High-intensity interval training with functional electrical stimulation cycling for incomplete spinal cord injury patients: A pilot feasibility study.

BACKGROUND: Consequences of spinal cord injury (SCI) with a sedentary lifestyle will progress to muscle weakness and muscle atrophy, leading to muscle fatigue. This study aimed to determine the feasibility and preliminary effects of high-intensity interval training (HIIT) using functional electrical stimulation (FES) cycling on changes in thigh muscle volume and muscle strength, in patients with incomplete SCI. METHODS: Eight incomplete SCI patients (mean age 50 years; 6 women) with stable SCI paraplegia (mean 6.75 years since injury) participated in the HIIT FES cycling (85%-90% peak Watts; 4 × 4-min intervals) three times a week (over 6 weeks). The main outcomes were adherence, participant acceptability, and adverse events. Secondary outcomes were muscle strength (peak torque) and leg volume changes. RESULTS: Our findings revealed that the program was well-received by participants, with high levels of adherence, positive feedback, and satisfaction, suggesting that it could be a promising option for individuals seeking to enhance their lower body strength and muscle mass. Additionally, all participants successfully completed the training without any serious adverse events, indicating that the program is safe for use. Finally, we found that the 6-week HIIT FES leg cycling exercise program resulted in notable improvements in isometric peak torque of the quadriceps (range 13.9%-25.6%), hamstring muscle (18.2%-23.3%), and leg volume (1.7%-18.2%). CONCLUSIONS: This study highlights HIIT FES leg cycling exercise program potential as an effective intervention for improving lower limb muscle function.

The International Functional Electrical Stimulation Society (IFESS): Highlights from the IFESS conference at Rehabweek 2023.

The annual conference of the International Functional Electrical Stimulation Society (IFESS) was held in conjunction with the 7th RehabWeek Congress, from September 24 to 28, 2023 at the Resorts World Convention Centre on Sentosa Island, in Singapore. The Congress was a joint meeting of the International Consortium on Rehabilitation Technology (ICRT) together with 10 other societies in the field of assistive technology and rehabilitation engineering. The conference features comprehensive blend of technical and clinical context of FES, a sustained value the society has offered over many years. The cross- and inter- disciplinary approach of medicine, engineering, and science practiced in the FES community had enabled vibrant interaction, creation, and development of impactful and novel contributions to the field of FES, translating FES directly into highly relevant and sustainable solutions for the users.

Mechanomyography reflects the changes in oxygenated hemoglobin during electrically evoked cycling in individuals with spinal cord injury.

BACKGROUND: Functional electrical stimulation (FES) cycling has been reported to enhance muscle strength and improve muscle fatigue resistance after spinal cord injury (SCI). Despite its proposed benefits, the quantification of muscle fatigue during FES cycling remains poorly documented. This study sought to quantify the relationship between the vibrational performance of electrically-evoked muscles measured through mechanomyography (MMG) and its oxidative metabolism through near-infrared spectroscopy (NIRS) characteristics during FES cycling in fatiguing paralyzed muscles in individuals with SCI. METHODS: Six individuals with SCI participated in the study. They performed 30 min of FES cycling with MMG and NIRS sensors on their quadriceps throughout the cycling, and the signals were analyzed. RESULTS: A moderate negative correlation was found between MMG root mean square (RMS) and oxyhaemoglobin (O2Hb) [r = -0.38, p = 0.003], and between MMG RMS and total hemoglobin (tHb) saturation [r = -0.31, p = 0.017]. Statistically significant differences in MMG RMS, O2Hb, and tHb saturation occurred during pre- and post-fatigue of FES cycling (p < 0.05). CONCLUSIONS: MMG RMS was negatively associated with O2Hb and muscle oxygen derived from NIRS. MMG and NIRS sensors showed good inter-correlations, suggesting a promising use of MMG for characterizing metabolic fatigue at the muscle oxygenation level during FES cycling in individuals with SCI.

Respiratory muscle training: a bibliometric analysis of 60 years' multidisciplinary journey.

