All‐Extremity High‐Intensity Interval Training and Moderate‐Intensity Continuous Training Improve Aerobic Fitness and Cardiac Function in Type 2 Diabetes

Abstract

High‐intensity interval training (HIIT) on the treadmill has been reported to be more effective in improving aerobic fitness and cardiac function compared with moderate‐intensity continuous training (MICT) in adults with cardiometabolic disorders. However, middle‐aged and older adults with type 2 diabetes (T2D) are often unable to tolerate weight‐bearing exercise which may hinder HIIT and MICT on the treadmill. Therefore, the purpose of this randomized clinical trial was twofold: 1) to test if non‐weight bearing all‐extremity HIIT and MICT are feasible in adults with T2D aged 50 to 79 yrs; and 2) to test whether HIIT is more effective in improving aerobic fitness and cardiac function than MICT. Fifty‐three sedentary adults with T2D (age: 63±1 yrs), free of cardiovascular disease, were randomized to HIIT (n=21), MICT (n=18) or non‐exercise control (CONT; n=14). HIIT (4×4‐min intervals at 90% of peak heart rate; HRpeak) and isocaloric MICT (70% of HRpeak) were performed on an all‐extremity ergometer, 4 times/week for 8 weeks under supervision. Aerobic fitness was assessed by oxygen consumption during an incremental maximal exercise test. Left ventricular (LV) function was assessed during rest by two‐dimensional echocardiography including conventional and tissue Doppler. All measures were obtained at pre‐ and post‐intervention. Approximately 80% of participants randomized to all‐extremity HIIT and MICT completed the exercise intervention. Aerobic fitness improved by 11% in HIIT (22.4±1.2 vs. 24.9±1.4 ml/kg/min, pre‐ vs. post‐intervention; P<0.0001) and 7% in MICT (21.4±1.3 vs. 23.0±1.3 ml/kg/min; P=0.004 and P=0.4 for HIIT vs. MICT), whereas it did not change in CONT (21.4±1.5 vs. 21.3±1.2 ml/kg/min; P=0.9). Ejection fraction, a measure of LV systolic function, increased in both HIIT and MICT by ~2% (HIIT: 54.7±0.7 vs. 56.6±0.9%; P=0.007 and MICT: 54.6±1.4 vs. 56.4±1.2%; P=0.04), whereas it remained unchanged in CONT (56.0±1.2 vs. 54.9±1.1%; P=0.2). Diastolic function was not significantly affected by the intervention (P≥0.06). In conclusion, all‐extremity HIIT and MICT are feasible in middle‐aged and older adults with T2D and are equally effective in improving aerobic fitness and LV systolic function.Support or Funding InformationThis work was supported by the National Institutes of Health (NIA AG 050203).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.