title: Ischemic preconditioning reduces hemodynamic response during metaboreflex activation.
abstract: Ischemic preconditioning (IP) has been shown to improve exercise performance and to delay fatigue. However, the precise mechanisms through which IP operates remain elusive. It has been hypothesized that IP lowers the sensation of fatigue by reducing the discharge of group III and IV nerve endings, which also regulate hemodynamics during the metaboreflex. We hypothesized that IP reduces the blood pressure response during the metaboreflex. Fourteen healthy males (age between 25 and 48 yr) participated in this study. They underwent the following randomly assigned protocol: postexercise muscle ischemia (PEMI) test, during which the metaboreflex was elicited after dynamic handgrip; control exercise recovery session (CER) test; and PEMI after IP (IP-PEMI) test. IP was obtained by occluding forearm circulation for three cycles of 5 min spaced by 5 min of reperfusion. Hemodynamics were evaluated by echocardiography and impedance cardiography. The main results were that after IP the mean arterial pressure response was reduced compared with the PEMI test (means ± SD +3.37 ± 6.41 vs. +9.16 ± 7.09 mmHg, respectively). This was the consequence of an impaired venous return that impaired the stroke volume during the IP-PEMI more than during the PEMI test (-1.43 ± 15.35 vs. +10.28 ± 10.479 ml, respectively). It was concluded that during the metaboreflex, IP affects hemodynamics mainly because it impairs the capacity to augment venous return and to recruit the cardiac preload reserve. It was hypothesized that this is the consequence of an increased nitric oxide production, which reduces the possibility to constrict venous capacity vessels.
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Mulliri
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Gianmarco
authors.initials: G
authors.lastname: Sainas
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Magnani
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Girolamo
authors.initials: G
authors.lastname: Palazzolo
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Milia
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Orrù
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Silvana
authors.initials: S
authors.lastname: Roberto
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Marongiu
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Milia
authors.affiliation: Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy crisafulli@tiscali.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: Crisafulli
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology; D005221:Fatigue; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D019194:Ischemic Preconditioning; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D009200:Myocardial Contraction / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology
keywords: blood pressure; cardiac preload; fatigue; myocardial contractility; stroke volume