Abstract
Introduction
Physical activity (PA) promotes cardiovascular (CV) health in older adults; however, traditional measures such as moderate-to-vigorous physical activity (MVPA) and steps/day do not capture PA accumulation throughout a day. Activity fragmentation may predict behavior patterns associated with CV health. The aim of the study is to determine whether daily PA fragmentation can predict CV health in older adults (≥ 55 years). We hypothesize that the Active to Sedentary Transition Probability (ASTP) will be more closely correlated to CV health compared to non-fragmented PA measures.
Methods
Adults (≥ 55 years) wore a physical activity monitor for 7 days to measure MVPA, steps/day, and ASTP. Heart rate variability (HRV) and brachial artery flow-mediated dilation (FMD) were assessed after 7-days using a Polar H10 heart rate monitor and Doppler Ultrasound, respectively.
Results
Sixteen participants (Age: 63±9.0y, Sex: 4 male and 12 female; Body Mass Index (BMI): 25.26±4.40 Kg/m^2, %Fat: 31.06±9.81) were recruited. MVPA and steps/day were poorly correlated to Root Mean Square of Successive Differences (RMSSD) (MVPA: r=0.288, Steps/day: r=0.370), Standard Deviation of Normal-to-Normal intervals (SDNN) (MVPA: r=0.173, Steps/day: r=0.206), and FMD (MVPA: r=0.349, Steps/day: r=0.313). ASTP showed very poor correlations with these CV measures (RMSSD: r=0.208, SDNN: r=0.167, FMD: r= -0.073).
Conclusion
These preliminary data demonstrate activity fragmentation has weaker correlation to CV measures than traditional PA. Given the limited sample size, these findings should be interpreted cautiously.