Physical activity and dose-characteristics in free-living conditions among patients awaiting coronary artery bypass graft surgery: a cross-sectional study.

Background: Physical activity prior to elective coronary artery bypass grafting (CABG) surgery can potentially improve postoperative outcomes. The aim of the study was to evaluate subjectively and objectively physical activity levels and dose-characteristics in free-living conditions in patients awaiting CABG surgery.

Methods: A single-centered cross-sectional subanalysis of 32 participants awaiting elective CABG surgery. Physical activity during the preoperative period was assessed subjectively with the SQUASH questionnaire and objectively with the Sensewear activity monitor (accelerometer with physiological sensors). The Wilcoxon signed-rank test was used to assess differences and Bland-Altman plots were used to assess the agreement between the measurement methods. Descriptive statistics were used for the dose-characteristics and Cohen's Kappa for the proportion of participants fulfilling the Dutch guideline for healthy physical activity (NNGB).

Results: Duration of vigorous activity was significantly higher when measured subjectively (120 min/week) than objectively (7 min/week, p = 0.001). Bland-Altman plots showed that differences between the methods increased with longer durations of moderate and total activity. The dose-characteristics of physical activity measured with the SQUASH varied widely among the participants and it consisted mainly of leisure time activities and light household activities. The percentage of participants complying with the NNGB guideline was 74% when measured subjectively and 90% when measured objectively (κ = 0.259, p = 0.089).

Conclusions: Surprisingly, both measurement methods suggest that the majority of patients awaiting CABG surgery met the recommendations of the NNGB guideline. The agreement between the methods however decreased with higher physical activity levels. Despite its limitations, the study suggests the complementary value of a subjective and objective measurement of physical activity in free-living conditions among CABG patients.