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Author Youngstedt, S.D.; Elliott, J.A.; Kripke, D.F. url  doi
  Title Human Circadian Phase-Response Curves for Exercise Type Journal Article
  Year 2019 Publication The Journal of Physiology Abbreviated Journal J Physiol  
  Volume 597 Issue 8 Pages 2253-2268  
  Keywords Human Health; Circadian Rhythm; Exercise  
  Abstract KEY POINTS: Exercise elicits circadian phase-shifting effects, but additional information is needed. The phase-response curve describing the magnitude and direction of circadian rhythm phase shifts depending on the time of the zeigeber (time cue) stimulus is the most fundamental chronobiological tool for alleviating circadian misalignment and related morbidity. 51 older and 48 young adults followed a circadian rhythms measurement protocol for up to 5.5 days, and performed 1 h of moderate treadmill exercise for 3 consecutive days at one of 8 times of day/night. Temporal changes in the phase of 6-sulphatoxymelatonin (aMT6s) were measured from evening onset, cosine acrophase, morning offset, and duration of excretion, establishing significant PRCs for aMT6 onset and acrophase with large phase delays from 7-10 PM and large phase advances at both 7 AM and 1-4 PM. Along with known synergism with bright light, the above PRCs with a second phase advance region (afternoon) could support both practical and clinical applications. ABSTRACT: Although bright light is regarded as the primary circadian zeitgeber, its limitations support exploring alternative zeitgebers. Exercise elicits significant circadian phase-shifting effects, but fundamental information regarding these effects is needed. The primary aim of this study was to establish phase-response curves (PRC) documenting the size and direction of phase shifts in relation to the circadian time of exercise. Aerobically fit older (n = 51, 59-75 y) and young adults (n = 48, 18-30 y) followed a 90-min laboratory ultra-short sleep wake cycle (60 min wake/30 min sleep) for up to 5 (1/2) days. At the same clock time on three consecutive days, each participant performed 60 min of moderate treadmill exercise (65-75% of heart rate reserve) at one of 8 times of day/night. To describe PRCs, phase shifts were measured for the cosine-fitted acrophase of urinary 6-sulphatoxymelatonin (aMT6s), as well as for the evening rise, morning decline, and change in duration of aMT6s excretion. Significant PRCs were found for aMT6s acrophase, onset and duration, with peak phase advances corresponding to clock times of 7 AM and 1PM-4PM, delays from 7 PM-10 PM, and minimal shifts around 4 PM and 2 AM. There were no significant age or sex differences. The amplitudes of the aMT6s onset and acrophase PRCs are comparable to expectations for bright light of equal duration. The phase advance to afternoon exercise and the exercise-induced PRC for change in aMT6s duration are novel findings. The results support further research exploring additive phase shifting effects of bright light and exercise and health benefits. This article is protected by copyright. All rights reserved.  
  Address Department of Psychiatry, University of California, San Diego, CA  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-3751 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30784068 Approved (up) no  
  Call Number GFZ @ kyba @ Serial 2230  
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