Functional Electrical Stimulation Exercise Research Articles

The Practical Utility of Functional Electrical Stimulation Exercise for Cardiovascular Health in Individuals with Spinal Cord Injury

The Practical Utility of Functional Electrical Stimulation Exercise for Cardiovascular Health in Individuals with Spinal Cord Injury

Energy Expenditure, Cardiorespiratory Fitness, and Body Composition Following Arm Cycling or Functional Electrical Stimulation Exercises in Spinal Cord Injury: A 16-Week Randomized Controlled Trial.

Background: Physical deconditioning and inactivity following spinal cord injury (SCI) are associated with multiple cardiometabolic risks. To mitigate cardiometabolic risk, exercise is recommended, but it is poorly established whether arm cycling exercise (ACE) or functional electrical stimulation (FES) leg cycling yields superior benefits. Objectives: To determine the adaptations of 16 weeks of FES cycling and ACE on exercise energy expenditure (EEE), cardiorespiratory fitness (CRF), and obesity after SCI. Methods: Thirteen physically untrained individuals were randomly assigned to FES (n = 6) or ACE (n = 7) exercise 5 days/week for 16 weeks. Pre- and post-intervention EEE, peak oxygen consumption (absolute and relative VO2Peak), and work were assessed using indirect calorimetry, while body composition was measured by dual-energy x-ray absorptiometry. Results: Main effects were found for peak power (p < .001), absolute (p = .046) and relative (p = .042) VO2Peak, and peak work (p = .013). Compared to baseline, the ACE group increased in EEE (+85%, p = .002), peak power (+307%, p < .001), VO2Peak (absolute +21%, relative +22%, p ≤ .024), peak work (19% increase, p = .003), and total body fat decreased (-6%, p = .05). The FES group showed a decrease in percentage body fat mass (-5%, p = .008). The ACE group had higher EEE (p = .008), peak power (p < .001), and relative VO2Peak (p = .025) compared to postintervention values in the FES group. Conclusion: In the current study, ACE induced greater increases in EEE and CRF, whereas ACE and FES showed similar results on body fat. Exercise promotional efforts targeting persons with SCI should use both FES and ACE to reduce sedentary behavior and to optimize different health parameters after SCI.

Cardiometabolic Effects of High-Intensity Hybrid Functional Electrical Stimulation Exercise after Spinal Cord Injury.

The prevalence of cardiometabolic disease following spinal cord injury is known to be high. However, it is unknown whether engaging in high-intensity exercise, which is advocated by recent guidelines, is beneficial or feasible for these individuals. To assess the effects of high-intensity, whole-body exercise on the prevalence of cardiometabolic disease in individuals with spinal cord injury. Combination of a randomized controlled trial and an open label intervention study of functional electrical stimulation legs plus arms rowing. Outpatient academic rehabilitation hospital. Forty individuals with spinal cord injury, with American Spinal Injury Association (ASIA) impairments scales A-D and neurological levels of injury C1-T12. Six months of high-intensity, hybrid-functional electrical stimulation rowing. Change in VO2max , serum lipids, and insulin resistance, prevalence of cardiometabolic disease. Individuals averaged 42.1± 22.0minutes of hybrid-functional electrical stimulation rowing a week over an average of 1.69 sessions per week over the 6months of intervention. This amounted to an average of 170.9± 100 km rowed, at a mean heart rate of 82.7% of individualized maximum. Only one of 40 individuals met current exercise guidelines for the full 6months. VO2max increased significantly (P< .001), yet prevalence of cardiometabolic disease did not change significantly (decrease from 22.5% to 20%, P= .70). Hemoglobin A1c did decrease significantly over this time (P= .01), although serum lipids and fasting glucose/insulin levels were unchanged. In exploratory subanalyses assessing individuals injured ≤12 months, those with more chronic injuries decreased their triglyceride-to-high-density lipoprotein (HDL) ratio (P= .04), a marker of cardiac mortality. Stratifying by neurological level of injury, individuals with paraplegia had worsened low-density lipoprotein (LDL) level (P= .02) and total cholesterol-to-HDL ratio (P= .04) over the 6-month intervention. Sustained high-intensity exercise with hybrid functional electrical stimulation rowing does not decrease the prevalence of cardiometabolic disease after spinal cord injury.

Acute Ventilatory Support During Whole-Body Hybrid Rowing in Patients With High-Level Spinal Cord Injury: A Randomized Controlled Crossover Trial

High-level spinal cord injury (SCI) results in profound spinal and supraspinal deficits, leading to substantial ventilatory limitations during whole-body hybrid functional electrical stimulation (FES)-rowing, a form of exercise that markedly increases the active muscle mass via electrically induced leg contractions. This study tested the effect of noninvasive ventilation (NIV) on ventilatory and aerobic capacities in SCI. This blinded, randomized crossover study enrolled 19 patients with SCI (level of injury ranging from C4 to T8). All patients were familiar with FES-rowing and had plateaued in their training-related increases in aerobic capacity. Patients performed two FES-rowing peak exercise tests with NIV or without NIV (sham). NIV increased exercise tidal volume (peak, 1.50 ± 0.31L vs1.36 ± 0.34 L; P< .05) and reduced breathing frequency (peak, 35 ± 7 beats/min vs38 ± 6 beats/min; P< .05) compared with the sham test, leading to no change in alveolar ventilation but a trend toward increased oxygen uptake efficiency (P= .06). In those who reached peak oxygen consumption (Vo2peak) criteria (n= 13), NIV failed to significantly increase Vo2peak (1.73 ± 0.66 L/min vs1.78 ± 0.59 L/min); however, the range of responses revealed a correlation between changes in peak alveolar ventilation and Vo2peak (r= 0.89; P< .05). Furthermore, those with higher level injuries and shorter time since injury exhibited the greatest increases in Vo2peak. Acute NIV can successfully improve ventilatory efficiency during FES exercise in SCI but may not improve Vo2peak in all patients. Those who benefit most seem to be patients with cervical SCI within a shorter time since injury. ClinicalTrials.gov; Nos.: NCT02865343 and NCT03267212; URL:www.clinicaltrials.gov.

Home FES: An Exploratory Review.

This review of literature focuses on the multiple uses of Functional Electrical Stimulation (FES) and how this modality may be a valuable home-based therapy. Papers pertaining to home FES exercise were collected using the Web of Science, Google Scholar databases and collegial hints. In our opinion, the following statements summarize the results. FES may be used to induce health benefits in populations with paralysis, and in persons with musculoskeletal, cardiorespiratory and renal pathology. The EU Project Rise showed how FES could have a variety of encouraging outcomes for patients with denervated muscles following traumatic injuries. As suggested by recent literature, FES has proven to be a viable form of exercise for elderly individuals. Thus, Home FES may be an option for patients looking for an additional form of muscle and cardiopulmonary physical therapy.

Lessons from Vienna: stakeholder perceptions of functional electrical stimulation technology and a conceptual model for practice

Aim: Functional electrical stimulation (FES) is a technology that can be used on paralyzed muscles to allow them to move. It has been used in populations with muscle paralysis or weakness for exercise, such as spinal cord injury (SCI) and multiple sclerosis. In order to improve technology, it is vital to understand from a qualitative perspective, issues surrounding device development and implementation.Materials and Methods: In 2016, a study was conducted at the Medical University of Vienna that sought to unravel perspectives of FES exercise from the perspective of clinicians, engineers and researchers. Semi-structured, qualitative interviews were conducted on a sample of participants from the conference (n = 22). Interviews were transcribed verbatim, and text data were analysed.Results: Following this analysis, a conceptual model of FES application in the home environment was derived. We show that the likelihood of continuing FES over time may be influenced by expectations and initial education, as perceived by stakeholders.Conclusion: This model provides a tool by which researchers or clinicians may implement FES in the home environment and may assist in the increased uptake of FES exercise at home for people who may reap benefits from its use.Implications for RehabilitationFunctional electrical stimulation (FES) is a technology that enables individuals with paralysis, such as Spinal Cord Injury or Multiple Sclerosis, to exercise.Motivation and support networks, along with adequate initial education, are essential should patients be able to successfully use FES for exercise.There are unique issues associated with performing FES in the home, and compliance may be influenced by how patients perceive FES with regard to providing benefits, and what their initial expectations are.Communication and education are essential for all parties involved in the provision of FES treatment, to ensure successful treatment with FES at home.

How to prepare a person with complete spinal cord injury to use surface electrodes for FES trike cycling.

