Effectiveness of Adult Health Promotion Interventions Delivered Through Professional Sport: Systematic Review and Meta-Analysis

Background Researchers are capitalising on the strong connections that sport fans have with their teams for health promotion programmes, yet no existing systematic reviews have evaluated the effectiveness of interventions delivered through professional sport. Objective The aim of this study was to systematically collate, evaluate, and synthesise the evidence on health promotion interventions implemented in professional sport settings. Methods Randomised controlled trials reporting on adult health promotion initiatives delivered in professional sport settings were identified through electronic database searches in CINAHL, MEDLINE, SPORTDiscus, Scopus, the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar. Data on health-related outcomes (e.g., weight, physical activity, dietary intake) were extracted and synthesised, and random effects meta-analyses were conducted to examine effects for weight and waist circumference. Risk of bias was examined using the Cochrane risk-of-bias tool for randomised controlled trials (RoB 2). Results Six studies reporting on five unique interventions met the inclusion criteria, and all included studies were gender-sensitised and exclusively targeted men. Intervention effects were observed for several health outcomes, including physical activity, dietary intake, and psychosocial health. All studies aimed to reduce weight, and for most studies (n = 4), weight was a primary outcome, either of the included study or to inform a future definitive trial. Findings from the meta-analysis revealed an overall significant difference in change in weight of − 3.2 kg (95% confidence interval [CI] − 4.6 to − 1.8) and waist circumference of − 3.9 cm (95% CI − 4.9 to − 2.8), both in favour of the intervention group at 12 weeks. Intervention effects were also reported for several other health outcomes (e.g., physical activity, dietary intake, psychosocial health); however, they were not consistently measured across the studies and thus were not meta-analysed. Conclusion Health promotion interventions delivered through professional sporting organisations can significantly improve weight- and lifestyle-related health outcomes. Representation across the socioeconomic spectrum and across culturally and linguistically diverse groups was limited. As only a limited number of studies met the inclusion criteria for this review, a need exists for rigorously designed interventions, standardised intervention approaches, with long-term follow-up, and the potential for scalability. PROSPERO Registration Number CRD42019123295. Supplementary Information The online version contains supplementary material available at 10.1007/s40279-022-01705-z.


