Muscle Activity Research Articles

Low-load Resistance Exercise with Perceptually Primed Practical Blood Flow Restriction Induces Similar Motor Performance Fatigue, Physiological Changes, and Perceptual Responses Compared to Traditional Blood Flow Restriction in Males and Females

In the recent past, practical blood flow restriction (pBFR) using non-pneumatic, usually elastic cuffs has been established as a cost-effective alternative to traditional blood flow restriction (BFR) using pneumatic cuffs, especially for training in large groups. This study investigated whether low-load resistance exercise with perceptually primed pBFR using an elastic knee wrap is suitable to induce similar motor performance fatigue as well as physiological and perceptual responses compared to traditional BFR using a pneumatic nylon cuff in males and females. In a randomized, counterbalanced cross-over study, 30 healthy subjects performed 4 sets (30-15-15-15 repetitions) of unilateral knee extensions at 20% of their one-repetition-maximum. In the pBFR condition, each individual was perceptually primed to a BFR pressure corresponding to 60% of their arterial occlusion pressure. Before and after exercise, maximal voluntary torque, maximal muscle activity, and cuff pressure-induced discomfort were assessed. Moreover, physiological (i.e., muscle activity, muscle oxygenation) and perceptual responses (i.e., effort and exercise-induced leg muscle pain) were recorded during exercise. Moderate correlations with no differences between pBFR and BFR were found regarding the decline in maximal voluntary torque and maximal muscle activity. Furthermore, no to very strong correlations between conditions, with no differences, were observed for muscle activity, muscle oxygenation, and perceptual responses during exercise sets. However, cuff pressure-induced discomfort was lower in the pBFR compared to the BFR condition. These results indicate that low-load resistance exercise combined with perceptually primed pBFR is a convenient and less discomfort inducing alternative to traditional BFR. This is especially relevant for BFR training with people who have a low cuff-induced discomfort tolerance.

Electromyographic Analysis of Upper- and Lower-extremity Muscles in Adults during Agro-healing Activities

This study investigated the activity of upper- and lower-extremity muscles for 15 agricultural tasks of agro-healing. For the development of an agro-healing program using farm resource types, 15 selected agro-healing activities (namely, digging, raking, fertilizing, planting transplants, tying plants to stakes, watering, harvesting, washing, cutting, cooking, collecting natural objects, decorating natural objects, interacting with dogs, walking dogs, and feeding fish) were extracted and performed in a total of 21 adults (average age: 42.29 ± 14.76 years) at D Care Farm in Cheongju, Korea, from June to July 2022. Before these activities, informed consent was obtained from participants and muscle activity of the upper and lower extremities was measured. Muscle activation during activity performance was measured using electromyography (EMG), and the rating of perceived exertion for each activity was investigated. Bipolar surface EMG electrodes were attached at 16 locations on the left and right upper-extremity muscles (anterior deltoid, biceps brachialis, brachioradialis, and flexor carpi ulnaris) and lower-extremity muscles (vastus lateralis, vastus medialis, biceps femoris, and gastrocnemius). The results indicated that the activity of the lower-extremity muscles was higher than that of the upper-extremity muscles during 15 agricultural activities. During plant-mediated activity and animal-assisted activities, the rate of right muscle use was higher than that of left muscle use among the upper-extremity muscles, whereas the rate of right and left muscle use showed a similar tendency among the lower-extremity muscles. During plant-mediated activities, agricultural activities involving the use of heavy tools highly activated the right forearm muscle (flexor carpi ulnaris), whereas holding and interacting with animals highly activated the left forearm muscles (biceps brachialis, brachioradialis, and flexor carpi ulnaris). It is expected that the EMG data obtained in this study can be used as basic biomechanical data when designing an agro-healing program to improve physical function.

Electromyography as a tool to motion analysis for people with Amyotrophic Lateral Sclerosis: A protocol for a systematic review.

