title: Neurohumoral and metabolic response to exercise in water.
abstract: Atrial natriuretic peptide (ANP) stimulates lipid mobilization and lipid oxidation in humans. The mechanism appears to promote lipid mobilization during exercise. We tested the hypothesis that water immersion augments exercise-induced ANP release and that the change in ANP availability is associated with increased lipid mobilization and lipid oxidation. In an open randomized and cross-over fashion we studied 17 men (age 31+/-3.6 years; body mass index 24+/-1.7 kg/m(2); body fat 17+/-6.7%) on no medication. Subjects underwent two incremental exercise tests on a bicycle ergometer. One test was conducted on land and the other test during immersion in water up to the xiphoid process. In a subset (n=7), we obtained electromyography recordings in the left leg. We monitored gas exchange, blood pressure, and heart rate. In addition, we obtained blood samples towards the end of each exercise step to determine ANP, norepinephrine, epinephrine, lactate, free fatty acids, insulin, and glucose concentrations. Heart rate, systolic blood pressure, and oxygen consumption at the anaerobic threshold and during peak exercise were similar on land and with exercise in water. The respiratory quotient was mildly reduced when subjects exercised in water. Glucose and lactate measurements were decreased whereas free fatty acid concentrations were increased with exercise in water. Water immersion attenuated epinephrine and norepinephrine and augmented ANP release during exercise. Even though water immersion blunts exercise-induced sympathoadrenal activation, lipid mobilization and lipid oxidation rate are maintained or even improved. The response may be explained by augmented ANP release.
authors.affiliation: Franz-Volhard Clinical Research Center, Medical Faculty of the Charité and HELIOS Klinikum, Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Wiesner
authors.forename: A L
authors.initials: AL
authors.lastname: Birkenfeld
authors.forename: S
authors.initials: S
authors.lastname: Engeli
authors.forename: S
authors.initials: S
authors.lastname: Haufe
authors.forename: L
authors.initials: L
authors.lastname: Brechtel
authors.forename: J
authors.initials: J
authors.lastname: Wein
authors.forename: M
authors.initials: M
authors.lastname: Hermsdorf
authors.forename: B
authors.initials: B
authors.lastname: Karnahl
authors.forename: M
authors.initials: M
authors.lastname: Berlan
authors.forename: M
authors.initials: M
authors.lastname: Lafontan
authors.forename: F C G J
authors.initials: FC
authors.lastname: Sweep
authors.forename: F C
authors.initials: FC
authors.lastname: Luft
authors.forename: J
authors.initials: J
authors.lastname: Jordan
mesh_terms: D000328:Adult; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D018592:Cross-Over Studies; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007101:Immersion; D019344:Lactic Acid / Q000097:blood; D050356:Lipid Metabolism / Q000502:physiology; D008297:Male; D008660:Metabolism / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D018377:Neurotransmitter Agents; D019344:Lactic Acid; D009320:Atrial Natriuretic Factor