Swimming as a Model of Task-Specific Locomotor Retraining After Spinal Cord Injury in the Rat

Neurorehabil Neural Repair, 2009 · DOI: 10.1177/1545968308331147 · Published: June 1, 2009

Simple Explanation

This research investigates how rats relearn to swim after a spinal cord injury, using swimming as a model to understand task-specific locomotor retraining. The study focuses on quantitatively describing the hindlimb movements during swimming before and after injury and retraining. The researchers found that uninjured rats do not significantly change their swimming kinematics over time, suggesting that they don't need to refine their hindlimb movements as they get used to swimming. After a spinal cord injury, retraining improved hindlimb excursion and limb position, but the speed of the movements remained slow. The study suggests that the neural circuits for swimming are somewhat hardwired in rats. After a spinal cord injury, simply repeating the swimming motion can lead to improvements in movement patterns, but it doesn't necessarily improve the force generated by the movements, leading to persistent deficits.

Study Duration

6 Weeks

Participants

Seven young adult female Sprague-Dawley rats

Evidence Level

Not specified

Key Findings

1
Uninjured rats exhibit consistent swimming kinematics, indicating that hindlimb movement doesn't change over time when first exposed to water as adults, suggesting the swimming pattern is hardwired.
2
After spinal cord injury, retraining improved hindlimb excursion and limb position during swimming, as shown by increased area in angle-angle plots, but the velocity of the movements remained slow.
3
Despite improvements in limb excursion post-spinal cord injury, the toe velocity remained significantly below baseline, suggesting that improvements in movement pattern are distinct from improvements in force generation.

Research Summary

This study examines swimming as a task-specific model for locomotor retraining after spinal cord injury in rats. The researchers quantitatively analyzed hindlimb kinematics before and after injury, and during retraining. The key findings show that uninjured rats exhibit consistent swimming kinematics, suggesting a hardwired pattern. Post-injury, retraining improved limb excursion and position, but not movement velocity. The research concludes that force (load) and pattern generation (recruitment) are independent and may need to be managed together in post-injury rehabilitation. Swimming provides a novel model of locomotor learning.

Practical Implications

Rehabilitation Strategies

The findings suggest that rehabilitation strategies for spinal cord injuries should consider both pattern generation and force generation, potentially combining loaded and unloaded exercises.

Task-Specific Training

Task-specific training, like swimming, can improve locomotor function, but may not translate to other activities like walking, indicating the need for diverse training approaches.

Understanding Neural Circuits

The study provides insight into the neural circuits underlying swimming and how they are affected by spinal cord injury, contributing to a better understanding of locomotor control and recovery mechanisms.

Study Limitations

1
Overground walking was not influenced by swim training.
2
The velocity remains significantly reduced when compared with the preinjury level of 91.8 ± 13.1 cm/s.
3
improvements due to swim training as indistinguishable.

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