Functional activation of the extensor carpi radialis muscles in humans Beven P. Livingston, MA, Richard L. Segal, PhD, PT, Allen Song, PhD, Katharine Hopkins, MD, Arthur W. English, PhD, Claudine C. Manning, MS  Archives of Physical Medicine and Rehabilitation  Volume 82, Issue 9, Pages 1164-1170 (September 2001) DOI: 10.1053/apmr.2001.24919 Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 1 Experimental overview showing the timing of the protocols used in the study. Session 2 was the experimental session that included a pre-exercise scan, 4 exercise bouts that were each immediately followed by a MRI scan, and 3 rest periods before the last 3 exercise bouts. Archives of Physical Medicine and Rehabilitation 2001 82, 1164-1170DOI: (10.1053/apmr.2001.24919) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 2 Sampling the ROIs for the active muscle (ECRL, ECRB), inactive muscle (FDP), and bone marrow of the radius (R). This image is from sections of a single task for 1 subject. The mean signal intensity of these areas was calculated for each subject across each task and each section. The images were enlarged on the computer monitor when analyses were performed. Archives of Physical Medicine and Rehabilitation 2001 82, 1164-1170DOI: (10.1053/apmr.2001.24919) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 3 T2-weighted MR images of the same section level across exercise tasks for 1 subject. The lighter areas of images within the muscle bellies are regions of muscle activated by the task. Notice that radial deviation involves activity of the radial portions of both the flexor and extensor compartments. Abbreviations: Pre-ex, pre-exercise; ext, extension; EDC, extensor digitorum communis; FCR, flexor carpi radialis; Rad Dev, radial deviation. Archives of Physical Medicine and Rehabilitation 2001 82, 1164-1170DOI: (10.1053/apmr.2001.24919) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 4 T2-weighted MR images for a subject across sections for the same exercise task (radial deviation at 60% of MVC; sections 4 to 10 are distal to proximal). Notice that ECRL and ECRB show much greater activity (lighter in image) than the adjacent brachioradialis and extensor digitorum communis muscles that are not active. Archives of Physical Medicine and Rehabilitation 2001 82, 1164-1170DOI: (10.1053/apmr.2001.24919) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 5 (A) T2 values (ms) for ECRL and ECRB ROI across exercise tasks (sections 4 to 10 are distal to proximal). Note that radial deviation tasks generated more change in T2 values. (B) Bar graphs of the T2 values (ms) for ROI ECRL and ECRB across sections (4 to 10 is distal to proximal direction). Note that proximal sections have smaller changes in T2 values. (C) Bar graphs of the T2 values (ms) for ROI FDP across sections. Although there were significant differences across sections, the average range of values was only 1.34ms (min = 28.99ms, max = 30.33ms). (D) Bar graphs of the T2 values (ms) for radius marrow across sections. Archives of Physical Medicine and Rehabilitation 2001 82, 1164-1170DOI: (10.1053/apmr.2001.24919) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions