High-intensity aerobic interval training improves aerobic fitness and HbA1c among persons diagnosed with type 2 diabetes

• Stоa Eva Maria
• Meling S.
• Nyhus L.-K.
• Stromstad G.
• Mangerud K.M.
• Helgerud J.
• Bratland–Sanda S.
• Stоren O.

Abstract

Purpose. It remains to be established how high-intensity aerobic interval training (HAIT) affects risk factors associated with type 2 diabetes (TD2). This study investigated effects of HAIT on maximal oxygen uptake (VO_2max), glycated Hemoglobin type A_1c (HbA_1c), insulin resistance (IR), fat oxidation (FatOx), body weight (BW), percent body fat (%BF), lactate threshold (LT), blood pressure (BP), and blood lipid profile (BLP) among persons with T2D. Results were compared to the effects after a moderate-intensity training (MIT) program.

Methods. Thirty-eight individuals with T2D completed 12 weeks of supervised training. HAIT consisted of 4x4 min of walking or running uphill at 85-95% of maximal heart rate, and MIT consisted of continuous walking at 70-75% of maximal heart rate.

Results. A 21% increase in VO_2max (from 25.6 to 30.9 ml x kg^-1 x min^-1, p<0.001), and a reduction in HbA_1c by -0.58% points (from 7.78 to 7.20%, p<0.001) was found in HAIT. BW and body mass index (BMI) was reduced by 1.9% (p<0.01). There was a tendency towards an improved FatOx at 60% VO_2max (14%, p=0.065). These improvements were significant different from MIT. Both HAIT and MIT increased velocity at LT, and reduced %BF, waist circumference, hip circumference, and BP, with no significant differences between the two groups. Correlations were found between change in VO_2max and change in HbA_1c when the two intervention groups were combined (fi=-0.52, p<0.01).

Conclusion. HAIT is an effective exercise strategy to improve aerobic fitness and reduce risk factors associ­ated with T2D.

Keywords:exercise intensity, interval training, maximal oxygen uptake, HbA1c, fat oxidation