Cited by 288Cardiovascular and exercise physiologyMuscle metabolism and nutritionAdvanced MRI Techniques and Applications

Relationships between in vivo and in vitro measurements of metabolism in young and old human calf muscles

McCully, K. K., Fielding, R. A., Evans, W. J., Leigh, J. S., Posner, J. D.·1993·Journal of Applied Physiology

Abstract

This study compared in vivo measurements of muscle metabolism in humans with magnetic resonance spectroscopy (MRS) and in vitro analysis of biopsies. Healthy subjects [4 young males, 28.2 +/- 6.8 (SD) yr, and 6 older subjects (5 males, 1 female), 66 +/- 6.0 yr] performed a maximal cycle ergometer test, and MRS measurements of the calf muscles and needle biopsies of the lateral gastrocnemius were performed. Biopsies were analyzed for fiber type and citrate synthase (CS) activity. MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr), ATP, and pH were made using a 1.8-T 78-cm clear-bore magnet-and-spectrometer system. Two or three 5-min bouts of plantar flexion were performed against variable resistance to deplete PCr levels to 50% of resting values (mean end pH 6.99). PCr values during recovery were fit to an exponential curve, and the rate constant (PCrrate) was calculated. PCrrate was used as an index of oxidative metabolism. Older subjects had lower peak O2 uptake (VO2 peak) values (19.2 +/- 5.6 vs. 49.5 +/- 8.1 ml O2.min-1 x kg-1), CS activities (16 +/- 2.8 vs. 25 +/- 2.6 mmol.kg wet wt-1 x min-1), and PCrrate values (25.3 +/- 8. vs. 37.5 +/- 5.3 mmol PCr.kg wet wt-1.min-1) than young subjects. PCrrate correlated with CS activity, and both PCrrate and CS activity correlated with VO2 peak (P < 0.05). No correlations were found between percent fiber type and PCrrate, CS activity, and VO2 peak. These results support studies that showed decreases in muscle metabolism with age in healthy humans and show a good correlation between in vivo and in vitro measurements of oxidative metabolism.

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Crossref · 10.1152/jappl.1993.75.2.813

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Authors
McCully, K. K., Fielding, R. A., Evans, W. J., Leigh, J. S., & Posner, J. D.
Affiliations
Department of Medicine, Medical College of Pennsylvania, Philadelphia 19129.
Venue
Journal of Applied Physiology
Published
1993-08-01
Volume
75
Issue
2
Pages
813-819
ISSN
  • 0161-7567 (ISSN-L)
  • 8750-7587
  • 1522-1601
OpenAlex
W2273652180
Cited by
288
References
28
Citations by year
2026: 3 · 2025: 5 · 2024: 7 · 2023: 6 · 2022: 10 · 2021: 4 · 2020: 10 · 2019: 11 · 2018: 9 · 2017: 7 · 2016: 10 · 2015: 13 · 2014: 15 · 2013: 16 · 2012: 13
FWCI
11.16
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Applied Physiology (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health (5p01ag003934-14)
  • National Institute on Aging (AG 03934)
Topics
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced MRI Techniques and Applications
Keywords
muscle metabolism, aging, oxidative metabolism, citrate synthase activity, triceps surae, lateral gastrocnemius, inorganic phosphate, muscle fiber type, peak oxygen uptake, plantar flexion, magnetic resonance spectroscopy, human skeletal muscle
MeSH terms
Adenosine Triphosphate, Adult, Aged, Aging, Citrate (si)-Synthase, Exercise Test, Female, Humans, Leg, Male, Middle Aged, Muscles, Magnetic Resonance Spectroscopy, Oxidation-Reduction, Oxygen Consumption, Phosphates, Phosphocreatine, In Vitro Techniques

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