Visual feedback improves propulsive force generation during treadmill walking in people with Parkinson disease.

Persons with Parkinson's disease experience gait alterations, such as reduced step length. Gait dysfunction is a significant research priority as the current treatments targeting gait impairment are limited. This study aimed to investigate the effects of visual biofeedback on propulsive force during treadmill walking in persons with Parkinson's. Sixteen ambulatory persons with Parkinson's participated in the study. They received real-time biofeedback of anterior ground reaction force during treadmill walking at a constant speed. Peak propulsive force values were measured and normalized to body weight. Spatiotemporal parameters were also assessed, including stride length and double support percent. Persons with Parkinson's significantly increased peak propulsive force during biofeedback compared to baseline (p <.0001, Cohen's dz = 1.69). Variability in peak anterior ground reaction force decreased across repeated trials (p <.0001, dz = 1.51). While spatiotemporal parameters did not show significant changes individually, stride length and double support percent improved marginally during biofeedback trials. Persons with Parkinson's can increase propulsive force with visual biofeedback, suggesting the presence of a propulsive reserve. Though stride length did not significantly change, clinically meaningful improvements were observed. Targeting push-off force through visual biofeedback may offer a potential rehabilitation technique to enhance gait performance in Persons with Parkinson's. Future studies could explore the long-term efficacy of this intervention and investigate additional strategies to improve gait in Parkinson's disease.

Pelvic floor muscle contraction automatic evaluation algorithm for pelvic floor muscle training biofeedback using self-performed ultrasound.

INTRODUCTION: Non-invasive biofeedback of pelvic floor muscle training (PFMT) is required for continuous training in home care. Therefore, we considered self-performed ultrasound (US) in adult women with a handheld US device applied to the bladder. However, US images are difficult to read and require assistance when using US at home. In this study, we aimed to develop an algorithm for the automatic evaluation of pelvic floor muscle (PFM) contraction using self-performed bladder US videos to verify whether it is possible to automatically determine PFM contraction from US videos. METHODS: Women aged ≥ 20 years were recruited from the outpatient Urology and Gynecology departments of a general hospital or through snowball sampling. The researcher supported the participants in their self-performed bladder US and videos were obtained several times during PFMT. The US videos obtained were used to develop an automatic evaluation algorithm. Supervised machine learning was then performed using expert PFM contraction classifications as ground truth data. Time-series features were generated from the x- and y-coordinate values of the bladder area including the bladder base. The final model was evaluated for accuracy, area under the curve (AUC), recall, precision, and F1. The contribution of each feature variable to the classification ability of the model was estimated. RESULTS: The 1144 videos obtained from 56 participants were analyzed. We split the data into training and test sets with 7894 time series features. A light gradient boosting machine model (Light GBM) was selected, and the final model resulted in an accuracy of 0.73, AUC = 0.91, recall = 0.66, precision = 0.73, and F1 = 0.73. Movement of the y-coordinate of the bladder base was shown as the most important. CONCLUSION: This study showed that automated classification of PFM contraction from self-performed US videos is possible with high accuracy.

An open trial of biofeedback for long COVID.

OBJECTIVE: Biofeedback is a therapeutic treatment model that teaches self-regulation of autonomic functions to alleviate stress-related symptoms. "Long COVID" refers to chronic physical and cognitive sequelae post-SARS-CoV-2 infection. This study examined the efficacy of a six-week intervention, consisting of weekly one-hour sessions combining heart rate variability and temperature biofeedback, for alleviating mood symptoms, somatic symptoms and sleep disturbance of patients diagnosed with long COVID. METHODS: Data were collected from 20 adult participants aged 22-63 (Mage = 44.1, SDage = 12.2) with varying long COVID symptoms. Within this single arm design, 16 of the 20 participants completed all six sessions of biofeedback; 14 completed an assessment at the three-month post-treatment time point. RESULTS: Participants self-reported significant improvements in somatic, anxiety, and depressive symptoms, sleep quality, quality of life, and number of "bad days" immediately after the intervention and three months later (Cohen's d effect size (ES) = 1.09-0.46). Reduced number of medical doctor visits (ES = 0.85) and prescription drug use over the last month (odds ratio = 0.33), as well as improved emotional wellbeing (ES = 0.97) were observed at the three-month time point only. CONCLUSION: Results suggest that this short, readily scalable intervention can be potentially efficacious in alleviating symptoms of long COVID. Despite notable improvements, the major limitation of this study is its lack of control group. While a randomized trial merits study, biofeedback appears to be a brief, effective, non-invasive, and low-cost treatment option for patients with chronic somatic symptoms secondary to SARS-CoV-2 infection. CLINICALTRIALS: govID: NCT05120648.

