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BACKGROUND: Physical activity (PA) is essential for physical and mental health, yet sustaining long-term PA engagement remains a challenge. Booster strategies-follow-up contacts delivered after the end of interventions-have been proposed as a strategy to support PA maintenance, but their effectiveness remains unclear. The primary objective of this systematic review and meta-analysis was to classify the boosters used in PA interventions depending on their type and number. The secondary objective was to explore the efficacy of boosters in supporting participants' PA maintenance. METHODS: A systematic search was conducted across seven databases, up to February 2025. Randomised controlled trials were included if they incorporated boosters and reported PA outcomes. Risk of bias was assessed using the RoB 2 tool. Meta-analysis examined changes in moderate-to-vigorous physical activity (MVPA) from baseline to the last available follow-up, and moderation analysis explored the effects of booster type, number of boosters administered, and follow-up duration on changes in MVPA. Studies not suitable for meta-analysis were synthesised narratively. RESULTS: Forty studies were included in the systematic review. The most common types of boosters used were phone calls and text messages, which were employed either alone or in combination with other types. 16 studies provided data for inclusion in the meta-analysis. There was conclusive evidence that including a booster in the intervention led to sustained increases in PA levels at follow-up. The estimated added effect of the booster over the intervention alone was a 6% increase. There was also conclusive evidence of increased MVPA for interventions with more boosters, and interventions that used remote and mixed-format delivery (vs in-person only) boosters. Finally, results showed conclusive evidence of increased MVPA for interventions that assessed MVPA using self-reported measures. CONCLUSIONS: Our findings suggest a trend indicating that boosters may support the maintenance of PA. Higher number of boosters and delivery through remote or mixed formats showed promising trends. Future research should also explore optimal booster numbers and formats to clarify their role in sustaining PA. REGISTRATION: PROSPERO (CRD42024510018) ; Protocol also available on Open Science Framework (OSF): https: //osf. io/6abkw/? viewₒnly=915375148520427db3dca76d2c32934d.
Tarantino et al. (Wed,) studied this question.