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31 P MRS measurement of mitochondrial function in skeletal muscle: reliability, force‐level sensitivity and relation to whole body maximal oxygen uptake
Author(s) -
LarsonMeyer D. Enette,
Newcomer Bradley R.,
Hunter Gary R.,
Hetherington Hoby P.,
Weinsier Roland L.
Publication year - 2000
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/(sici)1099-1492(200002)13:1<14::aid-nbm605>3.0.co;2-0
Subject(s) - skeletal muscle , chemistry , reliability (semiconductor) , mitochondrion , sensitivity (control systems) , biophysics , anatomy , biochemistry , biology , physics , power (physics) , quantum mechanics , electronic engineering , engineering
The reliability, relation to whole‐body maximal oxygen uptake (VO 2max ), and force‐level sensitivity of 31 P MRS markers of mitochondrial function were studied in 39 normal‐weight women. Following 90 s isometric plantar‐flexion exercises at 45, 70 and 100% of maximum voluntary contraction, skeletal muscle mitochondrial function was determined from the phosphocreatine recovery time constant (TC PCr ), the ADP recovery time constant (TC ADP ), and the rate of change in PCr during the first 14 s of recovery (OxPhos). VO 2max was measured on a treadmill. Test–retest measurements were obtained in a subset of seven women. Overall, TC PCr , TC ADP and OxPhos were reproducible for all exercises (coefficients of variation = 2.3–19.3%). With increasing force‐level, TC PCr was prolonged (29.0 ± 8.2, 31.9 ± 9.0 and 35.4 ± 9.5 s), OxPhos was increased (0.159 ± 0.081, 0.247 ± 0.090 and 0.310 ± 0.114), and TC ADP was shortened (22.4 ± 7.9, 21.3 ± 6.2, and 19.5 ± 6.7; p < 0.01). All MRS markers of mitochondrial function were correlated with VO 2max ( r = 0.41–0.72; p < 0.05). These results suggest that measurements of TC PCr , TC ADP and OxPhos yield reproducible results that correlate with whole‐body VO 2max and that vary in force‐level sensitivity. Copyright © 2000 John Wiley & Sons, Ltd.