Abstract:
:It has previously been observed that during isometric dorsiflexion exercise, the time course of T2-weighted signal intensity (SI) changes is spatially heterogeneous. The purpose of this study was to test the hypothesis that this spatial heterogeneity would increase at higher contraction intensities. Eight subjects performed 90-s isometric dorsiflexion contractions at 30% and 60% of maximum voluntary contraction (MVC) while T2-weighted (repetition time/echo time=4000/35 ms) images were acquired. SI was measured before, during and after the contractions in regions of interest (ROIs) in the extensor digitorum longus (EDL) muscle and the deep and superficial compartments of the tibialis anterior (D-TA and S-TA, respectively). For all ROIs at 30% MVC, SI changes were similar. The maximum postcontraction SI was greater than the SI during exercise. At 60% MVC, SI changes during contraction were greater in the S-TA than in the D-TA and EDL. For the EDL and D-TA, the maximum postcontraction SI was greater than those during exercise. For the S-TA, the maximum postcontraction change was greater than the changes at t=8, 20 and 56 s but not the end-exercise value. We conclude that spatial heterogeneity increases during more intense dorsiflexion contractions, possibly reflecting regional differences in perfusion or neural activation of the muscle.
journal_name
Magn Reson Imagingjournal_title
Magnetic resonance imagingauthors
Damon BM,Wadington MC,Lansdown DA,Hornberger JLdoi
10.1016/j.mri.2008.01.023subject
Has Abstractpub_date
2008-10-01 00:00:00pages
1114-21issue
8eissn
0730-725Xissn
1873-5894pii
S0730-725X(08)00051-9journal_volume
26pub_type
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