Kinetics of catecholamines and potassium, and heart rate during exercise testing in obese subjects: Heart rate regulation in obesity during exercise

• Published in: European journal of nutrition 2003-08, Vol.42 (4), p.181-187
• Main Authors: SALVADORI, Alberto, FANARI, Paolo, GIACOMOTTI, Emanuela, PALMULLI, Patrizia, BOLLA, Giuseppe, TOVAGLIERI, Ilaria, LUZI, Livio, LONGHINI, Erminio
• Format: Article
• Language: English
• Subjects: Adult; Analysis of Variance; Biological and medical sciences; Cardiac Output; Catecholamines - blood; Catecholamines - metabolism; Epinephrine - blood; Epinephrine - metabolism; Exercise - physiology; Exercise Test; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Heart Rate - physiology; Humans; Insulin Resistance - physiology; Kinetics; Male; Medical sciences; Metabolic diseases; Norepinephrine - blood; Norepinephrine - metabolism; Obesity; Obesity - blood; Obesity - physiopathology; Oxygen Consumption; Potassium - blood; Potassium - metabolism; Regression Analysis; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 1436-6207; 1436-6215
• DOI: 10.1007/s00394-003-0409-3

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. To assess plasma catecholamines and potassium levels and their relationship with cardiac activity during a physical effort up to exhaustion in young obese subjects. 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. 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. 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.