Biomechanical analysis of human movement plays an essential role in understanding functional changes in people with Amyotrophic Lateral Sclerosis (ALS), providing information on muscle impairment. Studies suggest that surface electromyography (sEMG) may be able to quantify muscle activity, identify levels of fatigue, assess muscle strength, and monitor variation in limb movement. In this article, a systematic review protocol will analyze the psychometric properties of the sEMG regarding the clinical data on the skeletal muscles of people with ALS. This protocol uses the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodological tool. A specific field structure was defined to reach each phase. Nine scientific databases (PubMed, Web of Science, Embase, Elsevier, IEEE, Google Scholar, SciELO, PEDro, LILACS E CENTRAL) were searched. The framework developed will extract data (i.e. study information, sample information, sEMG information, intervention, and outcomes) from the selected studies using a rigorous approach. The data will be described quantitatively using frequency and trend analysis methods, and heterogeneity between the included studies will be assessed using the I2 test. The risk of bias will be summarized using the most recent prediction model risk of bias assessment tool. Be sure to include relevant statistics here, such as sample sizes, response rates, P values or Confidence Intervals. Be specific (by stating the value) rather than general (eg, "there were differences between the groups"). This protocol will map out the construction of a systematic review that will identify and synthesize the advances in movement analysis of people with ALS through sEMG, using data extracted from articles.

Effects of the low Fowler's sleep position and methazolamide treatment on sleep bruxism: A randomized controlled trial.

Intracranial pressure is one of the determinants of sympathetic activities, and sleep bruxism is associated with increased sympathetic activities. This study aimed to investigate effects of the low Fowler's sleep position and methazolamide treatment on the occurrence of rhythmic masticatory muscle activities/sleep bruxism episodes in patients with sleep bruxism in a randomized controlled trial. Polysomnographic recordings were performed on the patients with sleep bruxism sleeping in the low Fowler's (15°-30°) or supine position (n = 11), and with methazolamide or placebo treatment (100 mg, 3-4 hr before bedtime, P.O., n = 9), and changes in sleep variables and heart rate variance during sleep in the low Fowler's position or with methazolamide treatment were determined. Sleep bruxism index, number of masseter muscle electromyographic bursts per hour of sleep, ratio of rhythmic masticatory muscle activities/sleep bruxism duration to the total sleep duration, index of total limb movements, index of limb movements with rhythmic masticatory muscle activities, and number of sleep bruxism clusters per hour of sleep in the low Fowler's position and after methazolamide intake were significantly smaller (p < 0.05-0.001) than those in the supine position and after placebo intake, respectively. The low-frequency heart rate variance powers during non-rapid eye movement sleep stage 2 (N2) in the low Fowler's position and with methazolamide treatment were significantly lower (p < 0.05) than those during sleep in the supine position and with placebo treatment, respectively. In conclusion, sleep in the low Fowler's position and methazolamide treatment were associated with significant decreases in the occurrence of rhythmic masticatory muscle activities/sleep bruxism episodes, which might be due to a reduction in intracranial pressure and sympathetic activities mainly during non-rapid eye movement sleep stage 2.

Soft tissue material properties based on human abdominal in vivo macro-indenter measurements

Simulations of human-technology interaction in the context of product development require comprehensive knowledge of biomechanical in vivo behavior. To obtain this knowledge for the abdomen, we measured the continuous mechanical responses of the abdominal soft tissue of ten healthy participants in different lying positions anteriorly, laterally, and posteriorly under local compression depths of up to 30 mm. An experimental setup consisting of a mechatronic indenter with hemispherical tip and two time-of-flight (ToF) sensors for optical 3D displacement measurement of the surface was developed for this purpose. To account for the impact of muscle tone, experiments were conducted with both controlled activation and relaxation of the trunk muscles. Surface electromyography (sEMG) was used to monitor muscle activation levels. The obtained data sets comprise the continuous force-displacement data of six abdominal measurement regions, each synchronized with the local surface displacements resulting from the macro-indentation, and the bipolar sEMG signals at three key trunk muscles. We used inverse finite element analysis (FEA), to derive sets of nonlinear material parameters that numerically approximate the experimentally determined soft tissue behaviors. The physiological standard values obtained for all participants after data processing served as reference data. The mean stiffness of the abdomen was significantly different when the trunk muscles were activated or relaxed. No significant differences were found between the anterior-lateral measurement regions, with exception of those centered on the linea alba and centered on the muscle belly of the rectus abdominis below the intertubercular plane. The shapes and areas of deformation of the skin depended on the region and muscle activity. Using the hyperelastic Ogden model, we identified unique material parameter sets for all regions. Our findings confirmed that, in addition to the indenter force-displacement data, knowledge about tissue deformation is necessary to reliably determine unique material parameter sets using inverse FEA. The presented results can be used for finite element (FE) models of the abdomen, for example, in the context of orthopedic or biomedical product developments.

