01718nas a2200181   4500000000100000008004100001100001500042700001600057700001600073700001300089700001400102245008600116250001500202300001000217490000700227520125600234020004601490       2012                            d1 aBilston L.1 aGandevia S.1 aHerbert Rob1 aGreen M.1 aSinkus R.00aMeasuring changes in muscle stiffness after eccentric exercise using elastography  a2012/01/17  a852-80 v253 a<p>
Muscle stiffness has been reported to increase following eccentric muscle exercise, but to date only indirect methods have been used to measure it. This study aimed to use Magnetic Resonance Elastography (MRE), a noninvasive imaging technique, to assess the time-course of passive elasticity changes in the medial gastrocnemius and soleus muscles before and after a bout of eccentric exercise. Shear storage modulus (G') and loss modulus (G'') measurements were made in eight healthy subjects for both muscles in vivo before, one hour after, 48 hours after and 1 week after eccentric exercise. The results show a 21% increase in medial gastrocnemius storage modulus following eccentric exercise with a peak occurring ~48 hours after exercise (before exercise 1.15 +/- 0.23 kPa, 48 hours after 1.38 +/- 0.27 kPa). No significant changes in soleus muscle storage modulus were measured for the exercise protocol used in this study, and no significant changes in loss modulus were observed. This study provides the first direct measurements in skeletal muscle before and after eccentric exercise damage and suggests that MRE can be used to detect the time course of changes to muscle properties. Copyright (c) 2012 John Wiley &amp; Sons, Ltd.
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