Jan Keller

Dr. Jan Keller

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Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 November 2017 in Health Psychology Review
Verified
Journal Article
Closed access
MBMonika Boberska
Monika Boberska
ZSZofia Szczuka
Zofia Szczuka
MKMagdalena Kruk
Magdalena Kruk
NKNina Knoll
Nina Knoll
JKJan Keller
Jan Keller
ALAleksandra Luszczynska
Aleksandra Luszczynska
Researchers have speculated that sedentary behaviour may reduce health-related quality of life (HRQOL), but the extent to which this is true remains unknown. Our study sought to systematically review and synthesise research on the relationship between sedentary behaviours and HRQOL and to investigate if these relationships are moderated by age, health status, and HRQOL domain. The review was registered with PROSPERO (no. CRD42016036342). We searched six electronic databases. The selection process resulted in including k = 27 original studies; k = 18 were included in a meta-analysis. Data were synthesised twice, using the methods of systematic review and meta-analysis, in order to reduce biases related to a small number of included studies. Both the systematic review and meta-analytical methods indicated that lower levels of sedentary behaviours were associated with higher physical HRQOL (estimate of average effect: r = −.140; 95% CI −.191, −.088). Moderator analyses indicated that associations between the physical HRQOL domain and sedentary behaviours may be similar in strength across age- and health status groups. Causal inferences could not be drawn as most studies were cross-sectional. Concluding, sedentary behaviours were related to better physical HRQOL but not reliably to mental and social HRQOL.

6 January 2021 in British Journal of Health Psychology
Verified
Journal Article
Open access
PDF file
JKJan Keller
Jan Keller
DKDominika Kwasnicka
Dominika Kwasnicka
PKPatrick Klaiber
Patrick Klaiber
LSLena Sichert
Lena Sichert
PLPhillippa Lally
Phillippa Lally
LFLena Fleig
Lena Fleig
Objectives: Habit formation has been identified as one of the key determinants of behaviour change. To initiate habit formation, self‐regulation interventions can support individuals to form a cue‐behaviour plan and to repeatedly enact the plan in the same context. This randomized controlled trial aimed to model habit formation of an everyday nutrition behaviour and examined whether habit formation and plan enactment differ when individuals plan to enact their behaviour in response to a routine‐based versus time‐based cue. Design: Following a baseline assessment, N = 192 adults (aged 18–77 years) were randomly assigned to a routine‐based cue or a time‐based cue planning intervention, in which they selected an everyday nutrition behaviour and linked it to a daily routine or a time cue. Methods: Participants responded to daily questionnaires over 84 days assessing plan enactment and the behaviour’s automaticity (as an indicator of habit formation). Multilevel models with days nested in participants were fitted. Results: As indicated by asymptotic curves, it took a median of 59 days for participants who successfully formed habits to reach peak automaticity. Group‐level analyses revealed that both routine‐based and time‐based cue planning led to increases in automaticity and plan enactment, but no between‐condition differences were found. Repeated plan enactment was a key predictor for automaticity. Conclusions: Linking one’s nutrition behaviour to a daily routine or a specific time was similarly effective for habit formation. Interventions should encourage persons to repeatedly carry out their planned behaviour in response to the planned cue to facilitate habit formation.

1 January 2017 in Health Psychology
Verified
Journal Article
Closed access
NKNina Knoll
Nina Knoll
DHDiana Hilda Hohl
Diana Hilda Hohl
JKJan Keller
Jan Keller
NSNatalie Schuez
Natalie Schuez
ALAleksandra Luszczynska
Aleksandra Luszczynska
SBSilke Burkert
Silke Burkert
Action planning can help translate physical activity intentions into action by linking situational cues with behavioral responses. Dyadic planning extends action planning and refers to target persons forming plans for their own behavior change together with partners. This study investigated whether a dyadic planning intervention could increase physical activity in target persons and their partners, whether these effects were moderated by relationship quality and mediated by action control, activity-specific received partner support, and control. Couples (n = 338; target persons randomized) were randomly assigned to (a) a dyadic planning condition (DPC); (b) an individual planning condition (IPC), in which target persons planned and partners worked on a distractor task; or (c) a control condition (CC), in which couples worked on a distractor task. During 3 assessments up to 6 weeks postintervention, moderate (primary outcome) and vigorous activity were objectively measured; other variables were self-reported. Multilevel and path models were fit. There were no beneficial direct effects of the intervention for DPC target persons. Over time, DPC partners' vigorous activity increased, but decreased again. At lower relationship quality, DPC target persons' activity decreased, whereas IPC target persons' vigorous activity increased. Mediation hypotheses were not supported. Mutual influence models indicated positive effects of partners' on target persons' moderate activity in DPC and CC, whereas for IPC, negative effects of target persons' on partners' moderate activity emerged. Findings revealed the complexity of effects of dyadic planning on behavior change. Adding relationship quality to the equation clarified effects of DPC and IPC on physical activity. (PsycINFO Database Record

1 September 2017 in Social Science & Medicine
Verified
Journal Article
Closed access
JKJan Keller
Jan Keller
LFLena Fleig
Lena Fleig
DHDiana Hilda Hohl
Diana Hilda Hohl
AWAmelie U. Wiedemann
Amelie U. Wiedemann
SBSilke Burkert
Silke Burkert
NKNina Knoll
Nina Knoll

30 April 2019 in BMC Public Health
Verified
Journal Article
Open access
PDF file
BSBartlomiej Stanczykiewicz
Bartlomiej Stanczykiewicz
ABAnna Banik
Anna Banik
NKNina Knoll
Nina Knoll
JKJan Keller
Jan Keller
DHDiana Hilda Hohl
Diana Hilda Hohl
ALAleksandra Luszczynska
Aleksandra Luszczynska
Although the number of studies examining the relationships between sedentary behaviors (SB) and anxiety is growing, an overarching evidence, taking into account children, adolescents, and adults as well as different types of SB and different categories of anxiety outcomes, is still missing. Thus, this systematic review and meta-analysis aimed at obtaining a comprehensive overview of existing evidence. A search in the following databases: PsycINFO, PsycARTICLES, Academic Search Complete, ERIC, HealthSource: Nursing/Academic Edition and MEDLINE, resulted in k = 31 original studies included in the systematic review (total N = 99,192) and k = 17 (total N = 27,443) included in the meta-analysis. Main inclusion criteria referred to testing the SB--anxiety relationship, the quality score (above the threshold of 65%), and the language of publications (English). The study was following the PRISMA statement and was registered at PROSPERO (CRD42017068517). Both the systematic review and meta-analysis indicated that overall average effects were small: higher levels of symptoms of anxiety were associated with higher levels of SB (weighted r = .093, 95% CI [.055, .130], p < .001). Moderator analyses indicated that trends for stronger effects were observed among adults, compared to children/adolescents (p = .085). Further longitudinal studies are necessary to elucidate the predictive direction of the anxiety—SB relationship and to clarify whether the effects depend on the type of anxiety indicators.

1 January 2018 in Appetite
Verified
Journal Article
Closed access
JKJan Keller
Jan Keller
SMSusannah Motter
Susannah Motter
MMMirjam Motter
Mirjam Motter
Ralf SchwarzerRalf Schwarzer
Ralf Schwarzer