Introduction
Noncommunicable diseases, including cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes, contribute to approximately 71% of deaths globally and are of significant public health concern [1]. Many of the risk factors associated with these diseases are modifiable and include overweight and obesity, tobacco smoking, inadequate dietary intake, alcohol consumption, high blood pressure, and physical inactivity [1]. Individual-level interventions provide important opportunities to modify health behaviours such as these; however some of the most potent drivers of poor health are complex and multilevel, influenced by structural, environmental, or political factors, often beyond an individual's control [2]. These factors disproportionately impact disadvantaged, disenfranchised, and marginalised communities, often leading to inequitable opportunities to achieve good health [3]. It is therefore important to develop health promotion interventions with these factors in mind.
Professional sporting organisations are in an optimal position to affect health positively at various levels. By using their reach and standing within the community, they have the potential to engage their supporters in meaningful ways that extend beyond match attendance and fan identification. Sport fans form strong social and psychological connections to their sports team [4] and the feelings of identity, belonging, and loyalty associated with being a fan have been shown to enhance mental health outcomes and promote social inclusion and connectedness [5]. Many professional sports organisations also have a strong sense of corporate social responsibility to their fans and broader communities they serve [6], and such organisations are increasingly engaging fans for the promotion of physical and mental wellness via community engagement initiatives [7]. Although fan affiliation is a powerful drawcard, until recently this has been an underutilised entry point for rigorously designed and evaluated evidence-based health promotion initiatives, therefore the overall effectiveness of health promotion initiatives in this context was largely unknown [8].
In recent years, the number of studies designed to recruit and engage sport fans for the promotion of physical and mental health has increased. Large-scale programs such as Premier League Health, offered through the English Premier League [9] and Football Fans in Training (FFIT), delivered via the Scottish Professional Football League (SPFL) [8,10], have successfully capitalised on men's passion for and affiliation with football as an entry point for health promotion, resulting in improved health and wellbeing outcomes. These interventions have successfully engaged hard-to-reach population groups, including middle-aged males and individuals from low socioeconomic communities, demonstrating that professional sporting organisations are efficacious settings for health promotion. FFIT [8] was the first public health intervention of its kind to be evaluated using a randomised controlled trial (RCT) study design and set an important precedent for health promotion initiatives in professional sport. This study recruited overweight male football fans into a gender-sensitised weight loss and healthy living programme, delivered through 13 SPFL clubs. Gender-tailored intervention designs aligning with the preferences, interests and needs of men have been shown to support weight loss [11,12] and physical activity [13] in a variety of contexts. The FFIT programme involved face-to-face, group-based education and physical activity sessions held weekly at each club's home stadium and was gender-sensitised in content, context, and delivery style, which involved peer-supported learning [8,10]. Harnessing the cultural and masculine appeal of sport, the success of this programme has led to the FFIT model being replicated in football in Europe [14] and Germany [15], ice hockey in Canada [16,17], rugby union in New Zealand [18], and Australian Rules Football in Australia [19], with further interventions underway and under development.
Several systematic reviews on health promotion in the broader sporting context have been published. For example, Priest et al. have conducted reviews exploring health promotion policies in sporting clubs [20] and examining interventions designed to increase participation in sport [21]. Walzel et al. conducted an integrative review on corporate social responsibility in professional team sport organisations [6], and Curran et al. have examined the role of professional football clubs in promoting mental health [22]. There are however no current systematic reviews examining RCT study designs of health promotion interventions targeting adults, delivered through professional sporting organisations.
The aim of this study was to systematically collate, evaluate and synthesise the evidence on health promotion interventions delivered through professional sporting organisations. Through a qualitative synthesis and metaanalysis, this systematic review provides evidence on the nature and effectiveness of health promotion interventions implemented in a professional or semi-professional sporting context and may help inform the design of future initiatives intended to engage communities through professional sport, and those targeting hard-to-reach or underserved population groups.

Methods
This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (electronic supplementary material [ESM] Appendix S1) and was prospectively registered in the International Prospective Register of Systematic Reviews (PROSPERO; registration number CRD42019123295).

Inclusion Criteria
Studies were eligible for inclusion if they met the following criteria: Participants: Studies targeting adults aged 18 years and over who were not professional athletes.
Intervention: Interventions targeting any health-related behaviours and outcomes (e.g., weight, physical activity, diet, mental health) that were delivered via a professional or semi-professional sporting organisation were considered.
Comparison: Studies must have compared an intervention to a control or comparison group such as a waitlist, minimal or alternate intervention, or no-treatment group.
Outcome: Studies that reported a health-related outcome (e.g., change in body weight, physical activity, dietary intake) were included.
Study design: To ensure the best quality evidence was included in this review, only studies using a RCT or cluster RCT study design were included.

Search Strategy
Studies reporting on health promotion initiatives delivered in professional sport settings including adult participants were identified through electronic database searches conducted in CINAHL, MEDLINE, SPORTDiscus, Scopus, the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar. The database searches were conducted in August 2019 and an updated search was conducted in July 2021 to ensure all relevant studies were identified and included in this review.
The full search strategy for one database (MEDLINE) is included in ESM Appendix S2. Filters were applied to only include human studies and those published in English, but no date limits were applied. When more than one article reported on the same intervention and the same sample, only the article reporting primary study outcomes was included. Articles reporting on the same intervention but including unique study samples (e.g., a pilot study and a fully powered RCT) were included as separate papers.

Screening
Two authors (EG and AR) independently screened each identified study based on the title and abstract (stage 1), followed by full-text screening (stage 2). In the event of a disagreement related to study inclusion or reason for exclusion, consensus was reached through discussion with a third author (AE). Reference lists of all included studies were reviewed for additional studies that potentially met the inclusion criteria.