Heart rate and breathing effects on attention and memory (HeartBEAM): study protocol for a randomized controlled trial in older adults.

BACKGROUND: In healthy people, the "fight-or-flight" sympathetic system is counterbalanced by the "rest-and-digest" parasympathetic system. As we grow older, the parasympathetic system declines as the sympathetic system becomes hyperactive. In our prior heart rate variability biofeedback and emotion regulation (HRV-ER) clinical trial, we found that increasing parasympathetic activity through daily practice of slow-paced breathing significantly decreased plasma amyloid-ß (Aß) in healthy younger and older adults. In healthy adults, higher plasma Aß is associated with greater risk of Alzheimer's disease (AD). Our primary goal of this trial is to reproduce and extend our initial findings regarding effects of slow-paced breathing on Aß. Our secondary objectives are to examine the effects of daily slow-paced breathing on brain structure and the rate of learning. METHODS: Adults aged 50-70 have been randomized to practice one of two breathing protocols twice daily for 9 weeks: (1) "slow-paced breathing condition" involving daily cognitive training followed by slow-paced breathing designed to maximize heart rate oscillations or (2) "random-paced breathing condition" involving daily cognitive training followed by random-paced breathing to avoid increasing heart rate oscillations. The primary outcomes are plasma Aß40 and Aß42 levels and plasma Aß42/40 ratio. The secondary outcomes are brain perivascular space volume, hippocampal volume, and learning rates measured by cognitive training performance. Other pre-registered outcomes include plasma pTau-181/tTau ratio and urine Aß42. Recruitment began in January 2023. Interventions are ongoing and will be completed by the end of 2023. DISCUSSION: Our HRV-ER trial was groundbreaking in demonstrating that a behavioral intervention can reduce plasma Aß levels relative to a randomized control group. We aim to reproduce these findings while testing effects on brain clearance pathways and cognition. TRIAL REGISTRATION: ClinicalTrials.gov NCT05602220. Registered on January 12, 2023.

Smoking cessation in pregnant women: A randomized controlled trial investigating the effectiveness of an eHealth intervention including heart rate variability-biofeedback training.

BACKGROUND: Prenatal smoking and stress are associated with adverse health effects for women themselves and are risk factors for adverse outcomes of the child. Effective interventions are needed to support women with smoking cessation and reducing stress. The aims were (1) to test the effectiveness of an 8-week eHealth intervention targeting stress reduction and smoking cessation; (2) to examine whether stress reduction mediated the intervention effect on smoking behavior; (3) to test motivation to quit as a moderator; and (4) to investigate a dose-response effect of program usage. METHODS: Pregnant women were included if they were >18 years of age, < 28 weeks pregnant at recruitment, and currently smoking. In total, 156 consenting participants were randomly assigned to the intervention or active control condition. Study outcomes on smoking (yes/no, frequency, and quantity) were collected via online questionnaires at pre-intervention (baseline; t0), post-intervention (8 weeks after t0; t1), and follow up at two weeks (t2) and three months (t3) after birth. RESULTS: Smoking and stress reduced over the 8-week period in both conditions. The intervention effect on smoking was not mediated by stress reduction. Motivation to quit was found to moderate the intervention effect (smoking frequency and quantity) and a dose-response effect was found for program usage in the intervention for the reduction on smoking frequency and quantity. CONCLUSION: Program usage and motivation to quit are important for smoking reduction in pregnant women. Further research is needed to examine how the intervention could be improved to increase treatment effectiveness.

Effects of stress management interventions on heart rate variability in adults with cardiovascular disease: a systematic review and meta-analysis.

