Cardiovascular Fitness for Robotically Assisted Treadmill Training in Persons With Chronic Incomplete Spinal Cord Injury

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 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, 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 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.