Can step count be used to identify older adults with high sedentary time and low moderate-to-vigorous physical activity?

Introduction: Combined high sedentary time (ST) and low moderate-to-vigorous physical activity (MVPA) has been associated with adverse cardiovascular events. However, accurately assessing ST and MVPA in older adults is challenging in clinical practice. Purpose: To investigate whether step count can identify older adults with unhealthier movement behavior (high ST/low MVPA) and poorer cardiometabolic profile. Methods: Cross-sectional study (n = 258; 66 +/- 5 years). Step count, ST, and MVPA were assessed by hip accelerometry during 7 days. The cardiometabolic profile was assessed using a continuous metabolic syndrome score (cMetS), including blood pressure, HDL-cholesterol, triglycerides, fasting glucose, and waist circumference. Receiving operating curve analysis was used to test the performance of step count in identifying older adults with unhealthier movement behavior (highest tertile of ST/lowest tertile of MVPA). Healthier movement behavior was defined as lowest tertile of ST/highest tertile of MVPA, with neutral representing the remaining combinations of ST/MVPA. Results: A total of 40 participants (15.5%) were identified with unhealthier movement behavior (ST >= 11.4 h/day and MVPA <= 10 min/day). They spent similar to 73% and 0.4% of waking hours in ST and MVPA, respectively. Step count identified those with unhealthier movement behavior (area under the curve 0.892, 0.850-0.934; cutoff: <= 5263 steps/day; sensitivity/specificity: 83%/81%). This group showed a higher cMetS compared with neutral (beta = .25, p = .028) and healthier movement behavior groups (beta = .41, p = .008). Conclusion: Daily step count appears to be a practical, simple metric for identifying community-dwelling older adults with concomitant high ST and low MVPA, indicative of unhealthier movement behavior, who have a poorer cardiometabolic profile.