Data Extraction and Synthesis
Data extracted from eligible studies included authors, year of publication, sporting context, study location, study aims, intervention duration and data collection points, intervention details (including comparison/control group condition and frequency of intervention sessions), study incentives, target population (sex, age, and retention rates), outcome measures, and significant changes in study outcomes. Characteristics of the included studies are reported in Table 1. If a study reported results of per protocol and intention-to-treat (ITT) analyses, ITT results demonstrating a significant difference between groups over time were reported. A qualitative synthesis of intervention elements, characteristics of target populations, and study outcomes are reported.

Risk of Bias in Individual Studies
Two authors (ESG and AE) independently assessed the risk of bias in the included studies using the revised Cochrane risk-of-bias tool for randomised trials (RoB 2) [23] (ESM Table S1). The RoB 2 assesses risk of bias across five key domains: the randomisation process, deviation from intended interventions, missing outcome data, outcome measurement, and selection of reported results [23]. For each domain, studies were assigned a rating of 'low risk of bias', 'some concerns', or 'high risk of bias'. After all five domains had been assessed, an overall risk-of-bias judgement was assigned. Studies assigned 'low risk' are those for which low-risk judgements had been assigned for all domains. An overall judgement of 'some concerns' was assigned when there were concerns in at least one domain, while an overall judgement of 'high risk' was assigned when
All participants received a standard British Heart Foundation booklet on weight management at baseline. Club-based incentives included T-shirts in club colours. Participants who attended the 12-month measurements were offered a £40 club voucher 12-week active (intervention) phase followed by 6 e-mail prompts over 9 months and group reunion at 6 months post- there was a high risk of bias in at least one domain or where 'some concerns' had been identified in multiple domains [23]. Using Cohen's kappa [24], the interrater reliability for risk-of-bias ratings between the independent reviewers was 0.91, indicating a high level of agreement [25].

Risk of Bias Across Studies
We examined a funnel plot to investigate risk of publication bias [26]. If smaller studies were found to have larger effects, there would be evidence that publication bias was present in the meta-analysis.

Data Preparation for Meta-Analysis
All included studies presented data on between-group differences in weight and waist circumference, therefore data on these outcomes were included in the meta-analysis. Authors of all the included studies were contacted to provide any missing data related to sample size, weight or waist circumference, and to verify data we extracted to be used in the meta-analysis. All but one author responded to our data request and we received missing data for four of the six included studies. For the remaining two studies, standard deviations for the change scores for weight and waist circumference were missing. To estimate these missing values, we used the following equation (Eq. 1), which is in line with guidance provided in the Cochrane Handbook [27].

Summary Measures and Synthesis of Results
The differences in change in weight and waist circumference between the intervention and control/comparison conditions from baseline to 12-week follow-up were the summary measures. We used Stata version 16 (StataCorp LLC, College Station, TX, USA) to conduct the meta-analyses using random-effects models. As all studies included in the metaanalyses used a common metric for weight (i.e., kilograms) and waist circumference (i.e., centimetres), non-standardised weighted mean differences were calculated. Variation attributable to heterogeneity was assessed using the I 2 statistic. If heterogeneity (I 2 > 50%) was found, meta-regression was used to test the impact of potential effect modifiers (i.e., mean baseline age, mean baseline weight/waist circumference). Risk-of-bias score was not investigated as a potential effect modifier due to limited variability.

Results
Database searches yielded 3824 results. An additional 24 papers were identified through checking reference lists of the included studies and through an updated search in July 2021. After duplicates were removed, 3304 references were screened, with 3249 of these references excluded based on title/abstract, leaving 55 papers for full-text screening. Included in Fig. 1 is the PRISMA flow diagram of study selection, including reasons for exclusion at full-text screening. The most common reasons for exclusion were studies not being delivered in a professional sporting context (n = 14) or studies not including a randomised control/comparison group (n = 18). A total of six studies reporting on five unique interventions met the inclusion criteria for this review.

