At the beginning of this project it was known that functional electrical stimulation (FES) rowing was technically feasible, but no studies on health benefits had been conducted and it was unclear what levels of fitness could be reliably attained by spinal cord injured (SCI) users. This thesis shows that training with the first-generation of the FES-rowing system (RowStim II), seven paraplegics achieved high V02peak values (21.0 - 27.9 ml-kg-1-min-1) and a significant (10%) increase in V02peak. This was also found to significantly improve insulin sensitivity and leptin levels but it had no significant effect on lipid profiles or body composition, possibly caused by technological limitations of the RowStim 11. However, training volumes were positively correlated with improvements in lipid profile and body composition. This motivated further technical development of the RowStim to enable paraplegics to train harder and longer. The development included a more stable seat configuration with redesigned trunk retaining straps, a rigid low friction carriage/brake system, improved leg stabiliser, improved stimulation control and a gravity-assisted return phase. This RowStim III has enabled paraplegics to participate in the British (2004, 2005 and 2006) and World Indoor Rowing Championships (2006). The rowers have achieved higher exercise intensities (26.8 -31.0 ml. kg- I .min-1) and increased exercise volumes (1,150 kcal-week-1) with the RowStim III. Such levels of physical activity, which are difficult to achieve for paraplegics using traditional exercises, are correlated with significant health benefits in the able-bodied. Preliminary results suggest that perfusion of the quadriceps muscle during FES-rowing might limit the exercise time in novice rowers. Other preliminary data from pressure mapping indicate that there is a dynamic pattern during FES-rowing, which might reduce the risk for pressure sores during FES-rowing. This thesis shows that FES-rowing is now a rapidly developing exercise modality, which has been shown to enable safe and well-tolerated exercise for individuals with SCI. It can offer unprecedented levels of cardiovascular fitness, competitive challenges and potentially important health benefits.

The restoration of arm-free standing in paraplegic individuals can be accomplished with the help of functional electrical stimulation (FES). The key component of such a system is a controller that can modulate FES induced muscle contractions in real-time, such that artificially produced forces in the legs and abdominal muscles are able to generate stable standing posture. A 57 year-old individual with chronic ASIA-A (American Spinal Injury Association), T3/4 level spinal cord injury (SCI) participated in this study. The objective was to determine if a proportional-derivative (PD) or proportional-integral-derivative (PID) controller could be used to regulate FES induced muscle contractions in the ankle joint to allow it to maintain balance of the entire body during quiet standing, while exhibiting physiological dynamics seen in able-bodied individuals while doing so.

Individuals with stroke often demonstrate impaired ankle-foot function, commonly termed dropped foot that affects their ability to walk safely at home and within their community. While interventions are available to improve gait function, they have inconsistency demonstrated positive effects due to the lack of evidence-based practice guidelines and a limited understanding of the mechanisms leading to dropped foot. The aim of this dissertation was to 1) determine the relationship between dropped foot gait deviations and impaired sensorimotor control, 2) compare gait biomechanics between stroke survivors with and without dropped foot impairment, and 3) evaluate the immediate effects of an ankle-foot orthotic (AFO) and functional electrical stimulation (FES) device among stroke survivors with dropped foot impairment. Our evaluation combined standardized clinical measures of ankle-foot function (i.e. sensorimotor control, strength, spasticity and range of motion) and gait analysis using advanced laboratory techniques (i.e. electromyography and electrical goniometers) to quantify mechanisms of dropped foot impairment. Fifty-five stroke survivors completed the assessment prior to discharge from inpatient rehabilitation. Individuals with poor generation of isometric dorsiflexor force and reduced passive ankle range of motion were likely to demonstrate greater plantarflexion in swing and limited stance phase ankle joint excursion, respectively. Results from the gait analysis revealed a delayed onset and reduced activation time of the ankle dorsiflexors, and decreased co-activation time in the stance phase as possible mechanisms leading to dropped foot. A detailed case series was performed with four stroke survivors with dropped foot currently using an AFO. Application of an AFO immediately improved peak dorsiflexion in the swing phase and limited ankle range of motion during stance. When walking with the FES device, individuals with moderate dorsiflexor muscle weakness improved their ankle position at initial contact and increased peak dorsiflexion during stance, while no significant changes were observed among individuals with greater impairment. Overall, the results highlighted individual differences in response to interventions aimed at improving dropped foot gait deviations. These findings contribute to a greater understanding of gait dysfunction post stroke, and may lead to the development of a more effective clinical assessment and intervention strategies to improve dropped foot impairment.

Functional electrical stimulation (FES) is a rehabilitative technology that can be used to improve walking in individuals with mobility impairments due to neurologic injury or disease. Feedback is essential for efficient FES-assisted walking. The overall goal of my project was to investigate external sensors to provide feedback for FES-assisted walking. The current study evaluated accelerometers, force sensitive resistors, segment orientation angles, and segment angular velocities to determine which were appropriate for determining the activation and deactivation of six major muscles used for walking. The results demonstrated that the segment orientation angles were the most appropriate sensors. Using the segment angle of the thigh, shank, and foot, the activation and deactivation times of the six muscles investigated could be determined within 6% of the step cycle. The shank segment angle performed the best for determining the activation and deactivation times when only one sensor was desired.

Following a spinal cord injury (SCI), the paralyzed extremities undergo muscle atrophy and decrease in bone mineral density (BMD) due in part to the loss of physiological loading. It is crucial to prevent musculoskeletal deterioration so the population is less susceptible to fractures, and could take advantage of stem cell treatment if it becomes available. Functional electrical stimulation (FES) has been shown to advantageously train the paralyzed extremities. However, there is a risk of fracture during FES due to low BMD of individuals with SCI. Therefore, the forces generated during FES need to be modeled so researchers and clinicians safely administer this intervention. The purpose of this project was to develop a biomechanical or mathematical model to estimate the internal compressive and shear forces at the distal femur, a common fracture site for individuals with SCI during FES. Therefore, a two-dimensional static model was created of the lower extremity in the supine and seated positions. The compressive and shear forces at the distal femur were estimated for both positions during FES. These internal compressive and shear forces estimated at the distal femur by the supine model were compared to those estimated by the standing model. Also, for the seated model, the compressive and shear forces at the distal femur estimated by a tetanic muscle contraction were compared to those estimated by a doublet muscle contraction. Finally, the supine model was validated using experimental testing. The primary findings are 1) the standing model estimated more compressive force and less shear force at the distal femur compared to the supine model when position and quadriceps muscle force remain constant and 2) for the seated model, a tetanic quadriceps muscle contraction predicts greater compressive and shear at the distal femur compared to a doublet muscle contraction. Also the validation testing revealed a 3.4% error between the supine model and the experimental testing. These models provide valuable insights into the internal forces at the distal femur during FES for those with SCI.

Background: Functional Electrical Stimulation (FES) stimulates peripheral nerves via electrical current to evoke muscle contractions and when combined with lower extremity cycling (LE), creates patterned leg movements. Previous studies demonstrated FES cycling is safe and effective in the spinal cord injury and stroke populations with improvements seen in walking speed, muscle mass, and bone density. Few studies have applied FES cycling to a neurodegenerative disorder, such as multiple sclerosis (MS). The aim of this study is to assess the effect of an 8-week training program using FES cycling, compared to Cycling Only, in people with MS (PWMS). Methods: Using a sample of convenience, PWMS were recruited to participate and randomized to the FES Cycling group or the Cycling Only group. Both groups received training three-times per week for 8- weeks using a LE ergometer. Scores on the 6 Minute Walk Test (6MWT), Times 25-Foot Walk Test (T25FW), Five Times Sit-to-Stand (5XSST), and Timed Up and Go (TUG), and spatiotemporal measure of gait were collected at baseline, (before the 1st session), 4-weeks (before the 13th session), 8-weeks (after the 24th training session), and at 4-week follow-up. Scores on the MS Quality of Life-54 (MSQOL), Modified Fatigue Impact Scale (MFIS), Multiple Sclerosis Walking Scale-12 (MSWS-12), and Activities-specific Balance Confidence Scale (ABC) were collected at baseline, 8-weeks, and at 4-week follow-up. Results: Fourteen participants (8 female, 6 male, mean age = 53.64 ± 10.16 years; Patient Determined Disease Steps (PDDS) mean = 3.71 ± .091) completed the training. Cycling power output significantly increased in both groups over time (FES Cycling, p = 0.03; Cycling only p = 0.004), but no differences were found between groups (p = 0.08). The Cycling Only group demonstrated a slightly larger effect size for power output than the FES Group (d = 0.72 vs. 0.66). Immediately after the intervention period, scores on the 6MWT, 5XSST, and MFIS, and subscores of the MSQOL-54 improved significantly, but changes did not consistently favor one group over the other (p >0.05). There were no significant differences between groups on any of the outcome measures. Conclusions: FES Cycling or Cycling Only may be an effective intervention for improving walking endurance, sit-to-stand, and QOL in PWMS. This unique pilot study compared FES cycling versus Cycling Only for PWMS using a customized progression protocol. Further research with larger sample sizes are needed to better understand the effects of FES Cycling on PWMS.

Spinal cord injury and stroke affect many people each year and can result in the loss of muscle function. Current research attempts to correct muscle paralysis through the use of mechanical braces or through open-loop stimulation methods. However, prosthetic systems that use closed-loop control strategies can offer improved functionality by accounting for the changing dynamics associated with the human body and external disturbances. In particular, closed-loop functional electrical stimulation (FES) offers the possibility of moving paralyzed muscles in a predetermined manner, allowing a paraplegic individual to regain the ability to perform some tasks. An experimental setup was designed for the development and testing of a closed-loop FES control system, as well as the characterization of muscle properties. Due to the complexities associated with using a human subject, an inverted pendulum model is utilized for this preliminary study. This model is a basic engineering control problem often used when studying postural control in humans. In particular, electrical stimuli will be applied to the gastrocnemius muscle of a frog in order to produce a contraction force that will drive an inverted pendulum and maintain its desired angle. The stimulation signal will be determined by control algorithms applied through the use of Matlab® and implemented in real-time with a data acquisition system. This setup will help provide an understanding of the muscle behavior and can be used to establish the validity of proposed controller methods.

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