title: Interrelationship between plasma potassium concentration, pulmonary ventilation and electrocardiographic change during and after highly intense exercise.
abstract: OBJECTIVE
  The purpose of this investigation was to induce elevated plasma concentrations of potassium (K+) efflux from active muscle cells during intense muscular exercise. The relationship between K+, pulmonary ventilation (VE) and EKG changes, specifically T-wave amplitude, is presently controversial.
  
  
  METHODS
  Repeated measures design.
  
  
  METHODS
  Human performance laboratory.
  
  
  METHODS
  Twelve volunteer trained recreational cyclists (10 males, mean age 31.9 +/- 7.4, and 2 females, mean age 27.5 +/- 0.7, mean VO2max 571.2 +/- 6.4 ml.kg.min-1).
  
  
  METHODS
  Subjects performed 10 min of pedaling at 90 rpm, yielding a power output of 45 W.min-1 on a mechanically braked cycle ergometer as a warm-up. Each exercise stage was 2 min in duration, beginning at 135 W and increased by 45 W thereafter until voluntary exhaustion. Respiratory gas exchange measures were obtained every 10 sec. Venous blood samples for K+ and lactate (LA-) determination were drawn at rest, at the end of stage 2, all subsequent stages, and during 3 and 10 min of recovery. EKG recordings were concurrent with venous sampling.
  
  
  RESULTS
  Statistical analyses for VE vs. K+, respiratory exchange ratio (RER) vs. K+ and RER vs. LA- revealed neither significant change nor an associative relationship from stages 1-3. However, stages 4-8 were statistically significant (p < .05) and highly correlated. No relationship was found between K+ change and T-wave amplitude during exercise or recovery.
  
  
  CONCLUSIONS
  These data indicate a strong relationship between selected respiratory gas exchange measures and K+ during intermediate to highly intense exercise.
authors.affiliation: Division of Cardiovascular Research, University of Massachusetts at Lowell 01854.
authors.forename: S P
authors.initials: SP
authors.lastname: von Duvillard
authors.forename: L M
authors.initials: LM
authors.lastname: LeMura
authors.forename: L
authors.initials: L
authors.lastname: Szmedra
authors.forename: P
authors.initials: P
authors.lastname: Di Vico
mesh_terms: D000328:Adult; D001642:Bicycling; D002245:Carbon Dioxide / Q000097:blood; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008451:Maximal Voluntary Ventilation; D010100:Oxygen / Q000097:blood; D011188:Potassium / Q000097:blood*; D011659:Pulmonary Gas Exchange
chemical_list: D002245:Carbon Dioxide; D011188:Potassium; D010100:Oxygen