Study Design and Follow-Up Duration
All included studies were either original FFIT studies [8,10] or an adaptation of the programme [14,[17][18][19], with varying degrees of modification [28], and all of these studies included members of the original FFIT research team as co-authors. Three studies were delivered via football (soccer) clubs in Scotland [8,10], Europe and England [14], one through ice hockey teams in Canada [17], one with rugby union in New Zealand [18] and one through Australian Rules football in Australia [19]. All six studies used RCT designs comparing an intervention to a waitlist control group that participated in the intervention after main outcome data were collected [8,10,14,[17][18][19]. Two studies were fullscale trials [10,14] and four were pilot randomised trials [8,[17][18][19].
Interventions were conducted across multiple professional sporting clubs in each included study and the number of clubs ranged from two [8,[17][18][19] to 15 [14]. All interventions in the included studies were 12 weeks in duration and two included an additional maintenance phase ranging from 9 months [10] to 40 weeks [17], with both comprising occasional e-mail prompts and group reunions or 'booster' sessions [10,17]. While all studies assessed intervention effects directly after the intervention (i.e., 12 weeks), five studies conducted longer-term post-baseline follow-up assessments. Two studies assessed between-group differences at 12 months [10,14], one study conducted 6-month follow-up assessments for intervention participants only [8], one study conducted 6-month follow-up assessments for the intervention group and waitlist control group, which had also completed the intervention by this time [19], and two studies assessed long-term changes at 12 months for intervention participants only [8,17]. The large-scale FFIT study by Hunt et al. [10] also included a 3.5-year follow-up with 488 men (65% of the original RCT participants) [29].

Participant Characteristics, Sample Size and Retention
One study targeted men aged between 25 and 65 years [18], one included those aged 30-65 years [14] and all remaining   [17] to 1113 [14]. The two fullscale studies reported conducting a power analysis to detect changes in primary outcomes [10,14], two pilot studies used a power analysis for a future full-scale trial to inform their pilot sample size [8,17], and two determined a pragmatic sample size based on guidelines for pilot studies [18,19]. End-of-intervention retention rates ranged from 75% [18] to 91% [14] in the intervention groups, and from 80% [8] to 93% [19] in the control groups. Of the studies that included a longer follow-up duration of 6 months [19] or 12 months post-intervention [10,14], retention ranged from 54% [19] to 89% [10] in the intervention groups and 71% [19] to 95% [10] in the waitlist control groups.
Self-monitoring devices were utilised in all interventions to assist with monitoring of physical activity, and included pedometers [8,10,17,18], Fitbit Zip devices [19], and a specifically-designed, pocket-worn device (SitFIT) designed to measure sedentary time and step counts [14]. Two interventions included access to a mobile application/ online programme enabling self-monitoring. One study utilised a customised mobile application (MatchFIT) designed specifically for the EuroFIT intervention [14] and the other included components from an evidence-based lifestyle prescription programme (HealtheSteps™) [17].
The group-based intervention design of all studies ensured that an element of social support was embedded within each intervention. Several studies reported additional social support mechanisms including access to mobile applications with social networking capabilities [14,17] and interaction through commonly used social media platforms such as Facebook and WhatsApp [14,19].
Intervention delivery personnel varied between studies and included male community coaches from professional clubs [8,10], male and female graduate kinesiology students with experience in coaching [17], qualified strength and conditioning trainers, club dietitians and medical practitioners, and local health professionals (e.g., nutrition educators) [18], licensed intervention coaches [14], and a combination of coaches from professional clubs and coaches identified by the research team [19]. All studies reported that coaches were trained to provide the intervention, although the detail on coach training varied and one study noted that training was completed by participating sport clubs and did not follow a standardised training protocol [18].

Study Quality
With regard to risk of bias, four studies were rated as 'low risk' [10,14,17,19], one study was rated as 'some concerns' [8], and one study was rated as 'high risk' of bias [18]. As all included studies tested a health promotion programme against a waitlist control group, there was no way of blinding participants or programme delivery staff to intervention assignment, and therefore this item was not included in the overall assessment-of-bias rating. Concerns regarding outcome assessments were raised in two studies [8,18], detail on allocation concealment was unclear in one study [8], and bias due to missing outcome data was identified in one study [18]. In this study, participants were randomised prior to baseline measurement sessions and only 87.5% of the reported baseline sample completed baseline measurement sessions [18].

Weight
Findings from the meta-analysis revealed an overall significant difference in change in weight of − 3.3 kg (95% confidence interval [CI] − 4.7 to − 2.0) in favour of the intervention group at 12 weeks (Fig. 2). Heterogeneity was high (τ 2 = 2.11, I 2 = 88.3%) and no predictors explained this variation (i.e., baseline age, weight). Review of a funnel plot (ESM Fig. S1) and Egger's test (p = 0.31) suggested no Five studies reported significant between-group differences in weight directly post-intervention [8,10,14,17,19], with between-group differences sustained in two studies at 12-month follow-up [10,14]. All five studies that led to significant changes in weight implemented a standardised programme across multiple clubs and incorporated classroombased education on behaviour change techniques such as goal setting and self-monitoring. All six studies provided education on physical activity and healthy eating in relation to weight loss and healthy living; however, the study by Wyke et al. [14], which had the greatest level of adaptation from the original FFIT programme, emphasised the importance of increasing physical activity and reducing sedentary time rather than weight loss (which was a secondary outcome). To explore the long-term maintenance of weight loss among participants in the FFIT RCT [10], Gray et al. conducted a 3.5-year longitudinal study with 488 men, representing 65% of all RCT participants. Weight loss was sustained in both intervention (− 2.90 kg; p < 0.001) and waitlist control participants (− 2.71 kg; p < 0.001) who had also participated in the intervention by this time [29].
Two other studies assessed intervention group weight loss at 6 months [19] and 12 months post-baseline [17] and weight loss was sustained in intervention participants in one study [17]. All four studies that examined differences in the percentage of weight lost reported significant differences between groups post-intervention [8,10,17,19], with weight loss ranging from 3.41% [19] to 5.23% [10].

Waist Circumference
Statistically significant between-group differences in waist circumference were reported in five of six studies at 12 weeks [8,10,14,17,18] and in two studies at 12 months [10,14]. Findings from the meta-analysis revealed an overall significant difference in change in waist circumference of − 3.9 cm (95% CI − 4.9 to − 2.8) in favour of the intervention group at 12 weeks (Fig. 3). Heterogeneity was high (τ 2 = 1.13, I 2 = 76.8%) and no predictors explained this variation (i.e., baseline age, waist circumference). Visual inspection of a funnel plot (ESM Fig. S2) shows some evidence of asymmetry; however, Egger's test suggested no evidence of small study bias (p = 0.29).

Physical Activity and Sedentary Time
Physical activity was objectively measured in three studies via accelerometry [19], ActivPAL devices [14], and pedometers [17], and self-reported in four studies [8,10,14,17]. One study included fitness as a secondary outcome, assessed using a 4 km cycle test [18]. Sedentary time was measured in four studies using accelerometry (n = 1) [19], ActivPAL devices (n = 1) [14], and self-report methods (n = 3) [8,14,17]. Five studies reported a significant between-group difference in a physical activity outcome at 12 weeks [8,10,14,17,19]. Significant between-group differences were observed in overall self-reported physical activity in three studies at 12 weeks [8,10,14] and two studies at 12 months [10,14]. Significant between-group differences were also reported for objectively measured moderate to vigorous physical activity in one study at 12 weeks [19], objectively measured steps per day in two studies at 12 weeks [14,17] and one study at 12 months [14]. Significant changes in favour of the intervention group were reported in one study [14] for upright time at 12 weeks, stepping time at 12 weeks and 12 months, and frequency of physically active choices at 12 weeks and 12 months. Significant between-group differ- Fig. 3 Forest plot showing the difference in change in waist circumference (centimetres) between the intervention and control conditions from baseline to 12-week follow-up. SD standard deviation, CI confidence interval ences were also reported for habits for physical activity in one study at 12 weeks [19]. Of the four studies that measured sedentary time, only one reported significant between-group differences for both objectively measured and self-reported sedentary time at 12 weeks and self-reported sedentary time at 12 months [14]. No other significant changes in sedentary time, either objectively measured or self-reported, were observed.

