V.G. Duffy (Ed.): DHM/HCII 2013, Part II, LNCS 8026, pp. 261–268, 2013. © Springer-Verlag Berlin Heidelberg 2013 Chair Based Measurements of Sitting Behavior a Field Study of Sitting Postures and Sitting Time in Office Work Matthijs P. Netten 1 , L.H.M. van der Doelen 1,2 , and Richard H.M. Goossens 1,3 1 Delft University of Technology, Faculty of Industrial Design Engineering, Section Applied Ergonomics and Design, Delft, The Netherlands {m.p.netten,R.H.M.Goossens}@tudelft.nl 2 BMA Ergonomics, Zwolle, The Netherlands B.van.der.doelen@bma-ergonomics.com 3 Erasmus University Rotterdam, Department of Neuroscience, The Netherlands Abstract. In order to understand the relation between prolonged sitting and the relation to health outcome, the behavior while being seated must be studied. A total of 41 office workers participated in a study whilst performing their regular work for eight weeks, whilst sitting on a measuring office chair (Smart Chair). The first two (control) weeks they were not aware of the measuring abilities of the chair. After this, two groups were made to distinguish between the effects of chair instruction and smart feedback on sitting postures (Van der Doelen et al. 2011). In this paper the data has been analyzed in another way. The aim of this paper is to explore the characteristics of sedentary behavior for 41 subjects during their regular office work over eight weeks by measuring the events of sitting and absence from their office chair. Results showed that the office workers in this study on average have very long sitting events, that exceed general recommendations. Results showed that the office workers in this study on average have very long sitting events, that exceed general recommendations. Recommendations for 5 minute breaks every hour are met by 85% of the participants. However recommendations on sitting les than 20 minutes were met by 5% of the participants. None of the participants met the recommendations on all of their days during the field study. The sedentary behavior shown in this study underlines the importance to monitor and influence sedentary behavior while considering the individual sedentary patterns. Further knowledge on analyzing sedentary patterns is needed. Keywords: device-based measures, sedentary behavior. 1 Introduction The amount of time spent in sedentary situations has increased since the introduction of new communication technologies, like the computer. Some studies report that prolonged sitting can have adverse effects on health outcomes [1]. For some people the workplace covers an important part of the sedentary life of people and it is