The effects of activity-based training on urinary tract function following spinal cord injury
1Hubscher C, 2Herrity A, 1Montgomery L, 3Angeli C, 2Harkema S
1University of Louisville, Department of Anatomical Sciences and Neurobiology, Louisville, KY, U.s.a.; 2University of Louisville, Department of Neurological Surgery, Louisville, KY, U.s.a.; 3University of Louisville, Frazier Rehab Institute, Louisville, KY, U.s.a.
Objective: One of the major challenges impacting overall health and quality of life following spinal cord injury (SCI) is the development of urinary tract dysfunction(1). Standard means of managing bladder dysfunction after SCI commonly includes a combination of catheterization and pharmacological approaches. While these methods may be necessary, they do not address the capacity for recovery of bladder function over time. We have previously found that 1-hour per day task-specific step training in a rodent model of SCI significantly improved bladder function and reduced polyuria, the post-SCI overproduction of urine (2, 3). Thus, the objective of this study was to investigate the effects of activity-based training on bladder outcomes after chronic SCI in humans and to begin addressing underlying mechanisms in our rodent model in parallel.
Design/Method: This study includes research participants (AIS A-D) who received 80 daily 1-hour sessions of either: locomotor training on a treadmill (4), stand training using a customized standing device, or non-weight bearing arm crank cycling. Bladder function was assessed via Urodynamics and by The International Spinal Cord Injury Data Sets Questionnaires for Urodynamics and Lower Urinary Tract Function at pre-and post-training time points. Mechanistic studies in our rodent model included a cohort of adult male Wistar rats given a T9 spinal contusion (215 kD) and randomly assigned to trained (either quadrupedal stepping on a treadmill with all limbs or forelimb stepping without hind-limb engagement for non-weight bearing exercise) and non-trained groups (daily training for one hour/seven days a week beginning two weeks post-SCI). Animal model measures included metabolic cages for voiding behavior and terminal study assessments after two months of training targeting both the lower (cystometrogram with external urethral sphincter EMG) and upper (Western blot analysis of kidney tissue) urinary tract.
Results: In the human study, cystometry measurements demonstrated significant increases in bladder capacity, voiding efficiency and detrusor contraction time as well as significant decreases in voiding pressure post-training relative to baseline in those that performed step training. Those who received stand training alone demonstrated improvements in bladder emptying, while those who completed arm crank training demonstrated improvements in bladder storage. A decrease in the frequency of nocturia and urinary incontinence for several research participants was also revealed. Our parallel rodent studies reveal a training-related decrease in urine output and limited SCI-induced loss of V2 and aquaporin 2 receptors in the kidney
Conclusion: These results suggest an appropriate level of sensory information provided to the spinal cord, generated through task-specific activity, appears to influence urinary tract function. Additional improvements in the non-weight bearing arm crank group may be attributed to the impact of exercise affecting the overall urinary system(3).
Support: NIH R01HD080205; Leona M. and Harry B. Helmsley Charitable Trust; The Christopher & Dana Reeve Foundation; Department of Defense (# W81XWH-15-1-0656), KSCIRC Neuroscience Core supported by NIH/NCRR P30 (8P30GM103507) grant.
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