title: Dose-response association of physical activity with HbA1c: Intensity and bout length.
abstract: OBJECTIVE
  The aims of this study were to characterize the dose-response relationship between moderate-to-vigorous intensity physical activity (MVPA), and light-intensity activity with HbA1c in adults at low, moderate, and high risks of type 2 diabetes, and to compare the relationship of short (1 to 9min) versus long (10+min) bouts of MVPA with HbA1c.
  
  
  METHODS
  Data from 2707 participants from the 2003-2006 National Health And Nutrition Examination Survey were analyzed in 2014-2015. Type 2 diabetes risk was classified into three groups based upon age (<40years; ≥40years) and BMI (<30; ≥30). The relationship between HbA1c and accelerometer-based physical activity variables was assessed using multiple regression models.
  
  
  RESULTS
  There was a curvilinear dose-response relationship between HbA1c with total activity and MVPA in adults at moderate or high risk for type 2 diabetes: higher amounts of physical activity were associated with lower HbA1c. The association of physical activity on HbA1c was stronger at lower levels of physical activity. There was no dose-response relationship in adults at low risk for type 2 diabetes. The relationship between short bouts with HbA1c was stronger than for bouts≥10min.
  
  
  CONCLUSIONS
  In adults at risk for type 2 diabetes, there is a dose-response relationship between physical activity and HbA1c levels such that the relationship: (1) is curvilinear; (2) is stronger when a higher percent of total activity comes from MVPA; and (3) is more potent with short bouts of MVPA. Fractionalized physical activity of at least moderate-intensity may contribute to long-term glucose control.
authors.affiliation: Department of Health Promotion and Behavior, University of Georgia, Athens, GA, USA. Electronic address: jlgay@uga.edu.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Gay
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana-Champaign, IL, USA. Electronic address: dbuchner@illinois.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Buchner
authors.affiliation: Department of Kinesiology, University of Georgia, Athens, GA, USA. Electronic address: schmidtm@uga.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion / Q000502:physiology*; D013997:Time Factors
chemical_list: D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
keywords: Adults; Exercise; Fractionalized physical activity; Glucose control