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Project

Passive Cycling: Muscle Stretch and the Skeletal Muscle Pump.

Funder: Craig H Neilsen Foundation

Funding period
USD 300 K
Funding amount
Abstract
Cardiovascular (CV) dysfunction is one of the most serious secondary complications that accompanies high thoracic and cervical spinal cord injuries (SCI). We believe that the severity of autonomic dysfunction arises from a combination of the injury itself plus the immediate and profound inactivity that the majority of human subjects experience. Over the first few weeks post-SCI there are very few feasible approaches that can meaningfully increase activity levels in individuals with severe SCIs. Passive leg cycling is one such approach that has been studied quite extensively, however the observable benefits have been highly variable and often indiscernible. In contrast, passive hindlimb cycling (PHLC) in rat models of high thoracic (full transection) injuries show dramatic and lasting effects on cardiovascular function including improved cardiac output and stroke volume. The primary goal of this project is to determine how PHLC in rats is beneficial and thus to provide specific hypotheses to test in future human studies. We hypothesize that the benefits of PHLC in rats are due to the activation of spinal reflexes during cycling that cause muscle contractions and activation of the skeletal muscle pump that increases venous return to the heart from the hindlimbs. We have instrumented a set of rat bicycles with new pedals that allow reaction forces generated by the paws to be measured simultaneously with hindlimb kinematics and either telemetry-based hindlimb muscle EMG or heart rate (HR) and blood pressure (BP). We will manipulate the cycle speed and pedal crank length thereby altering the muscle length changes. These data will be used in a computer model of the rat hindlimb to investigate the relationship between cycle speed, muscle length, rate of muscle length change, pedal reaction forces and instantaneous BP and HR. We will then choose two different combinations of parameters to assess the impact of daily PHLC exercise after SCI. (CHN: SCIRTS chn:wdg)
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System

Categories
  • FOR (ANZSRC)

    1106 Human Movement and Sports Science

  • RCDC

    Injury (total) Accidents/Adverse Effects

  • RCDC

    Injury - Trauma - (Head and Spine)

  • RCDC

    Cardiovascular

  • RCDC

    Bioengineering

  • RCDC

    Neurosciences

  • RCDC

    Rehabilitation

  • RCDC

    Spinal Cord Injury

  • RCDC

    Neurodegenerative

  • HRCS HC

    Cardiovascular

  • Health Research Areas

    Biomedical

  • Broad Research Areas

    Clinical Medicine and Science