BACKGROUND: Over the decades, many publications have established respiratory muscle training (RMT) as an effective way in improving respiratory dysfunction in multiple populations. The aim of the paper is to determine the trend of research and multidisciplinary collaboration in publications related to RMT over the last 6 decades. The authors also sought to chart the advancement of RMT among people with spinal cord injury (SCI) over the last 60 years. METHODS: Bibliometric analysis was made, including the publications' profiles, citation analysis and research trends of the relevant literature over the last 60 years. Publications from all time frames were retrieved from Scopus database. A subgroup analysis of publications pertinent to people with SCI was also made. RESULTS: Research on RMT has been steadily increasing over the last 6 decades and across geographical locations. While medicine continues to dominate the research on RMT, this topic also continues to attract researchers and publications from other areas such as engineering, computer science and social science over the last 10 years. Research collaboration between authors in different backgrounds was observed since 2006. Source titles from non-medical backgrounds have also published articles pertinent to RMT. Among people with SCI, researchers utilised a wide range of technology from simple spirometers to electromyography in both intervention and outcome measures. With various types of interventions implemented, RMT generally improves pulmonary function and respiratory muscle strength among people with SCI. CONCLUSIONS: While research on RMT has been steadily increasing over the last 6 decades, more collaborations are encouraged in the future to produce more impactful and beneficial research on people who suffer from respiratory disorders.

Mechanomyography and tissue oxygen saturation during electrically-evoked wrist extensor fatigue in people with tetraplegia.

BACKGROUND: Repetitive electrically-evoked muscle contractions lead to the early onset of muscle fatigue. This study assessed the relationship between muscle mechanomyography (%RMS-MMG) and tissue oxygen saturation (%TSI) in extensor carpi radialis (ECR) during electrically-evoked fatiguing exercise in individuals with tetraplegia. METHODS: Skin-surface mechanomyography (MMG) and near-infrared spectroscopy (NIRS) sensors were placed on the ECR of seven individuals with tetraplegia. All participants performed repetitive electrically-evoked wrist extension to fatigue while their muscle MMG and NIRS responses were monitored against their power output (PO). FINDINGS: One out of seven participants showed no changes in %TSI throughout the repeated wrist FES-evoked contraction. The other six participants' %TSI was positively correlated with %PO before fatigue onset. At 50%POpeak , %TSI was negatively correlated (0.489) significantly with declining %PO as the ability of the muscle to take up oxygen became limited. The %RMS-MMG behaved analogously during pre and post-fatigue against declining %PO, whereby both displayed positive correlations of 0.443 and 0.214, respectively, (%RMS-MMG decreased) throughout the exercise session. Regression analysis revealed that %TSI was proportional to pre-fatigue and inversely proportional to %RMS-MMG during post-fatigue. CONCLUSION: The significant changes in muscle mechanomyography and tissue oxygenation correlations after 50%POpeak implied that the muscle contraction mechanical-and-physiological behavior association had been altered following FES-evoked fatigue.

Mechanomyography and Torque during FES-Evoked Muscle Contractions to Fatigue in Individuals with Spinal Cord Injury.

A mechanomyography muscle contraction (MC) sensor, affixed to the skin surface, was used to quantify muscle tension during repetitive functional electrical stimulation (FES)-evoked isometric rectus femoris contractions to fatigue in individuals with spinal cord injury (SCI). Nine persons with motor complete SCI were seated on a commercial muscle dynamometer that quantified peak torque and average torque outputs, while measurements from the MC sensor were simultaneously recorded. MC-sensor-predicted measures of dynamometer torques, including the signal peak (SP) and signal average (SA), were highly associated with isometric knee extension peak torque (SP: r = 0.91, p < 0.0001), and average torque (SA: r = 0.89, p < 0.0001), respectively. Bland-Altman (BA) analyses with Lin's concordance (ρC) revealed good association between MC-sensor-predicted peak muscle torques (SP; ρC = 0.91) and average muscle torques (SA; ρC = 0.89) with the equivalent dynamometer measures, over a range of FES current amplitudes. The relationship of dynamometer torques and predicted MC torques during repetitive FES-evoked muscle contraction to fatigue were moderately associated (SP: r = 0.80, p < 0.0001; SA: r = 0.77; p < 0.0001), with BA associations between the two devices fair-moderate (SP; ρC = 0.70: SA; ρC = 0.30). These findings demonstrated that a skin-surface muscle mechanomyography sensor was an accurate proxy for electrically-evoked muscle contraction torques when directly measured during isometric dynamometry in individuals with SCI. The novel application of the MC sensor during FES-evoked muscle contractions suggested its possible application for real-world tasks (e.g., prolonged sit-to-stand, stepping,) where muscle forces during fatiguing activities cannot be directly measured.

Estimation of Electrically-Evoked Knee Torque from Mechanomyography Using Support Vector Regression.

The difficulty of real-time muscle force or joint torque estimation during neuromuscular electrical stimulation (NMES) in physical therapy and exercise science has motivated recent research interest in torque estimation from other muscle characteristics. This study investigated the accuracy of a computational intelligence technique for estimating NMES-evoked knee extension torque based on the Mechanomyographic signals (MMG) of contracting muscles that were recorded from eight healthy males. Simulation of the knee torque was modelled via Support Vector Regression (SVR) due to its good generalization ability in related fields. Inputs to the proposed model were MMG amplitude characteristics, the level of electrical stimulation or contraction intensity, and knee angle. Gaussian kernel function, as well as its optimal parameters were identified with the best performance measure and were applied as the SVR kernel function to build an effective knee torque estimation model. To train and test the model, the data were partitioned into training (70%) and testing (30%) subsets, respectively. The SVR estimation accuracy, based on the coefficient of determination (R²) between the actual and the estimated torque values was up to 94% and 89% during the training and testing cases, with root mean square errors (RMSE) of 9.48 and 12.95, respectively. The knee torque estimations obtained using SVR modelling agreed well with the experimental data from an isokinetic dynamometer. These findings support the realization of a closed-loop NMES system for functional tasks using MMG as the feedback signal source and an SVR algorithm for joint torque estimation.

Cardiorespiratory and Muscle Metabolic Responses During Conventional Versus Motion Sensor-Assisted Strategies for Functional Electrical Stimulation Standing After Spinal Cord Injury.

This is a case series study with the objective of comparing two motion sensor automated strategies to avert knee buckle during functional electrical stimulation (FES)-standing against a conventional hand-controlled (HC) FES approach. The research was conducted in a clinical exercise laboratory gymnasium at the University of Sydney, Australia. The automated strategies, Aut-A and Aut-B, applied fixed and variable changes of neurostimulation, respectively, in quadriceps amplitude to precisely control knee extension during standing. HC was an "on-demand" increase of stimulation amplitude to maintain stance. Finally, maximal FES amplitude (MA) was used as a control condition, whereby knee buckle was prevented by maximal isometric muscle recruitment. Four AIS-A paraplegics undertook 4 days of testing each, and each assessment day comprised three FES standing trials using the same strategy. Cardiorespiratory responses were recorded, and quadriceps muscle oxygenation was quantified using near-infrared spectroscopy. For all subjects, the longest standing times were observed during Aut-A, followed by Aut-B, and then HC and MA. The standing times of the automated strategies were superior to HC by 9-64%. Apart from a lower heart rates during standing (P = 0.034), the automation of knee extension did not promote different cardiorespiratory responses compared with HC. The standing times during MA were significantly shorter than during the automated or "on-demand" strategies (by 80-250%). In fact, the higher isometric-evoked quadriceps contraction during MA resulted in a greater oxygen demand (P < 0.0001) and wider arteriovenous oxygen extraction (P = 0.08) when compared with the other strategies. In conclusion, even though increased standing times were demonstrated using automated control of knee extension, physiological benefits compared with HC were not evident.

Detection of Prosthetic Knee Movement Phases via In-Socket Sensors: A Feasibility Study.

This paper presents an approach of identifying prosthetic knee movements through pattern recognition of mechanical responses at the internal socket's wall. A quadrilateral double socket was custom made and instrumented with two force sensing resistors (FSR) attached to specific anterior and posterior sites of the socket's wall. A second setup was established by attaching three piezoelectric sensors at the anterior distal, anterior proximal, and posterior sites. Gait cycle and locomotion movements such as stair ascent and sit to stand were adopted to characterize the validity of the technique. FSR and piezoelectric outputs were measured with reference to the knee angle during each phase. Piezoelectric sensors could identify the movement of midswing and terminal swing, pre-full standing, pull-up at gait, sit to stand, and stair ascent. In contrast, FSR could estimate the gait cycle stance and swing phases and identify the pre-full standing at sit to stand. FSR showed less variation during sit to stand and stair ascent to sensitively represent the different movement states. The study highlighted the capacity of using in-socket sensors for knee movement identification. In addition, it validated the efficacy of the system and warrants further investigation with more amputee subjects and different sockets types.

Technology efficacy in active prosthetic knees for transfemoral amputees: a quantitative evaluation.

Several studies have presented technological ensembles of active knee systems for transfemoral prosthesis. Other studies have examined the amputees' gait performance while wearing a specific active prosthesis. This paper combined both insights, that is, a technical examination of the components used, with an evaluation of how these improved the gait of respective users. This study aims to offer a quantitative understanding of the potential enhancement derived from strategic integration of core elements in developing an effective device. The study systematically discussed the current technology in active transfemoral prosthesis with respect to its functional walking performance amongst above-knee amputee users, to evaluate the system's efficacy in producing close-to-normal user performance. The performances of its actuator, sensory system, and control technique that are incorporated in each reported system were evaluated separately and numerical comparisons were conducted based on the percentage of amputees' gait deviation from normal gait profile points. The results identified particular components that contributed closest to normal gait parameters. However, the conclusion is limitedly extendable due to the small number of studies. Thus, more clinical validation of the active prosthetic knee technology is needed to better understand the extent of contribution of each component to the most functional development.

Piezoelectric bimorphs' characteristics as in-socket sensors for transfemoral amputees.

Alternative sensory systems for the development of prosthetic knees are being increasingly highlighted nowadays, due to the rapid advancements in the field of lower limb prosthetics. This study presents the use of piezoelectric bimorphs as in-socket sensors for transfemoral amputees. An Instron machine was used in the calibration procedure and the corresponding output data were further analyzed to determine the static and dynamic characteristics of the piezoelectric bimorph. The piezoelectric bimorph showed appropriate static operating range, repeatability, hysteresis, and frequency response for application in lower prosthesis, with a force range of 0-100 N. To further validate this finding, an experiment was conducted with a single transfemoral amputee subject to measure the stump/socket pressure using the piezoelectric bimorph embedded inside the socket. The results showed that a maximum interface pressure of about 27 kPa occurred at the anterior proximal site compared to the anterior distal and posterior sites, consistent with values published in other studies. This paper highlighted the capacity of piezoelectric bimorphs to perform as in-socket sensors for transfemoral amputees. However, further experiments are recommended to be conducted with different amputees with different socket types.

Evoked EMG versus muscle torque during fatiguing functional electrical stimulation-evoked muscle contractions and short-term recovery in individuals with spinal cord injury.

This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery.

Mechanomyographic parameter extraction methods: an appraisal for clinical applications.

The research conducted in the last three decades has collectively demonstrated that the skeletal muscle performance can be alternatively assessed by mechanomyographic signal (MMG) parameters. Indices of muscle performance, not limited to force, power, work, endurance and the related physiological processes underlying muscle activities during contraction have been evaluated in the light of the signal features. As a non-stationary signal that reflects several distinctive patterns of muscle actions, the illustrations obtained from the literature support the reliability of MMG in the analysis of muscles under voluntary and stimulus evoked contractions. An appraisal of the standard practice including the measurement theories of the methods used to extract parameters of the signal is vital to the application of the signal during experimental and clinical practices, especially in areas where electromyograms are contraindicated or have limited application. As we highlight the underpinning technical guidelines and domains where each method is well-suited, the limitations of the methods are also presented to position the state of the art in MMG parameters extraction, thus providing the theoretical framework for improvement on the current practices to widen the opportunity for new insights and discoveries. Since the signal modality has not been widely deployed due partly to the limited information extractable from the signals when compared with other classical techniques used to assess muscle performance, this survey is particularly relevant to the projected future of MMG applications in the realm of musculoskeletal assessments and in the real time detection of muscle activity.

The effectiveness of FES-evoked EMG potentials to assess muscle force and fatigue in individuals with spinal cord injury.

The evoked electromyographic signal (eEMG) potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES)-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p < 0.05) between the decline in the peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI) population.

Exercise Responses During Outdoor Versus Virtual Reality Indoor Arm+FES-Leg Cycling in Individuals with Spinal Cord Injury.

Background: Virtual reality (VR)-enhanced indoor hybrid cycling in people with spinal cord injury (SCI) can be comparable to outdoor hybrid cycling. Method: Eight individuals with chronic thoracic-lesion SCI performed voluntary arm and electrically assisted leg cycling on a hybrid recumbent tricycle. Exercises were conducted outdoors and indoors incorporating VR technology in which the outdoor environment was simulated on a large flat screen monitor. Electrical stimulation was applied bilaterally to the leg muscle groups. Oxygen uptake (VO2), heart rate, energy expenditures, and Ratings of Perceived Exertion were measured over a 30-minute outdoor test course that was also VR-simulated indoors. Immediately after each exercise, participants completed questionnaires to document their perceptual-psychological responses. Results: Mean 30-minute VO2 was higher for indoor VR exercise (average VO2-indoor VR-exercise: 1316 ± mL/min vs. outdoor cycling: 1255 ± 53 mL/min; highest VO2-indoor VR-exercise: 1615 ± 67 mL/min vs. outdoor cycling: 1725 ± 67 mL/min). Arm and leg activity counts were significantly higher during indoor VR-assisted hybrid functional electrical stimulation (FES) cycling than outdoors; 42% greater for the arms and 23% higher for the legs (P < 0.05). Similar responses were reported for exercise effort and perceptual-psychological outcomes during both modes. Conclusion: This study proposes that combining FES and VR technology provides new opportunities for physical activity promotion or exercise rehabilitation in the SCI population, since these modes have similar "dose-potency" and self-perceived effort. Human Research Ethics Committee of the University of Sydney Ref. No. 01-2010/12385.

Effects of releasing ankle joint during electrically evoked cycling in persons with motor complete spinal cord injury.

Literature has shown that simulated power production during conventional functional electrical stimulation (FES) cycling was improved by 14% by releasing the ankle joint from a fixed ankle setup and with the stimulation of the tibialis anterior and triceps surae. This study aims to investigate the effect of releasing the ankle joint on the pedal power production during FES cycling in persons with spinal cord injury (SCI). Seven persons with motor complete SCI participated in this study. All participants performed 1 min of fixed-ankle and 1 min of free-ankle FES cycling with two stimulation modes. In mode 1 participants performed FES-evoked cycling with the stimulation of quadriceps and hamstring muscles only (QH stimulation), while Mode 2 had stimulation of quadriceps, hamstring, tibialis anterior, and triceps surae muscles (QHT stimulation). The order of each trial was randomized in each participant. Free-ankle FES cycling offered greater ankle plantar- and dorsiflexion movement at specific slices of 20° crank angle intervals compared to fixed-ankle. There were significant differences in the mean and peak normalized pedal power outputs (POs) [F(1,500) = 14.03, p < 0.01 and F(1,500) = 7.111, p = 0.008, respectively] between fixed- and free-ankle QH stimulation, and fixed- and free-ankle QHT stimulation. Fixed-ankle QHT stimulation elevated the peak normalized pedal PO by 14.5% more than free-ankle QH stimulation. Releasing the ankle joint while providing no stimulation to the triceps surae and tibialis anterior reduces power output. The findings of this study suggest that QHT stimulation is necessary during free-ankle FES cycling to maintain power production as fixed-ankle.

Accessory respiratory muscles performance among people with spinal cord injury while singing songs with different musical parameters.

People with spinal cord injury (SCI) experience respiratory dysfunctions which include hypersecretions, bronchospasm, and respiratory muscles weakness. Singing therapy has been implemented as part of respiratory muscle training (RMT) to improve their muscle strength. Singing different types and genres of songs may elicit specific recruitment of respiratory muscles, attributed to the variation of the songs' characteristics including tempo, pitch, and rhythmic complexity. This study aims to determine the effect of singing songs with different characteristics on the accessory respiratory muscle performance among people with SCI. Thirteen male SCI participants of ASIA A and B (C4 -T11) were recruited. Respiratory muscle signals were retrieved by placing two mechanomyography (MMG) sensors on the sternocleidomastoid (SCM) and rectus abdominis (RA) muscles. Eight music experts categorized several songs into four categories based on their pitch, tempo, and rhythmic complexity. Each participant sang one song from each category. Findings showed statistically significant difference in RA and SCM responses among all categories (P < 0.01). The SCM muscle is most active while singing high pitch songs. While the RA is most active during slow tempo and easy rhythmic complexity. This shows that different accessory respiratory muscle is activated by people with SCI while singing songs with different characteristics. Clinicians could benefit from this knowledge while prescribing singing therapy or exercise among people with SCI in the future.

Development of a micro-gripper using piezoelectric bimorphs.

Piezoelectric bimorphs have been used as a micro-gripper in many applications, but the system might be complex and the response performance might not have been fully characterized. In this study the dynamic characteristics of bending piezoelectric bimorphs actuators were theoretically and experimentally investigated for micro-gripping applications in terms of deflection along the length, transient response, and frequency response with varying driving voltages and driving signals. In addition, the implementation of a parallel micro-gripper using bending piezoelectric bimorphs was presented. Both fingers were actuated separately to perform mini object handling. The bending piezoelectric bimorphs were fixed as cantilevers and individually driven using a high voltage amplifier and the bimorph deflection was measured using a non contact proximity sensor attached at the tip of one finger. The micro-gripper could perform precise micro-manipulation tasks and could handle objects down to 50 µm in size. This eliminates the need for external actuator extension of the microgripper as the grasping action was achieved directly with the piezoelectric bimorph, thus minimizing the weight and the complexity of the micro-gripper.

Effectiveness of FES-supported leg exercise for promotion of paralysed lower limb muscle and bone health-a systematic review.

Leg exercises through standing, cycling and walking with/without FES may be used to preserve lower limb muscle and bone health in persons with physical disability due to SCI. This study sought to examine the effectiveness of leg exercises on bone mineral density and muscle cross-sectional area based on their clinical efficacy in persons with SCI. Several literature databases were searched for potential eligible studies from the earliest return date to January 2022. The primary outcome targeted was the change in muscle mass/volume and bone mineral density as measured by CT, MRI and similar devices. Relevant studies indicated that persons with SCI that undertook FES- and frame-supported leg exercise exhibited better improvement in muscle and bone health preservation in comparison to those who were confined to frame-assisted leg exercise only. However, this observation is only valid for exercise initiated early (i.e., within 3 months after injury) and for ≥30 min/day for ≥ thrice a week and for up to 24 months or as long as desired and/or tolerable. Consequently, apart from the positive psychological effects on the users, leg exercise may reduce fracture rate and its effectiveness may be improved if augmented with FES.

Effects of a combined progressive resistance training and functional electrical stimulation-evoked cycling exercise on lower limb muscle strength of individuals with incomplete spinal cord injury: A randomized controlled study.

Objectives: This study was conducted to investigate the effects of combined progressive resistance training (PRT) and functional electrical stimulation-evoked leg cycling exercise (FES-LCE) on isometric peak torque and muscle volume in individuals with incomplete spinal cord injury. Patients and methods: In the single-blind, randomized controlled trial performed between April 2015 and August 2016, 28 participants were randomized between two exercise interventions (FES-LCE+PRT and FES-LCE alone), and training was conducted over 12 weeks. The isometric muscle peak torque and muscle volume for both lower limbs were measured at the baseline and after 6 and 12 weeks. Linear mixed-model analysis of variance was performed to test the effects of FES-LCE+PRT versus FES-LCE on each outcome measure over time via an intention-to-treat analysis. Results: Twenty-three participants (18 males, 5 females; mean age: 33.4±9.7 years; range 21 to 50 years) completed study (10 in the FES-LCE+PRT group, and 13 in the FES-LCE group). The 12-week pre-and posttraining change for left hamstrings' muscle peak torque in the FES-LCE+PRT group (mean difference=4.5±7.9 Nm, 45% change, p<0.05) was consistently higher than that in the FES-LCE group (mean difference=2.4±10.3 Nm, 4% change; p<0.018). The improvement in the right quadriceps muscle's peak torque of the FES-LCE+PRT group (mean difference=19±7.6 Nm, 31% change, p<0.05) was more significant compared to the FES-LCE group. The left muscle volume showed a remarkable increase after 12 weeks in the FES-LCE+PRT group (mean difference=0.3±9.3 L, 7% change, p<0.05). Conclusion: The combination of PRT and FES-LCE was better in improving lower limb muscle strength and volume in chronic incomplete individuals with spinal cord injury.