Muscle Loading Research Articles

Electrocortical activity during resistance exercises in healthy young adults—a systematic review

IntroductionResistance training (RT) is known to induce both peripheral and central adaptations, resulting in enhanced strength, sports performance, and health benefits. These adaptations are specific to the training stimuli. The acute cortical mechanisms of single sessions resistance exercise (RE) are not yet understood. Therefore, this review investigates the electrocortical activity during acute RE regarding the specific RE stimuli.MethodsA systematic literature search was conducted across three databases, focusing on the acute electrocortical activity associated with the muscle contraction type, load, and volume of RE in healthy young adults.ResultsOut of an initial 1,332 hits, 19 studies were included for data synthesis. The findings from these studies show that the RE load, contraction type, and volume during RE significantly affect brain activity. The current literature exhibits methodological heterogeneity attributed to variations in study quality, differences in the location of cortical sources, the cortical outcome parameter and the use of diverse training interventions.DiscussionDespite inconsistencies in the current literature, this review highlights the need to investigate time and frequency-specific characteristics when examining electrocortical activity during RE. More research is necessary to further explore the acute cortical mechanisms related to resistance exercise. Future research could improve our understanding of acute neural responses to RE and provide insights into mechanism underlying more long-term neuroplastic adaptations to RT.

Common sports-related nerve injuries seen by the electrodiagnostic medical consultant.

The high physiologic demands of sports create dynamic stress on joints, soft tissues, and nerves which may lead to injuries in the athlete. Electrodiagnostic (EDx) assessment is essential to identify the correct diagnosis, localization, and prognosis, to guide management of sports-related neuropathies. A comprehensive review was performed to provide the EDx medical consultant with a practical approach to the common peripheral nerve disorders seen in athletes. Sports-related neuropathies reviewed include transient traumatic irritation of the brachial plexus and/or cervical nerve roots ("Burners and stingers,") suprascapular and axillary neuropathies, ulnar neuropathy at the elbow (UNE) in throwers, ulnar neuropathy at the hand/wrist in cyclists, multi-ligamentous knee injury, and foot/ankle neuropathies including tarsal tunnel syndrome. A thorough understanding of peripheral anatomy, possible entrapment sites, mechanisms of injury, and key physical examination findings is essential for correct diagnosis. EDx assessments beyond routine studies are generally required for sports-related neuropathy, which may not necessarily follow typical entrapment patterns. Adjunct diagnostic imaging, such as point-of-care ultrasound and magnetic resonance imaging, are helpful tools to identify associated musculoskeletal pathology such as compressive cysts or nerve entrapment, which may be amenable to interventional or surgical treatment. When no clear reversible structural pathology exists, management of sports-related neuropathy is athlete-specific and generally multi-modal, involving a combination of physical rehabilitation techniques to address muscle imbalances, load management, protective equipment, and interventional pain procedures.

Inclusion of Muscle Forces Affects Finite Element Prediction of Compression Screw Pullout but Not Fatigue Failure in a Custom Pelvic Implant

Custom implants used for pelvic reconstruction in pelvic sarcoma surgery face a high complication rate due to mechanical failures of fixation screws. Consequently, patient-specific finite element (FE) models have been employed to analyze custom pelvic implant durability. However, muscle forces have often been omitted from FE studies of the post-operative pelvis with a custom implant, despite the lack of evidence that this omission has minimal impact on predicted bone, implant, and fixation screw stress distributions. This study investigated the influence of muscle forces on FE predictions of fixation screw pullout and fatigue failure in a custom pelvic implant. Specifically, FE analyses were conducted using a patient-specific FE model loaded with seven sets of personalized muscle and hip joint contact force loading conditions estimated using a personalized neuromusculoskeletal (NMS) model. Predictions of fixation screw pullout and fatigue failure—quantified by simulated screw axial forces and von Mises stresses, respectively—were compared between analyses with and without personalized muscle forces. The study found that muscle forces had a considerable influence on predicted screw pullout but not fatigue failure. However, it remains unclear whether including or excluding muscle forces would yield more conservative predictions of screw failures. Furthermore, while the effect of muscle forces on predicted screw failures was location-dependent for cortical screws, no clear location dependency was observed for cancellous screws. These findings support the combined use of patient-specific FE and NMS models, including loading from muscle forces, when predicting screw pullout but not fatigue failure in custom pelvic implants.

Lateralization has minimal biomechanical impact on tuberosity fixation with the use of a stem-based repair and a 135o humeral implant in reverse shoulder arthroplasty for four-part proximal humerus fracture

IntroductionLateralization in reverse shoulder arthroplasty (RSA) has many proven and potential benefits. Concern over the increase in tension on the tuberosities imparted by glenoid lateralization and the subsequent effect on tuberosity healing may limit its use in the setting of RSA performed for fracture. This study evaluated whether glenoid lateralization increased tuberosity fracture gapping in a biomechanical model of a 4-part proximal humerus fracture with a stem-based tuberosity repair. We hypothesized that increased lateralization would increase fracture gapping. Materials and MethodsEight cadaveric shoulders (mean age, 62 +/- 2.4 years; range 52-70 years) were tested with a custom testing system that permits loading of rotator cuff muscles and humerothoracic muscles. A four-part proximal humerus fracture was simulated and then repaired with a stem-based tuberosity repair. The repaired tuberosities were cycled in internal and external rotation with 1.1Nm torque at 2 mm and 6 mm of glenoid lateralization. For the 6mm lateralization RSA, the torque was then increased to reach the range of motion values achieved with the 2mm lateralized RSA and cycled 10 times, followed by doubling the torque values for 10 cycles. Range of motion, muscle length and fracture gapping were assessed at 2 mm and 6 mm of glenoid lateralization. ResultsInternal rotation and total ROM demonstrated a significant decrease in the 6 mm RSA when compared to the 2 mm RSA (p < 0.05). The 6 mm lateralized RSA significantly increased rotator cuff muscle lengths when compared to the 2 mm lateralized RSA condition except for infraspinatus by an average of 2.7 ± 1.9mm (p < 0.05). There was no significant gapping of the proximal fracture for any condition. There was a significant increase in the gapping of the distal fracture gap in the 6 mm lateralized component condition only after 10 cycles of doubled rotational torque, which measured 1.9 ± 1.5mm (p = .031). DiscussionWe hypothesized that lateralization would increase fracture gapping. Fracture gapping did not occur proximally and only occurred at a slight amount distally after 10 cycles of doubled rotational torque. This may have implications on the choice of glenoid components when performing a RSA for fracture.

Effects of Kitchen Cooking Height on Upper Limb Muscle Activation, Posture, and Perceived Discomfort of Chinese Older and Young Women.

Inappropriate kitchen cooking height may lead to uncomfortable and muscle fatigue. This study aims to compare the effects of kitchen cooking height on upper limb muscle activation, posture, and perceived discomfort among different age groups. Fifteen older women and fifteen young Chinese women each completed three consecutive 20 s simulated cooking tasks at five different heights. Surface electromyography, motion capture, and Borg CR10 scale were used to measure muscle loading. Results showed that the main power muscles of the cooking task were the anterior deltoid, brachioradialis, and biceps brachii. The higher muscle contribution rate of biceps brachii and triceps brachii was found in the younger group compared to the older group (p < 0.05). Muscle activation of the anterior deltoid (different in 1.28-2.87%), pectoralis major (different in 1.43-1.69%), and erector spinae (different in 0.6-1.21%), as well as right shoulder abduction (different in 5.91°-7.96°), were significantly higher in older group than in young group (p < 0.05). Muscle activation of the anterior deltoid and right shoulder abduction decreased significantly with decreasing height (p < 0.05). A height of 200-250 mm below the elbow was considered a more comfortable cooking height for both age groups. This provides data to support the design of cabinet sizes.

Muscle Compensation Strategies to Maintain Glenohumeral Joint Stability in Rotator Cuff Tears: A Cadaveric Study.

