Background
In recent years in-chair movements (ICM) have gained attention in comfort and discomfort studies, but the role of these movements in preventing and/or alleviating discomfort remains unclear. Furthermore, differences in study design and terminology make cross-study comparisons difficult.

Objective
This study aims to synthesize current research on ICM, particularly the categorization of different ICM types. It also aims to provide an overview of ICM over time, focusing on their progressions, characteristics, and possible patterns.

Methods
A systematic literature search was conducted based on the PRISMA framework using Scopus, PubMed, and Web of Science databases. Data from the included studies were extracted and organized according to three ICM descriptors: frequency, amplitude, and posture change.

Results
Eighteen out of 230 identified papers met the inclusion criteria. Substantial heterogeneity in terminology and measurement partly explains inconsistencies in findings. Across most studies, ICM frequency increased over time, although a minority reported decreased movement or a “stiffening effect”. Findings regarding ICM amplitude were inconsistent, while a shift or change toward more slumped posture appears to be especially common during driving activities. These variations suggest that ICM patterns are influenced by task demands, seat characteristics, and individual differences.

Conclusion
ICM patterns are not solely time-dependent but are shaped by seat characteristics, task demands, and individual factors. While several studies suggest correlations between ICM strategies and discomfort, the underlying mechanisms remain unclear. Developing a comprehensive ICM framework that integrates movement strategies, and active or dynamic seating approaches will benefit cross-study comparability and provide directions for future ICM research.

Comfort experiences are not caused by a single factor, but are the result of diverse components such as postures, cognitive- and emotional experiences, as well as a person’s activity. The present empirical study investigated the experienced comfort of car passengers in the rear seat. We varied typical car passengers’ activities such as listening to music, working, and looking out the window. Dependent variables were the passenger’s comfort rating, his emotional valence- and arousal-related experience, his heart rate, and his seating position. The results (N = 23/16) showed that music positively influences comfort experiences. Moreover, correlation analysis between the dependent variables showed that comfort was significantly correlated only to the positive emotional valence component, and not to more physiological components such as emotional arousal, heart rate or seating position. The results suggest that car designers can improve the comfort of rear passengers by focussing on music and emotion design in contrast to the more conventional approach of physical ergonomics.