Electromechanical Delay Research Articles

Discrete Hand Motion Intention Decoding Based on Transient Myoelectric Signals

In the application of human-robot interaction (HRI) rehabilitation exercise controlled by Electromyogram (EMG), if the discrete motion intention decoded by EMG signals is within the range of electromechanical delay (EMD), through the rehabilitation training, it will largely enhance the user's feeling feedback and fully activate the brain plasticity. So the decoding of hand movement intention by transient EMG is investigated to reach ideal characteristics needed in the HRI. The high-density EMG signal (HDEMG) database CapgMyo was used to decode the motion intention based on the transient EMG signals within the EMD rather than the whole recorded signals. We investigate the impact of the different decoding window lengths (WL) and training sets constructing methods when using several machine learning algorithms. In addition, the transient EMG signals decoding performance of the sparse multi-electrode EMG signal database NinaPro performing the same hand movement was compared. The visual inspection of the EMG map was used to determine the onset of HDEMG. The proposed approach was tested on EMG decoding window length of 150 ms, demonstrating a mean±SD testing performance of 94.21%±4.84% after voting. However, it is worth noting that sparse EMG signal did not achieve the desired decoding accuracy. The result showed that the high-density EMG signal could be used to decode the motion intention within EMD by simple machine learning algorithms, and extending the window length of training set could improve the decoding accuracy.

Impact of Left Bundle Branch Block on Left Ventricular Mechanics in Patients with Idiopathic Dilated Cardiomyopathy

Objectives: Left bundle branch block (LBBB) is commonly associated with heart failure. We evaluated the prevalence and impact of LBBB on left ventricular mechanics using 2D strain imaging in patients with idiopathic dilated cardiomyopathy (IDCM). Methods: We included 101 patients with IDCM with mean age 38 ± 18 years: 74% were males and 13.9% of them were in NYHA Class III-IV. LBBB was present in 26 (37%) of included patients. Myocardial mechanics including longitudinal, circumferential strain and rotation and LV synchronization were assessed using two-dimensional strain imaging. Results: LBBB group had higher LV volumes, and PAP compared with non LBBB. Peak LV longitudinal systolic strain (esys) of the septum and global LV SRsys were significantly lower in LBBB compared to non LBBB group (P < 0.01, <0.03). TTP-d was greater in LBBB in comparison to non LBBB group (274.5 ± 116 versus 209.4 ± 139, P < 0.02). The electromechanical delay between septal segments was 35 ± 18 ms and between lateral wall segments: 48 ± 24 ms, between anterior wall segments: 21 ± 11 and between inferior wall segments: 41 ± 12. Consequently, LV mechanical dyssynchrony was more evident in IDCM patients with LBBB. QRS width was correlated inversely with LV longitudinal strain and strain rate and electromechanical delay (P < 0.0001) in non LBBB group. In LBBB QRS width was not related to cardiac mechanics. Using univariate analysis and after a multiple covariate adjustment, the baseline LBBB was associated with a significantly increased LV dysfunction. Conclusion:After correcting for potential confounders, LBBB was found to be associated with more deterioration of LV mechanics and exaggerated LV dyssynchrony in patients with IDCM.

Timing and magnitude of regional right ventricular function and their relationship with early hospital mortality in patients with acute pulmonary embolism.

Objective:Right ventricular (RV) dysfunction in acute pulmonary embolism (APE) has been associated with increased mortality and morbidity. The aim of the present study was to assess the timing and magnitude of regional RV functions using speckle-tracking echocardiography (STE) and their relationship to early hospital mortality in patients with APE.Methods:One hundred forty-two patients were prospectively studied at the onset of an acute episode and after a median follow-up period of 30 days. Their clinical and laboratory characteristics were recorded. For all patients, conventional two-dimensional echocardiography and STE were performed within 24 h after the diagnosis of APE.Results:Twenty-eight (19.7%) patients died during the hospitalization follow-up. Patients who died during hospitalization were older and had higher high sensitivity cardiac troponin T levels, and a higher percentage of patients had simplified Pulmonary Embolism Severity Indexes. In STE analyses, they had lower RV free wall peak longitudinal systolic strain (PLSS) and higher RV peak systolic strain dispersion indexes. The time to PLSS difference between RV free wall and LV lateral was longer in patients who died during hospitalization than in those who survived, and this was an independent predictor of early hospital mortality with 85.7% sensitivity and 75.0% specificity in patients with APE.Conclusion:APE was associated with RV electromechanical delay and dispersion. Electromechanical delay index might be useful to predict early hospital mortality in patients with APE.

Variability of Cardiac Electromechanical Delay With Application to the Noninvasive Detection of Coronary Artery Disease

Heart rate variability (HRV), systolic period variability (SPV), and diastolic period variability (DPV) have shown potential for assessing cardiac function. It is unknown whether the time delay between the myocardial electrical and mechanical activities (i.e., electromechanical delay, EMD) also possesses variability, and if it does, whether this EMD variability (EMDV) could render additional value for cardiac function assessment. In this paper, we extracted the beat-to-beat EMD from 5-min simultaneously recorded electrocardiogram and phonocardiogram signals in 30 patients with coronary artery disease (CAD) and 30 healthy control subjects, and studied its variability using the same methods as applied for HRV including time-domain measures [mean and standard deviation (SD)], frequency-domain measures [normalized low- and high-frequency (LFn, HFn) and LF/HF)], and nonlinear measures [sample entropy (SampEn), permutation entropy (PE), and dynamical patterns]. In addition, we examined whether the addition of EMDV could offer improved performance for distinguishing between the two groups compared to using the HRV, SPV, and DPV features. Support vector machine with 10-fold cross-validation was used for classification. Results showed increased SD of SPV, increased mean, SD and decreased SampEn of EMDV in CAD patients. Besides, the dynamical pattern analysis showed that CAD patients had significantly increased fluctuated patterns and decreased monotonous patterns in EMDV. In particular, the addition of EMDV indices dramatically increased the classification accuracy from 0.729 based on HRV, SPV, and DPV features to 0.958. Our results suggest promising of the EMDV analysis that could potentially be helpful for detecting CAD noninvasively.

Optimal length, calcium sensitivity and twitch characteristics of skeletal muscles from mdm mice with a deletion in N2A titin.

During isometric contractions, the optimal length of skeletal muscles increases with decreasing activation. The underlying mechanism for this phenomenon is thought to be linked to length dependence of Ca2+ sensitivity. Muscular dystrophy with myositis (mdm), a recessive titin mutation in mice, was used as a tool to study the role of titin in activation dependence of optimal length and length dependence of Ca2+ sensitivity. We measured the shift in optimal length between tetanic and twitch stimulation in mdm and wild-type muscles, and the length dependence of Ca2+ sensitivity at short and long sarcomere lengths in mdm and wild-type fiber bundles. The results indicate that the mdm mutation leads to a loss of activation dependence of optimal length without the expected change in length dependence of Ca2+ sensitivity, demonstrating that these properties are not linked, as previously suggested. Furthermore, mdm muscles produced maximum tetanic stress during sub-optimal filament overlap at lengths similar to twitch contractions in both genotypes, but the difference explains less than half of the observed reduction in active force of mdm muscles. Mdm muscles also exhibited increased electromechanical delay, contraction and relaxation times, and decreased rate of force development in twitch contractions. We conclude that the small deletion in titin associated with mdm in skeletal muscles alters force production, suggesting an important regulatory role for titin in active force production. The molecular mechanisms for titin's role in regulating muscle force production remain to be elucidated.

Assessment of atrial electromechanical delay and P wave dispersion in patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is associated with atrial fibrillation (AF) and reduced forced expiratory volume (FEV1) is an independent predictor for new onset AF. The aims of this study were (1) to analyze the atrial electromechanical delay (AEMD) and P wave dispersion which are two predictors of AF development in patients with COPD and without any cardiovascular disease, and (2) to assess the relationship of those with pulmonary functions as quantified by FEV1 measurements. The study included 41 patients with COPD (33 male; mean age: 51 years) and 32 healthy controls. P wave dispersion was calculated as the difference between the maximum and minimum P wave duration in a 12-lead surface electrocardiography (ECG) recording. AEMD, defined as the time interval from the P wave onset on the ECG to the initiation of the late diastolic (Am) wave using a tissue Doppler examination, was measured from the lateral mitral annulus (LAEMD), septal annulus (SAEMD), and tricuspid lateral annulus (TAEMD). P wave dispersion was significantly longer in the COPD group than those in the controls (76±19 ms vs. 45±10 ms; p<0.001). All of the AEMD measurements demonstrated significant prolongation in patients with COPD (LAEMD: 74±9 ms vs. 64±11 ms; SAEMD: 66±10 ms vs. 57±12 ms; and TAEMD: 65±9 ms vs. 46±7 ms; p<0.001 for all). The only correlation with FEV1 was observed in the TAEMD values of the COPD group (rs: -401; p<0.009). Both P wave dispersion and AEMD parameters were significantly longer in COPD patients without any established structural or functional cardiac abnormalities, indicating an increased tendency for AF development, beginning from the initial stages of the disease.

Evaluation of Left Atrial Electromechanical Delay and Left Atrial Phasic Functions in Surgical Early Menopause Patients.

BACKGROUNDThis study evaluated the atrial electromechanical delay (AEMD) and the left atrial (LA) mechanical functions in patients with surgical early menopause.METHODSA total of 62 patients were included in the study: 33 patients with surgical early menopause and 29 age- and sex-matched healthy controls. The duration distance from the start of the P wave to the beginning of the A wave for the lateral mitral annulus, septal mitral annulus, and lateral tricuspid annulus was assessed by tissue Doppler echocardiography. The differences in these durations were used to calculate the inter- and intra-atrial mechanical delays. LA volumes were evaluated using the biplane area-length technique, and LA mechanical function values were measured.RESULTSThe baseline laboratory and clinical characteristics were similar between the two groups. Surgical early menopause patients displayed increased static atrial electromechanical connection (PA′) times for the septal mitral annulus and lateral tricuspid annulus compared to the controls. However, the lateral mitral annulus, the inter-atrial, the intra-LA, and the right atrial EMD PA′ times were not significantly altered in surgical early menopause patients compared to controls. Importantly, the LA volume index (28.1 ± 8.17 vs. 24.89 ± 7.96 mL/m2, p = 0.019), the maximal LA volume (49.6 ± 14.1 vs. 42.9 ± 16.1 mL, p = 0.004), the minimal LA volume (18.4 ± 7.0 vs. 15.2 ± 9.0 mL, p = 0.022), and the atrial precontraction LA volume (31.0 ± 10.9 vs. 24.9 ± 10.1 mL, p = 0.006) were higher in the patients with surgical early menopause compared to the controls. The LA reservoir, conduit and pumping functions and the total, passive, and active emptying volumes were all comparable between the two groups (p = 0.09; 0.06; 0.68; 0.06; 0.48; 0.07, respectively).CONCLUSIONSPatients with surgical early menopause demonstrated impaired atrial electrical delay and electromechanical functions.

The Influence of Verbal Instruction on Measurement Reliability and Explosive Neuromuscular Performance of the Knee Extensors.

The current study aimed to examine the effect of verbal instruction on explosive force production and between-session measurement reliability during maximal voluntary contractions of knee extensors. Following familiarization, 20 healthy males performed 3 maximal contractions with a “hard-and-fast” instruction and 3 maximal contractions with a “fast” instruction during 2 test-retest sessions. Knee extension maximal voluntary force (Fmax) and the maximal rate of force development (RFDmax) were measured. Maximal electromechanical delay (EMDmax), and the maximal rate of muscle activation (RMAmax) of quadriceps muscles were determined. No significant effect of instruction was observed on Fmax (p > 0.05). The RFDmax and RMAmax were significantly higher with the “fast” compared to the “hard-and-fast” instruction (36.07%, ES = 1.99 and 37.24%, ES = 0.92, respectively), whereas EMDmax was significantly lower with the “fast” instruction compared to the “hard-and-fast” instruction (-3.79%, ES = - 0.29). No significant differences between test and retest measurements were found (p < 0.05). However, the reliability of the RFDmax was higher with the fast instruction compared to the hard-and-fast instruction (CV: 7.3 vs. 16.2%; ICC: 0.84 vs. 0.56). Besides, the RFDmax was associated with the RMAmax and EMDmax with a significant effect of instruction. Data showed that the instruction given prior contracting muscle affected explosive force production and associated neuromuscular variables. As a result, the “fast” instruction may be preferred in the assessment of explosive force capacity of skeletal muscle during maximal efforts.

Evaluating the effect of nasal septoplasty on atrial electromechanical features

Recent studies have demonstrated that right ventricular (RV) dysfunction and increased pulmonary artery pressure may be frequent in patients with upper airway obstruction. In this study, we evaluated atrial conduction delays in patients with upper airway obstruction secondary to nasal septum deviation (NSD). A total of 32 patients with upper airway obstruction secondary to NSD undergoing a septoplasty procedure were enrolled in this study. Preoperative electrocardiography and transthoracic echocardiography were performed in all patients who underwent surgery. The mean pulmonary artery pressure (mPAP) and atrial conduction time (ACT) were recorded before and 6 months after the surgical procedures. The PAP was significantly lower postoperatively than preoperatively (20.75 ± 4.83 vs. 24.68 ± 5.26; P < 0.001). The postoperative Electromechanical Delay of Mitral septal wall (EMD-MS) value was significantly lower than that preoperatively (46.20 ± 8.5 vs. 40.5 ± 9.9; P < 0.001). The postoperative Electromechanical Delay of Mitral lateral wall (EMD-ML) value decreased significantly compared to the preoperative period (46.3 ± 7.4 vs. 40.6 ± 9.3; P < 0.001). The postoperative Electromechanical Delay of Tricuspit lateral wall (EMD-TL) value was significantly lower than that preoperatively (43.8 ± 7.0 vs. 38.1 ± 9.1; P < 0.001). There was no significant change in pre- or postoperative measurements of inter- and intra-atrial conduction delays. We demonstrated that upper airway obstruction secondary to NSD causes a significant increase in mPAP and a significant delay in ACT, which improved after nasal septoplasty. According to these results, we conclude that upper airway obstruction may be an important risk factor for pulmonary arterial hypertension, RV dysfunction, and atrial arrhythmias, especially in unoperated cases.

Computational Prediction of the Combined Effect of CRT and LVAD on Cardiac Electromechanical Delay in LBBB and RBBB.

Two case reports showed that the combination of CRT and LVAD benefits the end-stage heart failure patients with prolonged QRS interval significantly. In one of the reports, the patient had the LVAD removed due to the recovery of the heart function. However, the quantification of the combined devices has yet to be conducted. This study aimed at computationally predicting the effects of CRT-only or combined with LVAD on electromechanical behaviour in the failing ventricle with left bundle branch blocked (LBBB) and right bundle branch blocked (RBBB) conditions. The subjects are normal sinus rhythm, LBBB, RBBB, LBBB with CRT-only, RBBB with CRT-only, LBBB with CRT + LVAD, and RBBB with CRT + LVAD. The results showed that the CRT-only shortened the total electrical activation time (EAT) in the LBBB and RBBB conditions by 20.2% and 17.1%, respectively. The CRT-only reduced the total mechanical activation time (MAT) and electromechanical delay (EMD) of the ventricle under LBBB by 21.3% and 10.1%, respectively. Furthermore, the CRT-only reduced the contractile adenosine triphosphate (ATP) consumption by 5%, increased left ventricular (LV) pressure by 6%, and enhanced cardiac output (CO) by 0.2 L/min under LBBB condition. However, CRT-only barely affects the ventricle under RBBB condition. Under the LBBB condition, CRT + LVAD increased LV pressure and CO by 10.5% and by 0.9 L/min, respectively. CRT + LVAD reduced ATP consumption by 15%, shortened the MAT by 23.4%, and shortened the EMD by 15.2%. In conclusion, we computationally predicted and quantified that the CRT + LVAD implementation is superior to CRT-only implementation particularly in HF with LBBB condition.

Effects of Plyometric and Resistance Training on Muscle Strength, Explosiveness, and Neuromuscular Function in Young Adolescent Soccer Players.

McKinlay, BJ, Wallace, P, Dotan, R, Long, D, Tokuno, C, Gabriel, D, and Falk, B. Effects of plyometric and resistance training on muscle strength, explosiveness, and neuromuscular function in young adolescent soccer players. J Strength Cond Res 32(11): 3039-3050, 2018-This study examined the effect of 8 weeks of free-weight resistance training (RT) and plyometric (PLYO) training on maximal strength, explosiveness, and jump performance compared with no added training (CON), in young male soccer players. Forty-one 11- to 13-year-old soccer players were divided into 3 groups (RT, PLYO, and CON). All participants completed isometric and dynamic (240°·s) knee extensions before and after training. Peak torque (pT), peak rate of torque development (pRTD), electromechanical delay (EMD), rate of muscle activation (Q50), m. vastus lateralis thickness (VLT), and jump performance were examined. Peak torque, pRTD, and jump performance significantly improved in both training groups. Training resulted in significant (p ≤ 0.05) increases in isometric pT (23.4 vs. 15.8%) and pRTD (15.0 vs. 17.6%), in RT and PLYO, respectively. During dynamic contractions, training resulted in significant increases in pT (12.4 and 10.8% in RT and PLYO, respectively), but not in pRTD. Jump performance increased in both training groups (RT = 10.0% and PLYO = 16.2%), with only PLYO significantly different from CON. Training resulted in significant increases in VLT (RT = 6.7% and PLYO = 8.1%). There were no significant EMD changes. In conclusion, 8-week free-weight resistance and plyometric training resulted in significant improvements in muscle strength and jump performance. Training resulted in similar muscle hypertrophy in the 2 training modes, with no clear differences in muscle performance. Plyometric training was more effective in improving jump performance, whereas free-weight RT was more advantageous in improving peak torque, where the stretch reflex was not involved.

Prolonged electromechanical delay as an early predictor of trastuzumab-induced cardiotoxicity in patients undergoing treatment for breast cancer.

We aimed to investigate if left ventricular electromechanical delay (LVEMD) prolongation predicts trastuzumab-induced cardiotoxicity (TIC) in breast cancer patients. LVEMD prolongation on serial echocardiograms could be an indicator of subclinical TIC. We included 237 breast cancer patients receiving trastuzumab chemotherapy, who underwent echocardiography at baseline and at 6 and 12 months after trastuzumab initiation. LVEMD was defined as the time from electrical activation to myocardial contraction. TIC was defined as left ventricular ejection fraction (LVEF) worsening to <55%, either as symptomatic decrease of ≥5% or asymptomatic decrease of ≥10%. During a mean follow-up of 547 days, TIC occurred in 27 patients (11.4%). Changes in the time intervals from QRS onset on electrocardiography to the beginning and peak of transaortic flow on pulsed-wave Doppler echocardiography (ie, ΔLVEMDi and ΔLVEMDp, respectively) were independent predictors of TIC. On receiver operating characteristic curve analysis, the optimal cutoff value for TIC prediction was 23 milliseconds for ΔLVEMDi (sensitivity, 0.85; specificity, 0.78; area under the curve [AUC], 0.882) and 21 milliseconds for ΔLVEMDp (sensitivity, 0.96; specificity, 0.68; AUC, 0.860). The C-index for TIC prediction increased significantly after adding ΔLVEMDi and ΔLVEMDp to conventional models that included clinical variables, baseline LVEF, and changes in global longitudinal peak systolic strain. Similarly, adding ΔLVEMDi or ΔLVEMDp to conventional models provided significant improvement in discrimination capability for TIC prediction (integrated discrimination improvement and continuous net reclassification improvement index). ΔLVEMDi and ΔLVEMDp may serve as predictors of subclinical cardiac dysfunction in breast cancer patients receiving trastuzumab.

The influence of preceding activity and muscle length on voluntary and electrically evoked contractions.

Muscle length and preceding activity independently influence rate of torque development (RTD) and electromechanical delay (EMD), but it is unclear whether these parameters interact to optimize RTD and EMD. The purpose of this study was to determine the influence of muscle length and preceding activity on RTD and EMD during voluntary and electrically stimulated (e-stim) contractions. Participants (n = 17, males, 24 ± 3 years) performed isometric knee extensions on a dynamometer. Explosive maximal contractions were performed at 2 knee angles (35° and 100° referenced to a 0° straight leg) without preceding activity (unloaded, UNL) and with preceding activities of 20%, 40%, 60%, and 80% of maximal voluntary contraction (MVC) torque. Absolute and normalized voluntary RTD were slowed with preceding activities ≥40% MVC for long muscle lengths and all preceding activities for short muscle lengths compared with UNL (p < 0.001). Absolute and normalized e-stim RTD were slower with preceding activities ≥40% MVC compared with UNL (p < 0.001) for both muscle lengths. Normalized RTD was faster at short muscle lengths than at long muscle lengths (p < 0.001) for e-stim (∼50%) and voluntary (∼32%) UNL contractions, but this effect was not present for absolute RTD. Muscle length did not affect EMD (p > 0.05). EMD was shorter at 80% MVC compared with UNL (∼35%; p < 0.001) for both muscle lengths during voluntary but not e-stim contractions. While RTD is limited by preceding activity at both muscle lengths, long muscle lengths require greater preceding activity to limit RTD than short muscle lengths, which indicates long muscle lengths may offer a "protective effect" for RTD against preceding activity.

Scaling of sensorimotor delays in terrestrial mammals.

Whether an animal is trying to escape from a predator, avoid a fall or perform a more mundane task, the effectiveness of its sensory feedback is constrained by sensorimotor delays. Here, we combine electrophysiological experiments, systematic reviews of the literature and biophysical models to determine how delays associated with the fastest locomotor reflex scale with size in terrestrial mammals. Nerve conduction delay is one contributor, and increases strongly with animal size. Sensing, synaptic and neuromuscular junction delays also contribute, and we approximate each as a constant value independent of animal size. Muscle's electromechanical and force generation delays increase more moderately with animal size than nerve conduction delay, but their total contribution exceeds that of the four neural delays. The sum of these six component delays, termed total delay, increases with animal size in proportion to M0.21-large mammals experience total delays 17 times longer than small mammals. The slower movement times of large animals mostly offset their long delays resulting in a more modest, but perhaps still significant, doubling of their total delay relative to movement duration when compared with their smaller counterparts. Irrespective of size, sensorimotor delay is likely a challenge for all mammals, particularly during fast running.

Evaluation of Atrial Electromechanical Delay to Predict Atrial Fibrillation in Hemodialysis Patients.

Background and objective: Prevalence of atrial fibrillation is higher in hemodialysis patients as compared to the general population. Atrial electromechanical delay is known as a significant predictor of atrial fibrillation. In this study, we aimed to reveal the relationship between atrial electromechanical delay and attacks of atrial fibrillation. Materials and methods: The study included 77 hemodialysis patients over 18 years of age giving written consent to participate in the study. The patients were divided into two groups based on the results of 24-h Holter Electrocardiogram (Holter ECG) as the ones having attacks of atrial fibrillation and the others without any attack of atrial fibrillation. Standard echocardiographic measurements were taken from all patients. Additionally, atrial conduction times were measured by tissue Doppler technique and atrial electromechanical delays were calculated. Results: Intra- and interatrial electromechanical delay were found as significantly lengthened in the group of patients with attacks of atrial fibrillation (p = 0.03 and p < 0.001 respectively). The optimal cut-off time for interatrial electromechanical delay to predict atrial fibrillation was >21 ms with a specificity of 79.3% and a sensitivity of 73.7% (area under the curve 0.820; 95% confidence interval (CI), 0.716–0.898). In the multivariate logistic regression model, interatrial electromechanical delay (odds ratio = 1.230; 95% CI, 1.104–1.370; p < 0.001) and hypertension (odds ratio = 4.525; 95% CI, 1.042–19.651; p = 0.044) were also associated with atrial fibrillation after adjustment for variables found to be statistically significant in univariate analysis and correlated with interatrial electromechanical delay. Conclusions: Interatrial electromechanical delay is independently related with the attacks of atrial fibrillation detected on Holter ECG records in hemodialysis patients.

FOUR WEEKS OF ROLLER MASSAGE TRAINING DID NOT IMPACT RANGE OF MOTION, PAIN PRESSURE THRESHOLD, VOLUNTARY CONTRACTILE PROPERTIES OR JUMP PERFORMANCE

Roller massagers are popular devices that are used to improve range of motion (ROM), enhance recovery from muscle soreness, and reduce pain under acute conditions. However, the effects of roller massage training and training frequency are unknown. The objective was to compare two different roller massage training frequencies on muscle performance. Randomized controlled intervention study. Twenty-three recreationally active university students were randomly allocated to three groups: control (n=8;), rolling three (3/W; n=8;) and six (6/W; n=7) times per week for four weeks. The roller massage training consisted of unilateral, dominant limb, quadriceps and hamstrings rolling (4 sets x 30 seconds). Both legs of participants were tested pre- and post-training for active and passive hamstrings and quadriceps range of motion (ROM), electromyography (EMG) activity during a lunge movement, unilateral countermovement jumps (CMJ), as well as quadriceps and hamstrings maximum voluntary isometric contraction (MVIC) forces and electromechanical delay. Finally, they were tested for pain pressure threshold at middle and distal segments of their quadriceps and hamstrings. There were no significant training interactions for any measure with the exception that 3/W group exhibited 6.2% (p=0.03; Effect Size: 0.31) higher CMJ height from pre- (38.6 ± 7.1 cm) to post-testing (40.9 ± 8.1 cm) for the non-dominant limb. Whereas the literature has demonstrated acute responses to roller massage, the results of the present study demonstrate no consistent significant training-induced changes. The absence of change may highlight a lack of muscle and myofascial morphological or semi-permanent neurophysiological changes with rolling. 2c.

Examination of the neuromechanical factors contributing to golf swing performance

ABSTRACTThis study investigated the relationship between a range of neuromechanical variables in the lower- and upper-body, and golf performance. Participants were assessed for individual muscle stiffness, vertical stiffness (Kvert), flexibility, power and maximal isometric strength. Furthermore, golf performance was determined by handicap and club head speed. Pearson’s correlations quantified the relationships between neuromechanical variables and performance measures. Participants were also separated into relatively high club head speed (HC) and low club head speed (LC) groups and compared for physical characteristics. Club head speed showed positive relationships with Kvert and power and a negative relationship with hip mobility. The HC group exhibited superior Kvert and power, while strength and flexibility measures were not related to performance. Higher levels of lower-body stiffness, rate of force development and power output appear to be beneficial for generating superior club head speed. A stiffer system may reduce the time needed to remove the “slack” from the series elastic component therefore, reducing electromechanical delay and enhancing rate of force development. The large positive association with rate of force development suggests that increasing this component, along with power production may be superior focal components for training in golfers due to the short duration of the downswing.

Long term evaluation of electromechanical delay in patients with atrial septal defect after transcatheter closure.

Some studies have been showed that electromechanical delay, which may pose an increased tendency to atrial fibrillation, may prolong in patients with various clinical conditions. In addition, the electromechanical delay in patients with secundum type atrial septal defect (ASD) compared to healthy people have been reported previously. Therefore, in the present study, we prospectively evaluated the mid-term and long-term effects of the transcatheter closure of secundum type ASD on the lateral atrial conduction time (PA), septal PA, tricuspid PA, left and right intra-atrial electromechanical delay (ILeft-EMD and IRight-EMD, respectively) and inter-atrial electromechanical delay (IA-EMD) measured by means of Doppler echocardiography. Our prospective study included a total of 45 secundum type ASD patients who undergone percutaneous transcatheter closure from December 2012 to April 2015. All patients underwent transthoracic echocardiography (TTE) before the closure, at sixth and twelfth months after the closure. In comparison of the EMD sixth months after the device closure, there were statistically significant decrease in lateral PA, septal PA, tricuspid PA, ILeft-EMD, IRight-EMD and IA-EMD compared to pre-device closure values. Twelfth months after the device closure, we also observed statistically significant decrease in lateral PA, septal PA, tricuspid PA, ILeft-EMD, IRight-EMD and IA-EMD compared to 6-month post-device closure values. In the present study, we observed that the atrial EMD improves after device closure and continues to improve after twelfth month following post-device closure.

Assessment of Atrial Conduction Times in Patients with Newly Diagnosed Parkinson's Disease.

Background An increased risk of ischemic stroke has been reported in patients with Parkinson's disease (PD). Atrial fibrillation (AF) is strongly associated with ischemic stroke. Prolonged atrial electromechanical delay (EMD) is an independent predictor for the development of AF. Aims The aim of the present study was to evaluate the atrial conduction parameters in patients with PD and to assess their relation with the severity of PD. Study design We prospectively enrolled 51 consecutive patients with newly diagnosed PD and 31 age- and sex-matched non-PD subjects. Methods To assess atrial electromechanical coupling (PA), the time intervals from the onset of p wave on ECG to the late diastolic wave at the septal (PAs) and lateral (PAl) mitral annulus and lateral tricuspid annulus (PAt) were measured on Tissue Doppler Echocardiography (TDE). The difference between PAs-PAl, PAs-PAt, and PAl-PAt were defined as left intra-atrial, right intra-atrial, and interatrial EMD, respectively. P-wave dispersion (PWD) was calculated from the 12-lead ECG. Results PWD, PAs, PAl, and PAt durations were significantly prolonged in the PD group (all p < 0.001). Interatrial, right, and left intra-atrial EMD were also significantly longer in PD patients (p < 0.001, p < 0.001 and p=0.002, resp.). There were significant positive correlations between disease severity (UPDRS score) and PWD (r=0.34, p=0.041), left intra-atrial (r=0.39, p=0.005), and interatrial EMD (r=0.35, p=0.012). By multivariate analysis, PWD (OR: 1.13, 95% CI: 1.02–1.25; p=0.017), LA volume index (OR: 1.19, 95% CI: 1.02–1.37; p=0.021), left intra-atrial (OR: 1.12, 95% CI: 1.01–1.24; p=0.041), and interatrial EMD (OR: 1.08, 95% CI: 1.01–1.16; p=0.026) were found as independent predictors of PD. Conclusion Atrial conduction times were longer and correlated with the severity of disease in PD patients. Prolonged inter- and intra-atrial-EMD intervals were also found as independent correlates of PD. These findings may suggest an increased predisposition to atrial fibrillation in PD.

Ineffectiveness of muscle reaction time and torque of quadriceps in treating hamstrings using deep transverse friction massage

Deep transverse friction massage (DTFM) is used to treat pain and restricted range of motion. It is known to decrease nerve excitability and performance. However, few studies have focussed on the function of antagonist muscles. This study aimed to determine the effect of DTFM on the antagonist muscle in comparison with stretching. Overall, 33 healthy male participants (mean age, 23.1 ± 4.2 years) were randomised into three groups: DTFM ( n = 11), stretching ( n = 11), and control ( n = 11). DTFM was performed on the hamstrings for a duration of 10 minutes. Stretching of 10–40 seconds was statically applied to the hamstrings followed by 20-second rest. The control was provided 10-minutes of rest. Peak torque (PT) at a speed of 60°/s and 120°/s on quadriceps and hamstrings, respectively, were the outcome measures, and muscle reaction time, namely, pre-motor time (PMT) and electromechanical delay (EMD) on the rectus and biceps femoris. Two-way analysis of variance for repeated measures was used to evaluate statistical significance of all the measured variables. Therefore, no difference was found between the subjects and within groups in all measurements ( P < 0.05). The result indicated that adding DTFM or stretching on the hamstrings did not affect PT, PMT, and EMD on the quadriceps. A previous study described reaction time change only when the muscle tendon was treated using DTFM. It was also considered that the difference in treatment site could affect neural mechanisms. In conclusion, this study showed that using DTFM for the treatment of hamstrings improve neither PT nor muscle reaction time on the quadriceps.