The effect of exercise training on clinical outcomes in patients with the metabolic syndrome: a systematic review and meta-analysis

Background: Purpose: to establish if exercise training improves clinical outcomes in people with metabolic syndrome (MetS). Registered with PROSPERO international prospective register of systematic reviews (https://www. crd. york. ac. uk/PROSPERO/Identifier: CRD42017055491). Data sources: studies were identified through a MEDLINE search strategy (1985 to Jan 12, 2017), Cochrane controlled trials registry, CINAHL and SPORTDiscus. Study selection: prospective randomized or controlled trials of exercise training in humans with metabolic syndrome, lasting 12 weeks or more. Results: We included 16 studies with 23 intervention groups; 77,000 patient-hours of exercise training. In analyses of aerobic exercise studies versus control: body mass index was significantly reduced, mean difference (MD) -0.29 (kg m(-2)) (95% CI -0.44, -0.15, p < 0.0001); body mass was significantly reduced, MD -1.16 kg (95% CI -1.83, -0.48, p = 0.0008); waist circumference was significantly reduced MD -1.37 cm (95% CI - 2.02, -0.71, p < 0.0001), peak -VO2 was significantly improved MD 3.00 mL kg(-1) min(-1) (95% CI 1.92, 4.08, p < 0.000001); systolic blood pressure and diastolic blood pressure were significantly reduced, MD - 2.54 mmHg (95% CI - 4.34, - 0.75, p = 0.006), and, MD -2.27 mmHg (95% CI - 3.47, -1.06, p = 0.0002) respectively; fasting blood glucose was significantly reduced MD - 0.16 mmol L-1 (95% CI -0.32, -0.01, p = 0.04); triglycerides were significantly reduced MD - 0.21 mmol L-1 (95% CI -0.29, -0.13, p < 0.00001); and low density lipoprotein was significantly reduced MD - 0.03 mmol L-1 (95% CI -0.05, -0.00, p = 0.02). In analyses of combined exercise versus control: waist circumference, MD - 3.80 cm (95% CI -5.65, -1.95, p < 0.0001); peak -VO2 MD - 4.64 mL kg(-1) min(-1) (95% CI 2.42, 6.87, p < 0.0001); systolic blood pressure MD - 3.79 mmHg (95% CI -6.18, -1.40, p = 0.002); and high density lipoprotein (HDL) MD 0.14 (95% CI 0.04, 0.25, p = 0.009) were all significantly improved. We found no significant differences between outcome measures between the two exercise interventions. Conclusions: Exercise training improves body composition, cardiovascular, and, metabolic outcomes in people with metabolic syndrome. For some outcome measures, isolated aerobic exercise appears optimal.