The Effects of Adding Transcutaneous Spinal Cord Stimulation (tSCS) to Sit-To-Stand Training in People with Spinal Cord Injury: A Pilot Study.

Spinal cord stimulation may enable recovery of volitional motor control in people with chronic Spinal Cord Injury (SCI). In this study we explored the effects of adding SCS, applied transcutaneously (tSCS) at vertebral levels T10/11, to a sit-to-stand training intervention in people with motor complete and incomplete SCI. Nine people with chronic SCI (six motor complete; three motor incomplete) participated in an 8-week intervention, incorporating three training sessions per week. Participants received either tSCS combined with sit-to-stand training (STIM) or sit-to-stand training alone (NON-STIM). Outcome measures were carried out before and after the intervention. Seven participants completed the intervention (STIM N = 5; NON-STIM N = 2). Post training, improvements in International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) motor scores were noted in three STIM participants (range 1.0-7.0), with no change in NON-STIM participants. Recovery of volitional lower limb muscle activity and/or movement (with tSCS off) was noted in three STIM participants. Unassisted standing was not achieved in any participant, although standing with minimal assistance was achieved in one STIM participant. This pilot study has shown that the recruitment of participants, intervention and outcome measures were all feasible in this study design. However, some modifications are recommended for a larger trial.

Effects of endurance and strength-directed electrical stimulation training on the performance and histological properties of paralyzed human muscle: a pilot study.

Electrical stimulation (ES) improves muscle properties after spinal cord injury (SCI), but cycling power output (PO) remains low. We investigated the effect of endurance and strength ES training on these parameters. Assessments of quadriceps strength and fatigue resistance, cycling PO, and muscle biopsies were made in four well-trained SCI subjects (three cyclists and one rower) before and after additional weight training in the cyclists and once in the rower. Weight training improved muscle strength, but cycling PO was low in all subjects. There was no effect of training type on biopsy data. Biopsies showed non-specific signs of pathology, predominance of type IIa fibers, and uniform metabolic activity. Oxidative activity was low, as were capillary:fiber ratios in the cyclists. Cycling PO is limited by factors other than muscle strength. Future ES training studies should attempt to improve muscle oxidative capacity to optimize the potential benefits of ES exercise.

Long-term intensive electrically stimulated cycling by spinal cord-injured people: effect on muscle properties and their relation to power output.

Inactivity and muscular adaptations following spinal cord injury (SCI) result in secondary complications such as cardiovascular disease, obesity, and pressure sores. Functional electrically stimulated (FES) cycling can potentially reduce these complications, but previous studies have provided inconsistent results. We studied the effect of intensive long-term FES cycle training on muscle properties in 11 SCI subjects (mean +/- SEM: 41.8 +/- 2.3 years) who had trained for up to 1 hour/day, 5 days/week, for 1 year. Comparative measurements were made in 10 able-bodied (AB) subjects. Quadriceps maximal electrically stimulated torque increased fivefold (n = 5), but remained lower than in AB individuals. Relative force response at 1 HZ decreased, relaxation rate remained unchanged, and fatigue resistance improved significantly. Power output (PO) improved to a lesser extent than quadriceps torque and not to a greater extent than has been reported previously. We need to understand the factors that limit PO in order to maximize the benefits of FES cycling.

Cardiorespiratory and power adaptations to stimulated cycle training in paraplegia.

PURPOSE: The extent to which cardiorespiratory fitness and cycling power can be improved in individuals with paraplegia by progressive, high-volume, home-based, electrically stimulated (ES) cycle training was investigated using a novel, sensitive method and protocol that allowed high-resolution power output analyses to be performed for the first time in ES cycling. METHODS: Nine male and two female individuals with paraplegia trained progressively at home for up to five 60-min sessions x wk(-1) for 12 months. Peak power and cardiorespiratory parameters were estimated during quarterly feedback-controlled incremental work rate tests in the laboratory. RESULTS: Cycle training endurance increased from 10 to 60 min of continuous pedaling for all subjects. Peak power output (POpeak) increased by 132% (P = 0.001), peak oxygen uptake (VO2peak) increased by 56% (P < 0.001), and oxygen pulse increased by 34% (P = 0.002). All significant adaptations occurred during the first 6 months of training when training load was progressive and duration compliance (90%) and frequency compliance (88%) were at their highest. A strong positive relationship between the total training duration and the magnitude of improvements in both POpeak (r2 = 0.84, P < 0.001) and VO2peak (r2 = 0.52, P= 0.012) was found during the first 6 months only. CONCLUSIONS: High-volume, home-based ES cycle training using the current training and the ES strategies can significantly improve cardiorespiratory fitness and cycling power output in paraplegia but only while training is progressive. The training plateau reached by 6 months may be physiological in nature or due to the ES strategy used.

High-volume FES-cycling partially reverses bone loss in people with chronic spinal cord injury.

Spinal cord injury (SCI) leads to severe bone loss in the paralysed limbs and to a resulting increased fracture risk thereof. Since long bone fractures can lead to comorbidities and a reduction in quality of life, it is important to improve bone strength in people with chronic SCI. In this prospective longitudinal cohort study, we investigated whether functional electrical stimulation (FES) induced high-volume cycle training can partially reverse the loss of bone substance in the legs after chronic complete SCI. Eleven participants with motor-sensory complete SCI (mean age 41.9+/-7.5 years; 11.0+/-7.1 years post injury) were recruited. After an initial phase of 14+/-7 weeks of FES muscle conditioning, participants performed on average 3.7+/-0.6 FES-cycling sessions per week, of 58+/-5 min each, over 12 months at each individual's highest power output. Bone and muscle parameters were investigated in the legs by means of peripheral quantitative computed tomography before the muscle conditioning (t1), and after six (t2) and 12 months (t3) of high-volume FES-cycle training. After 12 months of FES-cycling, trabecular and total bone mineral density (BMD) as well as total cross-sectional area in the distal femoral epiphysis increased significantly by 14.4+/-21.1%, 7.0+/-10.8% and 1.2+/-1.5%, respectively. Bone parameters in the femoral shaft showed small but significant decreases, with a reduction of 0.4+/-0.4% in cortical BMD, 1.8+/-3.0% in bone mineral content, and 1.5+/-2.1% in cortical thickness. These decreases mainly occurred between t1 and t2. No significant changes were found in any of the measured bone parameters in the tibia. Muscle CSA at the thigh increased significantly by 35.5+/-18.3%, while fat CSA at the shank decreased by 16.7+/-12.3%. Our results indicate that high-volume FES-cycle training leads to site-specific skeletal changes in the paralysed limbs, with an increase in bone parameters at the actively loaded distal femur but not the passively loaded tibia. Thus, we conclude that high-volume FES-induced cycle training has clinical relevance as it can partially reverse bone loss and thus may reduce fracture risk at this fracture prone site.

Influence of different stimulation frequencies on power output and fatigue during FES-cycling in recently injured SCI people.

This study investigated whether power output during 30 min sessions of functional electrical stimulation (FES)-cycling can be increased by using stimulation frequencies higher than 30 Hz. The stimulation frequencies of FES-cycling training sessions of 19 recently injured para- and tetraplegics were randomly set at 30, 50, or 60 Hz and power output (PO) was measured continually. The mean PO of the 30 min, the PO of the last minute of each session, and the minimum PO were significantly greater at 60 and 50 Hz than at 30 Hz (ANOVA without cross-product). A 19% and 25% higher mean PO was reached at 50 and 60 Hz, respectively, compared to 30 Hz. The PO of the last minute of each session was almost always higher than the mean PO of the whole session and also higher at higher frequencies, which indicates that no muscle fatigue could be detected in 30 min FES-cycling at any of the tested frequencies.