Eccentric contraction injury in dystrophic canine muscle Martin K. Childers, DO, Carol S. Okamura, PhD, Daniel J. Bogan, BA, Janet R. Bogan, BS, Gregory F. Petroski, MS, Kerry McDonald, PhD, Joe N. Kornegay, DVM, PhD  Archives of Physical Medicine and Rehabilitation  Volume 83, Issue 11, Pages 1572-1578 (November 2002) DOI: 10.1053/apmr.2002.35109 Copyright © 2002 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 1 The eccentric contraction method. Supramaximal percutaneous stimulation of the sciatic nerve at mid-femur caused contraction of both tibiotarsal joint flexors and extensors. However, because the more powerful extensor muscles of the caudal tibial compartment predominated, flexor muscles of the cranial tibial compartment underwent eccentric (lengthening) contractions. Archives of Physical Medicine and Rehabilitation 2002 83, 1572-1578DOI: (10.1053/apmr.2002.35109) Copyright © 2002 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 2 Isometric force measures and the concentric contraction method. Anesthetized dogs were positioned in dorsal recumbency, with the tibia parallel to the table and perpendicular to the femur. The common peroneal nerve was stimulated distal to the stifle (knee) to measure maximal tetanic force. As a consequence of stimulation, the distal pelvic limb pulled (flexion) a lever interfaced with a force transducer and ergometer. Archives of Physical Medicine and Rehabilitation 2002 83, 1572-1578DOI: (10.1053/apmr.2002.35109) Copyright © 2002 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 3 Micrographs (200×) of 10μm cryosections from the cranial tibialis muscle of age-matched 12-month-old normal (top panels) and GRMD dog (bottom panels). Images were taken 3 days after eccentric contractions. Left panels: Evans blue dye (fluorescent at 510nm) is normally excluded from myofibers but permeates damaged (lightly colored) myofibers. This finding indicates myofiber damage in GRMD dogs. Middle panels: Nonspecific esterase activity in necrotic (darkly stained) myofibers. This finding denotes myofibers necrosis in GRMD dogs. Right panels: eMHC expression in regenerating (darkly stained, bottom right panel) myofibers. Note the clusters of centrally located nuclei characteristic of myofiber regeneration in GRMD dogs. Archives of Physical Medicine and Rehabilitation 2002 83, 1572-1578DOI: (10.1053/apmr.2002.35109) Copyright © 2002 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 4 Boxplot of weight-corrected isometric flexion forces measured 3 days after eccentric contractions in GRMD (n=10) and normal (n=10) dogs. Bars extending below the 0 on the abscissa indicate force deficits. Legend: +, mean; upper and lower ends of the boxes, 25th and 75th percentiles, respectively; line through the box, median; vertical lines, range of the data. Archives of Physical Medicine and Rehabilitation 2002 83, 1572-1578DOI: (10.1053/apmr.2002.35109) Copyright © 2002 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 5 Boxplot of weight-corrected isometric flexion forces measured 3 days after concentric contractions in GRMD (n=10) and normal (n=10) dogs. See figure 4 for explanations. Archives of Physical Medicine and Rehabilitation 2002 83, 1572-1578DOI: (10.1053/apmr.2002.35109) Copyright © 2002 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions