular economy: What influences purchasing of products with recycled material and recovered content by public sector organisations[END_REF]. Indeed, the European Commission views circular public procurement as a key element in the transition towards CE (European Commission, 2017; [START_REF] Kristensen | Circular public procurement practices in Danish municipalities[END_REF]. From complex construction projects of new stadiums to encouraging active transportation through new bike lanes to sourcing uniforms, equipment, medical services, and merchandise for sport events, public sport organizations' circular procurement touches all areas of sporting operations. [START_REF] Kristensen | Circular public procurement practices in Danish municipalities[END_REF] further emphasize that sustainable value co-creation enabled through circular public BMs needs to be considered from a multi-level perspective: on the product-level (e.g., buying recyclable materials and design for disassembly), supplier-level (e.g., prioritizing suppliers with take-back systems, repair services, rental, leasing and sharing options) and broader system level, including public-private partnerships (European Commission, 2017;[START_REF] Jones | Circular Procurement Best Practice Report[END_REF]. Furthermore, [START_REF] Klein | Circular Economy Practices and Strategies in Public Sector Organizations: An Integrative Review[END_REF] highlight the importance of collaborative approaches since the success of any circular procurement process depends on the decisions made by all stakeholders involved [START_REF] Grandia | It is not easy being green: increasing sustainable public procurement behaviour[END_REF][START_REF] Günther | The hurdle analysis. A self-evaluation tool for municipalities to identify, analyse and overcome hurdles to green procurement[END_REF]. Finally, [START_REF] Alhola | Exploiting the Potential of Public Procurement: Opportunities for Circular Economy[END_REF] promote a clear commitment to service instead of product ownership and encourage contracting suppliers to provide integrated solutions following pay-per-use and product-as-a-service models, which not only reduce operational costs through outsourcing maintenance activities but also keep materials and products longer in use.

Archetype 3: Circular Social Purpose SBMs

Social purpose organizations comprise various business models in the non-profit sport sector. They range from traditional non-profit models built on donations and patronage (e.g., community sport clubs, sport associations, and school sport) [START_REF] Babiak | Mapping Research on Interorganizational Relationships in Sport Management: Current Landscape and Future Research Prospects[END_REF] to sport for development organizations that use sport to address social issues such as public health, socialization of youth, social exclusion, racism and more [START_REF] Schulenkorf | Sport for Development: An Integrated Literature Review[END_REF], to hybrid models of social entrepreneurship [START_REF] Bjärsholm | Sport and Social Entrepreneurship: A Review of a Concept in Progress[END_REF][START_REF] Dacin | Social Entrepreneurship: A Critique and Future Directions[END_REF][START_REF] Reid | A fairytale narrative for community sport? Exploring the politics of sport social enterprise[END_REF][START_REF] Thompson | Social entrepreneurshipa new look at the people and the potential[END_REF]. While defined differently regarding their legal status, all these organizations have a social purpose as their raison d'être [START_REF] Moore | Managing for Value: Organizational Strategy in for-Profit, Nonprofit, and Governmental Organizations[END_REF] ingrained in their business model. Literature on social purpose business models [START_REF] Escamilla-Fajardo | Business Model Adaptation in Spanish Sports Clubs According to the Perceived Context: Impact on the Social Cause Performance[END_REF][START_REF] Staley | Challenges for sport organisations developing and delivering non-traditional social sport products for insufficiently active populations[END_REF], albeit nascent in sport management, is beginning to show mechanisms of sustainable value co-creation that are centered on social value and coopetition as opposed to competition [START_REF] Bradbury | Moving forward: business model solutions for amateur sport clubs[END_REF][START_REF] Crick | Coopetition and sales performance: evidence from nonmainstream sporting clubs[END_REF][START_REF] Dyer | The Relational View: Cooperative Strategy and Sources of Interorganizational Competitive Advantage[END_REF]. While critical for CE transformations, the link between social purpose organizations and CE principles has received limited attention within the sport discipline and beyond [START_REF] Dentchev | Embracing the variety of sustainable business models: A prolific field of research and a future research agenda[END_REF].

There is, however, increasing scholarly agreement that, in order to gain mainstream legitimacy, CE transformations must be locally appropriate and community-driven [START_REF] Fiksel | Steps toward a resilient circular economy in India[END_REF][START_REF] Stratan | Success factors of sustainable social enterprises through circular economy perspective[END_REF]. Indeed, many innovative CE transformation initiatives worldwide are being shaped by social entrepreneurs -from Bureo Skateboards. This US-based social enterprise produces skateboards and other products, from recycled fishing nets to Alive & Kicking. This social enterprise employs and develops skills with local people to make sport balls from recycled materials in Kenya, Zambia, and Ghana.

Circular social purpose SBMs enable sustainable value co-creation through innovative ways of mobilizing resources, collaboration in cross-sector partnerships, and active community engagement directed toward social progress and environmental stewardship [START_REF] Mcdermott | Social entrepreneurial opportunity and active stakeholder participation: Resource mobilization in enterprising conveners of cross-sector social partnerships[END_REF]. Circular social purpose SBMs provide a socio-economicsustainable bridge between economic growth, environmental stewardship, and social progress [START_REF] Fehrer | A systemic logic for circular business models[END_REF]. Increasing numbers of athletes are promoting social purpose organizations and actively building social enterprises as alternative models to drive inclusive growth [START_REF] Connolly | Social Entrepreneurship and Sport in Romania: How Can Former Athletes Contribute to Sustainable Social Change?[END_REF]. For example, Lornah Kiplagat, the Dutch professional longdistance runner, founded a famous high-altitude training center in Iten, Kenya. It was initially inspired by giving young Kenyan girls a place to train and maintain their academic studies. Now, it hosts athletes worldwide, and Kiplagat has established her own African-inspired sport brand.

More generally, social purpose organizations often raise awareness about circularity and advocate for CE policies and regulations. At the same time, they engage broad sets of stakeholders to join their movements for more sustainable business practices [START_REF] Mcdermott | Social entrepreneurial opportunity and active stakeholder participation: Resource mobilization in enterprising conveners of cross-sector social partnerships[END_REF]. For instance, the Ocean Race has implemented a social purpose CSBM, which is committed to all race villages and boats being built from recycled materials, and all waste is managed through recycling and composting. This influences local public and private sport organizations hosting the race to implement circularity in their business models, which can have wider spillover effects.

Archetype 4: Circular Platform SBMs

Recent literature in sport management refers to platform ecosystems as business models through which stakeholders co-create value within an economic community and beyond industry boundaries [START_REF] Buser | Toward a Sport Ecosystem Logic[END_REF][START_REF] Fehrer | A systemic logic for platform business models[END_REF][START_REF] Jacobides | Towards a theory of ecosystems[END_REF]. In the context of the sport industry, platform ecosystems encompass interconnected systems of services, tools, stakeholders, and technologies that operate within or around the realm of sport [START_REF] Buser | Toward a Sport Ecosystem Logic[END_REF]. These ecosystems are designed to create value by facilitating service exchange between market actors [START_REF] Fehrer | A systemic logic for platform business models[END_REF][START_REF] Parker | Platform Ecosystems How Developers Invert the Firm[END_REF][START_REF] Thomas | Architectural leverage: Putting platforms in context[END_REF]. As platform ecosystems have grown in other industries, sport, too, has been increasingly influenced by the rise of platform-centric strategies [START_REF] Buser | Toward a Sport Ecosystem Logic[END_REF].

Popular examples include streaming platforms such as Entertainment and Sports

Programming Network+ (ESPN+), DA ZONE (DAZN), and National Broadcasting Company (NBC) Sports Gold, which allow fans to stream live sport events [START_REF] Cook | The creation of shared value in the major sport event ecosystem: understanding the role of sponsors and hosts[END_REF][START_REF] Grohs | Value cocreation at sport events[END_REF]. Fitness platforms like Strava, MyFitnessPal, and Peloton have also emerged, creating communities centered around fitness and sport activities. Additionally, eSport platforms like Twitch and YouTube Gaming host and stream eSport competitions, forging connections between players, fans, and advertisers [START_REF] Bertschy | Esports extension of a football brand: stakeholder co-creation in action[END_REF][START_REF] Kunz | A perspective on value co-creation processes in eSports service ecosystems[END_REF].

However, the concept of platform ecosystems in sport extends beyond digital platforms. It also encompasses engagement platforms, such as physical sport events, sponsoring [START_REF] Buser | Going the extra mile' in resource integration: evolving a concept of sport sponsorship as an engagement platform[END_REF], and branding platforms [START_REF] Kunkel | Sport Brands: Brand Relationships and Consumer Behavior[END_REF]) that enable various stakeholders to integrate their resources to co-create value mutually [START_REF] Buser | Going the extra mile' in resource integration: evolving a concept of sport sponsorship as an engagement platform[END_REF]. For instance, sport events serve as intermediary platforms that connect sport teams, athletes, spectators, fans, coaches, sponsors, media companies, equipment manufacturers, and others [START_REF] Horbel | How context shapes value cocreation: spectator experience of sport events[END_REF][START_REF] Kolyperas | Sport fans' roles in value co-creation[END_REF]. [START_REF] Cook | The creation of shared value in the major sport event ecosystem: understanding the role of sponsors and hosts[END_REF] have explored how sport ecosystems built around major sport events can enable both economic and social value creation. Importantly, adopting a platform ecosystem perspective -rather than a narrow, firmcentric business model -expands the strategy spectrum from negotiating sponsorship agreements, managing sport events, and running sport organizations to orchestrating, navigating, and shaping the sport ecosystem to achieve mutual value creation at the environmental, social, and economic level. In this context, value co-creation is not an isolated act but a broad and inclusive process involving various stakeholders [START_REF] Doyle | Athlete branding via social media: examining the factors influencing consumer engagement on Instagram[END_REF][START_REF] Horbel | How context shapes value cocreation: spectator experience of sport events[END_REF]. The ecosystemic perspective highlights that the business models of all stakeholders in the ecosystem are as crucial for sustainable value co-creation as that of the focal organization [START_REF] Adner | Navigating the leadership challenges of innovation ecosystems[END_REF][START_REF] Buser | Toward a Sport Ecosystem Logic[END_REF][START_REF] Wieland | Business models as service strategy[END_REF]. Value co-creation involves a collaborative process where all parties negotiate value propositions. The goal is to achieve mutually agreeable (i.e., legitimized) sustainable outcomes.

The ecosystemic perspective is particularly insightful in understanding the complexity of CE transitions [START_REF] Aarikka-Stenroos | Circular economy ecosystems: a typology, definitions, and implications In[END_REF][START_REF] Boldrini | Designing and testing a new sustainable business model tool for multi-actor, multi-level, circular, and collaborative contexts[END_REF][START_REF] Konietzko | Circular ecosystem innovation: An initial set of principles[END_REF]. For example, [START_REF] Konietzko | Circular ecosystem innovation: An initial set of principles[END_REF] posit that circularity should be understood as a systemic property (e.g., the transportation system within a city) rather than a property of products or services (e.g., an electric vehicle or ridesharing provider). Moreover, a growing body of work emphasizes the significance of inter-organizational collaboration and complex network coordination [START_REF] Aarikka-Stenroos | Circular economy ecosystems: a typology, definitions, and implications In[END_REF][START_REF] Boldrini | Designing and testing a new sustainable business model tool for multi-actor, multi-level, circular, and collaborative contexts[END_REF][START_REF] Fehrer | Shaping Circular Service Ecosystems[END_REF]. Another set of studies centered around urban planning [START_REF] Nesticò | Multi-criteria methods for the optimal localization of urban green areas[END_REF][START_REF] Paes | Prospects for a circular bioeconomy in urban ecosystems: Proposal for a theoretical framework[END_REF] leans on the concept of ecosystem service to underscore the essential role of services provided by the environment, such as clean air, food, water, and infrastructure for human sustenance [START_REF] Costanza | The value of the world's ecosystem services and natural capital[END_REF][START_REF] Daily | Introduction: What are ecosystem services?[END_REF][START_REF] Xu | Ecological risk assessment of ecosystem services in the Taihu Lake Basin of China from 1985 to 2020[END_REF] offering insights beneficial for sporting events and infrastructure planning.

Indeed, an ecosystemic perspective not only provides a more comprehensive view of value co-creation in sport organizations but also reveals essential insights into how stakeholders can intentionally influence value co-creation by modifying and designing the ecosystems they are part of [START_REF] Derom | Extending the benefits of leveraging cycling events: evidence from the Tour of Flanders[END_REF][START_REF] Vink | Service Ecosystem Design: Propositions, Process Model, and Future Research Agenda[END_REF]. Similar to natural ecosystems, sport ecosystems demonstrate emergent qualities and are therefore beyond the control of any individual stakeholder [START_REF] Chandler | How Does Innovation Emerge in a Service Ecosystem[END_REF]. However, stakeholders can partially influence ecosystems' evolution [START_REF] Mele | Shaping service ecosystems: exploring the dark side of agency[END_REF] by reconfiguring the guiding institutions for value co-creation within ecosystems [START_REF] Koskela-Huotari | Innovation in service ecosystems-Breaking, making, and maintaining institutionalized rules of resource integration[END_REF][START_REF] Vargo | Innovation through institutionalization: A service ecosystems perspective[END_REF]. This might start with understanding institutional frictions (misaligned social structures) and using them as catalysts for sustainable innovation.

Globelet, a New Zealand-based enterprise, exemplifies this by recognizing the friction between large-scale sport events, like marathons, and the associated plastic waste. They devised a cleaning and collection system to reuse plastic cups during sport events and beyond.

Embracing an ecosystemic perspective can drive innovative sustainable strategies, enabling stakeholders to traverse complex networks and shape more sustainable markets. As the sport industry increasingly integrates digital and physical platform ecosystems, it has the potential to unlock opportunities for collaboration, inclusive growth, and environmental stewardship. Table 1 summarizes the four archetypes of sport business models and how they can be designed to align with circular business practices.

-------Insert Table 1 here -------

Discussion

Implications for Theory

The four CSBM archetypes provide a holistic understanding of the potential of CE for the sport industry. This typology supports scholars, managers, and policymakers in understanding the complexity of sustainable value co-creation. The first contribution of this study comes from demonstrating how these archetypes differ. We show how this differentiation can add precision to thinking, supporting more comprehensive reasoning about CSBMs and sustainable value co-creation processes. Each archetype builds on a different mechanism of value co-creation. The circular for-profit SBM archetype builds on closing material loops, slowing down end-of-life cycles, and narrowing resource use [START_REF] Bocken | Product design and business model strategies for a circular economy[END_REF][START_REF] Stewart | Circular economy in corporate sustainability strategies: A review of corporate sustainability reports in the fast-moving consumer goods sector[END_REF], which increases efficiency and effectiveness of resource integration processes while also reducing dependence on non-renewable resources. Circular public and social purpose SBM archetypes provide a socio-economic-sustainability bridge between economic growth, environmental stewardship, and social progress [START_REF] Fehrer | A systemic logic for circular business models[END_REF], and the circular platform SBM archetype offers an integrative perspective of platform-enabled value co-creation of broad sets of stakeholders in sport ecosystems [START_REF] Buser | Toward a Sport Ecosystem Logic[END_REF]. This nuanced understanding of sustainable value co-creation enabled by CSBMs informs research in the field of sport ecology. Specifically, it introduces the tripartite dimensions of environmental, social, and economic value co-creation to the debate. Research thus far has focused on how the organization of sport activities affects the natural environment [START_REF] Collins | Measuring the environmental sustainability of a major sporting event: a case study of the FA Cup Final[END_REF][START_REF] Mallen | The Assessment of the Environmental Performance of an International Multi-Sport Event[END_REF], and how nature and changes in the natural environment impact the practice of sport, sport events, and sport venues [START_REF] Kellison | Sport stadiums and environmental justice[END_REF][START_REF] Orr | Sport versus climate: Introducing the climate vulnerability of sport organizations framework[END_REF], and has more broadly acknowledged the inseparable nature of human beings, natural, and social environments [START_REF] Sartore-Baldwin | Equity-based sustainability and ecocentric management: Creating more ecologically just sport organization practices[END_REF]. Our research complements this discussion by offering concrete insights into value co-creation mechanisms that are less dependent on, and increasingly uncoupled from, natural resource depletion.

While our four archetypes are theoretically distinct, we acknowledge that these archetypes rarely exist in isolation; each represents a unique combination of stakeholders, value constellations, and design elements that, in practice, often co-exist. Patagonia, for example, could be classified under the for-profit CSBM as a company that manufactures and retails outdoor sport clothing and equipment. However, many of Patagonia's business practices align with those of social purpose organizations. An example is the creation of "Patagonia Action Works," an online platform that helps individuals connect with like-minded people to get involved in social and environmental activism (Patagonia, 2021a). With this initiative, Patagonia creates social value at a community and ecosystem level. Further, Patagonia's "Worn Wear" program encourages customers to repair and reuse their clothing instead of buying new clothes (Patagonia, 2021b), which indicates efforts to implement CE principles holistically by changing internal production processes and customer behavior. This pluralistic approach to CSBMs, as the Patagonia example shows, combines complementary features of all four archetypes on the micro-(firm-customer), meso-(network/markets), and macro-(society) level [START_REF] Benson-Rea | The plurality of co-existing business models: Investigating the complexity of value drivers[END_REF][START_REF] Castellas | Responding to Value Pluralism in Hybrid Organizations[END_REF].

As Patagonia powerfully illustrates, sport organizations often draw from multiple value cocreation processes, including economic, social, recreational, and environmental dimensions.

Where prior studies observed business models in silos (e.g., for-profit business models in sport tourism [START_REF] Perić | Comparing business models for event sport tourism: case studies in italy and Slovenia[END_REF] or professional sport [START_REF] Aversa | Business model configurations and performance: A qualitative comparative analysis in Formula One racing, 2005-2013[END_REF]), our framework fosters a comparative analysis, offering nuanced insights for complex sport organizations striving for circularity in their operational blueprint.

Our second contribution lies in presenting a novel business model archetype: circular platform SBMs. This archetype transcends the constraints of traditional sport business models that primarily concentrate on the focal firm's value creation while sidelining other stakeholders. As recent developments in the sport industry, such as eSport and online fitness communities, showcase, value creation processes are mutual, and stakeholders at the periphery of the sport ecosystem can play a significant role. Moving towards CE involves more than merely adopting new processes and technologies -it demands a profound reshaping of existing norms, regulations, societal values, and infrastructure [START_REF] Fehrer | Shaping Circular Service Ecosystems[END_REF]. This transformation process necessitates collective action and requires systemic thinking beyond the narrow boundaries of the focal organization. The circular platform SBM archetype provides a multifaceted view that embraces both firm-level considerations and the wider network, facilitating the exploration of value co-creation processes within and between nested and interconnected circular ecosystems [START_REF] Fehrer | Shaping Circular Service Ecosystems[END_REF].

Our third contribution relates to the specific characteristics of the sport industry, which offers new insights into the CE discourse in general. By their nature, business models in the sport industry combine economic and social dimensions of value co-creation and span across for-profit and non-profit sectors. Our study demonstrates how CSBMs collectively contribute to CE transformations across for-profit, public, and non-profit sectors. It is one of the first studies that explains how circularity in social purpose and public organizations unfolds. Our last contribution includes a research agenda for sport management scholars to explore how the CE concept can advance sport management theory and strategy (see Table 2).

-----Insert Table 2 here -----

Implications for Practice

Thus far, business model research in the sport industry has taken a rather traditional perspective on business models, reflecting value creation, delivery, and capture frameworks from an economic value creation and firm-centric perspective [START_REF] Teece | Business Models, Business Strategy and Innovation[END_REF]. Our research provides a wider spectrum of possible business models and value-creation mechanisms for sport managers and entrepreneurs to consider and progressively engage in. This study discusses how sport managers and entrepreneurs can incrementally apply CE principles to their business models. Furthermore, the circular platform SBM offers guidance for sport managers to broaden their mental model of doing business beyond the focal company and narrow stakeholder groups, such as athletes, fans, and customers. It provides insights to navigate value co-creation processes of broad stakeholder groups. It embraces complexity to deal with wicked issues and unavoidable goal conflicts when transitioning toward more sustainable business practices [START_REF] Fehrer | The role of public relations in shaping service ecosystems for social change[END_REF]. We want to encourage sport managers and entrepreneurs to work with systemic design tools, such as ecosystem mapping, stakeholder mapping, and value mapping [START_REF] Fehrer | A systemic logic for circular business models[END_REF], to transform their business models gradually into CSBMs.

For sport governing bodies and policymakers, this study offers an agenda to shape CSBMs on an industry level. We provide concrete suggestions for the for-profit, public, and non-profit sectors to embrace CE principles as part of their business practice. The nuanced description of our CSBM typology, summarized in Table 1, can help sport governing bodies to incentivize and fully embrace CE in the sport industry.

