Document Detail

Effect of aging on changes in plasma potassium during exercise.
MedLine Citation:
PMID:  8315226     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Exercising skeletal muscle releases large amounts of potassium into plasma. beta-adrenergic receptors enhance reuptake of potassium into muscle. Since beta-adrenergic responses decline with aging in many tissues, the elderly might be predisposed to hyperkalemia during exercise. METHODS: Venous plasma potassium (K+) was measured during graded bicycle exercise (30 W initial workload with 3-minute 30 W increments) in 18 healthy young men (24.0 +/- 2.9 yrs; mean +/- SD), 18 healthy untrained elderly men (70.0 +/- 3.6 yrs), and 7 elderly master athletes (70.0 +/- 4.6 yrs). Subjects exercised to exhaustion. RESULTS: Exercise times and maximal oxygen uptake were: young (N = 14; 19.6 +/- 4.4 min, 42.1 +/- 3.8 ml/kg/min), elderly (N = 13; 11.7 +/- 1.9 min, 26.6 +/- 8.0 ml/kg/min), elderly master athletes (N = 6; 16.8 +/- 2.4 min, 40.2 +/- 10.2 ml/kg/min). The rate of increase in K+ was greater in both elderly (89 +/- 59 mumol/l/min) and elderly master athletes (88 +/- 26) compared with healthy young men (60 +/- 30), p < .05. Despite this greater rate of increase, the elderly group did not achieve higher maximal K+ concentrations than the young because of the much shorter duration of exercise in the elderly group. For subjects performing a maximal exercise test, the maximal increase in K+ was similar in the elderly (1.15 +/- 0.91), but significantly greater in elderly master athletes (1.70 +/- 0.31), compared with healthy young men (1.31 +/- 0.45). CONCLUSIONS: Changes in K+ during short-lasting exercise are similar in untrained healthy elderly men compared with healthy young men, but elderly master athletes have greater changes in K+ during exercise. The greater rate of increase in potassium in healthy and athletic subjects supports the hypothesis of an age-related impairment of the beta 2-adrenergic process that mediates potassium flux into skeletal muscle.
G A Ford; T F Blaschke; R Wiswell; B B Hoffman
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of gerontology     Volume:  48     ISSN:  0022-1422     ISO Abbreviation:  J Gerontol     Publication Date:  1993 Jul 
Date Detail:
Created Date:  1993-07-29     Completed Date:  1993-07-29     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  0374762     Medline TA:  J Gerontol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  M140-5     Citation Subset:  AIM; IM    
Stanford University School of Medicine, Palo Alto, California.
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MeSH Terms
Aging / blood*
Physical Fitness
Potassium / blood*
Grant Support
Reg. No./Substance:

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