title: Upslope treadmill exercise enhances motor axon regeneration but not functional recovery following peripheral nerve injury.
abstract: Following peripheral nerve injury, moderate daily exercise conducted on a level treadmill results in enhanced axon regeneration and modest improvements in functional recovery. If the exercise is conducted on an upwardly inclined treadmill, even more motor axons regenerate successfully and reinnervate muscle targets. Whether this increased motor axon regeneration also results in greater improvement in functional recovery from sciatic nerve injury was studied. Axon regeneration and muscle reinnervation were studied in Lewis rats over an 11 wk postinjury period using stimulus evoked electromyographic (EMG) responses in the soleus muscle of awake animals. Motor axon regeneration and muscle reinnervation were enhanced in slope-trained rats. Direct muscle (M) responses reappeared faster in slope-trained animals than in other groups and ultimately were larger than untreated animals. The amplitude of monosynaptic H reflexes recorded from slope-trained rats remained significantly smaller than all other groups of animals for the duration of the study. The restoration of the amplitude and pattern of locomotor EMG activity in soleus and tibialis anterior and of hindblimb kinematics was studied during treadmill walking on different slopes. Slope-trained rats did not recover the ability to modulate the intensity of locomotor EMG activity with slope. Patterned EMG activity in flexor and extensor muscles was not noted in slope-trained rats. Neither hindblimb length nor limb orientation during level, upslope, or downslope walking was restored in slope-trained rats. Slope training enhanced motor axon regeneration but did not improve functional recovery following sciatic nerve transection and repair.
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Jill
authors.initials: J
authors.lastname: Cannoy
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Sam
authors.initials: S
authors.lastname: Crowley
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Allen
authors.initials: A
authors.lastname: Jarratt
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Kelly LeFevere
authors.initials: KL
authors.lastname: Werts
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Krista
authors.initials: K
authors.lastname: Osborne
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Sohee
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia medae@emory.edu.
authors.forename: Arthur W
authors.initials: AW
authors.lastname: English
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology / Q000502:physiology*; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D004576:Electromyography; D005081:Exercise Therapy; D005260:Female; D006614:Hindlimb / Q000294:innervation / Q000473:pathology / Q000503:physiopathology; D009046:Motor Neurons / Q000473:pathology / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000473:pathology / Q000503:physiopathology; D009416:Nerve Regeneration / Q000502:physiology*; D059348:Peripheral Nerve Injuries / Q000473:pathology / Q000503:physiopathology* / Q000534:rehabilitation; D011917:Rats, Inbred Lew; D020127:Recovery of Function / Q000502:physiology*; D012018:Reflex / Q000502:physiology; D012584:Sciatic Nerve / Q000293:injuries / Q000473:pathology / Q000503:physiopathology; D016138:Walking / Q000502:physiology*
keywords: EMG activity; exercise; kinematics; nerve regeneration