Can sedentary adults accurately recall the intensity of their physical activity?

Background. Physical activity, in particular vigorous activity (i.e., great er than or equal to6 METs), lowers mortality from chronic diseases such as cardiovascular disease (CVD). The 7-Day Physical Activity Recall (PAR), a s elf-administered activity log (LOG), and heart rate monitoring (HR) were us ed to quantify activity patterns among sedentary adults. We hypothesized th at individuals in this population could accurately estimate the duration, b ut not the intensity, of their activity. Methods. Sedentary adults (n = 94, 47.8 +/- 7.1 years) completed two PARs 1 week apart and underwent HR monitoring while completing a LOG for 1 day du ring the PAR assessment interval. Results. The relationship between PARs (kcal.kg(-1) day(-1)) was significan t (r = 0.80, 95% CI 0.68-0.87) among individuals (n = 63) reporting "typica l" activity patterns and among all individuals (n = 94) reporting "typical" and "not typical" activity patterns combined (r = 0.44, 95% CI 0.26-0.59). Quantity of moderate activity was greater (P = 0.0001) on PAR and LOG comp ared to that measured by HR. Quantity of hard (vigorous) activity was also greater (P = 0.019) on LOG compared to that measured by HR. Conclusions. Sedentary adults tend to overestimate the intensity of their a ctivity, specifically for moderate activity. Furthermore, the aerobic capac ity of our sedentary adult sample (about 7.3 METs) suggests that the defini tion of a threshold intensity level of activity necessary to reduce mortali ty from CVD should be reexamined, because a value of greater than or equal to6 METs appears to be too high in this population. (C) 2001 American Healt h Foundation and Academic Press.