Principal Investigators: Alexander Woll, Ulrich Ebner-Priemer

The aim of this project was to identify individualized (just-in-time) opportunities to promote modifiable behavioral risk factors—such as increasing physical activity and reducing sedentary behavior—by using data from activity-monitoring devices (e.g., wearable sensors) and contextual factors surrounding the individual (e.g., social and environmental influences). The approach also incorporated the goals and preferences of both the individual and the organization.

To achieve this, we analyzed data from an ambulatory assessment study involving 199 university employees. Physical behaviors were continuously measured throughout the day using thigh-worn accelerometers. Productivity and working memory performance (measured via a numeric updating task) were assessed up to six times per day through electronic diaries and smartphone-based tasks.

The study began with an in-person session lasting approximately three hours, during which participants completed cognitive tasks, filled out questionnaires, and performed an incremental treadmill test to volitional exhaustion. Following this session, participants underwent a 15-day ambulatory assessment during regular workdays. The study focused on three key objectives:

i) to examine the associations between daily compositions of physical behavior (i.e., light physical activity, moderate-to-vigorous physical activity, sedentary behavior, and sleep) and self-perceived work ability; ii) to investigate how daily patterns of physical behavior and sleep influence self-perceived work ability; and iii) to explore how cognitive performance and physical fitness, as assessed under standardized laboratory conditions, predict or relate to everyday physical activity and cognitive performance—thereby contributing to the discourse on ecological validity in behavioral research.

Initial analyses revealed that a higher proportion of moderate-to-vigorous physical activity—at the expense of sleep, light physical activity, or sedentary behavior—was positively associated with self-perceived work ability. In contrast, sleep, sedentary behavior, and light physical activity (each relative to the remaining behaviors) were not significantly associated with work ability. Exploratory compositional isotemporal substitution analyses suggested that reallocating daily time to or from moderate-to-vigorous physical activity can impact self-perceived work ability.

Further analyses indicated that better sleep quality and higher daily step counts were also positively associated with work ability. Notably, the relationship between sleep quality and productivity was moderated by workplace setting (e.g., remote vs. on-site work). Sedentary behavior, however, showed no significant effect on work ability. These findings highlight that maintaining an active and well-rested lifestyle may support productivity across diverse work environments.

Lastly, the third set of analyses suggested that laboratory data can be used to predict everyday variations in behavior. For instance, work ability scores from cross-sectional questionnaires and daily step counts predicted higher momentary self-perceived work ability. Laboratory-assessed working memory performance also predicted mobile working memory task performance in daily life. Additionally, both momentary work ability and VO₂max were associated with greater step counts during daily activities.

Further information: https://www.ifss.kit.edu/forschung/11231.php

Link to publication: https://www.nature.com/articles/s44184-024-00113-7