Dietary Intake
Five studies examined changes in dietary intake using an adapted version of the Dietary Instrument for Nutrition Education and a 7-day recall questionnaire to assess alcohol consumption [8,10,14,17,19], and one reported an overall healthful eating score [17]. Significant between-group differences were reported for fatty food in four studies at 12 weeks [10,14,17,19] and two studies at 12 months [10,14], fruit and vegetable intake in four studies at 12 weeks [8,10,14,17] and two studies at 12 months [10,14], and sugary food in three studies at 12 weeks [10,14,19] and two studies at 12 months [10,14]. Significant between-group differences were reported for alcohol consumption in one study at 12 weeks [10] and two studies at 12 months [10,14], breakfast consumption, bacon and processed meats, crisps, chocolates and sweets, biscuits, and sugary drinks in one study at 12 weeks [8], overall healthful eating score in one study at 12 weeks [17], and habits for eating in one study at 12 weeks [19].

Anthropometric Outcomes
All included studies assessed changes in blood pressure and significant betweengroup differences were reported for diastolic blood pressure at 12 weeks in three studies [10,14,18] and 12-month follow-up in two studies [10,14]. Significant changes in systolic blood pressure were also reported in three studies at 12 weeks [8,10,17] and in two studies at 12-month followup [10,14]. Of the three studies that measured body fat as a secondary outcome [8,10,18], two studies reported a significant reduction at 12 weeks [8,10] and one study reported 12-month follow-up [10]. Significant improvements in BMI were reported in all four studies that assessed changes for this outcome at 12 weeks [10,14,17,19] and in two studies at 12-month follow-up [10,14]. One study reported a significant difference in resting heart rate at 12 weeks [18] and one study that assessed cardiometabolic blood markers reported significant improvements in a range of these markers at 12 months [14].
3.1.6.6 Psychological and General Health-Related Outcomes A significant increase in self-esteem, assessed using the Rosenberg Self-Esteem Scale, was reported in four studies at 12 weeks [8,10,14,19] and two studies at 12-month follow-up [10,14]. Two studies reported a significant increase in positive affect at 12 weeks [10,19], with the increase sustained in one study at 12 months [10], and one reported a decrease in negative affect at 12 weeks and 12-month follow-up [10], assessed using the Positive and Negative Self Affect Schedule. One study reported significant between-group differences in wellbeing and vitality at 12 weeks and 12-month follow-up [14], one reported a significant between-group difference in overall health [19] and one reported a significant between-group difference in self-rated health [17] at 12 weeks. Of the four studies that assessed quality of life [8,10,14,19], one study [10] reported a significant change in physical health-related quality of life at 12 weeks and 12 months, and in mental healthrelated quality of life at the end of intervention. In one study, significant between-group differences were also reported at 12 weeks for basic need satisfaction in relation to weight loss and goal facilitation for weight loss [19].

Sleep
In the one study that measured sleep, sleep quality improved significantly at 12 weeks in favour of the intervention group [19].

