Electromyographic Activity Research Articles

Functional involvement of the sternohyoid muscle during breathing and swallowing in rats.

The sternohyoid muscle depresses the hyoid bone, but it is unclear whether the muscle contributes to respiratory and swallowing mechanisms. This study aimed to clarify whether the sternohyoid muscle participates in the respiration and swallowing reflex and how the activity is modulated in two conditions: with airway stenosis and with a fixed sternohyoid muscle length. Electromyographic activity in the sternohyoid, digastric, thyrohyoid, and diaphragm muscles was recorded in anesthetized rats. The sternohyoid muscle activity was observed in the inspiratory phase and during swallowing, and was well coordinated with digastric and thyrohyoid muscle activity. With airway stenosis, the respiratory activity per respiratory cycle was facilitated in all assessed muscles but the facilitation of activity per second occurred only in the digastric, thyrohyoid, and sternohyoid muscles. With airway stenosis, the swallowing activity was facilitated only in the digastric muscle but not in the thyrohyoid and sternohyoid muscles. Swallowing activity was not observed in the sternohyoid muscle in the condition with the sternohyoid muscle length fixed, although increased inspiratory activity remained. The current results suggest that 1) the sternohyoid muscle is slightly activated in the inspiratory phase, 2) the effect of airway stenosis on respiratory function may differ between the upper airway muscles and diaphragm, and 3) swallowing activity in the sternohyoid muscle is not dominantly controlled by the swallowing central pattern generator but instead occurs as a myotatic reflex.NEW & NOTEWORTHY We found that the sternohyoid muscle was activated in the inspiratory phase. However, increased airway resistance had different effects on the extrathoracic muscles than on the diaphragm. The swallowing activity of the sternohyoid disappeared when the muscle length was fixed. These findings suggest that the sternohyoid muscle may be activated not by the swallowing central pattern generator but as a myotatic reflex.

Comparative analysis of elevated and floor push-up exercises for activation of the pectoralis major muscle

This study aimed to measure muscle activation by comparing electromyography (EMG) of two types of pushups i.e., ground-based and elevated. 20 male active sportspersons (age 20.12±3.57years, weight 65.38±9.32kg, height 175.5±10.5cm) were recruited in the study. The upper body muscle pectoralis major (PM) was chosen as target muscle for the study. Root mean square (RMS) of EMG activities were analysed for the PM muscle to determine maximum muscle involvement. In the elevated pushups, the samples performed the pushups on an elevated pushup bar of 18-centimeter height, in which they gripped the bar as per their shoulder width. Also, their feet were ground-based on a similar height platform. The paired t-test was used as the statistical tool to compare the EMG activation of PM between both variations of pushups. Further, mean and standard deviation values were considered for descriptive statistics. The level of significance was set at 0.05. The result of the study showed that there was no statistically significant difference in EMG activities of PM muscle between the two pushup variations with a t-value of -0.89. However, the descriptive statistics showed that the mean value of elevated pushups (RMS, 350.63) was higher than the grounded pushups (RMS, 311.44). These findings suggest elevated pushups may induce greater PM muscle activation, potentially due to increased instability due to the influence of elveated exercise variations on muscle engagement. Key words: pushups, muscle activation, electromyography, pectoralis major, exercise variations, root mean square

First In Vivo Electromyographic Analysis of Mechanical Load Scenarios of the Cervicothoracic Junction During Daily Activities as a Basis for Future Postoperative Behavioral Instructions.

Clinical Research. Study participants were twenty- eigth healty volunteers. Soft tissue complications after posterior cervicothoracic fusion surgery occur frequently. Postoperative myofascial dehiscence (PMD) can cause disability and pain. So far, it is unknown whether patients can affect PMD development through behavioral adjustment. Consequently, this study aimed to analyze how much mechanical stress daily activities exert on the posterior muscles and fascia at the cervicothoracic junction. Surface electromyography was applied next to the upper thoracic spine at the trapezius muscle. All volunteers performed 22 different daily activities, such as tooth brushing, dressing, standing up, and different horizontal positions. During the exercises, the electromyographic activity was measured. For each volunteer, root mean square values were determined. All exercises were then repeated with the use of a clavicular bandage to unload the shoulder and cervicothoracic muscles. Afterwards, the rankings were statistically compared interindividually. Among the different tasks, significant differences in regard to the root mean square values were noted. For instance, horizontal positions caused significantly lower muscle activation compared with all other exercises (P≤ 0.001). Notably, no relevant electromyographic differences were detected between the tasks with and without a clavicular bandage. This in vivo electromyographic analysis of cervicothoracic muscle activity during daily activities demonstrates that myofascial strain differs among various daily activities. Data indicate that potential postoperative mobilization protocols and behavioral instructions may have the potential to reduce the biomechanical load and consequently the risk of PMD and, therefore, may reduce the risk for surgical wound-related complications, disability, and need for revision surgery.

Assessment of arthrogenic quadriceps muscle inhibition by physical examination in the supine position during isometric contraction is feasible as demonstrated by electromyography: a cross-sectional study

BackgroundPreventing severe arthrogenic muscle inhibition (AMI) after knee injury is critical for better prognosis. The novel Sonnery-Cottet classification of AMI enables the evaluation of AMI severity but requires validation. This study aimed to investigate the electromyography (EMG) patterns of leg muscles in the examination position from the classification during isometric contraction to confirm its validity. We hypothesised that the AMI pattern, which is characterised by quadriceps inhibition and hamstring hypercontraction, would be detectable in the supine position during isometric contraction.MethodsPatients with meniscal or knee ligament injuries were enrolled between August 2023 and May 2024. Surface EMG was assessed during submaximal voluntary isometric contractions (sMVIC) at 0° extension in the supine position for the vastus medialis (VM) and vastus lateralis (VL) muscles and at 20° flexion in the prone position for the semitendinosus (ST) and biceps femoris (BF) muscles. Reference values for normalisation were obtained from the EMG activity during the gait of the uninjured leg. The Kruskal–Wallis test was used to compare the activation patterns of the muscle groups within the same leg, and the post-hoc tests were conducted using the Mann–Whitney U test and Bonferroni correction.ResultsElectromyographic data of 40 patients with knee injuries were analyzed. During sMVIC, the extensor and flexor muscles of the injured leg showed distinct behaviours (P < 0.001), whereas the uninjured side did not (P = 0.144). In the injured leg, the VM differed significantly from the ST (P = 0.018), and the VL differed significantly from the ST and BF (P = 0.001 and P = 0.026, respectively). However, there were no statistically significant differences within the extensor muscle groups (VM and VL, P = 0.487) or flexor muscle groups (ST and BF, P = 0.377).ConclusionAMI was detectable in the examination position suggested by the Sonnery-Cottet classification. The flexor and extensor muscles of the injured leg exhibited distinct activation behaviours, with inhibition predominantly occurring in the quadriceps muscles, whereas the hamstrings showed excitation.

Biofeedback-Assisted pelvic floor muscle training combined with a short-duration drug regimen is safe and effective in women with overactive bladder: A randomized controlled trial