Superior translation of the humeral head is often identified in large and massive rotator cuff (RC) tears. However, the ability of the remaining RC muscles to compensate for the forces causing such superior translation in RC tears remains unclear. The purpose of this study was to investigate the impact of compensatory forces exerted by the remaining RC muscles on humeral head translation using a progressive RC tear model. Eight fresh-frozen cadaveric shoulders (mean donor age, 57 years) were tested using a custom shoulder testing system. In addition to an intact RC model, 3 RC tear models were created: a supraspinatus tear (Tear I); combined supraspinatus and infraspinatus tears (Tear II); and combined tears of the supraspinatus, infraspinatus, and superior one-third of the subscapularis (Tear III). Compensatory conditions were simulated by increasing the loading of the remaining RC muscles in each RC tear model. Humeral head translation was measured at different abduction and neutral rotation angles in each condition with normal and high deltoid muscle loading. Significant superior translation of the humeral head was observed in Tears II and III (but not Tear I), compared with the intact state, under high loading of the deltoid during abduction and during rotation. In Tear II, compensatory conditions involving increased loading of the teres minor and subscapularis muscles effectively reduced superior translation, so that no significant differences were observed compared with the intact state, even under high deltoid muscle loading. However, in Tear III, significant superior translation was still observed, regardless of the compensatory conditions. ompensation by the remaining RC muscles, particularly the teres minor and subscapularis, effectively reduced superior translation of the humeral head in the posterosuperior RC tear model, whereas this compensatory strategy was insufficient if tears also involved the superior one-third of the subscapularis. Patients with posterosuperior RC tears may find conservative treatment focusing on strengthening the remaining RC muscles, especially the subscapularis and teres minor, to be beneficial. Conversely, patients with repairable massive RC tears also involving the subscapularis tendon may benefit from surgical interventions aimed at primarily repairing the subscapularis tendon to restore the transverse force couple. Massive tears deemed not to be repairable should be evaluated for arthroplasty or other procedures.

In-vitro and in-vivo assessment of the bactericidal potential of peracetic acid and hydrogen peroxide disinfectants against A. hydrophila infection in Nile tilapia and their effect on water quality indices and fish stress biomarkers

This study aimed to assess the in vitro and in vivo disinfectant potential of peracetic acid (PAA) (1 mg/L) and hydrogen peroxide (H2O2) (20 mg/L) on the physicochemical and microbiological water quality parameters of fish aquaria, the microbial density of Nile tilapia muscular tissue, fish hepatic cortisol levels, and antioxidant biomarkers. In vitro, PAA and H2O2 reduced A. hydrophila colony viability by 5 log units after 30 and 5 min of contact time, respectively. PAA and H2O2 were added to aquaria water twice a week for the three-week experiment. Increased fish escape reflexes were observed only in the PAA group, which returned to normal within 10 min. No mortalities were reported in either the PAA or H2O2 groups. An in vivo experimental challenge with a pathogenic strain of A. hydrophila revealed a 20% reduction in mortality in the PAA group, with no mortalities in the H2O2 group. Cortisol levels and antioxidant markers were measured to assess the impact of PAA and H2O2 on fish health. Cortisol levels in the PAA and H2O2 groups were significantly higher than in the control group after disinfectant exposure, but they progressively returned to normal. A significant reduction in superoxide dismutase (SOD) and catalase (CAT) activity, along with considerably higher glutathione peroxidase (GPx) and malondialdehyde (MDA) enzymatic activity, was observed in the PAA and H2O2 groups compared to the control group. A substantial increase in total antioxidant capacity (TAC) was recorded in the PAA group. Physicochemical analyses revealed reduced pH and increased dissolved oxygen levels in the PAA and H2O2 groups. Microbiological analyses showed a significant reduction in bacterial density in water by 64% and 76% after 30 min of exposure to PAA and H2O2, respectively, with a non-significant increase in microbial count after bacterial challenge. Additionally, aerobic bacterial count, Aeromonas spp., and psychotropic bacterial count in fish muscle showed a significant reduction in the H2O2 group compared to the PAA and control groups before and after infection. The study concludes that regular application of PAA and H2O2 can temporarily reduce bacterial load in aquaria and fish muscle, regulate stress responses, and improve fish health by reducing A. hydrophila-induced infections and improving survival.

