Accelerometry in cardiovascular psychophysiology: New perspectives for ambulatory research

Interpretation of real-life stress-related cardiovascular responses requires knowledge of both the type and the amount of daily activities, since changes in body posture and locomotor activity have a profound effect on ambulatory recorded cardiovascular signals. Simultaneous recording of cardiovascular and locomotor activity may therefore facilitate the interpretation of prolonged cardiovascular measurements in clinical and experimental research. We evaluated accelerometry as a method to quantify both static (lying, sitting, standing) and dynamic activities in a study that was designed to assess the sedative effects of benzodiazepines on cardiovascular functioning in relation to normal daily activities. Our validation study showed that accelerometry by means of body-mounted sensors forms a valid method to quantify aspects of normal daily activities. Furthermore, our quantification of body postures and physical activity, in relation to heart rate, proved to be sufficiently sensitive to differentiate the placebo from the pharmacological conditions. Ambulatory monitoring of combined cardiovascular and accelerometer signals therefore proved to be a promising method for psychophysiological research.