Laboratory stress testing to assess real-life cardiovascular reactivity.

Thirty-six normotensive adults received laboratory stress testing (mental arithmetic, short-term memory, isometric handgrip, cold pressor tests) and 24-hour ambulatory blood pressure monitoring on two work days separated by a month. Laboratory and ambulatory measures of cardiovascular reactivity had low test-retest reliability. Increases in blood pressure during the memory and cold pressor tests were related to measures of reactivity obtained outside the laboratory (waking blood pressure variability, responses to home and work environments). However, the portion of ambulatory reactivity accounted for by laboratory reactivity was small. In the best case (r = 0.43), cold pressor diastolic pressure explained only 19% of diastolic pressure variability in the natural environment. Laboratory-ambulatory disagreement in reactivity was related to interindividual variability in physical activity on the day of ambulatory monitoring.