Implications for Future Research

We see much potential for future research on sustainability and circularity in sport. We have shown that the sport management literature lacks conceptualizations of business models in general and CBMs in particular. Despite two divergent trends in the sport industry -increasing professionalization and commercialization of the non-profit and public sector and the reorientation of for-profit organizations toward social purpose -we suggest that it is timely to stimulate an extended debate on CSBMs.

This study establishes a foundation for circular business models in the sport industry.

Future research could delve deeper into areas of strategic management, including strategic decision-making and planning, innovation, and operations strategies. Additionally, the marketing aspects of circular business practices, particularly in fan engagement, warrant further exploration. We propose that research on strategic management and fan engagement should more effectively align with and integrate the critical roles of sport organizations in environmental stewardship, promoting pro-environmental behavior, and advocating for social justice.

Building on our newly developed integrative framework of CSBMs, our fourth contribution is a research agenda centered around four important themes: (1) Circular for-profit SBM transformation, (2) CE transformation on the level of public sport organizations, (3) Advancing toward circular social purpose SBMs, and (4) Circular platform SBMs shaping circular ecosystems. Table 2 provides a detailed summary of future research themes and related research questions. We encourage sport management scholars and practitioners to consider CSBMs to shape a more sustainable sport industry.

Furthermore,

  [START_REF] Mcleod | Human Capital Ecosystem Construction in an Emerging Rugby Market[END_REF] highlight the shared interest among all stakeholders in the U.S. rugby ecosystem-including competitors and complementors-in co-creating aspirational value.

▪▪▪

  Value-in-experience: individually experienced but socially co-created between sport organizations and their stakeholders ▪ Social value: Social purpose at the regulatory level with business-like value creation (e.g., revenue creation) as second order goal ▪ Social value: Social purpose at the local community level with economic value creation as second order goal ▪ Ecosystem viability: Mutual value creation across stakeholder networks to increase individual well-being and ecosystem viability Closing of material loops to increase material efficiency ▪ Dematerialization through service and mutualization of assets ▪ Slowing loops through prolonging use and end-of-life cycle phases ▪ Narrowing loops through lower resource use ▪ Maintaining, potentially changing rules and code of a sport toward more circular business practices (e.g., fair trade; sustainable supply chains) ▪ Circular public procurement on product-, supplier-, and publicprivate partnership level ▪ Service contracts with suppliers based on pay-per-use and product-asa-service (PaaS) models ▪ Finding allies for social and sustainable innovation ▪ Collaborative (as opposed to competitive) orientation and strengthening of cross-sector partnership ▪ Distributed among stakeholders in the ecosystem, coordinated by shared social structures

Table 1 . Archetypes of Circular Sport Business Models Circular For-Profit SBMs Creating sustainable stakeholder experience and high degrees of stakeholder engagement Circular Public SBMs Representing a sport and its sustainability mission Circular Social Purpose SBMs Following a social purpose and enhancing community engagement in sustainable sport activities Circular Platform SBMs Linking stakeholders in the sport industry to shape and foster sustainable business practices Stakeholders

 1

	Main stakeholders	▪ Sport service providers,	▪ National, regional, and sport	▪ Non-government organizations, social	▪ Sport service providers,
		manufacturers, retailers	governing bodies (sport federations)	entrepreneurs, and other social	manufacturers, and retailers, including
		▪ Athletes/ Clubs	▪ Leagues/clubs with public ownership	purpose organizations	the network of suppliers and
		▪ Customers/fans	▪ Ministry for sport	▪ Volunteers	complementary service providers
		▪ Private leagues	▪ Sport service departments in	▪ Customers	▪ Sport entrepreneurs
			municipalities/ cities	▪ Local communities	▪ Athletes
				▪ Federations without state delegation	▪ Customers, spectators, fans
					▪ Non-government organizations, social
					entrepreneurs, and other social
					purpose organizations
					▪ Volunteers
					▪ Local communities
					▪ Sport governing bodies, leagues

The role of the state varies in different geographical regions and countries. In many European countries federations belong to the state, hence to the public sector(Henry,

2009).

Circular for-profit SBM transformation

For-profit sport BMs often follow a linear model of production and delivering service. While many sport practitioners might agree that the linear value chain models are not appropriate to reflect value co-creation processes in the sport industry, research on alternative models is still limited. Hence, further developing the CSBM concept and guidance for CSBM transformation processes is an important avenue for future research.