Abstract
BACKGROUND: A total of 6,500 to 8,000 steps per day are recommended for cardiovascular secondary prevention. The aim of this research was to examine how many steps per day patients achieve during ambulant cardiac rehabilitation (CR), and if there is a correlation between the number of steps and physical and cardiological parameters. METHODS: In all, 192 stable CR patients were included and advised for sealed pedometry. The assessed parameters included maximum working capacity and heart rate, body mass index (BMI), New York Heart Association (NYHA) class, ejection fraction (EF), coronary artery disease status, beta-blocker medication, age, sex, smoking behavior, and laboratory parameters. A regularized regression approach called least absolute shrinkage and selection operator (LASSO) was used to detect a small set of explanatory variables associated with the response for steps per day. Based on these selected covariates, a sparse additive regression model was fitted. RESULTS: The model noted that steps per day had a strong positive correlation with maximum working capacity (P=0.001), a significant negative correlation with higher age (P=0.01) and smoking (smoker: P<0.05; ex-smoker: P=0.01), a positive correlation with high-density lipoprotein (HDL), and a negative correlation with beta-blockers. Correlation between BMI and walking activity was nonlinear (BMI 18.5-24: 7,427±2,730 steps per day; BMI 25-29: 6,448±2,393 steps/day; BMI 30-34: 6,751±2,393 steps per day; BMI 35-39: 5,163±2,574; BMI >40: 6,077±1,567). CONCLUSION: Walking activity during CR is reduced in patients who are unfit, older, smoke, or used to smoke. In addition to training recommendations, estimated steps per day during CR could be seen as a baseline orientation that helps patients to stay generally active or even to increase activity after CR.