Overview of Findings
This is the first systematic review to explore the effectiveness of health promotion initiatives delivered in a professional sporting context. Meta-analyses revealed small but significant changes in weight and waist circumference in favour of the experimental conditions at 12 weeks. Improvements were also observed for outcomes including physical activity [8,10,14,17,19], sedentary time [14], dietary intake [8,10,14,17,19] and a range of psychological and social health outcomes [8,10,14,17,19].
Sport has long been recognised as an institution in which masculinity is constructed and reinforced [30,31], and sporting environments such as football clubs have been identified as both opportune spaces to engage men in "constructive reflection on their health and wellbeing" and spaces in which "damaging constructions of gender and inequalities" may be reproduced [32]. In recent years, and as demonstrated through this systematic review, sport has been established as a strong entry point through which to engage men for health promotion [8][9][10]. This is promising given that, compared with women, men tend to be less engaged with health services and in health promotion and weight loss initiatives [33][34][35]. All studies that met the inclusion criteria for this systematic review were designed specifically to engage men, with findings suggesting that the professional sporting context is a suitable and accessible setting through which men's physical and mental health can be promoted and supported. In line with the original aim and design of the FFIT programme, authors of all studies included in this review discussed the 'gender-sensitised' nature of their interventions [8,10,14,[17][18][19], which are designed to appeal to masculine ideals, preferences and needs. This gender-sensitised approach seeks to work with, rather than against, traditional constructions of masculinity, and key components of gender sensitisation in these studies include delivery of the intervention within the environment of a sporting club, provision of club-inspired merchandise (e.g., team training shirts), male-only groups, simple health messaging, and the use of humour or 'banter' to encourage camaraderie and open discussion [28]. There are many complex sociocultural factors influencing men's engagement with health behaviours [36,37] that must be considered in the design of gender-tailored health programs. One of the guiding principles for the development of the original FFIT programme was to enhance men's "physical and symbolic proximity to the club and fellow male supporters" in an effort to counter potential perceived threats to masculinity [38] and masculine capital [37], which may be associated with involvement in a weight management programme. The successful adaptation and implementation of the FFIT programme across multiple demographic and sporting contexts demonstrates the programme's success in supporting men to achieve lifestyle change [28].
The one programme that was identified through our database searches that exclusively targeted women used a pre-post-test study design to examine the feasibility of an FFIT adaptation for women [39]. Although this study did not meet the inclusion criteria for this review, as it was not conducted as a RCT, this feasibility study found that FFIT for women was feasible and acceptable and resulted in a mean 2.87 kg weight loss post-intervention. Findings from the mixed-methods feasibility study indicated that the programme appealed to women and was viewed favourably in comparison with other weight management programs and commercial dietary programs, which were often quite restrictive in their approaches. Women appreciated the group nature of the programme and the salience of the physical activity content, suggesting minor changes to enhance the programme for future delivery [39]. These findings suggest that recruiting women through a professional sport setting for the promotion of weight loss and healthy lifestyles may be efficacious and warrants further investigation.
In terms of weight loss, the findings from the current systematic review align with those of several other studies. In their review of male-only weight loss and weight maintenance interventions, Young et al. [40] found a significant difference in weight change favouring interventions in comparison with no-treatment controls. Characteristics of successful interventions included face-to-face intervention delivery in group settings, higher frequency of contact (i.e., ≥ 2.7 contacts per month), and inclusion of a prescribed energy restriction. Similarly, all studies included in the current systematic review were delivered in group settings and included face-to-face contact on a weekly basis. Borek et al. [41] also examined the effectiveness of group-based weight loss interventions promoting physical activity and nutrition. The mean difference in weight loss between intervention and control groups was 3.5 kg at 6 months, 3.4 kg at 12 months, and 2.6 kg at 24 months post-baseline. Findings from moderator analyses indicated that interventions that exclusively targeted men, those that explicitly targeted weight loss, and those that incorporated feedback mechanisms were more effective than those without these characteristics [41]. Importantly, most studies included in these reviews were of low study quality, prompting a call for rigorously designed, high-quality studies promoting weight loss and maintenance [40,41].
All included studies in this systematic review incorporated practical physical activity sessions as a technique to not only increase physical activity participation but to also build a sense of camaraderie and belonging amongst participants. Although the methods used to assess physical activity varied across studies, the majority of studies demonstrated a significant increase in physical activity at the end of intervention in comparison with a waitlist control [8,10,14,17,19]. In a recent meta-analysis exploring the effectiveness of behaviour change interventions on men's physical activity, Sharp et al. [42] found a significant intervention effect of 0.35 (Cohen's d), which is estimated to be equivalent to an increase of approximately 97 min of total physical activity per week, or 980 steps per day. Interventions included in the review by Sharp et al. [42] that were gender-sensitised, underpinned by a theoretical framework, delivered across a period of 12 weeks or less, and involved at least one contact session per week were associated with greater increases in physical activity in comparison with interventions without these characteristics.
Considering the strong psychological connections sport fans form with their team and the strong sense of camaraderie formed between supporters of the same team [5], it is somewhat surprising that none of the included studies directly promoted mental health through their interventions. By nature, all included interventions evoked the sense of belonging and camaraderie offered through sport participation and fandom, and significant between-group differences were observed for a range of psychosocial outcomes [8,10,14,19].
One study that included a specific focus on social connectedness, but did not meet the study design inclusion criteria for the current systematic review, was the HAT TRICK intervention [43]. This study used a pre-post-test study design without a control or comparison group and was delivered through a major junior ice hockey team in Canada. Significant treatment effects were reported for weekly minutes of moderate physical activity (objectively measured), self-reported moderate and vigorous physical activity, and fat scores, but there was no significant change in social connectedness [43]. In a subsequent study exploring the impact of the HAT TRICK programme on men's mental health, significant positive changes in depression (assessed using the Male Depression Risk Scale) and mental health (assessed using the MH12) [44] were observed.

