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Introduction: Functional electrical stimulation cycling has various health benefits, but the mechanical power output and efficiency are very low compared to volitional muscle activation. Stimulation with variable frequency showed significantly higher power output values in experiments with a knee dynamometer. The aim of the present work was to compare stochastic modulation of inter-pulse interval to constant inter-pulse interval stimulation during functional electrical stimulation cycling. Methods: Seventeen able-bodied subjects participated (n = 17). Quadriceps and hamstring muscle groups were stimulated with two activation patterns: P1-constant frequency, P2-stochastic inter-pulse interval. Power output was measured on functional electrical stimulation ergometer. Results: Overall, mean power output with the stochastically modulated pattern P2 was lower than with P1 (12.57 ± 3.74 W vs. 11.44 ± 3.81 W, P1 vs. P2, p = 0.022), but no significant differences during the first 30 s and the last 30 s were observed. Conclusions: This study showed that stimulation strategies that use randomized modulation of inter-pulse intervals can negatively affect power output generation during functional electrical stimulation cycling. To minimise voluntary contractions, power measurement and assessment should be focused on the periods where only the quadriceps are stimulated., Journal of Rehabilitation and Assistive Technologies Engineering, 5, ISSN:2055-6683

Recumbent cycling exercise achieved by functional electrical stimulation (FES) of the paralyzed leg muscles is effective for cardiopulmonary and musculoskeletal conditioning after spinal cord injury, but its full potential has not yet been realized. Mechanical power output and efficiency is very low and endurance is limited due to early onset of muscle fatigue. The aim of this work was to compare stochastic modulation of the inter-pulse interval (IPI) to constant-frequency stimulation during an isokinetic leg extension task similar to FES-cycling. Seven able-bodied subjects participated: both quadriceps muscles were stimulated (n = 14) with two activation patterns (P1-constant frequency, P2-stochastic IPI). There was significantly higher power output with P2 during the first 30 s (p = 0.0092), the last 30 s (p = 0.018) and overall (p = 0.0057), but there was no overall effect on fatiguability when stimulation frequency was randomly modulated., European Journal of Translational Myology, 26 (3), ISSN:2037-7452, ISSN:2037-7460

Background The robotics-assisted tilt table (RATT), including actuators for tilting and cyclical leg movement, is used for rehabilitation of severely disabled neurological patients. Following further engineering development of the system, i.e. the addition of force sensors and visual bio-feedback, patients can actively participate in exercise testing and training on the device. Peak cardiopulmonary performance parameters were previously investigated, but it also important to compare submaximal parameters with standard devices. The aim of this study was to evaluate the feasibility of the RATT for estimation of submaximal exercise thresholds by comparison with a cycle ergometer and a treadmill. Methods 17 healthy subjects randomly performed six maximal individualized incremental exercise tests, with two tests on each of the three exercise modalities. The ventilatory anaerobic threshold (VAT) and respiratory compensation point (RCP) were determined from breath-by-breath data. Results VAT and RCP on the RATT were lower than the cycle ergometer and the treadmill: oxygen uptake (V′O2) at VAT was [mean (SD)] 1.2 (0.3), 1.5 (0.4) and 1.6 (0.5) L/min, respectively (p < 0.001); V′O2 at RCP was 1.7 (0.4), 2.3 (0.8) and 2.6 (0.9) L/min, respectively (p = 0.001). High correlations for VAT and RCP were found between the RATT vs the cycle ergometer and RATT vs the treadmill (R on the range 0.69–0.80). VAT and RCP demonstrated excellent test–retest reliability for all three devices (ICC from 0.81 to 0.98). Mean differences between the test and retest values on each device were close to zero. The ventilatory equivalent for O2 at VAT for the RATT and cycle ergometer were similar and both were higher than the treadmill. The ventilatory equivalent for CO2 at RCP was similar for all devices. Ventilatory equivalent parameters demonstrated fair-to-excellent reliability and repeatability. Conclusions It is feasible to use the RATT for estimation of submaximal exercise thresholds: VAT and RCP on the RATT were lower than the cycle ergometer and the treadmill, but there were high correlations between the RATT vs the cycle ergometer and vs the treadmill. Repeatability and test–retest reliability of all submaximal threshold parameters from the RATT were comparable to those of standard devices., BioMedical Engineering OnLine, 14, ISSN:1475-925X

Purpose: Robotics-assisted tilt table technology with integrated leg drives for basic stepping functionality is clinically available for patients with neurological impairments. Initially introduced for early rehabilitation, it provides cyclical stepping movement and physiological loading in immobilized patients. This technology provides stability and support in patients with neurological disorders for whom weakness, balance and coordination problems would preclude cardiopulmonary performance testing using a treadmill or cycle ergometer. This type of device may facilitate the estimation of peak oxygen uptake and other important cardiopulmonary performance parameters in patients who have neurological deficits. The aim of the present study was to assess the feasibility and safety of this device for peak cardiopulmonary performance testing in able-bodied subjects. Methods: A robotics-assisted tilt table (Erigo, Hocoma AG, Switzerland) was augmented with force sensors in the thigh cuffs and a work rate estimation algorithm. A custom visual feedback system was employed to guide the subjects' work rate and to provide real time feedback of actual work rate. Each subject carried out an incremental exercise test to the limit of functional capacity with a work rate increment of 5 W/minute in female subjects and 8 W/minute in males. Outcome measures were peak oxygen uptake (VO2peak), peak heart rate (HRpeak), respiratory exchange ratio (RER), peak work rate (WRpeak) and the Borg CR10 scale to measure exertion and leg fatigue. Results: 11 able-bodied subjects were included (9 male, 2 female; age 29.6±7.1 years: mean ± SD). Resting VO2 was 4.6±0.7 ml/kg/min and VO2peak was 32.4±5.1 ml/kg/min. All participants reached at least 85% of their predicted HRmax value. RER at peak VO2 was 1.02±0.07. Eight participants (72.7%) reached their peak VO2 in 8-12 minutes, which is considered the optimal duration. The average WRpeak was 65.7 W for males and 41.5 W for females. All participants reported a Borg CR10 value for exertion and leg fatigue of 7 or more. There were no serious adverse events. Conclusions: The robotics-assisted tilt table augmented with work rate estimation and a visual feedback system is a feasible and safe method for peak cardiopulmonary performance testing in able-bodied subjects. Future work will evaluate test-retest reliability and compare peak cardiorespiratory performance values with those obtained from a treadmill and a cycle ergometer. The approach will then be piloted in subjects with neurological impairments.