Document Detail


Cardiovascular regulation during head-up tilt in healthy 20-30-year-old and 70-75-year-old men.
MedLine Citation:
PMID:  11171289     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study compared the heart rate, finger arterial pressure (AP) and electromyographic (EMG) activity of selected anti-gravity muscles during the initial and prolonged phases of orthostatic stress in healthy young and older men. Beat-by-beat recordings of heart rate, finger systolic pressure, diastolic pressure and mean AP were made during supine rest and 5 min of 90 degrees head-up tilt (HUT) in 18 young (23+/-1 years) and 15 older (73+/-1 years) men. The EMG activity of the soleus, tibialis anterior and vastus medialis muscles was recorded. During the first 30 s following 90 degrees HUT (immediate response), the young men exhibited significant (P<0.05) decreases in finger systolic pressure, diastolic pressure and mean AP, followed by a sustained increase in finger AP during the 5 min following 90 degrees HUT (prolonged response). The immediate and prolonged finger AP and diastolic pressure responses were not significantly different (P>0.05) from the values at supine rest for the older men. The mean root mean square EMG activity of the soleus, tibialis anterior and vastus medialis muscles during 90 degrees HUT was not significantly different (P>0.05) from that at supine rest for either group. These results demonstrate that, when compared with healthy older men, young men show larger reductions in finger AP during the initial phase of orthostatic stress. However, during the prolonged phase of orthostatic stress, older men maintain resting finger AP, whereas young men demonstrate a reflex overshoot in finger AP. Finally, differences in lower-limb anti-gravity muscle activation do not account for the contrasting finger AP responses of healthy young and older men.
Authors:
T J Gabbett; S B Weston; R S Barrett; G C Gass
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Clinical science (London, England : 1979)     Volume:  100     ISSN:  0143-5221     ISO Abbreviation:  Clin. Sci.     Publication Date:  2001 Feb 
Date Detail:
Created Date:  2001-02-22     Completed Date:  2001-03-22     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  7905731     Medline TA:  Clin Sci (Lond)     Country:  England    
Other Details:
Languages:  eng     Pagination:  199-206     Citation Subset:  IM    
Affiliation:
School of Physiotherapy and Exercise Science, Faculty of Health Sciences, PMB 50 Gold Coast Mail Centre, Griffith University Gold Coast, Queensland 9726, Australia. t.gabbett@mailbox.gu.edu.au
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MeSH Terms
Descriptor/Qualifier:
Adult
Aged
Aging / physiology*
Blood Pressure / physiology*
Dizziness / physiopathology
Electrocardiography
Electromyography
Epinephrine / blood
Exercise / physiology
Fingers / blood supply
Heart Rate / physiology*
Humans
Male
Muscle, Skeletal / physiology
Norepinephrine / blood
Oxygen Consumption / physiology
Plasma Volume / physiology
Posture / physiology*
Tilt-Table Test
Chemical
Reg. No./Substance:
51-41-2/Norepinephrine; 51-43-4/Epinephrine

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


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