Practical Implications
Study samples were relatively homogenous, with limited ethnic diversity and exclusively male samples. Five of the included studies [8,10,14,17,19] had a predominantly White sample (range 89.6-99.0%), with only one study reporting a sample comprising 37.75% non-White participants [18]. While the exact reason for the limited ethnic diversity in these samples is unclear, employing strategies to engage men from culturally diverse backgrounds will be key for future interventions designed to engage communities via professional sport. Socioeconomic diversity was also limited in some studies. While Hunt et al. [10] and Gray et al. [8] reported success in engaging men from across the socioeconomic spectrum, Kwasnicka et al. [19] and Petrella et al. [17] both noted limited socioeconomic representation and a need for further research on engaging men from diverse socioeconomic and cultural backgrounds.
All studies that were included in this systematic review were offered at no financial cost to participants. Three studies included the results of a cost-effectiveness analysis of the intervention [10,14,19]. One was found to be cost effective [10], one potentially cost effective [19], and one not cost effective in the short-term [14], possibly due to a ceiling effect for the quality-of-life measure on which cost effectiveness was based. The FFIT programme has been successfully scaled up and the original programme has since transitioned to a 'single-licence franchise model' that ensures programme fidelity, protects against commercialisation, and supports public health [28]. However, not all adaptations of the programme have been successfully scaled up and translated with greater reach. Considering the need for innovative and evidence-based approaches to engage men in health promotion and weight loss initiatives, it is imperative that these programmes are developed with a view to scalability. One potential approach to support long-term programme implementation, in the absence of ongoing funding, is to employ a paid registration model as is used in the MAN v FAT football programme in the UK and Australia [45]. This programme uses competitive sport, rather than the professional sport context, to support weight loss, and findings from a qualitative evaluation of men's experiences in the programme reinforce the importance of camaraderie and social connectedness [46]. However, it is worth noting that charging a fee to participate in a health promotion programme may limit participation from some population groups [47], thereby amplifying existing socioeconomic inequalities.

Strengths and Limitations
The strengths of this systematic review include the rigorous study design, focus on the professional sport environment, and use of meta-analysis to assess the effectiveness of included RCTs on weight and waist circumference. These anthropometric outcomes are directly associated with chronic disease risk and are of public health importance [48,49]. However, the findings of this systematic review should also be viewed in light of potential limitations. First, we only included studies that were published in English and did not search grey literature for studies that may not be published in scientific journals. Second, the results of the meta-analyses indicated high levels of heterogeneity (τ 2 = 2.57, I 2 = 94.2% for weight; and τ 2 = 1.13, I 2 = 76.8% for waist circumference), and none of the hypothesised predictors explained this variation. Third, this review only included RCTs as they are the highest level in the hierarchy of evidence for intervention studies. Although studies using other designs may also provide important evidence on the impact of health promotion initiatives delivered in a professional sporting context, they were not included in this review. Finally, of the studies that met our inclusion criteria, none were conducted in lowor middle-income countries, and ethnic and socioeconomic diversity was limited.

Conclusion
The findings of this systematic review highlight the potential for professional sport to be utilised as a vehicle for delivering successful health promotion initiatives for men. When designed to meet the needs of local communities and priority population groups, such interventions have the potential to positively influence health and wellbeing within their communities. The limited number of RCTs that met the inclusion criteria for this review emphasises the need for rigorously designed interventions, with standardised intervention approaches, long-term follow-up, and potential for scalability. Future research could explore the effectiveness of health promotion or weight loss interventions for female sport fans and those in low-and middle-income countries, and should include strategies to engage participants from culturally diverse backgrounds and areas of socioeconomic disadvantage.