ObjectiveWe hypothesized that combination therapy would provide a synergistic effect to improve treatment outcomes for overactive bladder (OAB), thus enhancing the motivation for continuous exercise, and that it would be associated with fewer adverse events than monotherapy. Therefore, we investigated whether biofeedback-assisted pelvic floor muscle training (PFMT), drug therapy, or a combination of both would be more effective in improving the symptoms of OAB. Study DesignThis randomized controlled trial included women diagnosed with OAB. Group 1 received biofeedback-assisted pelvic muscle floor training (PFMT) for 12 weeks; group 2 took 5 mg of solifenacin/day for 12 weeks; and group 3 received 5 mg of solifenacin/day in combination with biofeedback-assisted PFMT during the first 4 weeks and biofeedback-assisted PFMT for another 8 weeks. All participants had 5 follow-up visits. The primary outcomes were objective improvement of OAB symptoms and quality of life. The secondary outcomes were treatment-related adverse events, subjective improvement of OAB symptoms, and electromyographic activity of pelvic floor muscle (PFM) contraction. ResultsAll participants reported significant improvement of OAB symptoms and quality of life. Participants in group 2 experienced more pronounced adverse events than those in group 3. Intervention duration was positively associated with subjective improvement in OAB symptoms in groups 2 and 3. Drug-related adverse events, including dry mouth, myalgia, and restlessness, had a negative impact on the subjective improvement of OAB symptoms in group 2. In group 1, exercise adherence was positively correlated with subjective improvement of OAB symptoms, whereas in group 3, PFM contraction and biofeedback effect were positively correlated with symptom improvement. ConclusionCombination therapy is efficacious in treating women with OAB.

A Holistic Focus of Attention Increases Torque Production and Electromyography Activity in an Isokinetic Elbow Flexion

Recent research suggests that both a holistic focus of attention (i.e., focusing on the general feeling of a movement) and an external focus of attention improve motor performance relative to an internal focus of attention. The purpose of this study was to determine how a holistic, internal, and external focus impacts torque production and electromyography (EMG) activity in the biceps brachii during an isokinetic elbow flexion task. Twenty-four young adults completed five repetitions of an isokinetic elbow flexion task in internal, external, and holistic focus conditions. Peak torque, integrated torque, peak EMG amplitude, integrated EMG, and neuromuscular efficiency were averaged across trials in each condition. Peak torque, integrated torque, peak EMG amplitude, and integrated EMG were all significantly higher with a holistic focus than an internal or external focus. Internal and external focus conditions did not differ from each other in any variable. No differences due to focus were observed for neuromuscular efficiency. The present results suggest that using a holistic focus of attention can be a useful strategy for motor tasks requiring peak force production. However, it does not appear that this benefit is related to increased neuromuscular efficiency, as we hypothesized.

Sex-related differences in corticospinal excitability outcomemeasures of the biceps brachii during a submaximal elbow flexor contraction.

The purpose of this study was to investigate the effects of sex, muscle thickness, and subcutaneous fat thickness (SFT) on corticospinal excitability outcome measures of the biceps brachii. Eighteen participants (10 males and 8 females) completed this study. Ultrasound was used to assess biceps brachii muscle thickness and the overlying SFT. Transcranial magnetic stimulation (TMS) was used to determine corticospinal excitability by inducing motor-evoked potentials (MEPs) at eight different TMS intensities from 90% to 160% of active motor threshold (AMT) from the biceps brachii during an isometric contraction of the elbow flexors at 10% of maximum voluntary contraction (MVC). Biceps brachii maximal compound muscle action potential (Mmax) was also recorded prior to and after TMS. Males had higher (p < 0.001) biceps brachii muscle thickness and lower SFT, produced higher levels of MVC force and had, on average, higher (p < 0.001) MEP amplitudes at lower (p < 0.05) percentages of maximal stimulator output than females during the 10% elbow flexion MVC. Multiple linear regression modeling revealed that sex was not associated with any of the neurophysiological parameters examined, while SFT showed a positive association with the stimulation intensity required at AMT (p = 0.035) and a negative association with biceps brachii pre-stimulus electromyography (EMG) activity (p = 0.021). Additionally, there was a small positive association between muscle thickness and biceps brachii pre-stimulus EMG activity (p = 0.049). Overall, this study suggests that some measures of corticospinal excitability may be different between the sexes and influenced by SFT and muscle thickness.

Linking in vivo muscle dynamics to force-length and force-velocity properties reveals that guinea fowl lateral gastrocnemius operates at shorter than optimal lengths.

The isometric force-length (F-L) and isotonic force-velocity (F-V) relationships characterize the contractile properties of skeletal muscle under controlled conditions, yet it remains unclear how these properties relate to in vivo muscle function. Here, we map the in situ F-L and F-V characteristics of guinea fowl (Numida meleagris) lateral gastrocnemius (LG) to the in vivo operating range during walking and running. We test the hypothesis that muscle fascicles operate on the F-L plateau, near the optimal length for force (L0) and near velocities that maximize power output (Vopt) during walking and running. We found that in vivo LG velocities are consistent with optimizing power during work production, and economy of force at higher loads. However, LG does not operate near L0 at higher loads. LG length was near L0 at the time of electromyography (EMG) onset but shortened rapidly such that force development during stance occurred on the ascending limb of the F-L curve, around 0.8L0. Shortening across L0 in late swing might optimize potential for rapid force development near the swing-stance transition, providing resistance to unexpected perturbations that require rapid force development. We also found evidence of in vivo passive force rise in late swing, without EMG activity, at lengths where in situ passive force is zero, suggesting that dynamic viscoelastic effects contribute to in vivo force development. Comparison of in vivo operating ranges with F-L and F-V properties suggests the need for new approaches to characterize muscle properties in controlled conditions that more closely resemble in vivo dynamics.

Does a Hip Muscle Activation Home Exercise Program Change Movement Patterns on the Forward Step-Down Test?

Poor knee biomechanics contribute to knee joint injuries. Neuromuscular control over knee position is partially derived from the hip. It is unknown whether isolated activation training of the gluteal muscles improves lower-extremity frontal plane mechanics. This study examined if a home-based hip muscle activation program improves performance on the Forward Step-Down Test as well as increases surface electromyography (sEMG) activation of the gluteal muscles. The study utilized a single-group repeated-measures design. Thirty-five participants (24 females, mean age = 23.17 [SD 1.36] years) completed an 8-week hip muscle activation program. The Forward Step-Down Test score and sEMG of gluteus maximus and medius were assessed preintervention and postintervention. Forward Step-Down Test scores improved significantly from preintervention (Mdn = 3.5) to postintervention (Mdn = 3.0, T = 109, P = .010, r = .31.), but this result did not meet clinical significance. sEMG analysis revealed a significant increase in mean gluteus maximus activation (P = .028, d = 1.19). No significant dose-response relationship existed between compliance and the Forward Step-Down Test scores or sEMG results. A home-based hip activation program increases gluteus maximus activation without clinically significant changes in frontal plane movement quality. Future studies may find clinical relevance by adding motor learning to the activation training program to improve functional muscle use.

Airway mechanics alters generation of cough motor pattern.

Effects of sequential increase in airway resistance: no, low (5 kPa.s/l), high (24 kPa.s/l), and complete block in the inspiratory or expiratory phase of mechanically induced cough on the cough motor pattern were studied in 16 anesthetized (pentobarbital) spontaneously breathing cats (3.70±0.15 kg, 11♂, 5♀). Esophageal pressure and electromyographic activities of the diaphragm during inspiration and abdominal muscles during expiration were analyzed. No significant changes in the number of coughs occurred. Inspiratory occlusion caused a prolongation of cough inspiratory phase, cough inspiratory diaphragm activity, and all cough-related activity. Inspiratory occlusion along with high resistance increased inspiratory esophageal pressure amplitude, total cough cycle duration and the time between maximum activity of the diaphragm and abdominal muscles. High expiratory resistance and occlusion resulted in increased cough expiratory esophageal pressure amplitude, a longer active portion of cough expiration, and cough abdominal activity. Expiratory occlusion also prolonged cough expiratory phase, all cough activity, and total cough cycle. Significantly increased airway resistance and occlusion induce secondary, in addition to mechanical, changes in cough by significantly modulating the generated cough motor pattern. A certain level of resistance appears to be successfully compensated, resulting in minimal changes in coughing characteristics, including expiratory airflow and the rising time of the airflow. Afferent feedback from the respiratory tract, particularly volume feedback, represents a significant factor in modulating cough, mainly under various pathological conditions in the respiratory system.

