title: Swim training initiated acutely after spinal cord injury is ineffective and induces extravasation in and around the epicenter.
abstract: Activity-based rehabilitation is a promising strategy for improving functional recovery following spinal cord injury (SCI). While results from both clinical and animal studies have shown that a variety of approaches can be effective, debate still exists regarding the optimal post-injury period to apply rehabilitation. We recently demonstrated that rats with moderately severe thoracic contusive SCI can be re-trained to swim when training is initiated 2 weeks after injury and that swim training had no effect on the recovery of overground locomotion. We concluded that swim training is a task-specific model of post-SCI activity-based rehabilitation. In the present study, we ask if re-training initiated acutely is more or less effective than when initiated at 2 weeks post-injury. Using the Louisville Swim Scale, an 18-point swimming assessment, supplemented by kinematic assessment of hindlimb movement during swimming, we report that acute re-training is less effective than training initiated at 2 weeks. Using the bioluminescent protein luciferase as a blood-borne macromolecular marker, we also show a significant increase in extravasation in and around the site of SCI following only 8 min of swimming at 3 days post-injury. Taken together, these results suggest that acute re-training in a rat model of SCI may compromise rehabilitation efforts via mechanisms that may involve one or more secondary injury cascades, including acute spinal microvascular dysfunction.
authors.affiliation: Kentucky Spinal Cord Injury Research Center, Department of Neurological Surgery, Louisville, Kentucky 40202, USA.
authors.forename: Rebecca R
authors.initials: RR
authors.lastname: Smith
authors.forename: Edward H
authors.initials: EH
authors.lastname: Brown
authors.forename: Alice
authors.initials: A
authors.lastname: Shum-Siu
authors.forename: Ashley
authors.initials: A
authors.lastname: Whelan
authors.forename: Darlene A
authors.initials: DA
authors.lastname: Burke
authors.forename: Richard L
authors.initials: RL
authors.lastname: Benton
authors.forename: David S K
authors.initials: DS
authors.lastname: Magnuson