title: Cardiac output decline in prolonged dynamic exercise is affected by the exercise mode.
abstract: The aim of this study was to compare the cardiovascular responses to prolonged submaximal cycling and running. Eleven males [maximal oxygen uptake (VO(2max)): 3.58+/-0.15 l min(-1) for running and 3.84+/-0.16 l min(-1) for cycling; mean+/-SE] either cycled (C) or ran (R) for 90 min at 60% of mode-specific VO(2max), on two randomly assigned occasions. Cardiac output declined after 85 min of exercise in C (-1.9+/-0.5 l min(-1), P<0.01) but not in R, as a result of a more pronounced decrease in stroke volume in the former exercise mode (-22.7+/-3.8 ml beat(-1) vs -14.3+/-1.9 ml beat(-1), P<0.01) since heart rate did not differ between trials. Stroke volume responses were despite a higher level of dehydration (-3.3+/-0.2% in R vs -2.8+/-0.2% in C, P<0.05) and hyperthermia in R (39.6+/-0.1 vs 38.8+/-0.1 degrees C in C at 90 min, P<0.01). Finally, mean skin blood flow was lower in R than C (72+/-8 vs 89+/-10%; P<0.05). In conclusion, stroke volume and cardiac output decline was more pronounced in cycling than in running despite lower dehydration and rectal temperature in the former exercise mode.
authors.affiliation: Department of Sport Medicine and Biology of Physical Activity, Faculty of Physical Education and Sport Science, University of Athens, 41 Ethnikis Antistassis Street, 172 37, Daphne, Greece. ngeladas@cc.uoa.gr
authors.forename: George P
authors.initials: GP
authors.lastname: Nassis
authors.forename: Nickos D
authors.initials: ND
authors.lastname: Geladas
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D001810:Blood Volume; D001831:Body Temperature / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D006454:Hemoglobins; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D005082:Physical Exertion; D012007:Rectum / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012420:Running / Q000502:physiology*; D012649:Self Concept; D012867:Skin / Q000098:blood supply; D012881:Skin Temperature / Q000502:physiology; D013318:Stroke Volume; D013546:Sweating / Q000502:physiology; D015431:Weight Loss / Q000502:physiology
chemical_list: D006454:Hemoglobins