The effect of a novel low-volume aerobic exercise intervention on liver fat in type 2 diabetes: a randomised 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, glycaemia, and cardiorespiratory fitness using a randomised placebo-controlled design.

Research design and methods: Thirty-five inactive adults (54.6±1.4 years, 54% male; BMI 35.9±0.9kg/m2) with obesity and type 2 diabetes were randomised to 12 weeks of supervised: MICT (n=12) at 60% VO_2peak for 45 minutes, 3 days/week, HIIT (n=12) at 90% VO_2peak for 4 minutes, 3 days/week, or PLA (n=11). Liver fat % was quantified via proton magnetic resonance spectroscopy.

Results: Liver fat reduced in MICT (-0.9±0.7%) and HIIT (-1.7±1.1%) but increased in PLA (1.2±0.5%) (p = 0.046). HbA1c improved in MICT (-0.3±0.3%) and in HIIT (-0.3±0.3%) but not in PLA (0.5±0.2%) (p=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 (-1.5±0.9 ml/kg/min) (p=0.006).

Conclusions: MICT or a low-volume HIIT approach involving 12 minutes of weekly high-intensity exercise may improve liver fat, glycaemia, and cardiorespiratory fitness in 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 glycaemia.