Meta-analysis was used to investigate the potential benefits of stress management interventions (SMIs) on vagally-mediated heart rate variability (HRV) in adults with cardiovascular disease. Electronic bibliographic databases were searched through August 2022. Randomized controlled trials and quasi-experimental studies assessing effects of SMIs on HRV were included. Methodological quality was assessed with a standardized checklist. A pooled effect size was calculated for vagally-mediated HRV indices (standard deviation of normal-to-normal intervals, root mean square of the successive differences, and high frequency power) using random effects models. Fourteen studies (1202 participants, Mage: 59 ± 6.25 years; 25% ± 16% women; 61% ± 22% White) were included. Ten studies (11 effects) reported short-term HRV assessment; a small between-group difference emerged for vagally-mediated HRV (d+ = .27, 95% confidence interval [CI] 0.01-0.52, k = 11). Most interventions examined biofeedback; these studies yielded a small between-group difference on vagally-mediated HRV (d+ = 0.31, 95% CI 0.09-0.53, k = 7, Q [6] = 3.82, p = .70, I2 = 11%). This is the first systematic examination of the effect of SMIs on HRV in adults with CVD. Findings suggest a small effect of SMIs on vagally-mediated HRV, with biofeedback likely driving the effect. More research is required to fully understand whether this benefit on vagally-mediated HRV applies to other SMIs.

Acupuncture Versus Biofeedback for Treatment of Functional Anorectal Pain.

BACKGROUND/AIMS: Functional anorectal pain is one of several types of functional anorectal disorders. In this study, we compared the effectiveness of acupuncture (intervention) and biofeedback (control) as treatment for patients with functional anorectal pain. MATERIALS AND METHODS: This prospective, single-center, randomized, and comparative study examined 68 patients with functional anorectal pain who were recruited from June 2017 to January 2019 at the Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine. Patients were randomly assigned to receive acupuncture or biofeedback. Patients in the acupuncture group received acupuncture at Zhongliao (BL33), Xialiao (BL34), Ganshu (BL18), Shenshu (BL23), and Dachangshu (BL25). Patients in the biofeedback group received pelvic floor biofeedback therapy, consisting of Kegel pelvic floor muscle training and electrical stimulation. Patients in both groups received 20 treatments over 4 weeks. The primary outcome was pain score on a visual analog scale, and the secondary outcomes were results from the MOS 36-item short-form health survey (SF-36) quality of life questionnaire, the self-rating depression scale, and the self-rating anxiety scale. RESULTS: Visual analog scale pain scores significantly decreased in both of the groups with treatment (both P < .01). The final visual analog scale score was significantly lower in patients with pelvic floor dyssynergia who were treated with biofeedback (1.40 ± 0.97 vs. 5.30 ± 1.70) (P < .05). The 2 groups had similar decreases in self-rating depression scale and self-rating anxiety scale scores. Intriguingly, the acupuncture group had better mental health outcomes (P <.05). CONCLUSION: Both acupuncture and biofeedback therapy reduced the pain of patients with functional anorectal pain. Biofeedback provided more relief in patients with pelvic floor dyssynergia, and acupuncture provided greater improvements in mental health status.

Biobehavioral treatments of migraine.

Pharmacotherapies are the mainstays of migraine management, though it is not uncommon for them to be poorly tolerated, contraindicated, or only modestly effective. There is a clear need for nonpharmacologic migraine therapies, either employed alone or in combination with pharmacotherapies. Behavioral and psychosocial factors known to contribute to the onset, exacerbation, and persistence of primary headache disorders (e.g., stress, sleep, diet) serve as targets within a self-management model for migraine-a model that features headache pharmacotherapies, behavioral skills training, medication adherence facilitation, relevant lifestyle changes, and techniques to limit headache-related impairment. Behavioral self-management interventions for migraine with the strongest empirical validation (e.g., relaxation training, biofeedback training, cognitive-behavior therapies) presently are available in specialty headache treatment centers and routinely show promise for reducing headache pain frequency/severity and related impairment, reducing reliance on pharmacotherapies, enhancing personal control over headache activity, and reducing headache-related distress and symptoms. These approaches may be particularly well-suited among patients for whom pharmacotherapies are unwanted, poorly tolerated, or contraindicated. Though underutilized, clinical trials indicate that new and well-established behavioral therapies are similarly effective to migraine medications for migraine prevention among adults and can be successfully employed in various settings.

Pre-Implementation Analysis of the Usability and Acceptability of a Poststroke Complex Telehealth Biofeedback Intervention.

IMPORTANCE: Complex telehealth interventions can facilitate remote occupational therapy services and improve access for people living with chronic neurological conditions. Understanding the factors that influence the uptake of these technologies is important. OBJECTIVE: To explore the fit between electromyography (EMG) biofeedback and telerehabilitation for stroke survivors, optimize EMG biofeedback interventions, and, more broadly, support other efforts to develop complex telerehabilitation interventions. DESIGN: Pre-implementation mixed-methods analysis of usability and acceptability data collected during a pilot and feasibility study. SETTING: Community. PARTICIPANTS: Adult stroke survivors with hemiparesis (N = 11; M age = 54 yr). INTERVENTION: Game-based EMG biofeedback system for arm sensorimotor rehabilitation, delivered via telehealth. OUTCOMES AND MEASURES: Post-Study System Usability Questionnaire, an extended Unified Theory of Acceptance and Use of Technology model questionnaire, and semistructured interview. We coded the interview data using questionnaire constructs. RESULTS: Participants used an EMG biofeedback intervention at home. Quantitative measures show high levels of perceived usability and acceptability, supported by qualitative findings describing specific facilitators and barriers. CONCLUSIONS AND RELEVANCE: Pre-implementation studies can improve the design and relevance of complex telehealth interventions. One major conclusion from this study is the influence of therapy providers on acceptability and usability of complex telehealth interventions. Plain-Language Summary: This study contributes to an emerging body of literature that examines the use of complex telehealth interventions with survivors of neurological injury. The findings highlight the value and support the development and use of complex telehealth interventions, which have the potential to improve remote access to occupational therapy for clients living with chronic neurological conditions. Complex telehealth interventions can open doors for survivors of neurological injury who face barriers to accessing occupational therapy and would benefit from technology-enabled therapy at home.

Rhesus monkeys learn to control a directional-key inspired brain machine interface via bio-feedback.

Brain machine interfaces (BMI) connect brains directly to the outside world, bypassing natural neural systems and actuators. Neuronal-activity-to-motion transformation algorithms allow applications such as control of prosthetics or computer cursors. These algorithms lie within a spectrum between bio-mimetic control and bio-feedback control. The bio-mimetic approach relies on increasingly complex algorithms to decode neural activity by mimicking the natural neural system and actuator relationship while focusing on machine learning: the supervised fitting of decoder parameters. On the other hand, the bio-feedback approach uses simple algorithms and relies primarily on user learning, which may take some time, but can facilitate control of novel, non-biological appendages. An increasing amount of work has focused on the arguably more successful bio-mimetic approach. However, as chronic recordings have become more accessible and utilization of novel appendages such as computer cursors have become more universal, users can more easily spend time learning in a bio-feedback control paradigm. We believe a simple approach which leverages user learning and few assumptions will provide users with good control ability. To test the feasibility of this idea, we implemented a simple firing-rate-to-motion correspondence rule, assigned groups of neurons to virtual "directional keys" for control of a 2D cursor. Though not strictly required, to facilitate initial control, we selected neurons with similar preferred directions for each group. The groups of neurons were kept the same across multiple recording sessions to allow learning. Two Rhesus monkeys used this BMI to perform a center-out cursor movement task. After about a week of training, monkeys performed the task better and neuronal signal patterns changed on a group basis, indicating learning. While our experiments did not compare this bio-feedback BMI to bio-mimetic BMIs, the results demonstrate the feasibility of our control paradigm and paves the way for further research in multi-dimensional bio-feedback BMIs.

The Development of a Wearable Biofeedback System to Elicit Temporal Gait Asymmetry using Rhythmic Auditory Stimulation and an Assessment of Immediate Effects.

Temporal gait asymmetry (TGA) is commonly observed in individuals facing mobility challenges. Rhythmic auditory stimulation (RAS) can improve temporal gait parameters by promoting synchronization with external cues. While biofeedback for gait training, providing real-time feedback based on specific gait parameters measured, has been proven to successfully elicit changes in gait patterns, RAS-based biofeedback as a treatment for TGA has not been explored. In this study, a wearable RAS-based biofeedback gait training system was developed to measure temporal gait symmetry in real time and deliver RAS accordingly. Three different RAS-based biofeedback strategies were compared: open- and closed-loop RAS at constant and variable target levels. The main objective was to assess the ability of the system to induce TGA with able-bodied (AB) participants and evaluate and compare each strategy. With all three strategies, temporal symmetry was significantly altered compared to the baseline, with the closed-loop strategy yielding the most significant changes when comparing at different target levels. Speed and cadence remained largely unchanged during RAS-based biofeedback gait training. Setting the metronome to a target beyond the intended target may potentially bring the individual closer to their symmetry target. These findings hold promise for developing personalized and effective gait training interventions to address TGA in patient populations with mobility limitations using RAS.

Reduced center of mass acceleration during regular walking with electromyography biofeedback.

BACKGROUND: Regular walking in healthy adults is known to be kinematically stable, but it is unclear how to further kinematically stabilize regular walking. Electromyography biofeedback (EMG-BF) during walking improves walking ability in patients. However, the effect of EMG-BF on walking stability in healthy adults is unknown. Therefore, this study aimed to investigate whether EMG-BF enhances the stability of regular walking in healthy adults. RESEARCH QUESTION: Does the EMG-BF enhance the stability of regular walking in healthy adults? METHODS: Auditory biofeedback of single muscle activity was given to twelve participants during regular walking. The target muscles were the ankle plantar flexor, ankle dorsiflexor, and knee flexor. We compared the root mean square of the center of mass acceleration (RMS-CoMacc), which represents walking smoothness, between biofeedback conditions. RESULTS: We found that EMG-BF during regular walking partially reduced the RMS-CoMacc (p = 0.01). In particular, biofeedback of the ankle plantar flexor muscle reduced the RMS-CoMacc in both the anteroposterior and vertical directions. In the mediolateral RMS-CoMacc, no significant difference was found (p = 0.24). SIGNIFICANCE: Our study is novel because it is the first study to reveal the impact of EMG-BF on the stability of walking among healthy adults. It identifies the key muscles for EMG-BF, potentially leading to the development of a more effective EMG-BF system in the rehabilitation. Especially, biofeedback of the ankle plantar flexor muscle could improve walking stability in both the anteroposterior and vertical directions. The effect of EMG-BF for reducing the RMS-CoMacc during regular walking might depend on the target muscles of biofeedback.

Effectiveness of a Biofeedback Intervention Targeting Mental and Physical Health Among College Students Through Speech and Physiology as Biomarkers Using Machine Learning: A Randomized Controlled Trial.

Biofeedback therapy is mainly based on the analysis of physiological features to improve an individual's affective state. There are insufficient objective indicators to assess symptom improvement after biofeedback. In addition to psychological and physiological features, speech features can precisely convey information about emotions. The use of speech features can improve the objectivity of psychiatric assessments. Therefore, biofeedback based on subjective symptom scales, objective speech, and physiological features to evaluate efficacy provides a new approach for early screening and treatment of emotional problems in college students. A 4-week, randomized, controlled, parallel biofeedback therapy study was conducted with college students with symptoms of anxiety or depression. Speech samples, physiological samples, and clinical symptoms were collected at baseline and at the end of treatment, and the extracted speech features and physiological features were used for between-group comparisons and correlation analyses between the biofeedback and wait-list groups. Based on the speech features with differences between the biofeedback intervention and wait-list groups, an artificial neural network was used to predict the therapeutic effect and response after biofeedback therapy. Through biofeedback therapy, improvements in depression (p = 0.001), anxiety (p = 0.001), insomnia (p = 0.013), and stress (p = 0.004) severity were observed in college-going students (n = 52). The speech and physiological features in the biofeedback group also changed significantly compared to the waitlist group (n = 52) and were related to the change in symptoms. The energy parameters and Mel-Frequency Cepstral Coefficients (MFCC) of speech features can predict whether biofeedback intervention effectively improves anxiety and insomnia symptoms and treatment response. The accuracy of the classification model built using the artificial neural network (ANN) for treatment response and non-response was approximately 60%. The results of this study provide valuable information about biofeedback in improving the mental health of college-going students. The study identified speech features, such as the energy parameters, and MFCC as more accurate and objective indicators for tracking biofeedback therapy response and predicting efficacy. Trial Registration ClinicalTrials.gov ChiCTR2100045542.

Effects of ankle exoskeleton assistance and plantar pressure biofeedback on incline walking mechanics and muscle activity in cerebral palsy.

Ankle dysfunction affects more than 50 % of people with cerebral palsy, resulting in atypical gait patterns that impede lifelong mobility. Incline walking requires increased lower limb effort and is a promising intervention that targets lower-limb extensor muscles. A concern when prescribing incline walking to people with gait deficits is that this exercise may be too challenging or reinforce unfavorable gait patterns. This study aims to investigate how ankle exoskeleton assistance and plantar pressure biofeedback would affect gait mechanics and muscle activity during incline walking in CP. We recruited twelve children and young adults with CP. Participants walked with ankle assistance alone, biofeedback alone, and the combination while we assessed ankle, knee, and hip mechanics, and plantar flexor and knee extensor activity. Compared to incline walking without assistance or biofeedback, ankle assistance alone reduced the peak biological ankle moment by 12 % (p < 0.001) and peak soleus activity by 8 % (p = 0.013); biofeedback alone increased the biological ankle moment (4 %, p = 0.037) and power (19 %, p = 0.012), and plantar flexor activities by 9 - 27 % (p ≤ 0.026); assistance-plus-biofeedback increased biological ankle and knee power by 34 % and 17 %, respectively (p ≤ 0.05). The results indicate that both ankle exoskeleton assistance and plantar pressure biofeedback can effectively modify lower limb mechanics and muscular effort during incline walking in CP. These techniques may help in establishing personalized gait training interventions by providing the ability to adjust intensity and biomechanical focus over time.

Electromyographic biofeedback therapy for improving limb function after stroke: A systematic review and meta-analysis.

BACKGROUND: Upper and lower limb impairment is common after stroke. Electromyographic biofeedback therapy is a non-invasive treatment, and its effectiveness in functional rehabilitation of the limb after stroke still remains uncertain. OBJECTIVE: The objective of this study was to evaluate whether electromyographic biofeedback can improve upper and lower limb dysfunction in stroke patients. METHODS: PubMed, Embase, Cochrane Library, and Physiotherapy Evidence Database (PEDro) were searched from inception to 1st May 2022. Inclusion criteria were randomized controlled clinical trials of electromyographic biofeedback therapy interventions reporting changes in upper and lower limb function in post-stroke patients. Data were extracted by two independent reviewers and pooled in random-effects models using Review manager (RevMan) software. RESULTS: Our analyses included 10 studies enrolling a total of 303 participants. Electromyographic biofeedback therapy can effectively improve limb function after stroke (standardized mean difference [SMD], 0.44; 95% confidence interval [CI], 0.12-0.77; P = 0.008) and in subgroup analyses, the effect sizes of short-term effect (SMD, 0.33; 95% CI, 0.02-0.64; P = 0.04) was significant, but the long-term was not (SMD, 0.61; 95% CI, -0.11-1.33; P = 0.10). In addition, Electromyographic biofeedback therapy can improve the active range of motion of shoulder (SMD, 1.49; 95% CI, 2.22; P<0.0001) and wrist joints (SMD, 0.77; 95% CI, 0.13-1.42; P = 0.02) after stroke. CONCLUSION: In this meta-analysis, electromyographic biofeedback therapy intervention can improve upper and lower limb function in patients with stroke. Short-term (less than one month) improvement after electromyographic biofeedback therapy was supported, while evidence for long-term (more than one month) benefits was lacking. Range of motion in the glenohumeral and wrist joints were improved. Stronger evidence for individualized parameters, such as optimal treatment parameters and intervention period, is needed in the future. SYSTEMATIC REVIEW REGISTRATION: [https://www.crd.york.ac.uk/prospero/display_record.php?recordID=267596], identifier [CRD42022354363].

Nonlinear spatio-temporal filter to reduce crosstalk in bipolar electromyogram.

Objective.The wide detection volume of surface electromyogram (EMG) makes it prone to crosstalk, i.e. the signal from other muscles than the target one. Removing this perturbation from bipolar recordings is an important open problem for many applications.Approach.An innovative nonlinear spatio-temporal filter is developed to estimate the EMG generated by the target muscle by processing noisy signals from two bipolar channels, placed over the target and the crosstalk muscle, respectively. The filter is trained on some calibration data and then can be applied on new signals. Tests are provided in simulations (considering different thicknesses of the subcutaneous tissue, inter-electrode distances, locations of the EMG channels, force levels) and experiments (from pronator teres and flexor carpi radialis of 8 healthy subjects).Main results.The proposed filter allows to reduce the effect of crosstalk in all investigated conditions, with a statistically significant reduction of its root mean squared of about 20%, both in simulated and experimental data. Its performances are also superior to those of a blind source separation method applied to the same data.Significance.The proposed filter is simple to be applied and feasible in applications in which single bipolar channels are placed over the muscles of interest. It can be useful in many fields, such as in gait analysis, tests of myoelectric fatigue, rehabilitation with EMG biofeedback, clinical studies, prosthesis control.

Unique case study: Impact of single-session neuromuscular biofeedback on motor unit properties following 12 days of Achilles tendon surgical repair.

We explored the first evidence of a single-session neuromuscular biofeedback effect on motor unit properties, neuromuscular activation, and the Achilles tendon (AT) length 12 days after undergoing AT surgical repair. We hypothesized that immediate neuromuscular biofeedback enhances motor unit properties and activation without causing AT lengthening. After 12 days AT surgical repair, Medial Gastrocnemius (MG) motor unit decomposition was performed on a 58-year-old male before and after a neuromuscular biofeedback intervention (surface electromyography (sEMG) and ultrasonography), involving unressited plantar flexion. The analysis included motor unit population properties, sEMG amplitude, force paradigm, and AT length. There were increased MG motor unit recruitment, peak and average firing rate, coefficient of variation, and sEMG amplitude, and decreased recruitment and derecruitment threshold in the repaired AT limb. The non-injured limb increased the motor unit recruitment, and decreased the coefficient of variation, peak and average firing rate, inter-pulse interval, derecruitment threshold and sEMG amplitude. The AT length experienced -0.4 and 0.3 cm changes in the repaired AT and non-injured limb, respectively. This single-session neuromuscular biofeedback 12 days after AT surgery shows evidence of enhanced motor unit properties and activation without signs of AT lengthening when unresisted plantar flexion is performed in the repaired AT limb.

Difficult defecation in constipated patients: Diagnosis by minimally invasive diagnostic tests.

BACKGROUND AND AIMS: Defecation Disorders (DD) are a frequent cause of refractory chronic constipation. DD diagnosis requires anorectal physiology testing. Our aim was to evaluate the accuracy and Odds Ratio (OR) of a straining question (SQ) and a digital rectal examination (DRE) augmented by abdomen palpation on predicting a DD diagnosis in refractory CC patients. METHODS: Two hundred and thirty-eight constipated patients were enrolled. Patients underwent SQ, augmented DRE and balloon evacuation test before entering the study and after a 30-day fiber/laxative trial. All patients underwent anorectal manometry. OR and accuracy were calculated for SQ and augmented DRE for both dyssynergic defecation and inadequate propulsion. RESULTS: "Anal Muscles" response was associated to both dyssynergic defecation and inadequate propulsion, with an OR of 13.6 and 5.85 and an accuracy of 78.5% and 66.4%, respectively. "Failed anal relaxation" on augmented DRE was associated with dyssynergic defecation, with an OR of 21.4 and an accuracy of 73.1%. "Failed abdominal contraction" on augmented DRE was associated with inadequate propulsion with an OR >100 and an accuracy of 97.1%. CONCLUSIONS: Our data support screening constipated patients for DD by SQ and augmented DRE to improve management and appropriateness of referral to biofeedback.