title: Myocardial perfusion during exercise in endurance-trained and untrained humans.
abstract: Because of technical challenges very little is known about absolute myocardial perfusion in humans in vivo during physical exercise. In the present study we applied positron emission tomography (PET) in order to 1) investigate the effects of dynamic bicycle exercise on myocardial perfusion and 2) clarify the possible effects of endurance training on myocardial perfusion during exercise. Myocardial perfusion was measured in endurance-trained and healthy untrained subjects at rest and during absolutely the same (150 W) and relatively similar [70% maximal power output (W(max))] bicycle exercise intensities. On average, the absolute myocardial perfusion was 3.4-fold higher during 150 W (P < 0.001) and 4.9-fold higher during 70% W(max) (P < 0.001) than at rest. At 150 W myocardial perfusion was 46% lower in endurance-trained than in untrained subjects (1.67 +/- 0.45 vs. 3.00 +/- 0.75 ml x g(-1) x min(-1); P < 0.05), whereas during 70% W(max) perfusion was not significantly different between groups (P = not significant). When myocardial perfusion was normalized with rate-pressure product, the results were similar. Thus, according to the present results, myocardial perfusion increases in parallel with the increase in working intensity and in myocardial work rate. Endurance training seems to affect myocardial blood flow pattern during submaximal exercise and leads to more efficient myocardial pump function.
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland. marko.laaksonen@miun.se
authors.forename: Marko S
authors.initials: MS
authors.lastname: Laaksonen
authors.forename: Kari K
authors.initials: KK
authors.lastname: Kalliokoski
authors.forename: Matti
authors.initials: M
authors.lastname: Luotolahti
authors.forename: Jukka
authors.initials: J
authors.lastname: Kemppainen
authors.forename: Mika
authors.initials: M
authors.lastname: Teräs
authors.forename: Heikki
authors.initials: H
authors.lastname: Kyröläinen
authors.forename: Pirjo
authors.initials: P
authors.lastname: Nuutila
authors.forename: Juhani
authors.initials: J
authors.lastname: Knuuti
mesh_terms: D000328:Adult; D003326:Coronary Circulation / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000379:methods*; D006321:Heart / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D049268:Positron-Emission Tomography / Q000379:methods*; D012146:Rest / Q000502:physiology