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Different effects of exercise and edema on T 2 relaxation in skeletal muscle
Author(s) -
PloutzSnyder Lori L.,
Nyren Sven,
Cooper Thomas G.,
Potchen E. James,
Meyer Ronald A.
Publication year - 1997
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910370509
Subject(s) - skeletal muscle , edema , relaxation (psychology) , nuclear magnetic resonance , chemistry , medicine , physics
The hypothesis that increased muscle T 2 after exercise is caused by increased extracellular fluid volume was tested by comparing the effects of exercise versus external leg negative pressure on muscle T 2 relaxation in normal human subjects. T 2 in lower leg muscles was measured by echo‐planar imaging at 63 echo times from 24 to 272 ms, and the relaxation spectrum was calculated by using a non‐negative least squares algorithm. T 2 relaxation in anterior leg muscle before exercise was characterized by a single component with mean T 2 = 29.3 ± 0.7 (SE, n = 5). After ankle dorsiflexion exercise, this single component broadened, and mean T 2 increased to 38.3 ± 0.7 ms. In contrast, after leg negative pressure, which increased the total leg muscle cross‐sectional area by 21% (range 12–32% n = 6), there was a variable appearance of much slower‐relaxing components (60–500 ms). The results suggest that increased extracellular fluid can account for only a minor portion of the increase in muscle T 2 observed during exercise.