Relationship of resting heart rate and physical activity with insulin sensitivity in a population-based survey

Resting heart rate (RHR) has been identified as an independent risk factor for cardiovascular disease and mortality, contributing to atherosclerosis, the progression of heart failure, and myocardial ischemia and infarction. This study examines the association RHR and physical activity has with insulin resistance and insulin secretion in a multiethnic cohort from North Kohala, Hawai'i.

Cross-sectional data from 1,440 participants of Native Hawaiian, Japanese, Filipino, Caucasian, and mixed ethnic ancestries were analyzed for the study to include anthropometric measurements, and biochemical markers. Body fat was estimated by calculating body mass indices (BMI); body fat distribution by waist-hip ratios (WHR); and fasting plasma glucose and insulin levels were used to calculate insulin resistance using the Homeostasis Model (HOMA-IR). First phase insulin response was estimated using the insulin secretion ratio (ISR). Associations were estimated using general linear models (GLM).

Caucasians had lower mean RHR than all other ethnic groups; there were no statistically significant differences between other ethnic groups on mean RHR. HOMA-IR was associated with ethnic group, BMI and WHR, PA and RHR, while ISR was associated with age, ethnic group and BMI, but none of the primary risk factors. Both RHR and physical activity level remained significant for insulin resistance.

In a multiethnic cohort from a rural community in Hawai'i, increased RHR and a lower level of physical activity were both independently associated with increased risk for the development of insulin resistance, suggesting cardiovascular fitness may be as important as physical activity in preventing insulin resistance.