The Effects of Accumulated Versus Continuous Exercise on Postprandial Glycemia, Insulin, and Triglycerides in Adults with or Without Diabetes: A Systematic Review and Meta-Analysis

BACKGROUND: Postprandial dysmetabolism, an important cardiovascular disease risk factor, can be improved by exercise. Further systematic review and meta-analysis is needed to compare the effects of accumulated exercise with a single session of energy-matched continuous exercise on postprandial glucose (PPG), insulin, and triglycerides in adults with or without diabetes. METHODS: Eight electronic databases were searched on August 28, 2020, and updated on April 27, 2021. Eligible studies were randomized, quasi-randomized, or non-randomized controlled or crossover trials that evaluated the acute or longitudinal effects of accumulated exercise compared with a single session of energy-matched continuous exercise on PPG, postprandial insulin, and triglycerides in diabetic and non-diabetic adults. Same-day and second-morning effects were assessed separately for acute intervention studies. Subgroup analyses were conducted based on the number of exercise bouts (2–3 bouts or frequent brief bouts (e.g., 1–6 min) throughout the day at 20–60-min intervals (known as physical activity [PA] breaks, ≥ 5 bouts)), exercise intensity, and populations. Risk of bias was assessed using the revised Cochrane risk-of-bias tool for randomized trials. Pooled effects were reported as standardized mean differences (SMD) and 95% CI using a random effects model. RESULTS: Twenty-seven studies (635 participants) were included. A significant difference was found for same-day PPG control, which favored accumulated exercise over one bout of energy-matched continuous exercise (SMD − 0.36 [95%CI: (− 0.56, − 0.17)], P = 0.0002, I(2) = 1%), specifically in accumulated exercise with PA breaks (SMD − 0.36 [95%CI: (− 0.64, − 0.08)], P = 0.01, I(2) = 30%), low-moderate intensity exercise (SMD − 0.38 [(95%CI: (− 0.59, − 0.17)], P = 0.0005, I(2) = 0%), and in non-diabetic populations (SMD − 0.36 [95%CI: (− 0.62, − 0.10)], P = 0.007, I(2) = 16%). No differences were found for same-day postprandial insulin and triglycerides, and second-morning effects (postprandial or fasting glucose, insulin, and triglycerides) between different exercise patterns. CONCLUSION: Compared with one session of continuous exercise, accumulated exercise—specifically in subgroups of PA breaks, low-moderate intensity exercises—produced greater acute effects on same-day PPG control for non-diabetic adults. There were no differences between continuous and accumulated patterns of exercise in terms of same-day postprandial insulin and triglycerides, and second-morning effects on all previously mentioned markers. The findings provide additional PA options for PPG control for individuals with limited time or exercise capacity to engage in PA in one session. Registration: PROSPERO (identification code: CRD42021251325). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40798-021-00401-y.