Functional Electrical Stimulation (FES) cycling could benefit people with Spinal Cord Injury (SCI). The FES cycling involves large muscle groups during the training, and thus improves the cardiovascular function, increases the muscle bulk and reduces the secondary complications. This study developed an outdoor FES exercise cycling system for complete SCI persons to exercise their lower limbs without putting extra load on upper extremities. The mechanical structure of the cycling system was specially redesigned to secure the SCI persons in the cycling system. A six-phase-angle-driven control algorithm was designed to stimulate the quadriceps and hamstrings muscles. Two training modes, i.e., continuous mode and on-off mode, were designed and tested to increase the duration of the electrical stimulation to reduce muscle fatigue. A complete SCI volunteer participated in this training for six months. Beneficial effects could be observed such as paralyzed lower limb muscles had regained the muscle mass and reduced edema from the improved blood circulation. Moreover, the SCI volunteer attended the Cybathlon FES-bike competition in Zurich in October 2016 with Team Phoenix from the CUHK.

Energetic and Hemodynamic Response to Electrical Stimulation Cycling in Persons with Paralysis

Electronic stimulation can be used to stimulate contraction of paralyzed muscle, and when coordinated via computer processing, lower body muscles can power a cycle ergometer in a manner which increases whole-body energy expenditure. PURPOSE: When matched for charge input determine if calorie (kcal) expenditure and fuel partitioning measured during and immediately following a bout of functional electrical stimulation (FES) cycling differed when performed on two FES devices. METHOD: Six males with spinal cord injury (SCI; age: 49±17 yr; weight: 76±6 kg; level of injury: C4-T11) completed 30 min of steady-state FES exercise on four separate occasions at a charge-matched moderate stimulation intensity. Two sessions were completed on a commercially available unit (RT300, Restorative Therapies, MD) and two on a device that is in pre-production testing (MyoCycle, MYOLYN, FL) that employs a different electrical control paradigm. Before, during, and after cycling, energy expenditure and fuel homeostasis were calculated via pulmonary gas exchange (Oxycon, Jeager, CA), and central hemodynamics (for the MyoCycle device only) via impedance cardiography (PhysioFlow, Manatec Biomedical, FR). RESULTS: Rate of oxygen consumption (VO2) and cardiac output (CO) during FES were 34±20% and 49±23% of their respective VO2peak and COpeak achieved during maximal effort arm cycling. Both FES devices elicited similar rates of exercise energy expenditure (1.06±0.20 kcal/min) and fuel homeostasis (74:26 %CHO:%FAT). However, only the MyoCycle showed a statistically significant increase in energy expenditure at 20-30 min post-exercise time point (11.2% increase vs pre-exercise, p=.02), with this increase in energy expenditure accompanied by a 54% increase in CHO oxidation during the first 30 min of exercise recovery. CONCLUSION: Moderate intensity FES cycling qualifies as “low intensity” aerobic exercise according to authoritative guidelines, although increases in carbohydrate oxidation during and after cycling might have a meaningful impact on daily glucose regulation. Furthermore, the energetics of the recovery period seem to be influenced by the electrical control system.

Assessing kinematics and kinetics of functional electrical stimulation rowing

Hybrid functional electrical stimulation (FES) rowing has positive effects on cardiovascular fitness, producing significantly greater aerobic power than either upper body or FES exercise alone. However, there is minimal information on the kinematics, kinetics, and mechanical efficiency of FES-rowing in the spinal cord injured (SCI) population. This study examined the biomechanics of FES-rowing to determine how motions, forces, and aerobic demand change with increasing intensity. Six individuals with SCI and six able-bodied subjects performed a progressive aerobic capacity rowing test. Differences in kinematics (motion profiles), kinetics (forces produced by the feet and arms), external mechanical work, and mechanical efficiency (work produced/volume of oxygen consumed) were compared in able-bodied rowing vs. SCI FES-rowing at three comparable subpeak workloads. With increasing exercise intensity (measured as wattage), able-bodied rowing increased stroke rate by decreasing recovery time, while FES-rowing maintained a constant stroke rate, with no change in drive or recovery times. While able-bodied rowers increased leg and arm forces with increasing intensity, FES-rowers used only their arms to achieve a higher intensity with a constant and relatively low contribution of the legs. Oxygen consumption increased in both groups, but more so in able-bodied rowers, resulting in able-bodied rowers having twice the mechanical efficiency of FES-rowers. Our results suggest that despite its ability to allow for whole body exercise, the total force output achievable with FES-rowing results in only modest loading of the legs that affects overall rowing performance and that may limit forces applied to bone.

Ventilation Limits Aerobic Capacity after Functional Electrical Stimulation Row Training in High Spinal Cord Injury.

In the able-bodied, exercise training results in increased ventilatory capacity to meet increased aerobic demands of trained skeletal muscle. However, after spinal cord injury (SCI), peak ventilation can be limited by pulmonary muscle denervation. In fact, peak ventilation may restrict aerobic capacity in direct relation to injury level. Hybrid functional electrical stimulation (FES) exercise training results in increased aerobic capacity and dissociation between aerobic capacity and injury level in those with injuries at T3 and below. However, injuries above T3 have the greatest pulmonary denervation, and ventilatory capacity may restrict the increase in aerobic capacity with hybrid FES training. We assessed relationships among injury level, peak ventilation, and peak aerobic capacity and calculated oxygen uptake efficiency slope during hybrid FES exercise in 12 individuals (1 female) with SCI at level T2 to C4 (injury duration = 0.33-33 yr, age = 20-60 yr), before and after 6 months of FES-row training (FES-RT). Training increased peak aerobic capacity by 12% (P = 0.02) with only a modest increase in peak ventilation (7 of 12 subjects, P = 0.09). Both before and after training, injury level was directly related to peak ventilation (R = 0.48 and 0.43) and peak aerobic capacity (R = 0.70 and 0.55). Before training, the relationship of peak aerobic capacity to peak ventilation was strong (R = 0.62), however, after training, this relationship became almost completely linearized (R = 0.84). In addition, oxygen uptake efficiency slope increased by 11% (P < 0.05) after FES-RT. Despite the ability to increase exercise capacity via hybrid FES exercise, the inability to increase peak ventilation beyond limits set by SCI level in those with high-level injuries (above T3) appears to restrict aerobic capacity.

Effects of a Functional Electrical Stimulation-Assisted Cycling Program on Immune and Cardiovascular Health in Persons with Spinal Cord Injury.

Background: Spinal cord injury (SCI) is associated with both a state of chronic inflammation and an increased prevalence of cardiovascular disease (CVD). These disorders are closely linked and have been shown to negatively influence one another. Participation in regular exercise has been shown to be an effective intervention strategy in the treatment of each of these disorders. For individuals with SCI who may lack the lower limb motor capabilities to perform certain traditional exercise modalities, functional electrical stimulation (FES) cycling may provide an effective alternative. Objective: The purpose of this study was to examine the effects of 12 weeks of FES training performed 3 times per week on physiological indices of cardiovascular function as well as molecular indices of inflammation and cardiovascular health. Methods: Ten individuals with chronic SCI were included. Measures of central and peripheral cardiovascular function as well as hematological and immunological markers were assessed before and after the 12-week exercise program. Results: Enhancements in exercise performance as well as a corresponding increase in peripheral cardiovascular function were achieved, as shown by a significant 34% increase in pulse volume (P = .04) and trends toward increases in cross-sectional area (P = .09) and arterial inflow volume (P = .11) of the common femoral artery. Despite this, no change in any hematological or immunological markers was evident. Conclusion: Although the efficacy of FES exercise in enhancing exercise performance (time and distance to fatigue) and peripheral cardiovascular function has been reaffirmed, no alterations in any molecular indices of cardiovascular risk were achieved.

Strategies for Rapid Muscle Fatigue Reduction during FES Exercise in Individuals with Spinal Cord Injury: A Systematic Review.

