Comparative Effect of Moderate-intensity Continuous Training (MICT) or High-intensity Interval Training (HIIT) on Some Structural Parameters of the Heart in Two Types of Animal Models of Pre-diabetes and Type 2 Diabetes

The purpose of this study was to investigate the effect of exercise training with two different intensity levels on some structural parameters of the heart in mice with pre-diabetes and type 2 diabetes.

For this purpose, 39 male C57bl/6j mice were divided into two groups: High-fat Diet (HFD) and Normal Diet (ND). After 20 weeks of a 60% fat diet for HFD mice and normal food for ND mice, 12 of the HFD mice were injected with streptozotocin (STZ) and then divided into three subgroups: control (C), High-intensity Interval Training (HIIT), and Moderate-intensity Continuous Training (MICT). The mice of the exercise training groups were trained for eight weeks. Then, tissue factors, including heart weight, vascular density, fibrosis, steatosis, and degenerative changes in the heart, were examined . One-way analysis of variance and percentage frequency were used to analyze and report the results.

A high-fat diet decreased vascular density (30%) and degenerative changes, and STZ injection decreased vascular density (33%), myocardial fibrosis, and steatosis. Both exercise training types were associated with improvement of symptoms, including heart weight, fibrosis, steatosis, and degenerative changes. However, MICT had a stronger effect than HIIT on most factors.

A high-fat diet, with or without STZ, was associated with cardiac pathological changes. It seems that MICT can produce stronger effects in reducing these symptoms than HIIT.