The effect of a novel low-volume aerobic exercise intervention on liver fat in type 2 diabetes : a randomized controlled trial

OBJECTIVE The aim of this study was to examine the effect of a novel low-volume high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), or placebo (PLA) intervention on liver fat, glycemia, and cardiorespiratory fitness using a randomized placebo-controlled design. RESEARCH DESIGN AND METHODS Thirty-five inactive adults (age 54.6 ± 1.4 years, 54% male; BMI 35.9 ± 0.9 kg/m²) with obesity and type 2 diabetes were randomized to 12 weeks of supervised MICT (n 5 12) at 60% VO_2peak for 45 min, 3 days/week; HIIT (n 5 12) at 90% VO_2peak for 4 min, 3 days/week; or PLA (n 5 11). Liver fat percentage was quantified through proton MRS. RESULTS Liver fat reduced in MICT (20.9 ± 0.7%) and HIIT (21.7 ± 1.1%) but increased in PLA (1.2 ± 0.5%) (P 5 0.046). HbA_1c improved in MICT (20.3 ± 0.3%) and HIIT (20.3 ± 0.3%) but not in PLA (0.5 ± 0.2%) (P 5 0.014). Cardiorespiratory fitness improved in MICT (2.3 ± 1.2 mL/kg/min) and HIIT (1.1 ± 0.5 mL/kg/min) but not in PLA (21.5 ± 0.9 mL/kg/min) (P 5 0.006). CONCLUSIONS MICT or a low-volume HIIT approach involving 12 min of weekly high-intensity aerobic exercise may improve liver fat, glycemia, and cardiorespiratory fitness in people with type 2 diabetes in the absence of weight loss. Further studies are required to elucidate the relationship between exercise-induced reductions in liver fat and improvements in glycemia.