title: Effect of aerobic exercise intensity on glycemic control in type 2 diabetes: a meta-analysis of head-to-head randomized trials.
abstract: OBJECTIVE
  To conduct a meta-analysis of head-to-head trials comparing aerobic exercise training of different intensities on glycemic control in type 2 diabetes.
  
  
  METHODS
  Databases, including MEDLINE and EMBASE, were searched up to January 2016. Randomized trials of at least 12 weeks in duration that compared two exercise interventions of different intensities were identified. Two reviewers independently extracted data from eligible trials. Using fixed effect model, weighted mean differences (WMD) between different exercise intensities were calculated for changes in glycated hemoglobin (HbA1c) and secondary outcomes, such as fasting glucose and fasting insulin.
  
  
  RESULTS
  Eight studies with a total of 235 participants were eligible. The exercise interventions lasted from 12 weeks to 6 months. The prescribed exercise intensities varied among studies. Four studies utilized vigorous exercise intensities for short durations by performing interval training. Overall, higher-intensity exercise resulted in a greater reduction in HbA1c compared to lower-intensity exercise (WMD = -0.22 %; 95 % confidence interval [-0.38, -0.06]; or -2.4 mmol/mol [-4.15, -0.66], I (2) = 0). Adherence to exercise and proportion of dropouts did not differ within trials. No adverse events were reported in these small trials with selected inclusion criteria.
  
  
  CONCLUSIONS
  Although our meta-analysis had a limited sample size, increasing exercise intensity safely accentuated reductions in HbA1c in some people with type 2 diabetes. Different approaches have been used to increase exercise intensity (i.e., some used interval training, whereas others used higher-intensity continuous exercise). However, at this time, it is unclear which form, if any, leads to the most favorable results.
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, 1-052 Li Ka Shing Centre for Health Research Innovation, Edmonton, AB, T6G 2E1, Canada.
authors.forename: Yilina
authors.initials: Y
authors.lastname: Liubaoerjijin
authors.affiliation: Faculty of Rehabilitation Medicine, Department of Occupational Therapy, University of Alberta, 1-46 Corbett Hall, Edmonton, AB, T6G 2G4, Canada.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Terada
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, 1-052 Li Ka Shing Centre for Health Research Innovation, Edmonton, AB, T6G 2E1, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Fletcher
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, 1-052 Li Ka Shing Centre for Health Research Innovation, Edmonton, AB, T6G 2E1, Canada. nboule@ualberta.ca.
authors.forename: Normand G
authors.initials: NG
authors.lastname: Boulé
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000628:therapy*; D015444:Exercise; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic
chemical_list: D001786:Blood Glucose
keywords: HOMA of insulin resistance; HbA1c; Physical activity intensity; Systematic review