title: Changes in heart-rate variability of survivors of nasopharyngeal cancer during Tai Chi Qigong practice.
abstract: [Purpose] To explore the changes in heart-rate variability (HRV) of survivors of nasopharyngeal cancer (NPC) before, during, and after a Tai Chi (TC) Qigong exercise. [Subjects and Methods] Eleven survivors of NPC participated voluntarily in the study. The heart rate of each participant was measured continuously for 1 minute before the TC Qigong intervention, during the 5-minute TC Qigong intervention, and for 1 minute after the intervention, using a Polar heart-rate monitor. Spectral HRV was expressed in terms of normalised low frequency (LF) power, normalised high frequency (HF) power, and the low frequency/high frequency (LF/HF) power ratio. [Results] Both the LF-power and the HF-power components had significant time effects. However, the time effect of the LF/HF power ratio was not significant. Post hoc contrast analysis revealed a significant decrease in LF power and a concomitant increase in HF power during the 4th minute and 5th minute of the TC Qigong exercise. [Conclusion] Five minutes of TC Qigong exercise was found to improve HRV by increasing HF power and decreasing LF power, but these effects were transient. TC Qigong might be an appropriate exercise for improving the ANS function and psychological and cardiac health of survivors of NPC.
authors.affiliation: Institute of Human Performance, The University of Hong Kong: Pokfulam, Hong Kong.
authors.forename: Shirley S M
authors.initials: SS
authors.lastname: Fong
authors.affiliation: School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Janet Y H
authors.initials: JY
authors.lastname: Wong
authors.affiliation: Department of Health and Physical Education, Hong Kong Institute of Education, Hong Kong.
authors.forename: Louisa M Y
authors.initials: LM
authors.lastname: Chung
authors.affiliation: Department of Physiotherapy, David Trench Rehabilitation Centre, Hong Kong.
authors.forename: Timothy T T
authors.initials: TT
authors.lastname: Yam
authors.affiliation: Department of Health and Physical Education, Hong Kong Institute of Education, Hong Kong.
authors.forename: Joanne W Y
authors.initials: JW
authors.lastname: Chung
authors.affiliation: Polar H.K. Ltd., Hong Kong.
authors.forename: Y M
authors.initials: YM
authors.lastname: Lee
authors.affiliation: Department of Health and Physical Education, Hong Kong Institute of Education, Hong Kong.
authors.forename: Lina P Y
authors.initials: LP
authors.lastname: Chow
authors.affiliation: The Association of Licentiates of the Medical Council of Hong Kong, Hong Kong.
authors.forename: W S
authors.initials: WS
authors.lastname: Luk
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: Shamay S M
authors.initials: SS
authors.lastname: Ng
keywords: Autonomic nervous system; Head-and-neck cancer; Mind-body exercise