Continuous aerobic exercise improves glucose tolerance in type 2 diabetics (T2D), with greater improvements during exercise in hypoxia. Continuous exercise has been linked with poor adherence. Positive effects with intermittent exercise (IE) with reduced time commitments would have clear benefits. Exercise and hypoxia both increase pro-inflammatory cytokines, potentially reducing benefits of hypoxia. This study aimed to establish the effects of IE under hypoxic conditions in T2D on i) glucose homeostasis and ii) TNFα and adiopnectin.
Seven overnight fasted individuals with T2D completed 3 trials separated by ~7 days; i) 60 min continuous exercise at 90% lactate threshold (LT) in normobaric hypoxia (O2 ~14.9%) (HyEx60); 5 min exercise at 120% LT, separated by 5 min passive recovery repeated for 60 min in ii) normoxia (Nor5:5) or iii) hypoxia (Hy5:5). Rates of glucose appearance (Ra) and disappearance (Rd) were determined during, immediately post, 24 and 48 h post hypoxia. Homeostasis model of insulin resistance (HOMAIR) and Fast Insulin Resistance Index (FIRI) were estimated. Serum samples were analysed by ELISA for TNFα and adiponectin. Values are presented as means (±S.E.M.).
All trials acutely lowered blood glucose concentrations. Rd increased 24 h following HyEx60 (baseline:1.85 (0.11), 24 h:2.01 (0.12) mg/kg per min). No difference was seen in Rd in Nor5:5 or Hy5:5. HOMAIR and FIRI decreased by 29 and 27% 48 h post HyEx60. Difference in Ra and Rd was depressed in HyEx60 only. TNFα decreased below baseline in HyEx60 both 24 and 48 h post exercise. Hy5:5 decreased TNFα at 24 but not 48 h. No change in TNFα was seen in Nor5:5. Non-significant trends towards decreased adiponectin levels were seen post Hy5:5 and Nor5:5.
Continuous exercise demonstrated the greatest improvements in glucose tolerance, while decreasing systemic circulation of TNFα. Findings are in agreement with previous work and suggest that hypoxic exercise may have clinical applications in the treatment of T2D.