Effects of unstable load and unstable surface ontrunk muscles activation and postural control in healthy subjects

Exercise with an unstable load is considered a new training method to activate the core muscles. Research has shown consistency regarding an unstable surface but has not provided comprehensive findings about the effect of an unstable load. The study aimed to examine the impact of an unstable load and unstable surfaces on core muscle activation and postural control during lifting. Thirty-eight participants lifted a load equivalent to 10 % of their body weight under three conditions: a stable load on an unstable surface, a stable load on a stable surface, and an unstable load on a stable surface. The center of pressure (COP) displacement and electromyography activity of abdominal and back extensor muscles were measured during lifting. The results indicated that lifting on an unstable surface activated the lumbar erector spinae and multifidus muscles more than in a stable condition (P<0.05). However, there was no significant difference in the level of thoracic erector spinae muscle activity between the unstable load and unstable surface conditions. The stable condition increased activity in the internal oblique muscle (1.37 times) compared to the unstable conditions. The analysis of postural control revealed that lifting the load on an unstable surface significantly decreased COP displacement in the anteroposterior direction (P<0.05), while holding the load on the unstable surface significantly increased COP displacement in the anteroposterior direction compared to the other conditions. These findings could be valuable for future rehabilitation research, learning appropriate lifting techniques, and setting specific training goals in sports.

A comparison of foot and ankle biomechanics during running drills and distance running

ABSTRACT The aim of this study was to compare the foot-ankle joint mechanics of running drills and running. Seventeen long-distance runners performed five popular running drills (A-skip, B-skip, Bounding, Heel flicks, Straight leg running) and a run at 3.88 m/s. Kinematics, kinetics and power values were calculated for the ankle, midtarsal (MT) and metatarsophalangeal (MP) joints. Electromyographic activity was recorded for the soleus, gastrocnemius medialis, lateralis and abductor hallucis muscle. The A-skip, the B-skip and the Heel flicks induced a smaller ankle (p < 0.001, ŋ2 = 0.41), MT (p < 0.001, ŋ2 = 0.43) and MP (p < 0.001, ŋ2 = 0.47) dorsiflexion peak than running. No difference was found between the running drills and running for ankle, MT and MP moment. The Bounding induces a higher positive ankle power than running (diff: 5.5 ± 7.5 J/kg, p = 0.014, d = 1.05). The A-skip (diff: 2.8 ± 2.9 J/kg, p < 0.001, d = 1.5) and the B-skip (diff: 2.7 ± 2.1 J/kg, p < 0.001, d = 1.4) induce a smaller MT positive power than running. This study offers an analysis of the mechanical behaviour of the foot-ankle complex to help track and field coaches select their running drills in an evidence-based manner.

The effects of verbal cues on EMG activity during a quadriceps setting exercise.

A quadriceps setting (quad set) exercise is commonly utilized following knee injury, but there is great variation in cues that clinicians provide to patients when performing the exercise. To determine if internal, external, or visual cues results in the greatest quadriceps electromyographical (EMG) activity during a quadriceps setting exercise in healthy individuals. Descriptive laboratory study. University research laboratory. Thirty healthy individuals volunteered for this study. Participants were given one of five cues in a randomized order: internal cue "tighten your thigh muscles," internal cue "push your knee down," external cue "push into the bolster," external cue "push into the strap," or visual biofeedback using the cue "raise the value on the screen as high as you can." Normalized vastus lateralis EMG activity. Both visual biofeedback (83.2±24.9%) and "press into the strap" (76.8±24.4%) produced significantly greater (p< 0.001) EMG activity than the push knee down (53.2±27.0%), tighten thigh (52.7±27.3%), or push into the bolster (50.8±26.3) conditions. There was no significant difference (p= 0.10) between the visual biofeedback and "press into the strap" conditions as well as no significant difference (p> 0.38) between the push knee down, tighten thigh, or push into the bolster conditions. If the clinical aim during a quadriceps setting exercise is to obtain the greatest volitional muscle recruitment, the use of visual biofeedback or pressing into a strap is recommended.

Potential of a New, Flexible Electrode sEMG System in Detecting Electromyographic Activation in Low Back Muscles during Clinical Tests: A Pilot Study on Wearables for Pain Management.

While low back pain (LBP) is the leading cause of disability worldwide, its clinical objective assessment is currently limited. Part of this syndrome arises from the abnormal sensorimotor control of back muscles, involving increased muscle fatigability (i.e., assessed with the Biering-Sorensen test) and abnormal muscle activation patterns (i.e., the flexion-extension test). Surface electromyography (sEMG) provides objective measures of muscle fatigue development (median frequency drop, MDF) and activation patterns (RMS amplitude change). This study therefore assessed the sensitivity and validity of a novel and flexible sEMG system (NSS) based on PEVA electrodes and potentially embeddable in textiles, as a tool for objective clinical LBP assessment. Twelve participants wearing NSS and a commercial laboratory sEMG system (CSS) performed two clinical tests used in LBP assessment (Biering-Sorensen and flexion-extension). Erector spinae muscle activity was recorded at T12-L1 and L4-L5. NSS showed sensitivity to sEMG changes associated with fatigue development and muscle activations during flexion-extension movements (p < 0.05) that were similar to CSS (p > 0.05). Raw signals showed moderate cross-correlations (MDF: 0.60-0.68; RMS: 0.53-0.62). Adding conductive gel to the PEVA electrodes did not influence sEMG signal interpretation (p > 0.05). This novel sEMG system is promising for assessing electrophysiological indicators of LBP during clinical tests.

Influence of restricted mastication on swallowing function.

Oral food processing is an important part of daily food intake. A major part of this process is mastication, which prepares a bolus of food for swallowing by mechanically crushing and grinding ingested food between the teeth using rhythmic movements. Masticatory dysfunction is common in the elderly and in some neurological disorders and can have serious negative health consequences. This study investigated the effect of restricted mastication, achieved by experimentally reducing the duration of mastication, on masticatory patterns and subsequent swallowing function. Thirty healthy men (25 ± 3 years old) were instructed to chew gum jelly with a free mastication duration (G100), a half and a quarter duration of G100. Masseter and digastric electromyographic (EMG) activity was recorded to assess mastication and swallowing activity, respectively. In addition, the acceleration of the thyroid cartilage ridge was measured with an accelerometer. The root mean square (RMS) of muscle EMG activity in the masseter and digastric muscles, the number of masseter EMG bursts, time to peak and total duration of each masseter EMG burst, swallowing duration and laryngeal elevation latency were analysed. Restricting masticatory duration reduced the number of mastication cycles (p < .001), prolonged the time to peak (p < .001) and total duration of masseter EMG bursts (p < .001) and resulted in an overall increased RMS score of masseter muscle activity (p = .017). Furthermore, restricted masticatory duration led to a decrease in both swallowing duration (p = .001) and laryngeal elevation latency (p = .012), with a significant increase in the RMS score of digastric muscle activity (p < .001). Under the experimental conditions of restricted mastication, several adaptation features were observed, including changes in masticatory cycle characteristics and swallowing duration. Thus, although the overall masticatory efficiency was reduced, these adaptations allowed healthy individuals to still swallow safely.

Stochastic electrical stimulation of the thoracic or cervical regions with surface electrodes facilitates swallow in rats.