BackgroundRapid muscle fatigue during functional electrical stimulation (FES)-evoked muscle contractions in individuals with spinal cord injury (SCI) is a significant limitation to attaining health benefits of FES-exercise. Delaying the onset of muscle fatigue is often cited as an important goal linked to FES clinical efficacy. Although the basic concept of fatigue-resistance has a long history, recent advances in biomedical engineering, physiotherapy and clinical exercise science have achieved improved clinical benefits, especially for reducing muscle fatigue during FES-exercise. This review evaluated the methodological quality of strategies underlying muscle fatigue-resistance that have been used to optimize FES therapeutic approaches. The review also sought to synthesize the effectiveness of these strategies for persons with SCI in order to establish their functional impacts and clinical relevance.MethodsPublished scientific literature pertaining to the reduction of FES-induced muscle fatigue was identified through searches of the following databases: Science Direct, Medline, IEEE Xplore, SpringerLink, PubMed and Nature, from the earliest returned record until June 2015. Titles and abstracts were screened to obtain 35 studies that met the inclusion criteria for this systematic review.ResultsFollowing the evaluation of methodological quality (mean (SD), 50 (6) %) of the reviewed studies using the Downs and Black scale, the largest treatment effects reported to reduce muscle fatigue mainly investigated isometric contractions of limited functional and clinical relevance (n = 28). Some investigations (n = 13) lacked randomisation, while others were characterised by small sample sizes with low statistical power. Nevertheless, the clinical significance of emerging trends to improve fatigue-resistance during FES included (i) optimizing electrode positioning, (ii) fine-tuning of stimulation patterns and other FES parameters, (iii) adjustments to the mode and frequency of exercise training, and (iv) biofeedback-assisted FES-exercise to promote selective recruitment of fatigue-resistant motor units.ConclusionAlthough the need for further in-depth clinical trials (especially RCTs) was clearly warranted to establish external validity of outcomes, current evidence was sufficient to support the validity of certain techniques for rapid fatigue-reduction in order to promote FES therapy as an integral part of SCI rehabilitation. It is anticipated that this information will be valuable to clinicians and other allied health professionals administering FES as a treatment option in rehabilitation and aid the development of effective rehabilitation interventions.

Involuntary, forced and voluntary exercises are equally capable of inducing hippocampal plasticity and the recovery of cognitive function after stroke

Objectives:Forced and voluntary exercises are known to improve cognition and induce neuroprotection after stroke, however, any effects of involuntary movement induced by functional electrical stimulation (FES) are unclear. The effects of involuntary exercise induced by FES, forced and voluntary exercise on the recovery of cognitive function in vascular dementia and the regional repair of ischaemic lesions were investigated using a rat model.Methods:Wistar rats were randomly assigned to a sham group, a vascular dementia control group (VD), an involuntary exercise group (I-Ex), a forced exercise group (F-Ex) or a voluntary exercise group (V-Ex). An object recognition test (ORT) and an object location test (OLT) were used to evaluate the recovery of cognitive function. Levels of synapsin I (SYN), synaptophysin (SYP), postsynaptic density 95 (PSD-95), microtubule-associated protein 2 (MAP-2) and Tau in the hippocampus were evaluated using western blotting and immunohistochemistry. Nissl staining was applied to visualise the loss of viable neurons from the hippocampus.Results:Involuntary exercise and voluntary exercise both improved cognition in terms of ORT and OLT results. Forced exercise only improved ORT results. The levels of SYN, PSD-95, MAP-2 and Tau in the hippocampus were enhanced by all three patterns of exercise training. Moreover, all three patterns reduced losses of dendrons and neurons in the hippocampal CA1 and CA2 zones, but without significant differences among the three exercise regimens.Conclusion:Involuntary exercise induced by FES has beneficial effects on cognitive function after vascular dementia comparable to those of forced and voluntary exercise.

Assessing Kinetics of Functional Electrical Stimulation Rowing in Spinal Cord Injury Patients

‘Hybrid’ functional electrical stimulation (FES) ergometer rowing is a novel training therapy that enables the spinal cord injury (SCI) population to exercise the innervated upper body together with the electrically stimulated lower body muscles. This produces significantly greater aerobic power and peak oxygen consumption than either upper body or FES exercise alone. However, there is minimal information on the mechanical efficiency of FES‐rowing in the SCI population. A Concept 2 rowing ergometer was adapted to accommodate SCI patients and was instrumented to record upper body force and lower limbs forces. The objective of this work was to characterize efficiency during FES‐rowing by measuring the forces applied by the arms and the legs and the parameters observed during maximal aerobic capacity tests in SCI and able‐bodied rowers. The current setup allows correlating changes in oxygen consumption with changes in effective muscle forces collected at the feet and handle at three submaximal rowing intensities and during a submaximal bout of rowing to fatigue in SCI and able‐bodied rowers. The data suggests that while able‐bodied rowers increase legs and arms forces proportional with increased rowing intensity, the SCI rowers use primarily their arms to achieve a higher rowing wattage. FES‐rowing has positive effects on cardio‐respiratory fitness showing an increase in oxygen consumption; however, we hypothesize that this effect would be greatly enhanced by increasing the mechanical work done by the legs in SCI rowers.

Functional electrical stimulation: cardiorespiratory adaptations and applications for training in paraplegia.

Regular exercise can be broadly beneficial to health and quality of life in humans with spinal cord injury (SCI). However, exercises must meet certain criteria, such as the intensity and muscle mass involved, to induce significant benefits. SCI patients can have difficulty achieving these exercise requirements since the paralysed muscles cannot contribute to overall oxygen consumption. One solution is functional electrical stimulation (FES) and, more importantly, hybrid training that combines volitional arm and electrically controlled contractions of the lower limb muscles. However, it might be rather complicated for therapists to use FES because of the wide variety of protocols that can be employed, such as stimulation parameters or movements induced. Moreover, although the short-term physiological and psychological responses during different types of FES exercises have been extensively reported, there are fewer data regarding the long-term effects of FES. Therefore, the purpose of this brief review is to provide a critical appraisal and synthesis of the literature on the use of FES for exercise in paraplegic individuals. After a short introduction underlying the importance of exercise for SCI patients, the main applications and effects of FES are reviewed and discussed. Major findings reveal an increased physiological demand during FES hybrid exercises as compared with arms only exercises. In addition, when repeated within a training period, FES exercises showed beneficial effects on muscle characteristics, force output, exercise capacity, bone mineral density and cardiovascular parameters. In conclusion, there appears to be promising evidence of beneficial effects of FES training, and particularly FES hybrid training, for paraplegic individuals.

Hybrid Functional Electrical Stimulation Exercise Training Alters the Relationship Between Spinal Cord Injury Level and Aerobic Capacity

To test the hypothesis that hybrid functional electrical stimulation (FES) row training would improve aerobic capacity but that it would remain strongly linked to level of spinal cord lesion because of limited maximal ventilation. Longitudinal before-after trial of 6 months of FES row training. Exercise for persons with disabilities program in a hospitaL. Volunteers (N=14; age range, 21-63y) with complete spinal cord injury (SCI) (T3-11) who are >2 years postinjury. Six months of FES row training preceded by a variable period of FES strength training. Peak aerobic capacity and peak exercise ventilation before and after 6 months of FES row training. FES row training significantly increased peak aerobic capacity and peak minute ventilation (both P<.05). Prior to FES row training, there was a close relation between level of SCI and peak aerobic capacity (adjusted R(2)=.40, P=.009) that was markedly reduced after FES row training (adjusted R(2)=.15, P=.10). In contrast, the relation between level of injury and peak minute ventilation was comparable before and after FES row training (adjusted R(2)=.38 vs .32, both P<.05). The increased aerobic capacity reflects more than increased ventilation; FES row training effectively circumvents the effect of SCI on peak aerobic capacity by engaging more muscle mass for training, independent of the level of injury.

A Feasibility Study to Investigate the Effect of Functional Electrical Stimulation and Physiotherapy Exercise on the Quality of Gait of People With Multiple Sclerosis

To examine the effect of Functional Electrical Stimulation (FES) for dropped foot and hip instability in combination with physiotherapy core stability exercises. Twenty-eight people with secondary progressive multiple sclerosis and unilateral dropped foot participated in a randomized crossover trial. Group1 received FES for correction of dropped foot for six weeks with the addition of hip extension for a further six weeks. In weeks 12-18, FES was continued with the addition of eight sessions of core stability physiotherapy with home-based exercise. FES and home-based exercise were continued until weeks 19-24. Group 2 received the same physiotherapy intervention over the first 12 weeks, adding FES in the second 12 weeks. FES improved walking speed and Rivermead Observational Gait Analysis (ROGA) score, whereas physiotherapy did not. Adding gluteal stimulation further improved ROGA score. Both interventions reduced falls, but adding FES to physiotherapy reduced them further. FES had greater impact on Multiple Sclerosis Impact Scale, MSIS-29. The intervention was feasible. FES for dropped foot may improve mobility and quality of life and may reduce falls. Adding gluteal stimulation further improved gait quality. Adding physiotherapy may have enhanced the effect of FES, but FES had the dominant effect.

