Premium
Pitfalls in accelerometer‐based measurement of physical activity: The presence of reactivity in an adult population
Author(s) -
Baumann S.,
Groß S.,
Voigt L.,
Ullrich A.,
Weymar F.,
Schwaneberg T.,
Dörr M.,
Meyer C.,
John U.,
Ulbricht S.
Publication year - 2018
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.12977
Subject(s) - accelerometer , physical activity , population , reactivity (psychology) , medicine , sedentary behavior , activity monitor , physical medicine and rehabilitation , computer science , pathology , alternative medicine , environmental health , operating system
When a behavior is monitored, it is likely to change, even if no change may be intended. This phenomenon is known as measurement reactivity. We investigated systematic changes in accelerometer‐based measures over the days of monitoring as an indicator of measurement reactivity in an adult population. One hundred seventy‐one participants from the general population (65% women; mean age = 55 years, range: 42‐65 years) wore accelerometers for 7 consecutive days to measure sedentary behavior and physical activity (PA). Latent growth models were used (a) to investigate changes in accelerometer wear time over the measurement days and (b) to identify measurement reactivity indicated by systematic changes in sedentary time ( ST ), light physical activity ( LPA ), and moderate‐to‐vigorous physical activity ( MVPA ). Over the measurement days, participants reduced accelerometer wear time by trend (rate of change [ b ] = −4.7 min/d, P = .051, Cohen's d = .38), increased ST ( b = 2.4 min/d, P = .018, d = .39), and reduced LPA ( b = −2.4 min/d, P = .015, d = .38). Participants did not significantly reduce MVPA ( P = .537). Our data indicated that accelerometry might generate reactivity. Small effects on ST and LPA were found. Thus, the validity of accelerometer‐based data on ST and LPA may be compromised. Systematic changes observed in accelerometer wear time may further bias accelerometer‐based measures. MVPA seems to be less altered due to the presence of an accelerometer.