Lower face contouring through botulinum toxin therapy: an overview

Botulinum toxin (Botox) has been used cosmetically to reduce and prevent wrinkles since 1989, but its application has since expanded to include treatment of other patient concerns, including masseter muscle hypertrophy. Abnormal enlargement of the masseter, a muscle located in the jaw, can give patients a larger or squarish facial appearance; the injection of Botox, through causing temporary paralysis of the masseter and a resultant reduction in muscle activity, can lead to a slimmer and less square jawline. However, careful patient selection is required, and approaches to injection technique and dosage vary. Francesca Ramadan provides an overview.

Effects of Different Na+ Concentrations on cAMP-Dependent Protein Kinase Activity in Postmortem Meat

cAMP-dependent protein kinase (PKA) activity regulates protein phosphorylation, with Na+ playing a crucial role in PKA activity. The aim of this study was to investigate the effects of different Na+ concentrations on PKA activity and protein phosphorylation level in postmortem muscle. The study consisted of two experiments: (1) NaCl of 0, 20, 100, 200 and 400 mM was added to a muscle homogenate incubation model to analyze the effect of Na+ concentration on PKA activity, and (2) the same concentrations were added to pure PKA in vitro incubation models at 4 °C to verify the effect of Na+ on PKA activity. The PKA activity of the muscle homogenate model increased with storage time in groups with different Na+ concentrations. High concentrations of Na+ inhibited sarcoplasmic protein phosphorylation. The PKA activity at 24 h of storage and the sarcoplasmic protein phosphorylation level at 12 h of storage in the group with 200 mM Na+ was lower than that of the other groups. After 1 h incubation, the PKA activity of samples in the 200 mM Na+ group was inhibited and lower than that in the other Na+ groups in the in vitro incubation model. These results suggest that the Na+ concentration at 200 mM could better inhibit PKA activity. This study provided valuable insights for enhancing curing efficiency and improving meat quality.

Impact of COVID-19 pandemic on the circadian rhythm of cesarean section deliveries.

Circadian rhythms synchronize all biological functions, enabling humans to foresee and respond better to periodic environmental changes. The coronavirus disease (COVID-19) lockdown regulations significantly changed the lighting conditions in pregnant women, leading to chronological disruption. This study aimed to investigate the impact of the COVID-19 on the circadian rhythm of cesarean deliveries. We investigated whether the circadian rhythm of cesarean section deliveries changed during the first year of the COVID-19 pandemic at a tertiary hospital in Van Province, eastern Turkey. We analyzed the distribution of birth times for 1476 cesarean deliveries performed between March 01, 2020 and January 20, 2021 (1st year of the COVID-19 pandemic) and compared this information with data from 1194 cesarean deliveries performed during a similar period in the previous year. The primary outcome was the change in the circadian rhythm of cesarean deliveries. Secondary outcomes included cesarean section (CS) delivery rates, indications for CS, 1st and 5th minutes Appearance (skin color), Pulse (heart rate), Grimace (reflex irritability), Activity (muscle tone), and Respiration scores, and anesthesia technique use rates. Regarding the time distribution of CS deliveries in the first year of the COVID-19 pandemic, the maximum number of cesarean deliveries (n = 234, 16%) occurred between 14:00 and 16:00 (P = .112). Cesarean deliveries in pre-COVID-19 group were most frequently performed between 10:00 and 12:00, at a rate of 18% (n = 216) (P = .001). In both groups, the time point at which CS deliveries were the least performed was 04:00 to 06:00, and the rates were different (n = 35, 2% and n = 14, 1%, respectively) (P = .022). A 4-hour phase shift was detected at the peak of the birth time in the first year of the COVID-19 pandemic compared to the previous year. These results suggest that the circadian rhythm of cesarean deliveries is affected by the pandemic.

Realizing the gravity of the simulation: adaptation to simulated hypogravity leads to altered predictive control

Accurate predictive abilities are important for a wide variety of animal behaviors. Inherent to many of these predictions is an understanding of the physics that underlie the behavior. Humans are specifically attuned to the physics on Earth but can learn to move in other environments (e.g., the surface of the Moon). However, the adjustments made to their physics-based predictions in the face of altered gravity are not fully understood. The current study aimed to characterize the locomotor adaptation to a novel paradigm for simulated reduced gravity. We hypothesized that exposure to simulated hypogravity would result in updated predictions of gravity-based movement. Twenty participants took part in a protocol that had them perform vertically targeted countermovement jumps before (PRE), during, and after (POST) a physical simulation of hypogravity. Jumping in simulated hypogravity had different neuromechanics from the PRE condition, with reduced ground impulses (p ≤ .009) and muscle activity prior to the time of landing (i.e., preactivation; p ≤ .016). In the 1 g POST condition, muscle preactivation remained reduced (p ≤ .033) and was delayed (p ≤ .008) by up to 33% for most muscles of the triceps surae, reflecting an expectation of hypogravity. The aftereffects in muscle preactivation, along with little-to-no change in muscle dynamics during ground contact, point to a neuromechanical adaptation that affects predictive, feed-forward systems over feedback systems. As such, we conclude that the neural representation, or internal model, of gravity is updated after exposure to simulated hypogravity.

Effects of effortful swallowing against kinesiology taping resistance on the swallowing function in patients with poststroke dysphagia: A randomized controlled trial.

A dysphagia rehabilitation method using kinesiology taping (KT) was recently introduced, and its potential for clinical efficacy was demonstrated by evaluating muscle activity and thickness. However, its effect on the swallowing function in patients with dysphagia remains unclear. This study aimed to investigate the effects of effortful swallowing against KT resistance on the swallowing function in patients with post stroke dysphagia. Thirty patients with poststroke dysphagia were recruited and randomly assigned to the experimental and placebo groups. In the experimental group, the KT was attached to the front of the neck (the hyoid bone between the sternum) with a tension of approximately 70% to 80%, and effortful swallowing was performed against the KT tension. In contrast, the placebo group performed effortful swallowing with KT applied at the same location without tension. The intervention was performed 30 times/day, 5 days/week for 6 weeks. The videofluoroscopic dysphagia scale (VDS) and penetration-aspiration scale (PAS) based on a videofluoroscopic swallowing study were used to analyze oropharyngeal swallowing function. The experimental group showed statistically significant improvements in the oral and pharyngeal phases of the VDS (P = .029 and .007, respectively) and PAS (P = .034) compared with the placebo group. Effect sizes were observed for the oral (0.3) and pharyngeal phases (0.5) of the VDS and PAS (1.1). This study demonstrated that effortful swallowing against resistance to KT is an effective therapeutic exercise for improving the swallowing function in patients with poststroke dysphagia.

Development of Sensory Virtual Reality Interface Using EMG Signal-Based Grip Strength Reflection System

In virtual reality (VR), a factor that can maximize user immersion is the development of an intuitive and sensory interaction method. Physical devices such as controllers or data gloves of existing VR devices are used to control the movement intentions of the user, but their shortfall is that grip strength and detailed muscle strength cannot be reflected. Therefore, this study intended to establish a more sensory VR environment compared to existing methods by reflecting the grip strength of the flexor digitorum profundus of the user of the VR content. In this experiment, the muscle activity of the flexor digitorum profundus was obtained from six subjects based on surface electromyography, and four objects with differing intensity were created within a VR program in which the objects were made to be destroyed depending on muscle activity. As a result, satisfaction was improved because the users could sensitively interact with the objects inside the VR environment, and the intended motion control of the user was reflected in the VR content.

#2072 Impact of the GoodRENal platform on lower-limbs muscle strength in a Spanish sample

Abstract Background and Aims People with chronic kidney disease on hemodialysis have low levels of physical activity and low lower-limbs muscle strength, partly due to the sedentary lifestyle, and a big number of hours sitting or in a recumbent position. The GoodRENal project aimed at creating an intradialysis health platform to improve health-related quality of life. The present study focused on the impact of the GoodRENal intradialysis platform on lower-limbs muscle strength. Method People in hemodialysis treatment from Spain were included. Participants were randomized into two groups, the GoodRENal or the usual care group. The participants used the GoodRENal platform for 12 weeks, 3 times a week. Games using non-immersive virtual reality were created aiming at educating on nutritional habits, increasing physical activity during the HD session, improving cognitive skills and increasing psychological well-being. All of them included dual tasks, so that the movement of the legs was used in every game. An Azure Kinect camera was used to capture the movement and all activities were dual, so that movement of lower limbs was promoted in every game. A handheld dynamometer was used to assess hip flexors and abductors muscle strength during the hemodialysis session. This procedure has proven to be reliable and save. An ANOVA mixed model (group and time factors) was used to analyze the results. Results 19 participants were included (Control n = 9; GoodRENal n = 10). Participants’ mean age was 73.4 years for the control and 68.3 years for the GoodRENal group, with a hemodialysis vintage, median 34 months (minimum 3- maximum 277) and 25 months (minimum 5- maximum 48) for the control and GoodRENal groups. Right hip flexor muscles changed in the control group over time: Baseline 124.7 (23.2) N; 4 weeks 121.3 (20.3) N; 12 weeks 119.0 (21.1) N. In the GoodRENal group, the data were: Baseline 116.7 (34.7) N; 4 weeks 124.7 (36.7) N; 12 weeks 142.7 (44.7) N. The ANOVA showed a significant time × group interaction (F = 11.347 p &amp;lt; 0.001) with a significant improvement in the GoodRENal group. Left hip abductor muscles changed in the control group over time: Baseline 124.5 (24.0) N; 4 weeks 123.0 (26.1) N; 12 weeks 122.0 (24.7) N. In the GoodRENal group, the data were: Baseline 111.1 (30.4) N; 4 weeks 119.2 (33.0) N; 12 weeks 138.5 (36.3) N. The ANOVA showed a significant time × group interaction (F = 15.218 p &amp;lt; 0.001) with a significant improvement in the GoodRENal group. Both left hip flexors (F = 19.055 p &amp;lt; 0.001) and abductors (F = 15.036 p &amp;lt; 0.001) showed a significant time per group interaction, with an improvement in the GoodRENal group. Conclusion The GoodRENal platform is a feasible strategy to increase the muscle strength of the hip flexors and abductors muscles. Future studies with bigger samples should confirm these results.

#2366 Beneficial effects of TRIM33 on myokine-mediated renal function recovery in diabetic and obese mice

Abstract Background and Aims Myokines secreted from myocytes are related to improving metabolic diseases such as diabetes, obesity, and chronic kidney disease (CKD). Patients with diabetic kidney disease (DKD) have lower irisin levels, suggesting that a low level of irisin is a risk factor for the progression of CKD. However, it is not well known how myokines can alleviate metabolic kidney injury. This study aimed to investigate the effect of TRIM33, a negative regulator of TGF-β1 signaling, as a novel strategy to treat multiple metabolic complications simultaneously in the kidneys and muscles of obese db/db mice. Method For the in vivo experiment, five-week-old male db/db mice were assigned to three groups: db/m+, db/db, and db/db with TRIM33 plasmid mice. TRIM33 plasmid (40 μg/mice) was administered intraperitoneally. Serum glucose and myokine levels, urinary albumin excretion, renal and muscle morphology, and myokine expression in muscles were assessed. In vitro, C2C12 cells were cultivated with 2% horse serum and lipid insult in the absence or presence of TRIM33 plasmid and were analyzed for myocyte differentiation and myokines expression or production. Results TRIM33 treatment showed beneficial effects on tubular injury, tubulointerstitial fibrosis, mesangial expansion, renal dysfunction, variations in skeletal muscle fiber size and arrangement, skeletal muscle activity, and serum myokines levels in db/db mice. During the differentiation of C2C12 cells, myokine mRNA and protein expression and secretion were increased in TRIM33-transfected cells. Reduced levels of myokines expression and secretion in C2C12 cells with palmitate were improved by TRIM33 transfection. In coculture with HK-2 and C2C12 cells, increased EMT transition in TGF-b-treated HK-2 cells by coculture with palmitate-treated C2C12 cells was decreased in coculture with palmitate-treated C2C12 cells with TRIM33 transfection. Conclusion This study showed that TRIM33 is involved in the recovery of renal dysfunction via myokine in mice with diabetes and obesity.

The relationship between ankle landing kinematics, isokinetic strength, muscle activity, and the prevalence of lower extremity injuries in university-level netball players during a single season

Background: Safe landing in netball is fundamental. Research on the biomechanics of multidirectional landings is lacking, especially among netball players. Furthermore, few studies reporting the associations between ankle kinematics, isokinetic ankle muscle strength, muscle activities, and injury prevalence in South African netball have been undertaken. Objectives: To determine the relationships between ankle kinematics, kinetics, isokinetic strength, and muscle activity during jump-landing tasks, as well as the prevalence of lower extremity injuries in university-level netball players during a single season. Methods: This cross-sectional repeated-measure study consisted of ten university-level female netball players. The injury prevalence data was collected during the 2022 netball season. The ankle muscle activity, kinematic, and kinetic data were collected during multidirectional single-leg landing and muscle strength was collected from plantar- and dorsiflexion trials. Results: Netball players' ankle strength was generally below average. There was evidence of negative correlations between the ankle range of motion (ROM), isokinetic strength, and muscle activity amplitudes. A lack of evidence prevented the conclusion that lower extremity dominance predisposed players to injury, and that any specific body part was more likely to be injured among netball players. Conclusion: Landing forces and muscle activity are direction-dependent, especially for the dominant limb. Lower extremity strength and neuromuscular control (NMC) across multiple jump-landing directions should be an area of focus for female netball players.

The female urethral closure mechanism during physical stress.

The closure of the urethra under the condition of stress is the result of a reflex contraction of the urethral rhabdosphincter and pelvic floor muscles. This is likely induced by activity of the abdominal muscles due to a sudden increase in abdominal pressure. This reflex contraction with an increase of urethral pressure occurs a few milliseconds before an increase in intraabdominal pressure. The urethral pressure increase during stress is only possible with fixation of the urethra by the pubourethral ligaments (PUL), facilitating urethral kinking. The highest and most important increase in pressure and resistance occurs in the distal urethra due to this kinking of the urethra.

Automatic quantification of REM sleep without atonia reliably identifies patients with REM sleep behavior disorder: a possible screening tool?

REM Sleep Behavior Disorder (RBD) is characterized by absence of physiological muscle atonia during REM sleep (REM sleep without atonia, RWA). Nigro-striatal dopaminergic impairment is a feature of Parkinson disease (PD) and can be identified in prodromal stages as well, such as idiopathic RBD (iRBD). Aims of this study are to explore the efficacy of an automatic RWA quantification in identifying RBD patients and the correlation between RWA and nigro-striatal dopaminergic function. Forty-five iRBD, 46 PD with RBD, 24 PD without RBD patients and 11 healthy controls were enrolled in the Genoa Center (group A) and 25 patients with iRBD (group B) were enrolled in the Danish Center. Group A underwent brain [123I]FP-CIT-SPECT and group B underwent brain [18F]PE2I-PET as measures of nigro-striatal dopaminergic function. Chin muscle activity was recorded in all subjects and analyzed by applying a published automatic algorithm. Correlations between RWA and nigro-striatal dopaminergic function were explored. The automatic quantification of RWA significantly differentiated RBD from non-RBD subjects (AUC = 0.86), although with lower accuracy compared with conventional visual scoring (AUC = 0.99). No significant correlation was found between RWA and nigro-striatal dopaminergic function. The automatic quantification of RWA is a reliable tool to identify subjects with RBD and may be used as a first-line screening tool, but without correlations with nigro-striatal dopaminergic functioning.

The Effects of Simulated Gastroesophageal Reflux on Infant Pig Oropharyngeal Feeding Physiology.

The neural connectivity among the oral cavity, pharynx, and esophagus is a critical component of infant feeding physiology. Central integration of oral and pharyngeal afferents alters motor outputs to structures that power swallowing, but the potential effects of esophageal afferents on pre-esophageal feeding physiology are unclear. These effects may explain the prevalence of oropharyngeal dysphagia in infants suffering from gastroesophageal reflux (GER), though the mechanism underlying this relationship remains unknown. Here we use the validated infant pig model to assess the impacts of simulated GER on pre-esophageal feeding parameters. We used high-speed videofluoroscopy and electromyography to record bottle-feeding prior to and following infusion of a capsaicin-containing solution into the lower esophagus. Sucking parameters were minimally affected by capsaicin exposure, such that genioglossus activity was unchanged and tongue kinematics were largely unaffected. Aspects of the pharyngeal swallow were altered with simulated GER, including increased thyrohyoid muscle activity, increased excursions of the hyoid and thyroid per swallow, decreased swallow frequency, and increased bolus sizes. These results suggest that esophageal afferents can elicit changes in pharyngeal swallowing. Additionally, decreased swallowing frequency may be the mechanism by which esophageal pathologies induce oropharyngeal dysphagia. While recent work indicates that oral or pharyngeal capsaicin may improve dysphagia symptoms, the decreased performance following esophageal capsaicin exposure highlights the importance of designing sensory interventions based upon neurophysiology and the mechanisms underlying disordered feeding. This mechanistic approach requires comprehensive data collection across the entirety of the feeding process, which can be achieved using models such as the infant pig.

A comparative study of biomechanical assessments in laboratory and field settings for manual material handling tasks using extractor tools and exoskeletons

To enhance physical capabilities of workers who regularly perform physically demanding tasks involving heavy lifting and awkward postures, various tools and occupational exoskeletons can be used. Most of the studies aiming to explore the efficiency of these tools and exoskeletons have been performed in confined and controlled laboratory spaces, which do not represent the real-world work environment. This study aimed to compare the outcome of biomechanical assessment of using a back support exoskeleton and assistive tools (Lever and Jake) in the procedure of a high demanding manual material handling task versus the results found by performing the same task in a laboratory. Ten able-bodied participants and ten able-bodied utility workers performed the same manhole removal task in-lab and in-field, respectively, with the aid of an exoskeleton and Lever and Jake tools. Muscle activity and Rapid Entire Body Assessment (REBA) scores were recorded using surface electromyography and inertial measurement units, respectively and compared between in-lab and in-field trials. The field experiments indicated significant differences (p &amp;lt; 0.05) in normalized muscle activity across most muscles when compared to laboratory data. These results revealed how muscle activity is affected by the controlled lab setting compared to real-world field conditions. However, REBA scores indicate similar ergonomic implications regardless of the utilization of exoskeletons or tools. These findings underscore that real-world field assessments are crucial for evaluating ergonomic risks and effects of occupational exoskeletons and tools to account for environmental factors and workers’ skills in ergonomic evaluations of this nature.

Passive exercise provides a simultaneous and postexercise executive function benefit

IntroductionPassive exercise involves limb movement via an external force and is an intervention providing an immediate postexercise executive function (EF) benefit. It is, however, unknown whether EF is improved simultaneous with passive exercise—a salient question given the advent of passive (and active) exercise workstations designed to enhance productivity and wellbeing for individuals engaged in sedentary occupations.MethodsHere, participants (N = 23) completed separate 20-min conditions involving active (i.e., via volitional muscle activation) and passive (i.e., via mechanically driven cycle ergometer) cycle ergometry and a non-exercise control condition. EF was assessed prior to (i.e., preintervention), simultaneous with, and immediately after (post-intervention) each condition via the antipointing task. Antipointing involves a goal-directed limb movement mirror-symmetrical to a target and is an ideal tool for the current investigation given that the task is mediated via EF inhibitory control networks that show response-dependent changes following a single bout of exercise.Results and discussionResults showed that passive exercise produced a simultaneous and post-intervention reduction in antipointing reaction time (RT), whereas active exercise selectively produced a post-intervention—but not simultaneous—RT reduction. Thus, passive and active exercise elicited a postexercise EF benefit; however, only passive exercise produced a simultaneous benefit. That passive—but not active—exercise produced a simultaneous benefit may reflect that the intervention provides the necessary physiological or psychological changes to elicit improved EF efficiency without the associated dual-task cost(s) of volitional muscle activity.

Analysis of ankle muscle activity: A study on static balance with eyes closed and high-heeled shoes

BackgroundChanges in sensory afferent interfere with the control of postural stability by the central nervous system. Wearing high-heeled shoes is an example of an external disturbance that changes sensory inputs and results in several postural adjustments to control stability. Thus, our purpose is to investigate the influence of high-heeled shoes and visual absence on maintenance of static balance and on ankle muscle activity among young women. Our hypothesis is that the combination of high-heeled shoes with visual absence lead to an increase of postural sway and of levels of activation of the stabilizing ankle muscles. MethodsNine volunteers remained in an unrestrained erect posture on a force platform for collecting of stabilometric and electromyographic parameters in four bipodal conditions: barefoot with open eyes, barefoot with closed eyes, with high heels and open eyes and with high heels and closed eyes. ResultsWhen comparing the experimental condition open and closed eyes with high heels, there were significant differences for all stabilometric variables, except for the confidence ellipse area. Statistical differences were found for the medial gastrocnemius muscle in all comparison pairs with high heels. ConclusionThe wearing high-heeled shoes showed to be the most influencing disturbance on static balance. Our findings suggest ankle muscle activity is adapted according to changes of the center of pressure sway and the wearing of high heels changes the muscle activation and postural sway.