title: Evidence of Preserved Oxidative Capacity and Oxygen Delivery in the Plantar Flexor Muscles With Age.
abstract: Studies examining the effect of aging on skeletal muscle oxidative capacity have yielded equivocal results; however, these investigations may have been confounded by differences in oxygen (O(2)) delivery, physical activity, and small numbers of participants. Therefore, we evaluated skeletal muscle oxidative capacity and O(2) delivery in a relatively large group (N = 40) of young (22 ± 2 years) and old (73 ± 7 years) participants matched for physical activity. After submaximal dynamic plantar flexion exercise, phosphocreatine (PCr) resynthesis ((31)P magnetic resonance spectroscopy), muscle reoxygenation (near-infrared spectroscopy), and popliteal artery blood flow (Doppler ultrasound) were measured. The phosphocreatine recovery time constant (Tau) (young: 33 ± 16; old: 30 ± 11 seconds), maximal rate of adenosine triphosphate (ATP) synthesis (young: 25 ± 9; old: 27 ± 8 mM/min), and muscle reoxygenation rates determined by the deoxyhemoglobin/myoglobin recovery Tau (young: 48 ± 5; old: 47 ± 9 seconds) were similar between groups. Similarly, although tending to be higher in the old, there were no significant age-related differences in postexercise popliteal blood flow (area under the curve: young: 1,665 ± 227 vs old: 2,404 ± 357 mL, p = .06) and convective O(2) delivery (young: 293 ± 146 vs old: 404 ± 191 mL, p = .07). In conclusion, when physical activity and O(2) delivery are similar, oxidative capacity in the plantar flexors is not affected by aging. These findings reveal that diminished skeletal muscle oxidative capacity is not an obligatory accompaniment to the aging process.
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah. Department of Exercise and Sport Science.
authors.forename: Corey R
authors.initials: CR
authors.lastname: Hart
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah. Department of Medicine, Division of Geriatrics, and.
authors.forename: Gwenael
authors.initials: G
authors.lastname: Layec
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah. Department of Medicine, Division of Geriatrics, and.
authors.forename: Joel D
authors.initials: JD
authors.lastname: Trinity
authors.affiliation: Department of Radiology, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Radiology, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City.
authors.forename: Seong-Eun
authors.initials: SE
authors.lastname: Kim
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah. Department of Exercise and Sport Science.
authors.forename: H Jonathan
authors.initials: HJ
authors.lastname: Groot
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339, Marseille, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Fur
authors.affiliation: Department of Exercise and Sport Science.
authors.forename: Jacob R
authors.initials: JR
authors.lastname: Sorensen
authors.affiliation: Department of Radiology, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City.
authors.forename: Eun-Kee
authors.initials: EK
authors.lastname: Jeong
authors.affiliation: Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah. Department of Exercise and Sport Science, Department of Medicine, Division of Geriatrics, and r.richardson@hsc.utah.edu.
authors.forename: Russell S
authors.initials: RS
authors.lastname: Richardson
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000368:Aged; D000375:Aging / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D005080:Exercise Test; D005260:Female; D005528:Foot / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009211:Myoglobin / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D011150:Popliteal Artery / Q000000981:diagnostic imaging; D019265:Spectroscopy, Near-Infrared; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D009211:Myoglobin; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; C100003:deoxyhemoglobin; D010744:Phosphoric Monoester Hydrolases; D010100:Oxygen
keywords:     31P MRS; Aging; Blood flow; Muscle oxygenation