Accumulated or continuous exercise for glycaemic regulation and control: A systematic review with meta-analysis

© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Objective To compare the effectiveness of accumulating exercise in multiple bouts of at least 10 min throughout a day with exercise completed in a single bout (continuous or interval), or no exercise, on glycaemic control and regulation in inactive people without diagnosed glycaemic dysfunction. Design Systematic review and meta-analysis. Data sources Seven electronic databases were searched: CINAHL (EBSCO), Cochrane Library, EMBASE (Ovid), MEDLINE 1948-(Ovid), SCOPUS (Elsevier), SPORTDiscus (EBSCO) and Web of Science (ISI) with no restrictions on date and included all titles indexed up to February 2018. Eligibility criteria for selecting studies Articles reporting insufficiently active adults (19 to 64 years) without metabolic dysfunction, measuring glycaemic control or regulation following at least 6 weeks of aerobic exercise. Results Only one study compared accumulated exercise to single-bout exercise with no significant effect on fasting glucose (95% CI: a '0.04 to 0.24 mmol·L -1) or fasting insulin (95% CI: a '1.79 to 9.85 pmol·L -1) reported 48 hours after the final bout. No studies compared accumulated exercise with no-exercise. Compared with no-exercise, single-bout exercise reduces insulin resistance (mean difference (MD): a '0.53 pmol·L -1; 95% CI: a '0.93 to a '0.13). Insulin resistance was clearly reduced with moderate-intensity (a '0.68 (a '1.28 to a '0.09)) but not with high-intensity (a '0.38 (a '1.20 to 0.44)) exercise. Single-bout exercise was not statistically more beneficial than no-exercise for glycated haemoglobin (HbA 1c) (MD: a '0.11 %; 95% CI: a '0.24 to 0.02) in metabolically healthy individuals. Summary/conclusion The glycaemic response to accumulated exercise or single-bout exercise might not be different, however exercise intensity might influence the mechanisms generating the response. PROSPERO registration number CRD42015025042.