Prevalence and correlates of self-reported and accelerometer-determined sedentary behavior and physical activity of German university students: cross-sectional results of the SmartMoving study

BACKGROUND: Sedentary behavior (SB) and the absence of physical activity (PA) have become increasingly prevalent in modern societies due to changes in physical and social-environmental conditions, particularly in university students. This cross-sectional study aimed to describe and identify the prevalence and correlates of self-reported and accelerometer-determined SB and PA of German university students. METHODS: A convenience sample of 532 students participated in a questionnaire survey during the lecture period in the summer term 2018. Self-reported total PA, university-, travel-, and leisure-time-related PA were calculated, in addition to self-reported sitting time (ST) within the university. A sub-sample of forty-six participants also received body composition measurements and then wore an ActiGraph wGT3X-BT for seven consecutive days to objectively determine SB, PA, and sleep duration. Differences in descriptive characteristics between samples were analyzed using independent t-test for normally distributed variables or the nonparametric or Mann-Whitney U-Test for not normally distributed variables. Forward stepwise logistic regression analyses were used to analyze correlates associated with self-reported SB and PA in the university context. Stepwise, multiple linear regression analysis was used to determine the associations of anthropometric, sociodemographic, study-related, self-reported SB and PA variables with objectively-determined SB controlling for potential confounders. RESULTS: Self-reported ST within the university was 2020.5 min/week (95% CI: 1915.8-2125.1), while females reported a 4 h per day higher ST compared with male students (p = 0.023). Self-reported PA exclusively at the university was 211.9 min/week (195.3-228.6) with additional time in active travel (AT) of 266.1 min/week (236.8-295.4). Students with higher amounts of sitting (e.g. in the library or in lectures; p < 0.001) and students who had lower time in AT (p = 0.023) were more likely to be sedentary in the university context. Furthermore, students with a higher monthly net household income (p = 0.043), higher values in university-related PA (e.g. walking between lectures or stair climbing; p < 0.001) and students who were also engaged in higher times of AT (p = 0.004) were more physically active at the university compared with students in the reference group. Correlates associated with accelerometer-determined SB included light-intensity PA (LIPA; p < 0.001), moderate-to-vigorous PA (MVPA; p < 0.001), sleep duration (p < 0.001), monthly net household income (p = 0.006) and total cycling time at the university (p = 0.032). CONCLUSION: Our sample of university students were highly sedentary, but also very active and met current PA recommendations. Daily LIPA, MVPA and also sleep duration were negatively associated with accelerometer-determined SB. Beyond that, daily AT might be a supporting correlate to reduce SB in university students and should be considered as a key variable in future longitudinal interventional studies on activity-friendly and health promoting university environments.