title: Blood pressure and calf muscle oxygen extraction during plantar flexion exercise in peripheral artery disease.
abstract: Peripheral artery disease (PAD) is an atherosclerotic vascular disease that affects 200 million people worldwide. Although PAD primarily affects large arteries, it is also associated with microvascular dysfunction, an exaggerated blood pressure (BP) response to exercise, and high cardiovascular mortality. We hypothesized that fatiguing plantar flexion exercise that evokes claudication elicits a greater reduction in skeletal muscle oxygenation (SmO2) and a higher rise in BP in PAD compared with age-matched healthy subjects, but low-intensity steady-state plantar flexion elicits similar responses between groups. In the first experiment, eight patients with PAD and eight healthy controls performed fatiguing plantar flexion exercise (from 0.5 to 7 kg for up to 14 min). In the second experiment, seven patients with PAD and seven healthy controls performed low-intensity plantar flexion exercise (2.0 kg for 14 min). BP, heart rate (HR), and SmO2were measured continuously using near-infrared spectroscopy (NIRS). SmO2is the ratio of oxygenated hemoglobin to total hemoglobin, expressed as a percent. At fatigue, patients with PAD had a greater increase in mean arterial BP (18 ± 2 vs. vs. 10 ± 2 mmHg,P= 0.029) and HR (14 ± 2 vs. 6 ± 2 beats/min,P= 0.033) and a greater reduction in SmO2(-54 ± 10 vs. -12 ± 4%,P= 0.001). However, both groups had similar physiological responses to low-intensity, nonpainful plantar flexion exercise. These data suggest that patients with PAD have altered oxygen uptake and/or utilization during fatiguing exercise coincident with an augmented BP response.NEW & NOTEWORTHYIn this laboratory study, patients with peripheral artery disease performed plantar flexion exercise in the supine posture until symptoms of claudication occurred. Relative to age- and sex-matched healthy subjects we found that patients had a higher blood pressure response, a higher heart rate response, and a greater reduction in skeletal muscle oxygenation as determined by near-infrared spectroscopy. Our data suggest that muscle ischemia contributes to the augmented exercise pressor reflex in peripheral artery disease.
authors.affiliation: Penn State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey Pennsylvania; and.
authors.forename: J Carter
authors.initials: JC
authors.lastname: Luck
authors.affiliation: Penn State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey Pennsylvania; and.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Miller
authors.affiliation: Penn State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey Pennsylvania; and.
authors.forename: Faisal
authors.initials: F
authors.lastname: Aziz
authors.affiliation: Penn State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey Pennsylvania; and.
authors.forename: John F
authors.initials: JF
authors.lastname: Radtka
authors.affiliation: Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, Hershey, Pennsylvania.
authors.forename: David N
authors.initials: DN
authors.lastname: Proctor
authors.affiliation: Penn State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey Pennsylvania; and.
authors.forename: Urs A
authors.initials: UA
authors.lastname: Leuenberger
authors.affiliation: Penn State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey Pennsylvania; and.
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Sinoway
authors.affiliation: Penn State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey Pennsylvania; and mmuller1@hmc.psu.edu.
authors.forename: Matthew D
authors.identifier: http://orcid.org/0000-0002-7411-8816
authors.initials: MD
authors.lastname: Muller
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007383:Intermittent Claudication / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D058729:Peripheral Arterial Disease / Q000175:diagnosis / Q000503:physiopathology*; D010865:Pilot Projects; D000069262:Plantar Plate / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology
keywords: exercise physiology; heart rate; muscle metabolism; sympathetic nervous system