title: Intermittent exercise with and without hypoxia improves insulin sensitivity in individuals with type 2 diabetes.
abstract: BACKGROUND
  Hypoxia and muscle contraction stimulate glucose transport activity in vitro. Exercise and hypoxia have additive effects on insulin sensitivity in type 2 diabetics (T2D).
  
  
  OBJECTIVE
  The objective of the study was to examine the effectiveness of intermittent exercise with and without hypoxia on acute- and moderate-term glucose kinetics and insulin sensitivity in T2D.
  
  
  METHODS
  The study was conducted at a university research center.
  
  
  METHODS
  Eight male T2D patients completed the following: 1) 60 min of continuous exercise at 90% lactate threshold in hypoxia (HyEx60); 2) intermittent exercise at 120% lactate threshold, separated by periods of passive recovery (5:5 min) in hypoxia [Hy5:5; O₂ ∼ 14.7 (0.2)%]; and 3) intermittent exercise (5:5 min) at 120% lactate threshold in normoxia (O₂ ∼ 20.93%).
  
  
  METHODS
  Glucose appearance and glucose disappearance, using an adapted non-steady-state one-compartment model were measured. Homeostasis models of insulin resistance (HOMA(IR)), fasting insulin resistance index (FIRI), and β-cell function were calculated 24 and 48 h after exercise conditions.
  
  
  RESULTS
  Glucose disappearance increased from baseline (1.85 mg/kg · min⁻¹) compared with 24 h (2.01 min/kg · min⁻¹) after HyEx60 (P = 0.031). No difference was noted for both Hy5:5 (P = 0.064) and normoxia (P = 0.385). Hy5:5 demonstrated improvements in HOMA(IR) from baseline [d 1, 6.20 (0.40)] when comparisons were made with d 2 [4.83 (0.41)] (P = 0.0013). HOMA(IR) and FIRI improved in the 24 h (HOMA(IR), P = 0.002; FIRI, P = 0.003), remaining reduced 48 h after HyEx60 (HOMA(IR), P = 0.028; and FIRI, P = 0.034).
  
  
  CONCLUSIONS
  HyEx60 offered the greatest improvements in acute and moderate-term glucose control in T2D. Intermittent exercise stimulated glucose disposal and improved post-exercise insulin resistance, which was enhanced when exercise was combined with hypoxia (Hy5:5). The data suggest a use of hypoxic exercise in treatment of T2D.
authors.affiliation: School of Life Sciences, University of Westminster, 115 New Cavendish Street, London W1W 6UW, United Kingdom. r.mackenzie@westminster.ac.uk
authors.forename: R
authors.initials: R
authors.lastname: Mackenzie
authors.forename: N
authors.initials: N
authors.lastname: Maxwell
authors.forename: P
authors.initials: P
authors.lastname: Castle
authors.forename: B
authors.initials: B
authors.lastname: Elliott
authors.forename: G
authors.initials: G
authors.lastname: Brickley
authors.forename: P
authors.initials: P
authors.lastname: Watt
mesh_terms: D000465:Algorithms; D001786:Blood Glucose / Q000032:analysis; D018592:Cross-Over Studies; D003903:Deuterium; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D015444:Exercise; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia / Q000517:prevention & control; D006946:Hyperinsulinism / Q000517:prevention & control; D000860:Hypoxia / Q000209:etiology*; D007333:Insulin Resistance; D050417:Insulin-Secreting Cells / Q000378:metabolism; D007700:Kinetics; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010100:Oxygen / Q000097:blood*; D057185:Sedentary Behavior
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid; D003903:Deuterium; D005947:Glucose; D010100:Oxygen