Aim: High intensity interval training (HIIT) induces similar metabolic adaptations to traditional steady state aerobic exercise training. Until recently, most HIIT studies have examined maximum efforts in healthy populations. The current study aimed to examine the effects of a 2 week modified HIIT program on the homeostatic model of insulin resistance (HOMA-IR) in individuals with type 2 diabetes (T2D). It was hypothesized that HIIT would improve HOMA-IR.
Methods: Nine individuals with T2D (age=40.2±9.7 y; BMI=33.9±5.3; fasting plasma glucose [FPG]=8.7±2.9 mmol/L; HbA1C=7.3±1.2%; [mean±SD]) performed 6 individualized training sessions of HIIT (4x30 seconds at 100% of estimated maximum workload followed by 4 minutes of active rest) over 2 weeks. HOMA-IR was calculated from FPG and serum insulin and compared against a prior 2 week baseline period.
Results: Blood glucose was reduced immediately after each HIIT session (P<0.05). Anthropometrics, FPG, serum insulin, and HOMA-IR were unchanged after training. However, 6 of the 9 individuals exhibited reduced HOMA-IR values after the training period and there was a significant negative correlation between HOMA-IR value prior to training and change in HOMA-IR after HIIT.
Conclusion: These observations tend to support the positive health benefits of HITT for individuals with T2D reported in recently published data using a modified HIIT protocol. However, they suggest that the magnitude of the disease should be assessed when examining the effects of exercise interventions in individuals with T2D.