Kinetics of catecholamines and potassium, and heart rate during exercise testing in obese subjects. Heart rate regulation in obesity during exercise.
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.
Salvadori
Alberto
A
Divisione di Riabilitazione Respiratoria, Istituto Auxologico Italiano Verbania, Italy.
Fanari
Paolo
P
Giacomotti
Emanuela
E
Palmulli
Patrizia
P
Bolla
Giuseppe
G
Tovaglieri
Ilaria
I
Luzi
Livio
L
Longhini
Erminio
E
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
D002395:Catecholamines; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine