Cardiovascular Parameters for Lokomat Training in Chronic Incomplete SCI

Little information is available about the cardiovascular effects of robotically assisted partial weight support treadmill training devices such as Lokomat in chronic incomplete spinal cord injured subjects. Task-oriented aerobic exercise has the potential to improve both neuromuscular function and cardiovascular metabolic fitness in neurological populations. Since spinal cord injured individuals are at an increased risk of developing premature cardiovascular disease, the investigation of robotic-assisted interventions in spinal cord injury (SCI) such as the Lokomat may have important health benefits in both cardiovascular fitness as well as functional mobility.

This proposal investigates the hypothesis that progressive aerobic exercise with Lokomat is feasible in motor incomplete SCI, and three months of training will improve cardiovascular fitness and gait functionality when compared to physical therapy controls. We propose a two-phase study to examine the feasibility, reliability and utility of aerobic exercise metabolic testing and training during robotically assisted partial weight support treadmill walking in individuals with chronic motor incomplete spinal cord injury (CMISCI). During the first phase of the study we will manipulate Lokomat training parameters of treadmill speed and percent of partial weight support to assess the effect of these changes on heart rate, perceived exertion, and oxygen consumption in untrained chronic motor incomplete spinal cord injured subjects. Subjects will be asked to maintain cardiovascular or muscular effort during testing and will be monitored in this regard by the force biofeedback system built into the Lokomat. After determining threshold levels for initial cardiovascular response, submaximal and then peak exercise testing will be attempted. These studies will be repeated on a separate day to determine the reliability of the testing results. Thirty-six subjects with varying levels of injury between C4 and L2 and ASIA (American Spinal Injury) Impairment Scales of C and D will be recruited. We anticipate that subjects with greater ASIA motor scores will require either a faster initial treadmill speed or less partial weight support to produce an initial cardiovascular response. It is also anticipated that peak exercise testing using open circuit spirometry with subjects on the Lokomat will be a feasible, reliable and valid measurement. This phase of the study will be aimed at establishing guidelines for determining initial training parameters for use in an aerobic exercise protocol using the Lokomat.

The second phase of this pilot study will be a controlled trial of three-month progressive aerobic Lokomat exercise in chronic incomplete spinal cord injured subjects. The aim of this trial will be to determine whether progressive Lokomat training will improve cardiovascular fitness and ambulatory function when compared to matched impairment severity CMISCI subjects receiving the same duration of usual physical therapy care. Thirty-six subjects will be recruited into this phase of the study. Open spirometric evaluation of cardiovascular parameters as outlined in phase one of the proposal will be measured at baseline, 1 months, and 3 months. Initial, six-week and post-study ambulatory function evaluations including the WISCI (Walking Index for Spinal Cord Injury), a timed 10 meter walk, a measured walk over 6 minutes, and a gait analysis will also be determined. It is hypothesized that aerobic Lokomat exercise will improve cardiovascular fitness as determined by an increase in VO2 (oxygen consumption) peak and improve function as determined by timed walks and gait parameters in these subjects. The results of this pilot and development study will provide the necessary information to design larger randomized clinical trials.