Introduction
Cardiovascular diseases (CVDs), such as ischaemic heart disease, are the leading cause of death worldwide.1 The development of diagnostics, drug therapy and interventional procedures has decreased CVD mortality. However, the CVDs still cause 32% of deaths globally.1 Medical and invasive therapies also have side effects, and they induce great economical burden to society.2 Exposing factors behind CVDs are sex, old age, genetic vulnerability, impaired physical fitness, smoking, elevated low-density lipoprotein (LDL) cholesterol, hypertension and diabetes.3 4 . These factors have been exploited to build models that predict individual’s risk of developing a CVD in the future, such as the well-established Framingham Risk Score (FRS).5
Sedentary behaviour (SB) was recently demonstrated to be a risk factor of CVDs and mortality.3 6 7 SB is defined as energy expenditure ≤1.5 metabolic equivalent (MET) (=3.5 mL/kg/min O2 consumption), which indicates energy consumed in seated, reclined or lying position. Low physical activity (PA) is another important risk factor of CVDs. PA is defined as energy expenditure >1.5 MET.8 9 Previous studies have confirmed an inverse association between PA and CVDs.10 In addition, the longitudinal effects of PA have been discovered to be beneficial in preventing CVDs.11
Assessment of PA and SB can be conducted by subjective or objective methods. Traditionally, subjective methods, such as questionnaires, have been used to determine the amount of SB and PA.12 13 One objective means is to use an accelerometer.9 Previous studies have shown that objective measurements are more accurate in investigating the associations of SB and PA with CVDs than self-report tools.14 15 Objective measurements might allow more precise dose–response relationship between CVDs and SB or PA than self-reported estimates.3 6 Accelerometer data have mostly been analysed with count-based units.6 15 However, the count-based data from various studies are largely incomparable because cut-points and algorithms are varying between studies.9 16
The specific differences in SB and PA profiles among patients with CVD and non-CVD peers should be determined to design lifestyle-based strategies for the primary and secondary prevention of CVDs. The purpose of the present study was to objectively investigate SB and PA parameters, for example, number and accumulated times of different bout lengths among subjects with high CVD risk or established CVD compared with their healthy peers with low CVD risk.