Aspiration pneumonia, a leading cause of mortality, poses an urgent challenge in contemporary society. Neuromuscular electrical stimulation (NMES) has been commonly used in dysphagia rehabilitation. However, given that NMES at motor threshold targets only specific muscles, it carries a potential risk of further compromising functions related to swallowing, respiration, and airway protection. Considering that the swallow motor pattern is orchestrated by the entire swallow pattern generator (the neural mechanism governing a sequence of swallow actions), a rehabilitation approach that centrally facilitates the entire circuit through sensory nerve stimulation is desirable. In this context, we propose a novel stimulation method using surface electrodes placed on the back to promote swallowing. The efficacy of the proposed method in promoting swallowing was evaluated by electrically stimulating sensory nerves in the back or neck. Probabilistic stimulus was applied to either the back or neck of male and female rats. Swallows were evoked by an oral water stimulus, and electromyographic (EMG) activity of the mylohyoid, thyroarytenoid, and thyropharyngeus muscles served as the primary outcome measure. Gaussian frequency stimulation applied to the skin surface of the thoracic back elicited significant increases in EMG amplitude of all three swallow-related muscles. Neck stimulation elicited a significant increase in EMG amplitude of the thyroarytenoid during swallow, but not the mylohyoid or thyropharyngeus muscles. While the targeted thoracic spinal segments T9-T10 have been investigated for enhancing respiration, the promotion of swallowing through back stimulation has not been previously studied. Furthermore, this study introduces a new probabilistic stimulus based on Gaussian distribution. Probabilistic stimuli have been reported to excel in nerve stimulation in previous research. The results demonstrate that back stimulation effectively facilitated swallow more than neck stimulation and suggest potential applications for swallowing rehabilitation.

The effects of combining sensorimotor training with transcranial direct current stimulation on the anticipatory and compensatory postural adjustments in patients with chronic low back pain

Purpose To investigate the effects of concurrent sensorimotor training (SMT) and transcranial direct current stimulation (tDCS) on the anticipatory and compensatory postural adjustments (APAs and CPAs) in patients with chronic low back pain (CLBP). Method The interventions included (1) SMT plus tDCS and (2) SMT plus sham tDCS. Outcome measures were the normalized integrals of electromyography activity (NIEMG) during the phases of anticipatory and compensatory, and muscle onset latency. The investigated muscles were ipsilateral and contralateral multifidus (MF), transversus abdominus/internal oblique (TrA/IO), and gluteus medius (GM). Results Between-group comparisons demonstrated that ipsilateral TrA/IO NIEMG during CPA1 (p = 0.010) and ipsilateral GM NIEMG during CPA1 (p = 0.002) and CPA2 (p = 0.025) were significantly lower in the SMT combined with tDCS than in the control group. Furthermore, this group had greater NIEMG for contralateral GM during APA1 than the control group (p = 0.032). Moreover, the onset latency of contralateral TrA/IO was significantly earlier after SMT combined with tDCS (p = 0.011). Conclusions Both groups that received SMT showed positive effects, but anodal tDCS had an added value over sham stimulation for improving postural control strategies in patients with CLBP. Indeed, SMT combined with tDCS leads to stronger APA and less demand for CPA. RCT registration number IRCT20220228054149N1 Registration date 2022-04-04

Could the anterior cruciate ligament reconstruction and pronated feet affect the plantar pressure variables and muscular activity during running? A comparative study

The unilateral anterior cruciate ligament reconstruction can create asymmetry in vertical ground reaction force and muscle activities, which could be amplified by pronated feet. The study compared plantar pressure variables, amplitude, and muscular frequency in individuals with pronated feet and anterior cruciate ligament reconstruction (PF/ACLR) versus control during running. As part of a cross-sectional study, 15 individuals with PF/ACLR (aged 23.2 ± 4.5 years) and 15 healthy control participants (aged 22.9 ± 4.1 years) ran barefoot at a speed of 3.3 m/s±5% on an 18-m runway. During running, a foot scan and electromyography systems were used to record the peak plantar pressure variables and electromyography activity of the main lower limb muscles, respectively. Results demonstrated lower peak plantar pressure values at the Toe 1 region (p < 0.001, d = 1.83) for the PF/ACLR group. The PF/ACLR group had larger peak plantar pressure values at toes second to fifth (p = 0.013, d = 1.15), fourth (p = 0.026, d = 0.97), fifth (p < 0.001, d = 1.74) metatarsal, and medial (p = 0.002, d = 1.41), and lateral (p = 0.001, d = 1.51) heel regions. The PF/ACLR group presented larger tibialis anterior (p = 0.003, d = 1.15), vastus lateralis (p = 0.001, d = 1.27), and gluteus medius (p = 0.009, d = 0.60) amplitude at the loading phase. At the mid-stance phase, larger tibialis anterior (p = 0.039, d = 0.99) and vastus lateralis (p = 0.00.024, d = 1.52) amplitudes were observed. For the push-off phase, the PF/ACLR group presented larger vastus medialis (p = 0.037, d = 0.82), biceps femoris (p = 0.004, d = 1.14), and semitendinosus (p = 0.001, d = 0.96) amplitudes. Our results demonstrated that pronated feet and anterior cruciate ligament reconstruction significantly impact plantar pressure variables and muscular amplitude in the lower limb during running.

