High-intensity aerobic interval training improves aerobic fitness and HbA1c among persons diagnosed with type 2 diabetes.
Level 2 - randomized trial
Controlled clinical trial comparing two supervised exercise interventions
PubMed 28160083 · doi:10.1007/s00421-017-3540-1
What was done
Thirty-eight individuals with type 2 diabetes completed a 12-week supervised exercise intervention comparing two protocols: high-intensity aerobic interval training (HAIT; 4 × 4 minutes of walking or running uphill at 85-95% of maximal heart rate) versus moderate-intensity training (MIT; continuous walking at 70-75% of maximal heart rate). Measured outcomes included VO2max, HbA1c, body weight, BMI, fat oxidation, lactate threshold, body composition, blood pressure, and blood lipids.
What was found
Compared to MIT, HAIT led to significantly greater improvements in VO2max (+21%, from 25.6 to 30.9 ml kg-1 min-1, p < 0.001), HbA1c reduction (-0.58 percentage points, from 7.78 to 7.20%, p < 0.001), and body weight/BMI reduction (-1.9%, p < 0.01), with a trend toward improved fat oxidation at 60% VO2max (+14%, p = 0.065). Both groups improved velocity at lactate threshold, percent body fat, waist and hip circumference, and blood pressure with no significant differences between groups. Change in VO2max correlated with change in HbA1c across combined groups (R = -0.52, p < 0.01).
Why it matters
This study demonstrates that high-intensity aerobic interval training is more effective than standard moderate continuous exercise for improving cardiorespiratory fitness and glycemic control in type 2 diabetes.
Limits
The sample size is small (n = 38 completers), and the abstract does not state if participants were randomized or if intention-to-treat analysis was performed. Specific numerical outcomes for insulin resistance and lipid profiles were not reported in the abstract, and long-term adherence beyond 12 weeks was not evaluated.
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