High intensity interval training improves liver and adipose tissue insulin sensitivity

Area of Science:

• Metabolic disease research
• Exercise physiology
• Molecular biology

Background:

• Endurance exercise training improves insulin resistance, but the mechanisms of high-intensity interval training (HIIT) for lowering blood glucose independently of weight loss are unclear.
• Intense exercise activates AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) pathway, crucial for fatty acid metabolism and insulin sensitivity, but its role in HIIT is unknown.

Purpose of the Study:

• To investigate the effects of HIIT on glucose regulation and insulin sensitivity.
• To determine the role of the AMPK-phosphorylation of ACC pathway in mediating HIIT's metabolic benefits.

Main Methods:

• Obese mice (wild-type and AccDKI mutants) underwent 6 weeks of HIIT.
• Evaluated changes in blood glucose, exercise capacity, food intake, activity levels, carbohydrate oxidation, and insulin sensitivity in liver and adipose tissue.

Main Results:

• HIIT reduced blood glucose and enhanced exercise capacity, food intake, and activity in both wild-type and AccDKI mice.
• Metabolic improvements, including increased carbohydrate oxidation and insulin sensitivity in liver and adipose tissue, occurred independently of weight loss or changes in adiposity and inflammation.

Conclusions:

• HIIT effectively lowers blood glucose by improving adipose and liver insulin sensitivity.
• These benefits are achieved independently of weight loss, reduced adiposity, inflammation, liver fat, or the AMPK-phosphorylation of ACC pathway.