Firefighters' muscle activity change during firefighting training program.

Research on muscle activity to reduce injuries during firefighting training has getting increasing attention. The purpose of this study was to assess the activity changes in nine muscles of firefighters during the seven firefighting training programs, and to analyze the influence of different firefighting training programs on muscle activity. Ten healthy male firefighters were recruited to measure the field surface electromyographic activities (including the percentage of Maximum Voluntary Contraction electromyography (% MVC) and the integrated electromyography value (iEMG)) during all the firefighting training programs. The results showed that the electromyographic activity of gastrocnemius (GA) was stronger in climbing the hooked ladder and climbing the six-meter long ladder training programs. Arms, shoulders, and lower limb muscles were more activated, myoelectric activities were more intense, and fatigue in these areas was more likely to occur during climbing five-story building with loads. Compared with other muscles, erector spine (ES) had a higher degree of activation during different postures of water shooting. The Borg scale scores of shoulders, trunk, thighs and calves were also higher. After completing all training programs, GA, tibialis anterior (TA), trapezius (TR), and ES were strongly activated, and all muscles had obvious force. The % MVC and iEMG analyses correspond well with the Borg Scale score. The results can provide certain reference for reducing the musculoskeletal injury of firefighters, carrying out scientific training and formulating effective injury prevention measures for them.

Motor effects of fentanyl in isoflurane-anaesthetized pigs and the subsequent effect of ketanserin or naloxone

ObjectiveTo examine the effect of ketanserin and naloxone on fentanyl-induced motor activity in isoflurane-anaesthetized pigs. Study designRandomized, blinded, prospective two-group study. AnimalsA group of 12 crossbred pigs weighing 22–31 kg. MethodsFentanyl was administered to isoflurane-anaesthetized pigs at 7.5 μg kg–1 hour–1 for 40 minutes intravenously, followed by an intravenous injection of naloxone 0.1 mg kg–1 or ketanserin 1 mg kg–1. Electromyography (EMG) and accelerometry were used to record motor unit activity and tremors, respectively. To test the effect of drug administration on motor activity, data from a 5 minute period at baseline, immediately before and after antagonist injection were compared in a mixed model; p < 0.05. ResultsResults are reported with the median difference, 95% confidence intervals and corresponding p-values in brackets. Fentanyl significantly increased EMG activity [30.51 (1.84–81.02) μV, p = 0.004] and induced tremors [0.09 (0.02–0.18) m s–2, p < 0.001] in 10 of 12 pigs. Ketanserin significantly reduced EMG [32.22 (6.29–136.80) μV, p = 0.001] and tremor [0.10 (0.03–0.15) m s–2, p = 0.007] activity. No significant effect was found for naloxone on EMG [26.76 (–13.28–91.17) μV, p = 0.4] or tremors [0.08 (–0.01–0.19) m s–2, p = 0.08]. Conclusions and clinical relevanceFentanyl can induce motor activity in anaesthetized pigs, with a suggested link to the serotonergic system. This study shows that ketanserin can antagonize this activity, which supports the role of serotonin. This knowledge contributes to the general understanding of the motor effects of fentanyl and especially the problem of tremors in anaesthetized pigs.