Determinants of non-adherence to exercise or physical activity in people with metabolic syndrome: a mixed methods review

BACKGROUND: Long-term adherence to exercise or physical activity (EPA) is necessary for effective first-line management of metabolic syndrome (MetS). Little is known about the determinants of adherence in this population. This systematic review aims to identify the determinants of adherence to EPA in people with MetS. METHODS: Six databases (MEDLINE, CINAHL Complete, PubMed, PsycINFO, SPORTDiscus, and Cochrane Central Register of Controlled Trials (CENTRAL)) were searched for studies published before April 26, 2021. Primary research studies investigating factors affecting EPA adherence in adults with MetS in outpatient settings were included. Risk of bias was assessed using the QUIPS (Quality in Prognostic Factor Studies) and CASP (Critical Appraisal Skills Program) tools, for quantitative and qualitative methodologies, respectively. RESULTS: Four quantitative studies (n = 766) and one qualitative (n = 21) study were included in the review, evaluating 34 determinants of adherence to EPA in MetS. Limited evidence was found for an association between ten determinants and non-adherence to EPA: lower self-rated health, lower baseline EPA, lower high-density lipoprotein cholesterol (HDL-C), fewer walk-friendly routes within 1 km, less consciousness raising, lower self-re-evaluation, lower self-liberation, reporting more arguments against EPA (cons), lower social support, and fewer positive psychological constructs. There was limited evidence of no association or conflicting evidence for the remaining 24 determinants. CONCLUSION: A small number of included studies, most of low methodological quality, resulted in limited confidence in the findings for all determinants. The identified determinants associated with non-adherence are all potentially modifiable, thus further high-quality studies are required to increase confidence in the determinants of EPA in people with MetS, and test interventions.