The identification of genetic pathways involved in vascular adaptations after physical deconditioning versus exercise training in humans

Physical inactivity and exercise training result in opposite adaptations of vascular structure. However, the molecular mechanisms behind these adaptations are not completely understood. We used a unique study design to examine both vascular characteristics of the superficial femoral artery (using ultrasound) and gene expression levels (from a muscle biopsy) in human models for physical deconditioning and exercise training. Initially, we compared able-bodied control subjects (n=6) with spinal cord-injured individuals (n=8) to assess the effects of long-term deconditioning. Subsequently, able-bodied control subjects underwent short-term lower limb deconditioning using 3weeks of unilateral limb suspension. Spinal cord-injured individuals were examined before and after 6weeks of functional electrical stimulation exercise training. Baseline femoral artery diameter and hyperaemic flow were lower after short- and long-term deconditioning and higher after exercise training, whilst intima-media thickness/lumen ratio was increased with short- and long-term deconditioning and decreased with exercise training. Regarding gene expression levels of vasculature-related genes, we found that groups of genes including the vascular endothelial growth factor pathway, transforming growth factorβ1 and extracellular matrix proteins were strongly associated with vascular adaptations in humans. This approach resulted in the identification of important genes that may be involved in vascular adaptations after physical deconditioning and exercise.

Expression of genes involved in fatty acid transport and insulin signaling is altered by physical inactivity and exercise training in human skeletal muscle

Physical deconditioning is associated with the development of chronic diseases, including type 2 diabetes and cardiovascular disease. Exercise training effectively counteracts these developments, but the underlying mechanisms are largely unknown. To gain more insight into these mechanisms, muscular gene expression levels were assessed after physical deconditioning and after exercise training of the lower limbs in humans by use of gene expression microarrays. To exclude systemic effects, we used human models for local physical inactivity (3 wk of unilateral limb suspension) and for local exercise training (6 wk of functional electrical stimulation exercise of the extremely deconditioned legs of individuals with a spinal cord injury). The most interesting subset of genes, those downregulated after deconditioning as well as upregulated after exercise training, contained 18 genes related to both the "insulin action" and "adipocytokine signaling" pathway. Of these genes, the three with strongest up/downregulation were the muscular fatty acid-binding protein-3 (FABP3), the fatty acid oxidizing enzyme hydroxyacyl-CoA dehydrogenase (HADH), and the mitochondrial fatty acid transporter solute carrier 25 family member A20 (SLC25A20). The expression levels of these genes were confirmed using RT-qPCR. The results of the present study indicate an important role for a decreased transport and metabolism of fatty acids, which provides a link between physical activity levels and insulin signaling.

Increased Aerobic Fitness After Neuromuscular Electrical Stimulation Training in Adults With Spinal Cord Injury

Carty A, McCormack K, Coughlan GF, Crowe L, Caulfield B. Increased aerobic fitness after neuromuscular electrical stimulation training in adults with spinal cord injury. ObjectivesTo evaluate the efficacy of a novel neuromuscular electrical stimulation (NMES) system for improving aerobic fitness in individuals with spinal cord injury (SCI). It was hypothesized that training with this NMES system would increase peak oxygen consumption (Vo2peak) and peak heart rate (HRpeak) in a sedentary adult SCI population. DesignProspective cohort study. SettingAll testing took place at a university human performance laboratory. ParticipantsVolunteer participants with SCI (N=16; T4-11 American Spinal Injury Association Impairment Scale grades A and B) were recruited from the national SCI outpatient and outreach service databases. All completed the training program, but results from 2 participants were excluded because posttraining tests were invalid. Therefore, 14 participants (11 men, 3 women) completed the program and testing. InterventionsFour electrodes (175cm2) were placed bilaterally on the quadriceps and hamstrings muscle groups, and subtetanic contractions were elicited using an NMES device. Training was undertaken unsupervised at home for 1 hour, 5d/wk for 8 weeks. Main Outcome MeasuresAn incremental treadmill wheelchair propulsion exercise test with simultaneous cardiopulmonary gas exchange analysis was used to determine Vo2peak and HRpeak. ResultsA statistically significant increase in Vo2peak (P=.001) and HRpeak (P=.032) between baseline and follow-up was observed. ConclusionsThis novel form of NMES is an effective method of improving aerobic fitness in an SCI population. Results are comparable to those with current functional electrical stimulation exercise systems.