Abstract
Traditional physical activity metrics include reported time spent in various levels of exertion, from sedentary to vigorous. Previous research has shown an association between time spent in moderate or vigorous activities and maximal aerobic capacity (VO2 max) in older adults, but the association between accelerometry derived activity metrics and VO2 max remains undefined. We modeled the association between VO2 max and objectively measured physical activity and heart rate in 411 BLSA participants (53% male, mean age 67, range 31–88), using percentages of heart rate reserve to define intensity of daily activities. Although the association between time spent in vigorous activities and VO2 max was significant, a continuous measure of total daily activity provided stronger results and a better model fit (accounting for 12% vs. 8% of unexplained variance), suggesting that total daily activity is a better predictor of VO2 max with aging, likely due to reduced intensity of daily activities.