Stimulation Of Lower Limb Muscles Research Articles

Prediction of leg muscle activities from arm muscle activities in arm and leg cycling.

Functional electrical stimulation (FES) driven leg cycling is usually controlled by previously established stimulation patterns. We investigated the potential utilization of a particular computational method for controlling electrical stimulation of lower limb muscles by real-time electromyography (EMG) signals of arm muscles during hybrid arm and leg cycling. In hybrid arm and leg cycling, arm cranking is performed voluntarily, while leg cycling is driven by FES. In this study, we investigate arm and leg cycling movements of able-bodied persons when both arm and leg cycling is performed voluntarily without FES. We present a neural network-based model in which the input of the neural network is given by a time series of upper limb muscle activities (EMG), and the output provides potential lower limb muscle activities. The particular neural network was a nonlinear autoregressive exogen (NARX) neural network. The measured EMG signals of the lower limb muscles were compared to the signals that were predicted by the neural network. The neural network was trained with data recorded from four participants. Our preliminary results show notable differences between the predicted and the experimentally measured lower limb muscle activities. The prediction was good only for 60% of the movement time. We conclude that-while including arm cycling in the movement-simpler control modalities or further consideration of applying machine-learning techniques has to be taken into account to improve voluntary upper limb-controlled FES assisted leg cycling.

Timing and Modulation of Activity in the Lower Limb Muscles During Indoor Rowing: What Are the Key Muscles to Target in FES-Rowing Protocols?

The transcutaneous stimulation of lower limb muscles during indoor rowing (FES Rowing) has led to a new sport and recreation and significantly increased health benefits in paraplegia. Stimulation is often delivered to quadriceps and hamstrings; this muscle selection seems based on intuition and not biomechanics and is likely suboptimal. Here, we sample surface EMGs from 20 elite rowers to assess which, when, and how muscles are activated during indoor rowing. From EMG amplitude we specifically quantified the onset of activation and silencing, the duration of activity and how similarly soleus, gastrocnemius medialis, tibialis anterior, rectus femoris, vastus lateralis and medialis, semitendinosus, and biceps femoris muscles were activated between limbs. Current results revealed that the eight muscles tested were recruited during rowing, at different instants and for different durations. Rectus and biceps femoris were respectively active for the longest and briefest periods. Tibialis anterior was the only muscle recruited within the recovery phase. No side differences in the timing of muscle activity were observed. Regression analysis further revealed similar, bilateral modulation of activity. The relevance of these results in determining which muscles to target during FES Rowing is discussed. Here, we suggest a new strategy based on the stimulation of vasti and soleus during drive and of tibialis anterior during recovery.

Design and Test of a Biomechanical Model for the Estimation of Knee Joint Angle During Indoor Rowing: Implications for FES-Rowing Protocols in Paraplegia.

Functional electrical stimulation of lower limb muscles during rowing provides a means for the cardiovascular conditioning in paraplegia. The possibility of shaping stimulation profiles according to changes in knee angle, so far conceived as changes in seat position, may help circumventing open issues associated with muscle fatigue and movement coordination. Here, we present a subject-specific biomechanical model for the estimation of knee joint angle during indoor rowing. Anthropometric measurements and foot and seat positions are inputs to the model. We tested our model on two samples of elite rowers; 15 able-bodied, and 11 participants in the Rio 2016 Paralympic games. Paralympic rowers presented minor physical disabilities (LTA-PD classification), enabling them to perform the full rowing cycle (with legs, trunks, and arms). Knee angle was estimated from the rowing machine seat position, measured with a linear encoder, and transmitted wirelessly to a computer. Key results indicate the root mean square error (RMSE) between estimated and measured angles did not depend on group and stroke rate ( ). Significantly greater RMSE values were observed, however, within the rowing cycle ( ), reaching on average 8 deg in the mid-recovery phase. Differences between estimated and measured knee angle values resulted in slightly earlier (5%) detection of knee flexion, regardless of the group and stroke rate considered. Offset of knee extension, knee angle at catch and range of knee motion were identified equally well with our model and with inertial sensors. These results suggest our model describes accurately the movement of knee joint during indoor rowing.

Effect of functional electrical stimulation on cardiovascular outcomes in patients with chronic heart failure.

Background/design Functional electrical stimulation of lower limb muscles is an alternative method of training in patients with chronic heart failure (CHF). Although it improves exercise capacity in CHF, we performed a randomised, placebo-controlled study to investigate its effects on long-term clinical outcomes. Methods We randomly assigned 120 patients, aged 71 ± 8 years, with stable CHF (New York Heart Association (NYHA) class II/III (63%/37%), mean left ventricular ejection fraction 28 ± 5%), to either a 6-week functional electrical stimulation training programme or placebo. Patients were followed for up to 19 months for death and/or hospitalisation due to CHF decompensation. Results At baseline, there were no significant differences in demographic parameters, CHF severity and medications between groups. During a median follow-up of 383 days, 14 patients died (11 cardiac, three non-cardiac deaths), while 40 patients were hospitalised for CHF decompensation. Mortality did not differ between groups (log rank test P = 0.680), while the heart failure-related hospitalisation rate was significantly lower in the functional electrical stimulation group (hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.21-0.78, P = 0.007). The latter difference remained significant after adjustment for prognostic factors: age, gender, baseline NYHA class and left ventricular ejection fraction (HR 0.22, 95% CI 0.10-0.46, P < 0.001). Compared to placebo, functional electrical stimulation training was associated with a lower occurrence of the composite endpoint (death or heart failure-related hospitalisation) after adjustment for the above-mentioned prognostic factors (HR 0.21, 95% CI 0.103-0.435, P < 0.001). However, that effect was mostly driven by the favourable change in hospitalisation rates. Conclusions In CHF patients, 6 weeks functional electrical stimulation training reduced the risk of heart failure-related hospitalisations, without affecting the mortality rate. The beneficial long-term effects of this alternative method of training require further investigation.

Effects of transcutaneous electrical stimulation of lower limb muscles on experimental fatty liver

Background and aimsAlthough the beneficial effects of exercise on fatty liver have been described, a previous study conducted at our department showed that transcutaneous electrical muscle stimulation (TEMS) of lower abdominal muscles aggravated fatty liver. The present study aims to evaluate the ability of TEMS of the lower limb muscles to improve fatty liver infiltration. Material and methodsThirty male Wistar rats were randomly allocated into three groups: control; fructose-fed (F), fed fructose-enriched diet for 6weeks; and fructose-fed with transcutaneous electrical muscle stimulation (F+TEMS), fed fructose-enriched diet for 6weeks and lower limb muscles subjected to TEMS during the last 3weeks of feeding, five sessions/week. Body weight, length, body mass index (BMI), and abdominal and lower limb circumferences were all recorded. Fasting blood glucose, serum insulin, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, serum albumin, high density lipoprotein cholesterol (HDL-C), triglyceride (TG), and total cholesterol (TC) levels were measured. LDL cholesterol (LDL-C) and the atherogenic index (AI) were calculated. Absolute and relative hepatic weights as well as histological examination of the liver were assessed. ResultsFinal body weight, abdominal and lower limb circumferences, absolute liver weight, homoeostasis model assessment (HOMA) score, and TG, LDL-C, AI, serum ALT, and AST levels were all significantly reduced in the (F+TEMS) group compared to the (F) group. There was a significant increase in GPx and HDL-C levels, HDL/LDL ratio, and total protein and serum albumin content in (F+TEMS) rats compared to (F) rats. Histologically, hepatic tissue from (F+TEMS) rats had minimal steatotic changes that were restricted to zone 1 and less marked inflammatory cell infiltration compared to (F) rats. ConclusionTEMS was able to reverse steatosis, hyperglycaemia, insulin resistance, dyslipidaemia, and fatty liver caused by fructose feeding. The study confirmed that the variation in the anatomical site of skeletal muscle contraction affects fatty liver in different ways.

Functional electrical stimulation of lower limb muscles as an alternative mode of exercise training in chronic heart failure: practical considerations and proposed algorithm.

Functional electrical stimulation of lower limb muscles as an alternative mode of exercise training in chronic heart failure: practical considerations and proposed algorithm.

Efficacy and safety of functional electrical stimulation of lower limb muscles in elderly patients with chronic heart failure: A pilot study

Exercise training is an established modality in chronic heart failure. Functional electrical stimulation (FES) is an effective alternative mode of training in patients unwilling or unable to exercise; however, it has not been investigated in elderly patients. We sought to investigate the effects of FES on functional status, quality of life, emotional status and endothelial function in chronic heart failure patients aged 70 years or higher. Thirty patients with stable systolic chronic heart failure (mean age 75 ± 3 years, New York Heart Association (NYHA) class II/III, 37%/63%) randomly underwent a six-week FES training programme or placebo. Questionnaires addressing quality of life (Kansas City Cardiomyopathy Questionnaire (KCCQ), functional and overall) and emotional stress (Zung self-rating depression scale (SDS), Beck Depression Inventory (BDI)), as well as endothelial function (flow-mediated dilatation) were assessed at baseline and upon protocol completion. A significant improvement in NYHA class (p=0.005), KCCQ-functional (F=68.6, p for interaction<0.001), KCCQ-overall (F=66.9, p<0.001), BDI (F=66.3, p<0.001) and Zung SDS (F=95.1, p<0.001) was observed in the FES group compared to placebo. Patients in the FES group also had a significant increase in flow-mediated dilatation compared with placebo (F=59.1, p<0.01). FES-induced per cent change in flow-mediated dilatation was significantly correlated with respective per cent change in KCCQ functional (r=0.386, p=0.039). In this pilot study, FES effectively improved functional status, quality of life, motional stress and endothelial function in elderly chronic heart failure patients and warrants further investigation in this particular group of patients.

Significance of Body Sway Velocity-Power-Spectrum Analysis in Postural Equilibrium Dysfunction

The method and objective of the analysis of equilibrium dysfunction based on the indices of gravitudinal fluctuations as well as the expression of the body sway in mathematical values have contributed in the diagnosis of the location of disturbance and the classification of diseases.The power spectrum analysis of deviation is one of the analytical methods which have gained much popularity in practice in recent years.We have recently conducted a power spectrum analysis of body sway velocity. It was not possible to analyze the directional component of a body sway by this method, but observation of sways in terms of velocity was possible. Formerly, it was difficult to analyse the high frequency of the body sway in terms of the power spectrum : however, by converting the body sway into the velocity power spectrum, the analysis of the high frequency body sway could be easily be performed.We used this method for the analysis of 19 cases of spinocerebellar degeneration, seven cases of Parkinson's disease, 22 cases of hemiplegia, and eight cases of Meniere's disease.For basic data, tetanic stimulation of lower limb muscles was given by connecting plate electrodes to the tibial nerves bilaterally below the knees to induce body movements.In this experiment, a peak was observed which coincided with the loaded frequency in the sway velocity power spectrum. It was discovered also in this experiment that the velocity component of body sway in the normal person was a noise which was inversely proportional to the Feurier's frequency, which is said to be Schottky effect (by Johnson 1925, 1/f noise).When various neurological diseases was analysed using this method, a distinct finding was observed at higher frequencies, i.e. a deviation in the slope of the spectrum from that of the 1/f noise.How a method like this can be utilized for the analysis of body movements was discussed.