Root Mean Square Of Signal Research Articles

Paraspinal Muscle Stiffness during Hamstring Exercise Using Shear-Wave Elastography.

Soccer teams integrate specific exercises into their typical workout programs for injury prevention. This study examined the effects of hamstring exercise on paraspinal and hamstring stiffness. These findings can inform training and rehabilitation programs to improve muscle health and prevent injuries. Fifteen young, healthy males performed passive and active (submaximal) knee flexion efforts from 0°, 45°, to 90° angle of knee flexion from the prone position. Using shear-wave elastography (SWE) and surface electromyography, we measured the elastic modulus and root mean square (RMS) signal of the erector spinae (ES), multifidus (MF), semitendinosus (ST), and semimembranosus (SM) during different knee flexion angles. Passive SWE modulus at 0° was 12.44 ± 4.45 kPa (ES), 13.35 ± 6.12 kPa (MF), 22.01 ± 4.68 kPa (ST), and 21.57 ± 5.22 kPa (SM) and it was greater (p < 0.05) compared to 45° and 90°. The corresponding values during knee flexion contractions at 0° increased to 18.99 ± 6.11 kPa (ES), 20.65 ± 11.31 kPa (MF), 71.21 ± 13.88 kPa (ST), and 70.20 ± 14.29 kPa (SM) and did not differ between angles (p > 0.05). Compared to rest, the relative increase in the SWE modulus during active contraction had a median value (interquartile range) ranging from 68.11 (86.29) to 101.69 (54.33)% for the paraspinal muscles and it was moderately to strongly correlated (r > 0.672) with the corresponding increase of the hamstring muscles [ranging from 225.94 (114.72) to 463.16 (185.16)%]. The RMS signal was greater during active compared to passive conditions, and it was lower at 90° compared to 45° (for SM/ST) and 0° (for all muscles). The association between paraspinal and hamstring passive muscle stiffness indicates a potential transmission of forces through myofascial connections between the lumbar spine and the lower limbs. In this laboratory setting, hamstring exercises affected the stiffness of the paraspinal muscles.

A Novel Noise Reduction Approach of Acoustic Emission (AE) Signals in the SiC Lapping Process on Fixed Abrasive Pads.

Acoustic emission (AE) technology has been widely utilized to monitor the SiC wafer lapping process. The root-mean-square (RMS) of the time-domain eigenvalues of the AE signal has a linear relationship with the material removal rate (MRR). However, the existence of background noise severely reduces signal monitoring accuracy. Noise interference often leads to increased RMS deviation and signal distortion. In the study presented in this manuscript, a frequency threshold noise reduction approach was developed by combining and improving wavelet packet noise reduction and spectral subtraction noise reduction techniques. Three groups of SiC lapping experiments were conducted on a fixed abrasive pad, and the lapping acoustic signals were processed using three different noise reduction approaches: frequency threshold, wavelet packet, and spectral subtraction. The results show that the noise reduction method using the frequency threshold is the most effective, with the best coefficient of determination (R2) for the linear fit of the RMS to the MRR.

Arm muscle synergies enhance hand posture prediction in combination with forearm muscle synergies

Objective. We analyze and interpret arm and forearm muscle activity in relation with the kinematics of hand pre-shaping during reaching and grasping from the perspective of human synergistic motor control. Approach. Ten subjects performed six tasks involving reaching, grasping and object manipulation. We recorded electromyographic (EMG) signals from arm and forearm muscles with a mix of bipolar electrodes and high-density grids of electrodes. Motion capture was concurrently recorded to estimate hand kinematics. Muscle synergies were extracted separately for arm and forearm muscles, and postural synergies were extracted from hand joint angles. We assessed whether activation coefficients of postural synergies positively correlate with and can be regressed from activation coefficients of muscle synergies. Each type of synergies was clustered across subjects. Main results. We found consistency of the identified synergies across subjects, and we functionally evaluated synergy clusters computed across subjects to identify synergies representative of all subjects. We found a positive correlation between pairs of activation coefficients of muscle and postural synergies with important functional implications. We demonstrated a significant positive contribution in the combination between arm and forearm muscle synergies in estimating hand postural synergies with respect to estimation based on muscle synergies of only one body segment, either arm or forearm (p < 0.01). We found that dimensionality reduction of multi-muscle EMG root mean square (RMS) signals did not significantly affect hand posture estimation, as demonstrated by comparable results with regression of hand angles from EMG RMS signals. Significance. We demonstrated that hand posture prediction improves by combining activity of arm and forearm muscles and we evaluate, for the first time, correlation and regression between activation coefficients of arm muscle and hand postural synergies. Our findings can be beneficial for myoelectric control of hand prosthesis and upper-limb exoskeletons, and for biomarker evaluation during neurorehabilitation.

Effects of Error Modulation-Based Visual and Haptic Feedback Fusion Strategies on Motor Learning and Motivation

Visual or haptic feedback based on error modulation has been used to improve the effect of robot-assisted rehabilitation training. However, there are several investigations on the effects of error modulation-based visual and haptic feedback fusion strategies on motor learning and motivation. To observe the influence of different feedback fusion strategies on motor learning and motivation, a parallel controlled study was conducted, dividing 30 healthy subjects into three groups with similar skill levels. The no error modulation group received visual and haptic feedback without error modulation; the visual amplification haptic reduction group received visual error amplification combined with haptic error reduction, and the visual reduction haptic amplification (VRHA) group received visual error reduction combined with haptic error amplification. Each subject implemented a trajectory-tracking task with an upper limb rehabilitation robot. They went through baseline, training, assessment, and generalization tests and completed 340 consecutive tracking movements. To evaluate motor learning and motivation, the average tracking error, the root mean square (RMS) of surface electromyography (sEMG) signals, and the intrinsic motivation inventory scale were all examined. In the assessment tests, the average tracking error was significantly decreased in all three groups. In particular, the VRHA group had a larger reduction in average tracking error in the generalization test, lower RMS of sEMG signals both in the assessment and generalization tests and higher perceived competence in the assessment tests. The VRHA fusion strategy significantly improved the subjects’ motor learning and transfer ability, decreased muscle activation, and increased motor learning motivation. These findings may provide some new insights for multisensory feedback fusion technology in the application of rehabilitation robots.

Non-Destructive Damage Detection of Structural Joint by Coaxial Correlation Method in 6D Space

Failure of joints can lead to structural collapse. It is vital to monitor joint stiffness during operation to prevent such failures. This paper proposes a novel method for the quality assessment of structural joints using coaxial correlation in 6D space. Coaxially placed 6D sensors on either side of the joint implemented by 3D accelerometers and 3D gyroscopes with wide frequency range, automatic synchronisation between the input signal and receivers and response signal averaging are presented. The root mean square (RMS) value from the obtained signals convolution is proposed as a measure of the similarity between two signals for monitoring joint degradation. The method’s effectiveness was tested on steel beam splice connection, where it was found that the RMS of convolution signals in 6D space showed a direct correlation between the calculated RMS value in X, Y, GX, and GY axes directions and the stiffness grades of the joint. The paper concludes that the nature of the RMS during the degradation of the joint may change in different axes, and wrongly chosen axes may lead to wrong conclusions regarding the state of the investigated joint, especially in the case of complex joints, so that the measurements in 6D provide higher reliability of the result interpretation.

Mechanocardiography-Based Measurement System Indicating Changes in Heart Failure Patients during Hospital Admission and Discharge.

Heart failure (HF) is a disease related to impaired performance of the heart and is a significant cause of mortality and treatment costs in the world. During its progression, HF causes worsening (decompensation) periods which generally require hospital care. In order to reduce the suffering of the patients and the treatment cost, avoiding unnecessary hospital visits is essential, as hospitalization can be prevented by medication. We have developed a data-collection device that includes a high-quality 3-axis accelerometer and 3-axis gyroscope and a single-lead ECG. This allows gathering ECG synchronized data utilizing seismo- and gyrocardiography (SCG, GCG, jointly mechanocardiography, MCG) and comparing the signals of HF patients in acute decompensation state (hospital admission) and compensated condition (hospital discharge). In the MECHANO-HF study, we gathered data from 20 patients, who each had admission and discharge measurements. In order to avoid overfitting, we used only features developed beforehand and selected features that were not outliers. As a result, we found three important signs indicating the worsening of the disease: an increase in signal RMS (root-mean-square) strength (across SCG and GCG), an increase in the strength of the third heart sound (S3), and a decrease in signal stability around the first heart sound (S1). The best individual feature (S3) alone was able to separate the recordings, giving 85.0% accuracy and 90.9% accuracy regarding all signals and signals with sinus rhythm only, respectively. These observations pave the way to implement solutions for patient self-screening of the HF using serial measurements.

Monitoring the fluidized bed reactor for polyethylene polymerization based on fibre optic acoustic emission sensor

AbstractThis paper presents applications of a new class of fibre optic acoustic emission (FOAE) sensor to monitor the operation of fluidized bed reactors used in polyethylene production. Specifically, the sensor was implemented to detect undesired, abnormal phenomena related to particle agglomeration, wall sheeting, fine overflow, and variations in the superficial gas velocity. The experiments were executed using a fluidized bed cold model setup for polyethylene powders with average particle sizes of 250, 1000, and 2000 μm. The results demonstrated that the presence of agglomerated particles in the fluidized bed reactor increases the kurtosis of the acoustic emission (AE) signal. Furthermore, the overflow of small particles can be detected by mounting the FOAE sensor below the gas distributor plate and monitoring an increase in the root mean square (RMS) of the AE signal. The AE signal RMS increased with the rising superficial gas velocity. Besides, forming a sheet layer on the reactor wall decreased the AE signal RMS. The proposed sensor's main benefits are its simple design, rapid response to abnormal conditions in the fluidized bed reactor, immunity against electromagnetic noise, high‐temperature resistance, and safety in hazardous areas.

Postmortem Electrical Conductivity Changes of Dicentrarchus labrax Skeletal Muscle: Root Mean Square (RMS) Parameter in Estimating Time since Death.

Simple SummaryThe estimation of postmortem interval (PMI) still poses a major challenge for pathologists worldwide, making the search for new and more accurate technologies to assist in PMI estimation worthy of growing scientific interest. This study aimed to explore for the first time the use of an oscilloscope coupled with a signal generator, as innovative technology, to evaluate changes in the electrical conductivity of skeletal muscle of sea bass specimens during the early postmortem interval, to find an accurate, quantitative parameter useful in PMI estimation. The use of the oscilloscope, especially for the RMS measured parameter, has been shown here as a promising technology for studying dielectric muscle properties during the early postmortem interval, with the advantage of being a rapid, non-destructive, and inexpensive method.Electric impedance spectroscopy techniques have been widely employed to study basic biological processes, and recently explored to estimate postmortem interval (PMI). However, the most-relevant parameter to approximate PMI has not been recognized so far. This study investigated electrical conductivity changes in muscle of 18 sea bass specimens, maintained at different room temperatures (15.0 °C; 20.0 °C; 25.0 °C), during a 24 h postmortem period using an oscilloscope coupled with a signal generator, as innovative technology. The root mean square (RMS) was selected among all measured parameters, and recorded every 15 min for 24 h after death. The RMS(t) time series for each animal were collected and statistically analyzed using MATLAB®. A similar trend in RMS values was observed in all animals over the 24 h study period. After a short period, during which the RMS signal decreased, an increasing trend of the signal was recorded for all fish until it reached a peak. Subsequently, the RMS value gradually decreased over time. A strong linear correlation was observed among the time series, confirming that the above time-behaviour holds for all animals. The time at which maximum value is reached strongly depended on the room temperature during the experiments, ranging from 6 h in fish kept at 25.0 °C to 14 h in animals kept at 15.0 °C. The use of the oscilloscope has proven to be a promising technology in the study of electrical muscle properties during the early postmortem interval, with the advantage of being a fast, non-destructive, and inexpensive method, although more studies will be needed to validate this technology before moving to real-time field investigations.

SVM-Based Bearing Anomaly Identification with Self-Tuning Network-Fuzzy Robust Proportional Multi Integral and Smart Autoregressive Model

In this paper, the combination of an indirect self-tuning observer, smart signal modeling, and machine learning-based classification is proposed for rolling element bearing (REB) anomaly identification. The proposed scheme has three main stages. In the first stage, the original signal is resampled, and the root mean square (RMS) signal is extracted from it. In the second stage, the normal resampled RMS signal is approximated using the AutoRegressive with eXternal Uncertainty (ARXU) technique. Moreover, the nonlinearity of the bearing signal is solved using the combination of the ARXU and the machine learning-based regression, which is called AMRXU. After signal modeling by AMRXU, the RMS resampled signal is estimated using a combination of the proportional multi-integral (PMI) technique, the variable structure (VS) Lyapunov technique, and a self-tuning network-fuzzy system (SNFS). Finally, in the third stage, the difference between the original signal and the estimated one is calculated to generate the residual signal. A machine learning-based classification technique is utilized to classify the residual signal. The Case Western Reserve University (CWRU) dataset is used to evaluate anomaly identification performance of the proposed scheme. Regarding the experimental results, the average accuracy for REB crack identification is 98.65%, 97.7%, 97.35%, and 97.67%, respectively, when the motor torque loads are 0-hp, 1-hp, 2-hp, and 3-hp.

ELECTROMYOGRAPIC ACTIVITY OF THE ABDOMINAL AND PARAVERTEBRAL MUSCLES DURING COFFEE HARVESTING

ABSTRACT Introduction The rural worker involved in the coffee harvest is an important person for the economy of the many countries. However, scientific studies on the health of this worker are rare. Objective To analyze the lumbar paravertebral musculature and abdominal rectus of rural workers during coffee harvesting with the manual machines with different footrest bases (inclined, declined and horizontal), by means of electromyography. Methods Eight male rural workers from the region of Muzambinho participated in the study. All procedures and electromyographic routines were applied according to the SENIAN protocol. The workers made the usual coffee harvesting movements, using the manual machine for one minute. The data are expressed as means and standard deviations. The RMS (root mean square) signal and the median frequency (FM) were also analyzed. Results It was observed that the type of footrest base did not influence the electromyographic activity RMS or the FM, but we found that the paravertebral muscles have greater electromyographic activation when compared to the abdominal muscles, regardless of the type of footrest base. Conclusion For the task performed, the paravertebral muscles present greater electromyographic activation compared to the abdominal rectus. Level of Evidence III; Diagnostic studies - Investigating a diagnostic test.

A new monitoring method for metal rust removal states in pulsed laser derusting via acoustic emission techniques

Considering that the direct visualization and real-time control of the laser derusting is challenging mainly in virtue of traditional microscopic procedures, it is very difficult for operators to judge the complicated derusting conditions accurately. Acoustic emission (AE) monitoring could be a promising technique to assess the termination of rust removal process, avoid thermal damage of carbon steel substrate efficiently. The AE monitoring and high-speed camera were successfully integrated for reliable investigation of laser derusting mechanism. Dynamic removal characteristics and microscopic changes of rust layer observed and analyzed using AE signals and high-speed images are utilized for further improvement of the mechanism of rust removal by pulsed laser. Based on the spectrum analysis of Fast Fourier Transform (FFT), three characteristic frequency contents including 15˜35 kHz, 65˜85 kHz and 140˜160 kHz of the filtered root mean square (RMS) signals closely associated to laser source impacting on steel substrate or rust layer were determined respectively, which provides the observable AE features relating to the thermal damage of substrate surface. Direct correction between RMS signals and specific laser derusting parameters was established to realize the monitoring of the process of complete rust removal using two representative laser fluences. The FFT was carried out during the same period within 0.3 s in order to validate any changes in the frequency content of 15˜35 kHz relating to the rust removal effect.

Effect of suspension exercise training on motor and balance functions in children with spastic cerebral palsy

To study the effect of suspension exercise training on motor and balance functions in children with spastic cerebral palsy. A total of 97 children with spastic cerebral palsy were randomly divided into an observation group with 49 children and a control group with 48 children. Both groups were given routine rehabilitation training, and the children in the observation group were given suspension exercise training in addition. The scores of the D and E domains of the 88-item version of the Gross Motor Function Measure (GMFM-88) and Berg Balance Scale (BBS) were recorded before treatment and at 1, 3, and 6 months after treatment. Surface electromyography was performed to observe the changes in the root mean square (RMS) of surface electromyogram signals of the adductor muscle and the gastrocnemius muscle. Over the time of treatment, both groups had varying degrees of improvement in the scores of the D and E domains of GMFM-88 and BBS. Compared with the control group, the observation group had significantly greater improvements in D and E functional areas and balance function (P<0.05). Both groups had reductions in the RMS of the surface electromyogram signals of the adductor muscle and the gastrocnemius muscle over the time of treatment, and the observation group had significantly greater reductions than the control group (P<0.05). Suspension exercise training can effectively improve the motor and balance functions of children with spastic cerebral palsy.

Hemiplegia affects the biomechanics of reaching with the unaffected upper limb

Objective To analyze the bio-mechanics when hemiplegics reach with the unaffected upper limb. Methods Thirty post-stroke hemiplegics were selected into the patient group, while 23 healthy counterparts were chosen for the control group. Both groups completed a reaching test of their upper limbs which divided reaching into a moving stage and a holding stage. Surface electromyography (sEMG) data were recorded during the tests along with the degree of torso twist, the range of motion of the shoulder, movement velocity, smoothness of movement and angle divergence collected using a wearable micro-sensor motion capture system. Results For the stroke patients whose dominant upper limb was unaffected, the average root mean square (RMS) signal from the upper trapezius (34.3 μV) and the average torso twist (-1.4°) in the moving phase were significantly larger than among the control subjects (19.7 μV and -2.3°), but their average movement velocity was significantly slower. In the holding phase the average RMS signal from the upper trapezius (55.4 μV) was still significantly higher than in the control group, but their average pectoralis major signal and the integrated EMG ratio of the anterior segments of the deltoid and upper trapezius muscle pairs were significantly lower. For the stroke patients whose dominant upper limbs were affected, in the moving phase their average signal from the middle segments of the deltoid were significantly greater than those of the controls, but their movement velocity was significantly slower. For the control subjects, in the moving phase the average signal from the upper trapezius on their non-dominant side was significantly higher than that from the dominant upper limb. The integrated EMG ratio from the anterior segments of the deltoid and upper trapezius muscle pairs on that side was smaller throughout the whole reaching movement. Conclusion The bio-mechanical characteristics in reaching of the unaffected upper limbs of stroke patients are not the same as those of the corresponding upper limbs of healthy subjects. It is more reasonable to select the corresponding upper limbs of healthy subjects as controls when a bio-mechanical study of the affected upper limbs is conducted. Key words: Stroke; Reaching; Kinematics; Electromyography

Feasibility study of monitoring the steel quenching process using acoustic emission technology

This paper presents a non-destructive method of monitoring and evaluating the steel immersion quenching process using AE (acoustic emission) technology. The immersion quenching process is used in the heat treatment industry in order to harden metals and to achieve the required mechanical properties. During quenching, several stages of heat transfer occur, each stage with its own thermo-fluid dynamic phenomena and an AE signature. In order to ensure high quality of quenched workpieces and repeatability of the production process, a method of quality control is required. Several cylindrical steel specimens are quenched in water or in aqueous polymer solutions with 10% or 20% concentration. AE signature of the quenching process is recorded using a piezoelectric hydrophone. AE signal characteristics are considered in correlation with video recordings. After quenching, mechanical properties of specimens such as hardness and tensile strength are determined. A correlation between AE signal characteristics and mechanical properties is established. Results show a non-linear correlation between AE signal peak amplitude, signal RMS (root mean square) value and mechanical properties, and a nearly linear correlation between AE signal duration or number of signal packets and mechanical properties. The total elastic energy correlation is omitted due to high sample standard deviations. Based on the results, it is concluded that AE is a reasonable way of monitoring the steel quenching process and mechanical properties of quenched workpieces.

Acute effects of direct inhibitory pressure over the biceps brachii myotendinous junction on skeletal muscle activation and force output

Force (F) reduction is reported with myotendinous junction (MTJ) manipulation. Autogenic inhibition reflex (AIR) activation is supposed to be the main mechanism. Still, its role remains unclear. The study aimed at assessing the effects of MTJ direct inhibitory pressure (DIP) on neuromuscular activation and F in the elbow flexor (agonist) and extensor (antagonist) muscles. After maximum voluntary contraction (MVC) assessment, thirty-five participants randomly performed submaximal contractions at 20, 40, 60, and 80% MVC. Electromyographic (EMG), mechanomyographic (MMG), and F signals were recorded. Protocol was repeated under (i) DIP (10-s pressure on the biceps brachii MTJ) with the elbow at 120° (DIP120), (ii) DIP with the elbow at 180° (DIP180), and (iii) without DIP (Ctrl). Electromechanical delay (EMD) components, EMG and MMG root mean square (RMS), and rate of force development (RFD) were calculated. Independently from the angle, DIP induced decrements in MVC, RFD, and RMS of EMG and MMG signals and lengthened the EMD components in agonist muscles (P<0.05). The DIP-induced decrease in F output of the agonist muscles seems to be possibly due to a concomitant impairment of the neuromuscular activation and a transient decrease in stiffness. After DIP, the antagonist muscle displayed no changes; therefore, the intervention of AIR remains questionable.

A new EMG-based index towards the assessment of elbow spasticity for post-stroke patients.

The commonly used method for grading spasticity in clinical applications is Modified Ashworth Scale (MAS). The MAS-based method depends on the subjective evaluations and the experience of physicians, which may lead to imprecise and inconsistent evaluations. In this study, we propose a novel index (A-ApA, which was calculated with the root mean square (RMS) of agonist muscle activity by the mean between the RMS of agonistic and antagonistic muscle activations extracted from surface electromyography (sEMG) signals to quantitatively assess elbow spasticity. 39 post-stroke patients with elbow spasticity caused by hemiplegia participated in the experiments, and their elbow spasticity was assessed with MAS by one experienced physiotherapist. Patients were thereafter divided into four groups according to the MAS scales. The sEMG signals were recorded simultaneously on the patients' biceps and triceps when they extended or bended their elbows passively. The correlations between MAS and RMS of sEMG signals as well as the newly proposed index were calculated. The results demonstrated that the correlation between the MAS and the sEMG-based index in the assessment of elbow spasticity was significant. This suggests that the EMG-based index would be helpful for the assessment of spasticity..

Experimental investigation into vibro-acoustic emission signal processing techniques to quantify leak flow rate in plastic water distribution pipes

Leakage from water distribution pipes is a problem worldwide, and are commonly detected using the Vibro-Acoustic Emission (VAE) produced by the leak. The ability to quantify leak flow rate using VAE would have economic and operational benefits. However the complex interaction between variables and the leak’s VAE signal make classification of leak flow rate difficult and therefore there has been a lack of research in this area. The aim of this study is to use VAE monitoring to investigate signal processing techniques that quantify leak flow rate. A number of alternative signal processing techniques are deployed and evaluated, including VAE counts, signal Root Mean Square (RMS), peak in magnitude of the power spectral density and octave banding. A strong correlation between the leak flow rate and signal RMS was found which allowed for the development of a flow prediction model. The flow prediction model was also applied to two other media types representing buried water pipes and it was found that the surrounding media had a strong influence on the VAE signal which reduced the accuracy of flow classification. A further model was developed for buried pipes, and was found to yield good leak flow quantification using VAE. This paper therefore presents a useful method for water companies to prioritise maintenance and repair of leaks on water distribution pipes.

Feedback control of oxygen uptake during robotics-assisted end-effector-based stair climbing

ABSTRACTA heart rate (HR) feedback control system for end-effector gait rehabilitation robots was previously developed and successfully tested, but oxygen uptake () is thought to better characterize physiological exercise intensity. The aim of the present study was to identify and compare and HR dynamics, and to develop and test a controller for an end-effector robot operated in stair climbing mode. Six able-bodied subjects were recruited for controller testing. Command response, disturbance rejection and robustness were assessed by means of three quantitative outcome measures: root-mean-square (RMS) error of (), average control signal power () and RMS error of volitionally controlled power (). The nominal first-order linear model for had time constant s and steady-state gain k=0.0174 (l/min)/W. The mean time constant s for HR was significantly higher than for , where (p=0.048). Command responses for a target profile gave consistent and accurate tracking with l/min, W2 and W (). Disturbance rejection performance was also found to be satisfactory. The results of the controller tests confirm the feasibility of the proposed feedback control strategy. Robustness was verified as the single LTI controller was specific to only one of the subjects and no difference in outcome values was apparent across all subjects. Subject-specific variability in breath-by-breath respiratory noise is the main challenge in feedback control of.

Changes in Electromyographic Activity of Lumbar Paraspinal Muscles According to Type of Inverted-Spinal-Traction

We analyzed changes in electromyographic (EMG) activity in the lumbar paraspinal muscles according to Inverted-Spinal-Traction (IST) protocols, and based on the results, identified how the various protocols affected the relaxation of lumbar paraspinal muscles. Sixty healthy adult males participated in this study. They were randomly divided into three groups according to different traction protocols: 30°---30°, 30°---60°, and 60°---60°. IST was performed for 6 min in two phases, with each phase lasting 3 min. The root mean square (RMS) of EMG signals from the left and right lumbar paraspinal muscles was measured during IST, and changes in EMG activity were analyzed by examining the differences between the phases. The greatest difference in the RMS of EMG signals from the left and right lumbar paraspinal muscles during IST occurred between the phases in the 30°---60° group. The RMS of EMG signals from the right L2 and left L4 paraspinal muscles exhibited statistically significant differences between the phases. Although the RMS of EMG signals from the left L2 and right L4 paraspinal muscles did not show statistically significant differences between phases, they did exhibit similar patterns. In this study, the progressive 30°---60° IST protocol was the most effective for relaxing lumbar paraspinal muscles.

Detecting the Elusive P-Wave: A New ECG Lead to Improve the Recording of Atrial Activity.

In this study, we report on a lead selection method that was developed to detect the optimal bipolar electrode placement for recording of the P-wave. The study population consisted of 117 lead body surface potential maps recorded from 229 healthy subjects. The optimal bipolar lead was developed using the training set (172 subjects) then extracted from the testing dataset (57 subjects) and compared to other lead systems previously reported for improved recording of atrial activity. All leads were assessed in terms of P-wave, QRS, and STT root mean square (RMS). The P/QRST RMS ratio was also investigated to determine the atrioventricular RMS ratio. Finally, the effect of minor electrode misplacements on the P-lead was investigated. The P-lead discovered in this study outperformed all other investigated leads in terms of P-wave RMS. The P-lead showed a significant improvement in median P-wave RMS (93 versus 72 μV, p < 0.001) over the next best lead, Lead II. An improvement in QRS and STT RMS was also observed from the P-lead in comparison to lead II (668 versus 573 μV, p < 0.001) and (327 versus 196 μV, p < 0.001). Although P-wave RMS was reduced by incorrect electrode placement, significant improvement over Lead II was still evident. The P-lead improves P-wave RMS signal strength over all other investigated leads. Also the P-lead does not reduce QRS and STT RMS making it an appropriate choice for atrial arrhythmia monitoring. Given the improvement in signal-to-noise ratio, an improvement in algorithms that rely on P-wave analysis may be achieved.