Document Detail

Reactivity of ambulatory blood pressure to physical activity varies with time of day.
MedLine Citation:
PMID:  16505205     Owner:  NLM     Status:  MEDLINE    
Blood pressure (BP) fluctuates over a 24-hour period, but it is unclear to what extent this variation is governed completely by changes in physical activity. Our aim was to use a BP "reactivity index" to investigate whether the BP response to a given level of physical activity changes during a normal sleep-wake cycle. Hypertensive patients (n=440) underwent simultaneous 24-hour ambulatory BP, heart rate (HR), and activity monitoring. BP and HR were measured every 20 minutes. Actigraphy data were averaged over the 15 minutes that preceded a BP measurement. Individual BP and HR reactivity indices were calculated using least-squares regression for twelve 2-hour periods. These indices were then analyzed for time-of-day differences using a general linear model. Systolic BP and HR were generally more reactive to physical activity than diastolic BP. The highest reactivity of systolic BP (mean+/-SE=4+/-1 mm Hg per logged unit change in activity) was observed between 8:00 AM and 10:00 AM (P=0.014). Between 10:00 AM and 12:00 PM, BP reactivity then decreased (P=0.048) and showed a secondary rise in the early afternoon. These 24-hour changes in BP reactivity did not differ significantly between groups formed on the basis of early and late wake times (P=0.485), medication use, age, and sex (P>0.350). In conclusion, under conditions of normal living, the reactivity of BP and HR to a given unit change in activity is highest in the morning and shows a secondary rise in the afternoon.
Helen Jones; Greg Atkinson; Andrew Leary; Keith George; Michael Murphy; Jim Waterhouse
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Publication Detail:
Type:  Journal Article     Date:  2006-02-27
Journal Detail:
Title:  Hypertension     Volume:  47     ISSN:  1524-4563     ISO Abbreviation:  Hypertension     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-03-24     Completed Date:  2006-04-20     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  United States    
Other Details:
Languages:  eng     Pagination:  778-84     Citation Subset:  IM    
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 2ET, United Kingdom.
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MeSH Terms
Blood Pressure*
Blood Pressure Monitoring, Ambulatory*
Circadian Rhythm*
Heart Rate
Hypertension / diagnosis,  physiopathology*
Middle Aged
Motor Activity*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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