title: Kinetics of catecholamines and potassium, and heart rate during exercise testing in obese subjects. Heart rate regulation in obesity during exercise.
abstract: BACKGROUND
  Obesity is characterised by a marked insulin resistance which involves an abnormal regulation of K(+) uptake and metabolism. Less is known about the effect of physical exercise on K(+) kinetics.
  
  
  OBJECTIVE
  To assess plasma catecholamines and potassium levels and their relationship with cardiac activity during a physical effort up to exhaustion in young obese subjects.
  
  
  METHODS
  Blood samples for epinephrine (E), norepinephrine (NE), potassium (K+) and heart rate (HR) were collected at the end of every step during a progressive cycloergometric test up to exhaustion in twelve obese subjects (6 males, aged 26+/-2, BMI 39.9+/-1) and twelve normal subjects (6 males, aged 28.2+/-2, BMI 22+/-1). In every subject anaerobic threshold (AT) was detected.
  
  
  RESULTS
  In obese subjects plasma catecholamines rose faster but had a lower peak in correspondence of maximal work-loads, with respect to controls. Catecholamines had a linear correlation in the obese group and a quadratic one in the control group when plotted vs O(2) consumption. The increase of plasma potassium was less in obesity than in control.
  
  
  CONCLUSIONS
  During physical exercise K(+) and catecholamines kinetics differ significantly in obese subjects vs normals and they may justify a less prompt cardiac response at the higher work-loads and a lower work capacity. The present data can be interpreted in the light of the insulin resistance syndrome of obesity, which causes an abnormal regulation of the Na-KATPase and of K(+) channels during physical exercise. The results of the present study may be relevant to nutritionists when suggesting physical exercise to obese subjects.
authors.affiliation: Divisione di Riabilitazione Respiratoria, Istituto Auxologico Italiano Verbania, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Salvadori
authors.forename: Paolo
authors.initials: P
authors.lastname: Fanari
authors.forename: Emanuela
authors.initials: E
authors.lastname: Giacomotti
authors.forename: Patrizia
authors.initials: P
authors.lastname: Palmulli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bolla
authors.forename: Ilaria
authors.initials: I
authors.lastname: Tovaglieri
authors.forename: Livio
authors.initials: L
authors.lastname: Luzi
authors.forename: Erminio
authors.initials: E
authors.lastname: Longhini
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002302:Cardiac Output; D002395:Catecholamines / Q000097:blood* / Q000378:metabolism; D004837:Epinephrine / Q000097:blood / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D007700:Kinetics; D008297:Male; D009638:Norepinephrine / Q000097:blood / Q000378:metabolism; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D010101:Oxygen Consumption; D011188:Potassium / Q000097:blood* / Q000378:metabolism; D012044:Regression Analysis
chemical_list: D002395:Catecholamines; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine