Electromyographic Root Mean Square Research Articles

Acute intrathecal BDNF enhances functional recovery after cervical spinal cord injury in rats.

Unilateral C2 hemisection (C2SH) disrupts descending inspiratory-related drive to phrenic motor neurons and thus, silences rhythmic diaphragm muscle (DIAm) activity. There is gradual recovery of rhythmic DIAm EMG activity over time post-C2SH, consistent with neuroplasticity, which is enhanced by chronic (2 wk) intrathecal BDNF treatment. In the present study, we hypothesized that acute (30 min) intrathecal BDNF treatment also enhances recovery of DIAm EMG activity after C2SH. Rats were implanted with bilateral DIAm EMG electrodes to verify the absence of ipsilateral eupneic DIAm EMG activity at the time of C2SH and at 3 days post-C2SH. In those animals displaying no recovery of DIAm EMG activity after 28 days (n = 7), BDNF was administered intrathecally (450 mcg) at C4. DIAm EMG activity was measured continuously both before and for 30 min after BDNF treatment, during eupnea, hypoxia-hypercapnia, and spontaneous sighs. Acute BDNF treatment restored eupneic DIAm EMG activity in all treated animals to an amplitude that was 78% ± 9% of pre-C2SH root mean square (RMS) (P < 0.001). In addition, acute BDNF treatment increased DIAm RMS EMG amplitude during hypoxia-hypercapnia (P = 0.023) but had no effect on RMS EMG amplitude during sighs. These results support an acute modulatory role of BDNF signaling on excitatory synaptic transmission at phrenic motor neurons after cervical spinal cord injury.NEW & NOTEWORTHY Brain-derived neurotrophic factor (BDNF) plays an important role in promoting neuroplasticity following unilateral C2 spinal hemisection (C2SH). BDNF was administered intrathecally in rats displaying lack of ipsilateral inspiratory-related diaphragm (DIAm) EMG activity after C2SH. Acute BDNF treatment (30 min) restored eupneic DIAm EMG activity in all treated animals to 78% ± 9% of pre-C2SH level. In addition, acute BDNF treatment increased DIAm EMG amplitude during hypoxia-hypercapnia but had no effect on EMG amplitude during sighs.

Tracking of Individual Motor Units Following Concentric and Eccentric Exercise‐induced Fatigue Reveals Contraction‐type Specific Changes in Discharge Properties

Muscle fatigue is characterised by a reduction in force output, with increases in force production partly mediated by adjustments in motor unit (MU) firing properties. Conflicting research has found MU firing rate (FR) to both increase and decrease following fatiguing exercise and this disparity may be influenced by contraction type. Using high density surface electromyography (HD-EMG) we have previously reported a decrease in FR following concentric (CON), and an increase following eccentric (ECC) contractions (1). However, HD-EMG also enables the tracking of individual MUs across tasks (2), potentially revealing more detailed MU-specific adaptations to fatigue. The aims of this study were to track the FR of individual MUs following CON and ECC contractions of the vastus lateralis (VL) muscle. HD-EMG was used to identify individual MU potentials (MUPs) from the VLs of 8 young volunteers (4 females; 21 ± 0.5 years). All MUPs were recorded during 4 sustained isometric contractions held at a target line of 25 and 40% of the participants maximum voluntary contraction (MVC) before and after completing CON and ECC fatiguing exercise (CON: ‘stepping up’ with one leg, ECC: ‘stepping down’ on the other leg, wearing a weighted vest +25-40% body weight). The coefficient of variation of force was calculated to assess force steadiness (FS). A total of 43 MUs were tracked pre and post fatigue. Paired t-tests were used for comparisons of tracked MUs. Significance was assumed when p<0.05. MVC decreased in both CON and ECC legs post exercise (-15.3% and -21.1% respectively; p<0.01) and EMG root-mean square amplitude (RMS) significantly decreased in both legs after fatigue (both p≤0.001). FS deteriorated in ECC only at both 25% and 40% MVC (p=0.004 and p=0.04 respectively), with no change in CON. Data from individual tracked MUs supported our previous finding with a decreased FR following CON (-4.7%; p=0.037) but no difference in FR with ECC (+6.9%; p=0.168). These data demonstrate that motor control and MU FR following exercise-induced fatigue differ according to exercise modality. HD-EMG enables specific changes in single motor units to be studied across sessions in addition to the overall MU population effects, and here the FR did not change following ECC exercise even with a notably reduced absolute force (21%). The possibility of differential MU recruitment strategies compensating for discharge characteristics and impacting motor control requires further investigation as this may have translational relevance in ageing, neuromuscular conditions and for post-exercise recovery from fatigue. 1. Jones EJ, Martinez-Valdes E, Negro F, McCormick D, Atherton PJ, Phillips BE, et al. Motor unit discharge properties following concentric and eccentric exercise-induced fatigue are dependent upon contraction type. American Physiological Society: Integrative Physiology of Exercise. 2020. 2. Martinez-Valdes E, Negro F, Falla D, Dideriksen JL, Heckman C, Farina D. Inability to increase the neural drive to muscle is associated with task failure during submaximal contractions. J Neurophysiol. 2020.

Motor Unit Recruitment and VO 2 Responses to All Out Maximal versus Constant Load Exercise Tests

The 3 min all-out cycling test has been used in several studies to establish peak oxygen uptake (VO2pk) and critical power. We have previously shown that the prior recruitment of motor units in excess of that needed to meet the metabolic demands of a subsequent bout of exercise had little impact on both the absolute or relative O2 cost. However, the effect of continuous supra-maximal exercise, such as that performed during a 3 min all-out test, has not been systematically compared to constant load, submaximal exercise that is performed at the same absolute work rate (WR). Thus, the purpose of this study was to compare VO2p and motor unit activation during a 3 min all-out maximal exercise test versus a constant load exercise test performed at the same absolute WR. Five healthy males (25 ± 3 yrs, 84.2 ± 9.1 kg, 178.2 ± 10.5 cm, VO2pk: 40.4 ± 7.3 mL/kg/min; mean ± SD) completed a ramp exercise test (25 W/min) to volitional fatigue for the identification of the lactate threshold (LT) and peak VO2p (VO2pk) as well as the linear factor for use in the subsequent 3 min all-out test. Critical power (CP) was determined using a 3 min all-out exercise test (3MAO) performed on a cycle ergometer set to the linear mode where resistance is dependent on cadence. The subject was instructed to pedal as fast as possible for 3 min. After no less than 48 hrs of rest, subjects completed a 6 min constant load exercise test (CLCP) at CP (i.e. the WR corresponding to the last 30 s of the 3MAO test). VO2p was measured breath-by-breath using a metabolic cart and interpolated to 1s intervals. For both the 3MAO and CLCP tests, end exercise VO2p (EEVO2p) was determined as the mean VO2p during the last 30 s of exercise. VO2p gain was calculated as ΔEEVO2p/ΔWR. sEMG was measured using electrodes placed over the vastus lateralis (VL) and vastus medialis (VM) muscles. The root mean square (RMS) was normalized as the percent (%) increase above RMS EMG data collected at a fixed WR of 75W for each subject. There was no difference (p>0.05) between the normalized VL and VM responses within 3MAO or CLCP trials; therefore, overall motor unit activation at end exercise for each exercise condition is reported as the mean RMS for the VL and VM. Relative to VO2p, there was no difference in EEVO2p for 3MAO (90.5 ± 10.0 %, p>0.05) or CLCP (81.9 ± 15.5%, p=0.06) nor was there a difference (p=0.07) in EEVO2p between 3MAO (3093 ± 575 mL/min) and CLCP (2777 ± 523 mL/min).ΔEEVO2p/ΔWR was higher (p<0.05) following 3MAO (13.4 ± 0.3 mL/min/W) compared to CLCP (12.0 ± 1.2 mL/min/W). Normalized RMS was higher (p<0.05) following 3MAO (243 ± 40 %) compared to CLCP (169 ± 42 %). EEVO2p, when expressed relative to normalized RMS, was lower (p<0.05) during 3MAO compared to CLCP. Both the EEVO2p relative to muscle activation as well as the higher gain during the 3MAO compared to the CLCP trials found in the present study are similar to those of previous studies demonstrating a dissociation of motor unit activation and O2 cost during heavy-to-severe intensity exercise. Further investigations into the effect of muscle fatigue on the integrated responses of force production and the resulting metabolic responses during heavy-to-severe intensity exercise are warranted.

No effect of passive stretching on neuromuscular function and maximum force-generating capacity in the antagonist muscle

PurposeThe present study investigated whether or not passive stretching increases the force-generating capacity of the antagonist muscle, and the possible neuromuscular mechanisms behind.MethodsTo this purpose, the neuromuscular function accompanying the force-generating capacity was assessed in 26 healthy male volunteers after passive stretching and in a control session. Before and after passive intermittent static stretching of the plantar flexors consisting of five sets × 45 s + 15 s-rest, maximum voluntary isometric contraction (MVC) and surface electromyographic root mean square (sEMG RMS) were measured in the tibialis anterior (the antagonist muscle). Additionally, evoked V wave, H-reflex, and M wave were elicited by nerve stimulation at rest and during MVC. Ankle range of motion (ROM) and plantar flexors MVC and EMG RMS were measured to check for the effectiveness of the stretching manoeuvre.ResultsNo change in MVC [p = 0.670; effect size (ES) − 0.03] and sEMG RMS/M wave during MVC (p = 0.231; ES − 0.09) was observed in the antagonist muscle after passive stretching. Similarly, no change in V wave (p = 0.531; ES 0.16), H-reflex at rest and during MVC (p = 0.656 and 0.597; ES 0.11 and 0.23, respectively) and M wave at rest and during MVC (p = 0.355 and 0.554; ES 0.04 and 0.01, respectively) was observed. An increase in ankle ROM (p < 0.001; ES 0.55) and a decrease in plantar flexors MVC (p < 0.001; ES − 1.05) and EMG RMS (p < 0.05; ES − 1.72 to − 0.13 in all muscles) indicated the effectiveness of stretching protocol.ConclusionNo change in the force-generating capacity and neuromuscular function of the antagonist muscle after passive stretching was observed.

External Anal Sphincter Fatigability: An Electromyographic and Manometric Study in Patients With Anorectal Disorders.

Background/AimsExternal anal sphincter (EAS) plays an important role in fecal and gas voluntary continence. Like every muscle, it can be affected by repeated efforts due to fatigability (physiological response) and/or fatigue (pathological response). No standardized fatiguing protocol and measure method to assess EAS fatigability has existed. The aim is to test a simple, standardized protocol for fatiguing and measuring EAS fatigability and fatigue to understand better the part of EAS fatigability in the pathophysiology of fecal incontinence.MethodsPatients with anorectal disorders evaluated with anorectal manometry were included. They had to perform 10 repetitions of maximum voluntary contraction (MVC) of 20 seconds. Measurement was made with an anorectal manometry catheter and a surface recording electromyography (EMG). The primary outcome was the difference in EMG root mean square between the first and the last MVC. Secondary outcomes were differences in other EMG and manometry parameters between the first and the last MVC. Difficulties and adverse effects were recorded.ResultsNineteen patients underwent the fatiguing protocol. All patients completed the entire protocol and no complications were found. No difficulty was declared by the examiner. A significant decrease in root mean square was found between the first and last MVC (0.01020 ± 0.00834 mV vs 0.00661 ± 0.00587 mV; P = 0.002), in maximum anal pressure area under the curve of continuous recordings of anal pressure and mean and total EMG power (P < 0.05).ConclusionsThis protocol is simple and minimally invasive to measure EAS fatigue and fatigability. We highlighted a fatigue of EAS in many patients with anorectal disorders.

Neuromuscular responses at acute moderate and severe hypoxic exposure during fatiguing exercise of the biceps brachii.

PurposeThe present study examined acute normobaric hypoxic exposure on the number of repetitions to failure, electromyographic (EMG) repetition duration (Time), EMG root mean square (RMS) and EMG mean power frequency (MPF) during biceps brachii (BB) dynamic constant external resistance (DCER) exercise.MethodsThirteen subjects performed two sets of fatiguing DCER arm curl repetitions to failure at 70% of their one repetition maximum under normoxic (NH), moderate hypoxia FiO2 = 15% (MH) and severe hypoxia FiO2 = 13% (SH). Electromyography of the BB was analyzed for EMG Time, EMG RMS, and EMG MPF. Repetitions were selected as 25%, 50%, 75%, and 100% of total repetitions (%Fail) completed. Pulse oximetry (SpO2) was measured pre-and post-fatigue.ResultsThere was no significant three-way (Condition x Set x %Fail) or two-way (Condition x Set) interaction for any variable. The number of repetitions to failure significantly decreased from (mean ± SEM) 18.2 ± 1.4 to 9.5 ± 1.0 with each Set. In addition, EMG Time increased (25% < 50%<75% < 100%), EMG RMS decreased (50% > 75%>100%), and EMG MPF decreased (75% > 100%) as a result of fatiguing exercise. SpO2 was lower during MH (Δ5.3%) and SH (Δ9.2%) compared to NH and as a result of fatiguing exercise increased only in MH (Δ2.1%) and SH (Δ5.7%).ConclusionThe changes in BB EMG variables indicated exercise caused myoelectric manifestations of fatigue, however, acute moderate or severe hypoxia had no additional influence on the rate of fatigue development or neuromuscular parameters.

Influence of Spectral Peaks on EMG Parameter Estimation for Vibration-Exercise Analysis

Many studies have proposed vibration exercise (VE) as a novel training modality for neuromuscular conditioning and rehabilitation. Surface electromyography (sEMG) is widely used for effective measurement of muscle activity. Unfortunately, sharp spectral peaks (SSP) are usually present in the EMG signals recorded during VE. The explanation of these sharp peaks, as muscle activity or motion artifacts, is controversial, complicating EMG parameter extraction for the analysis of VE. The present study aims to quantify the impact of these SSP on the estimation of EMG parameters irrespective of their nature. High-density sEMG was therefore recorded from the biceps brachii muscle during VE with different vibration amplitudes (VA) and frequencies (VF). The power around (±0.5 Hz) VF and its first harmonic was calculated and normalized with the entire EMG power in order to obtain a relative power ( P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> ) of these peaks. In addition, before and after excluding the SSP, three EMG parameters, i.e., mean frequency (MF), root mean square (RMS), and conduction velocity (CV), were estimated and compared. Our results reveal an average P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> of 21.18± 15.68 %. The relative difference in EMG RMS and MF are 12.2± 3.8 % and 2.10± 1.04 %, respectively. In addition, the impact of these peaks on the MF and RMS seems also to be affected by vibration conditions, such as VA and VF. However, the CV estimation seems not to be significantly influenced by these peaks, indicating these peaks to be primarily reflecting muscle activity and therefore should be included in VE EMG analysis.

Leg Muscle Activity and Perception of Effort before and after Four Short Sessions of Submaximal Eccentric Cycling

Background: This study tested muscle activity (EMG) and perception of effort in eccentric (ECC) and concentric (CON) cycling before and after four sessions of both. Methods: Twelve volunteers naïve to ECC cycling attended the laboratory six times. On day 1, they performed a CON cycling peak power output (PPO) test. They then carried-out four sessions comprising two sets of 1 to 1.5-min cycling bouts at 5 intensities (30, 45, 60, 75, and 90% PPO) in ECC and CON cycling. On day 2 and day 6 (two weeks apart), EMG root mean square of the vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF), and soleus (SOL) muscles, was averaged from 15 to 30 s within each 1-min bout and perception of effort was asked after 45 s. Results: Before the four cycling sessions, while VL EMG was lower in ECC than CON cycling, most variables were not different. Afterwards, ECC cycling exhibited lower RF EMG at 75 and 90% PPO (all p < 0.02), lower VL and BF EMG at all exercise intensities (all p < 0.02), and inferior SOL EMG (all p < 0.04) except at 45% PPO (p = 0.07). Perception of effort was lower in ECC cycling at all exercise intensities (all p < 0.03) but 60% PPO (p = 0.11). Conclusions: After four short sessions of ECC cycling, the activity of four leg muscles and perception of effort became lower in ECC than in CON cycling at most of five power outputs, while they were similar before.

An Electromyographic Analysis of Lateral Raise Variations and Frontal Raise in Competitive Bodybuilders.

The present study examined the muscle activation in lateral raise with humerus rotated externally (LR-external), neutrally (LR-neutral), internally (LR-internal), with flexed elbow (LR-flexed) and frontal raise during both the concentric and eccentric phase. Ten competitive bodybuilders performed the exercises. Normalized surface electromyographic root mean square (sEMG RMS) was obtained from anterior, medial, and posterior deltoid, pectoralis major, upper trapezius, and triceps brachii. During the concentric phase, anterior deltoid and posterior deltoid showed greater sEMG RMS in frontal raise (effect size (ES)-range: 1.78/9.25)) and LR-internal (ES-range: 10.79/21.34), respectively, vs. all other exercises. Medial deltoid showed greater sEMG RMS in LR-neutral than LR-external (ES: 1.47 (95% confidence-interval—CI: 0.43/2.38)), frontal raise (ES: 10.28(95% CI: 6.67/13.01)), and LR-flexed (ES: 6.41(95% CI: 4.04/8.23)). Pectoralis major showed greater sEMG RMS in frontal raise vs. all other exercises (ES-range: 17.2/29.5), while upper trapezius (ES-range: 2.66/7.18) and triceps brachii (ES-range: 0.41/3.31) showed greater sEMG RMS in LR-internal vs. all other exercises. Similar recruitment patterns were found during the eccentric phase. When humerus rotates internally, greater activation of posterior deltoid, triceps brachii, and upper trapezius occurs. Humerus external rotation increases the activation of anterior and medial deltoid. Frontal raise mainly activates anterior deltoid and pectoralis major. LR variations and frontal raise activate specifically shoulders muscles and should be proposed accordingly.

Inspiratory muscles contributions to postural control in healthy older women

It was hypothesized that induced inspiratory muscles effort, by an acute inspiratory resistance load (IRL) use, increases the postural sway and the neuromuscular activity of postural muscles in older adults. Fifteen older women breathed spontaneously, controlled (15 cycles/minute), and with acute IRL (15 cycles/minute and target load of 30 % of maximal inspiratory pressure) in random order. The breathing tasks were performed in an orthostatic position (eyes closed) during one minute on a baropodometer plate to acquire center-of-pressure (COP) oscillations and with electromyography (EMG) recording. The root mean square (RMS) of EMG was calculated. COP oscillations were higher with IRL use than spontaneous and controlled breathing tasks, but not between spontaneous and controlled conditions. EMG activity of Tibialis anterior and Soleus muscles were higher with IRL use in comparison to spontaneous and controlled breathing conditions. In conclusion, IRL use influenced the postural control through increased postural sway and neuromuscular compensation of the lower limbs in older women.

The Effect Of Responsive Equine Simulator Therapy Device On Biomechanics Of Sitting

A responsive equine simulator therapy (REST) system is a sitting device replicating motions experienced during horse riding. The mild motion introduced by the REST could promote a more active sitting experience to users. Although the REST system could potentially provide the benefits associated with active sitting, the effect of a REST system on trunk motion, trunk and leg muscle activations over that of sitting on a normal chair has yet to be examined. PURPOSE: To quantify trunk motion patterns and trunk and leg muscle activity during sitting on a REST system compared to an office chair. METHODS: 20 healthy participants (22±2 yr, 75±10 kg, 1.71±7.9 m) sat on the REST device and an office chair for 20 minutes in randomized order. Electromyography (EMG) sensors were placed bilaterally on the external oblique, rectus abdominis, erector spinae, adductor longus, soleus, and tibialis anterior. 3D Motion capture was conducted while participants performed the two sitting conditions. One way repeated measures ANOVA was used to determine differences in trunk motion and root mean square (RMS) EMG between the two sitting conditions. RESULTS: For any given 10-sec sitting interval, the trunk center of mass traveled a greater distance during the REST condition (25.4±7.9 cm) over that of the Chair condition (3.6±1.5 cm) (p<0.001). Also, mean angular speeds of the trunk during sitting on the REST was greater in the sagittal plane (0.20±0.12 deg/s vs. 0.07±0.06 deg/s) (p<0.001) and in the transverse plane (0.11±0.04 deg/s vs. 0.05±0.09 deg/s) (p=0.011) than those of the Chair condition. Furthermore, average RMS EMGs of the external oblique (6.13±0.34 mv vs. 5.95±0.30 mv) (p=0.037), tibialis anterior (18.96±0.37 mv vs. 18.73±0.30 mv) (p=0.007), and soleus (9.58±0.65 mv vs. 8.70±1.10 mv) (p=0.018) were significantly higher in the REST condition than those in the Chair condition during a 10-sec interval. CONCLUSION: Using a REST device resulted in a significant increase in trunk motion. The elevated activities in trunk and leg muscles serve to maintain and control upper body posture. These biomechanical responses imply that people could assist in helping to establish an active lifestyle by using the REST device on a regular basis.

An Investigation Of Bilateral Differences In Emg Responses During Submaximal Arm Ergometry

PURPOSE: To determine bilateral differences in neuromuscular fatigue patterns in the Biceps Brachii (BB), Triceps (Tri), and Latissimus Dorsi (LD) muscle groups during arm cranking exercise. METHODS: A sample of 4 male and 4 female subjects (aged 22.2 ± 2.2 yrs) performed a submaximal arm cranking test for 10-minutes each @ 40% and 60% of the maximal workload attained previously, in randomized order. Oxygen consumption was determined continuously via indirect calorimetry. Mean EMG Root Mean Square (EMGRMS) was calculated for 10 epochs from 15-second recordings at each minute. Slope coefficients were determined and a 2-way repeated measures ANOVA was used to analyze the differences between exercise intensity and side (left vs. right) for each of the three muscle groups. RESULTS: Submaximal VO2 @ 60% (1.54 L·min-1 ± 0.2) was significantly greater (p ≤ 0.01) than the VO2 @ 40% (1.2 L·min-1 ± 0.2) indicating an expected energy cost difference. However, there were non-significant differences in EMGRMS for muscle (F=1.8, p≥ 1.0) and intensity (F=0.49, p ≥ 0.4). CONCLUSIONS: During submaximal arm ergometry at two different workloads, possible limb dominant asymmetries were not evident, indicating similar time-dependent acute neuromuscular adaptations for the three muscle groups studied.

The potential influence of stochastic resonance vibrations on neuromuscular strategies and center of pressure sway during single-leg stance

BackgroundStochastic resonance vibrations are known to enhance balance in the elderly and patients with impaired plantar sensation. However, the underlying mechanisms of plantar vibrations on balance capacity are not well resolved. This study investigated the impact of stochastic resonance vibrations on activities of major extrinsic foot muscles and center of pressure sway in tactile inhibited subjects. MethodsUsing a customized vibration insole, single-leg stance tests were performed in fourteen healthy subjects at control, ice-intervention-only (inhibited foot sensation) and ice-intervention plus vibration conditions. The sway parameters and the root mean square of electromyography of medial gastrocnemius, tibialis anterior, peroneus longus, and extensor digitorum longus were examined. FindingsThe sway area in the ice-intervention-only condition was significantly increased compared with the control (P < .001). Following vibrations, the sway area, however, was significantly decreased. Regression analysis showed the activity levels of all extrinsic foot muscles were positively correlated with sway area when foot sensation was inhibited. In contrast, following vibrations, only that of the tibialis anterior muscle was positively correlated with sway area, indicative of a muscle control strategy similar to the control condition. InterpretationThe study showed that stochastic resonance vibrations could effectively reduce body sway in the healthy subjects with inhibited foot sensation. The effects seemed to be associated with improved muscle activities in particular to the tibialis anterior muscle. It suggested that vibration insole may be used as a means to affect neuromuscular strategies to enhance balance control in people with diminished plantar sensations.

Effects of a low concentration of ropivacaine on maternal labor force during labor analgesia

Objective To investigate the effects of a low concentration of ropivacaine on the contraction of the uterine and abdominal muscles during labor analgesia. Methods One hundred and fifty primiparous women who expected to have a natural birth were selected. Then, 100 primiparous women were divided into two groups according to the random number table method: a 0.062 5% ropivacaine group (group ropivacaine, n=50) and a 0.062 5% levobupivacaine group (group levobupivacaine, n=50). Meanwhile, 50 primiparous women who did not take analgesic measures during vaginal delivery were set as a control group. Their age, body mass index(BMI), gestational age, cesarean section rate, forceps delivery rate, the duration of the first and second stages of labor, the rate of oxytocin use, and blood loss 2 h after delivery were recorded. The maternal pain was evaluated on the basis of Visual Analogue Scale (VAS) scores at the beginning of labor analgesia (T1), 15 min after labor analgesia (T2), 30 min after labor analgesia (T3) and 45 min after labor analgesia (T4). Then, the parameters of electromyography (EMG) burst wave energy were recorded, including the number and duration of burst waves, root mean square (RMS), and power and peak frequency, so as to comprehensively evaluate the contraction of the uterine and abdominal muscles. Results There was no significant difference in age, BMI, gestational age, cesarean section rate, forceps delivery rate, and blood loss 2 h after delivery among the three groups (P>0.05). Compared with groups control and ropivacaine, group levobupivacaine presented significantly extended duration of the first and second stages of labor, and marked increases in the rate of oxytocin use (P<0.05). Compared with group control, groups ropivacaine and levobupivacaine showed obviously decreased maternal VAS scores at T2, T3, and T4 (P<0.05). In the first stage of labor, compared with group control, the RMS of uterine muscle EMG in groups ropivacaine and levobupivacaine significantly reduced (P<0.05), compared with groups control and ropivacaine, the maternal power of group levobupivacaine significantly reduced (P<0.05). In the second stage of labor, compared with groups control and ropivacaine, group levobupivacaine presented significantly extended duration of EMG burst wave in the uterine muscle (P<0.05), compared with group control, groups ropivacaine and levobupivacaine showed significantly reduced RMS (P<0.05). Conclusions The use of 0.062 5% ropivacaine for epidural analgesia can achieve good effects, without significant impacts on maternal labor force, and does not prolong labor stage. Key words: Ropivacaine; Levobupivacaine; Labor analgesia; Electromyography; Labor stage

Analysis of the activation modalities of the lower limb muscles during walking.

Walking is a basic human activity and many orthopedic diseases can manifest with gait abnormalities. However, the muscle activation intervals of lower limbs are not clear. The aim of this study was to explore the contraction patterns of lower limb muscles by analyzing activation intervals using surface electromyography (SEMG) during walking. Four muscles including the tibialis anterior (TA), lateral gastrocnemius (LG), medial gastrocnemius (MG), and rectus femoris (RF) of bilateral lower extremity of 92 healthy subjects were selected for SEMG measurements. The number of activations (activation intervals) and the point of the highest root mean square (RMS) EMG signal in the percentage of the gait cycle (GC) were used to analyze muscle activities. The majority of TA and RF showed two activation intervals and both gastrocnemius parts three activation intervals during walking. The point of the highest RMS EMG signal in the percentage of the GC for TA, LG, MG and RF are 5%, 41%, 40%, and 8%, respectively. The activation intervals were mostly affected by age, height, different genders and bilateral limbs. This study identified the different activation intervals (four for each muscle) and the proportion of healthy adults in which they occurred during the normal gait cycle. These different activation intervals provided a new insight to evaluate the function of nerves and muscles. In addition, the activation interval and RMS peak time proposed in this study can be used as new parameters for gait analysis.

Effect of modified Gualou-Guizhi decoction combined with hyperbaric oxygen on muscle tension and motor function in stroke patients with spastic hemiplegia

Objective To observe the effect of modified Gualou-Guizhi decoction combined with hyperbaric oxygen on muscle tension and motor function in stroke patients with spastic hemiplegia. Methods A total of 70 stroke patients with spastic hemiplegia met the inclusion criteria were randomly divided into the observation group and the control group, with 35 in each group. The control group was given the conventional treatment and hyperbaric oxygen treatment, while the observation group was treated with Gualou-Guizhi decoction on the basis of the control group. Lindmark scale was used to assess limb motor function, Fugl-Meyer Assessment Scale (FMA) was used to assess the degree of limb motor dysfunction, and Modified Ashworth Scale (MAS) was used to assess muscle tension. The root mean square (RMS) and frequency median (FM) of surface electromyography of quadriceps femoris were measured by automatic electromyography, and the clinical efficacy was evaluate. Results The total effective rate of the observation group was 91.4% (32/35), and the total effective rate of the control group was 71.4% (25/35). The total effective rate of the 2 groups was statistically significant (χ2=4.629, P=0.0314). After treatment, the scores of motor coordination ability and sensory function in the observation group were significantly higher than those in the control group (t value were 5.936, 5.182, all Ps<0.05), the FMA scores of upper and lower limbs were significantly higher than those in the control group (t value were 12.310, 11.996, all Ps<0.01), and the score of improved Ashworth muscle strength scale was significantly lower than that in the control group (t=5.083, P=0.031). After treatment, the EMG RMS (79.13 ± 7.02 vs. 68.45 ± 7.01 , t=5.697), FM (99.31 ± 9.65 Hz vs. 90.73 ± 9.49 Hz, t=5.382) of the observation group were significantly higher than those of the control group (P<0.05). Conclusions The application of Gualou-Guizhi decoction add and subtract combined with hyperbaric oxygen on muscle tension and motor function in stroke patients with spastic hemiplegia can improve the muscle strength of stroke hemiplegic patients and improve the motor dysfunction of the patients, which can help to promote the recovery of the movement function of the patientst. Key words: Stroke; Spasm; Hemiplegia; Muscle tonus; Dyskinesias; Gualou-Guizhi decoction; Medicinal bath lotions; Hyperbaric oxygenation

The audio-visual integration effect on music emotion: Behavioral and physiological evidence.

Previous research has indicated that, compared to audio-only presentation, audio-visual congruent presentation can lead to a more intense emotional response. In the present study, we investigated the audio-visual integration effect on emotions elicited by positive or negative music and the role of visual information presentation durations. The participants were presented with audio-only condition, audio-visual congruent condition, and audio-visual incongruent condition and then required to judge the intensity of emotional experience elicited by the music. Their emotional responses to the music were measured using self-ratings and physiological aspects, including heart rate, skin temperature, EMG root mean square and prefrontal EEG. Relative to the audio-only presentation, the audio-visual congruent presentation led to a more intense emotional response. More importantly, the audio-visual integration occurred both in the positive music and in the negative music. Furthermore, the audio-visual integration effect was larger for positive music than for negative music; meanwhile the audio-visual integration effect was strongest with the visual information presented within 80s for negative music, which indicated that this integration effect was more likely to occur in the negative music. These results suggest that when the music was positive, the effect of audio-visual integration was greater. When the music was negative, the modulation effect of the presentation durations of visual information on the music-induced emotion was more significant.

Partial Range of Motion Exercise Is Effective for Facilitating Muscle Hypertrophy and Function Through Sustained Intramuscular Hypoxia in Young Trained Men.

Goto, M, Chikako, M, Hirayama, T, Terada, S, Nirengi, S, Kurosawa, Y, Nagano, A, and Hamaoka, T. Partial range of motion exercise is effective for facilitating muscle hypertrophy and function through sustained intramuscular hypoxia in young trained men. J Strength Cond Res 33(5): 1286-1294, 2019-The acute response to and long-term effects of partial range of motion exercise (PRE) and full range of motion exercise (FRE) of elbow extensors were compared in young trained men. The PRE was expected to increase the intramuscular hypoxic environment, which was theorized to enhance muscular hypertrophy. Forty-four resistance-trained men were divided into 2 training groups, PRE (n = 22) or FRE (n = 22) group, and performed the PRE or FRE acute exercise protocol. The PRE (elbow range from 45° to 90°) and FRE (from 0° to 120°) acute protocols consisted of 3 sets of 8 repetitions, with an 8RM, and an equivalent workload. After the initial testing, the training program for each group, comprised 3 training sessions per week for 8 weeks, was started. The acute responses of area under the oxygenated hemoglobin (Oxy-Hb) curve, blood lactate concentration, and root mean square of electromyography were significantly higher both before and after PRE than FRE training. Long-term effects were produced by both PRE and FRE, with significant (p ≤ 0.05) increases in cross-sectional area (CSA) of triceps brachii and isometric strength. The CSA increased significantly greater after PRE (48.7 ± 14.5%) than after FRE (28.2 ± 10.9%). Furthermore, during the PRE program, a positive correlation was detected between the percent increase in CSA and area under the Oxy-Hb curves before and after 8-week exercise training (before 8-week exercise training: r = 0.59, after 8-week exercise training: r = 0.70, p < 0.01). These results suggest that intramuscular hypoxia might facilitate muscular hypertrophy with PRE being more effective than FRE.

Measurement of Uterine and Abdominal Muscle Electromyography in Pregnant Women for Estimation of Expulsive Activities during the 2nd Stage of Labor

Background: The progression of labor and delivery of the fetus is dependent upon uterine contractions and the voluntary effort of abdominal muscle contractions. A good monitor of uterine contractions and pushing is necessary for obstetrical care. Electromyography (EMG) is the underlying basis for contractility of muscle including the myometrium. Objectives: The aim of this study was to determine the relationship between EMG activity of uterine and abdominal muscles and the duration of the 2nd stage of labor in pregnant women. Methods: EMG of both uterine and abdominal muscles was simultaneously recorded from electrodes placed on the abdominal surface of 45 active 2nd stage-laboring nulliparous patients. EMG was recorded using filters to separate uterine and abdominal EMG signals, and various EMG signal parameters were analyzed. The duration of the 2nd stage of labor and other maternal and fetal characteristics were also recorded. Results: Uterine EMG bursts precede abdominal bursts and are accompanied by feelings of “urge to push” by the patients. Abdominal root mean square (RMS) and power, but not uterine EMG parameters, are reduced (p< 0.005) in patients with longer labors and linear regression analysis demonstrated a negative correlation to the duration of 2nd stage of labor (p < 0.001). Multivariate linear regression analysis of clinical characteristics (fetal weight, body mass index, placental location, etc.) and parameters of EMG showed that only abdominal RMS is negatively correlated with the duration of labor. Conclusions: (1) Uterine and abdominal EMG activities reflect the expulsive involuntary (uterine) and voluntary (abdominal) muscular activities during the 2nd stage of labor. (2) RMS and power of abdominal EMG diminish with longer labor when uterine EMG intensities are similar. (3) Recording of uterine and abdominal muscle activity provides objective evaluation of the muscle activity during the 2nd stage of labor and may aid in the evaluation of any interventions.

Can Postural Instability in Individuals with Distal Radius Fractures Be Alleviated by Concurrent Cognitive Tasks?

Can Postural Instability in Individuals with Distal Radius Fractures Be Alleviated by Concurrent Cognitive Tasks?