title: Circadian rhythm mediates the relationship between physical activity and quality of life in younger and older cancer survivors.
abstract: Increasing evidence suggests that physical activity (PA) improves the quality of life (QoL) of cancer survivors. However, the biological mechanisms underlying the relationship between PA and QoL are unclear. The purpose of this study was to determine whether the relationship between PA and QoL differs in younger and older cancer survivors and whether circadian rhythm (CR) mediates this relationship. We also explored the effect of the CR on QoL. The participants were 235 cancer survivors, comprising 143 younger and 92 older patients. Data were collected using the Taiwanese versions of the Physical Activity Scale for the Elderly and Short Form-36. The robustness and stability of the CR were measured using an actigraph. Mediation was tested using multiple mediation analyses. The CR mediated the relationship between PA and the physical domain of QoL in younger and older cancer survivors (23% and 59% mediating effects, respectively). The CR partially mediated the effect of PA on the mental dimension of QoL in older cancer survivors (36% mediating effect), but not in younger cancer survivors. Cancer survivors with a more robust CR had a significantly higher QoL, particularly in the physical functioning domain (d = 0.43, p < 0.001). The results provided evidence that the CR mediated the relationship between PA and QoL. Moreover, this mediating effect differed in younger and older cancer survivors. These results can serve as a reference for designing individualized PA programs for cancer survivors.
authors.affiliation: a Graduate Institute of Nursing, College of Nursing , Taipei Medical University , Taipei , Taiwan .|b School of Nursing, Chung-Jen Junior College of Nursing, Health Sciences and Management , Chia Yi County , Taiwan .
authors.forename: Ching-Ching
authors.initials: CC
authors.lastname: Su
authors.affiliation: c Department of Gastroenterology , Changhua Christian Hospital , Changhua , Taiwan .
authors.forename: Pei-Yuan
authors.initials: PY
authors.lastname: Su
authors.affiliation: d Loretto Heights School of Nursing, Regis University , Denver , CO , USA , and.
authors.forename: Shu-Yi
authors.initials: SY
authors.lastname: Wang
authors.affiliation: e School of Nursing, College of Nursing , Taipei Medical University , Taipei , Taiwan.
authors.forename: Chia-Chin
authors.initials: CC
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002940:Circadian Rhythm / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009369:Neoplasms; D011788:Quality of Life; D011795:Surveys and Questionnaires; D017741:Survivors; D055815:Young Adult
keywords: Cancer survivors; circadian rhythm; mediating effect; physical activity; quality of life