Different effects of exercise and edema on T2 relaxation in skeletal muscle

✍ Scribed by Lori L. Ploutz-Snyder; Sven Nyren; Thomas G. Cooper; E. James Potchen; Ronald A. Meyer

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 599 KB
• Volume: 37
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1910370509

✦ Synopsis

Abstract

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.