Greater squat stance width alters three-dimensional hip moment demands

Barbell squat exercise may be performed with different stance widths, which will influence lower limb kinematics and joint reaction forces. Consequently, three-dimensional hip moments may vary with stance width, influencing muscle loading, and the muscles trained when performing squat exercise. To examine how squat stance width affects hip moments, males (n = 11) and females (n = 13) performed barbell squats at narrow, medium, and wide stance widths. Motion capture and force platform data were used to calculate three-dimensional hip net joint moments (NJM) as indicators of the muscular moments required. Hip extensor NJM was greater for wide than medium (P < 0.001) and narrow (P < 0.001) stance squats. Hip adductor NJM was not different between squat stance widths (P = 0.414). Hip lateral rotator NJM was greater in medium versus narrow squats (P < 0.001), and in wide versus medium (P < 0.001) and narrow (P < 0.001) squats. Taken together, the rotational demands at the hip increase as stance width increases, due to higher hip extensor and lateral rotator NJM. In contrast hip adductor NJM is invariant. These data provide insight into the three-dimensional requirements that muscles must meet at the hip when squat exercise is performed at different stance widths.

Evaluation of the pharmacological efficiency of the lipid extract from the tunic of the marine hydrobiont Halocynthia aurantium (Pallas, 1774)

It was studied effect of the lipid extract isolated from the tunic of the marine hydrobiont Halocynthia aurantium. It was evaluated its administration during hypothermia, hyperthermia, muscle load and the introduction of hexenal as well as its embryotoxic and teratogenic effects The impact of stress (vertical fixation of rats by the dorsal neck fold) was accompanied by an increase in plasma levels of total lipids, total cholesterol, cholesterol/phospholipid ratios and a decrease in total phospholipids, as well as by a change in the quantitative characteristics of classes of neutral and phospholipid. It was carried out a correction of the developed changes by a lipid extract of ascidia and a commercial reference preparation “Omega-3”. The lipid extract of H. aurantium showed a higher efficiency in restoring the lipid composition of the blood plasma under stress impact compared to the preparation “Omega-3” due to a wider range of neutral and phospholipid classes, polyunsaturated fatty acids of the n-3 and n-6 families. The tunica of ascidian can be used as a raw material for obtaining preparations with stress-protector and lipid-correcting properties.

The application of aquatic resistance exercises in different diseases

Aquatic exercise is an active exercise that make full use of the physical and hydrodynamic characteristics of water in a water environment to achieve a similar strength increase effect as land training, while avoiding the aggravation of joint stress and muscle microdamage caused by repetitive training. It has been widely studied in the field of sports rehabilitation and public fitness, while its form is basically presented in the form of aerobic exercise or interval training, the aquatic resistance exercises are often ignored by people. Due to the influence of the physical characteristics of water, the main form of muscle contraction of athletes performing resistance training in water is similar to isokinetic contraction, and the force used by practitioners is proportional to the resistance of water, which increases the centrifugal load of muscles and greatly reduces the risk of sports injury. In addition to the athletes, aquatic resistance exercises also have certain benefits for other clinical diseases. In this paper, the application of this training in swimming performance, rheumatoid arthritis, postmenopausal osteoporosis and knee osteoarthritis was reviewed in order to improve the clinical understanding and promote its rational application.

349 The relationship of heart score with hot carcass weight and fat depth in Angus cattle

Abstract Congestive Heart Failure (CHF) is a cardiopulmonary condition observed in cattle raised in feedlots situated at elevations above 800 m. This condition leads to right-sided heart failure caused by increased pulmonary vessel pressures and cardiopulmonary remodeling, known as pulmonary hypertension (PH). In cattle experiencing PH, pulmonary arterial pressure (PAP) becomes abnormally high, increasing heart muscle load. This load stretches muscle fibers and enlarges the right side of the heart which can lead to heart failure and death. To assess the severity of PH, animals are assigned a heart score (HS) on a scale ranging from 1 to 5 at harvest. A score of 1 represents a normal heart, while a score of 5 indicates extreme heart remodeling. Understanding the relationship between hot carcass weight (HCW), fat depth (FD), and HS in Angus cattle will provide useful information on the impacts of this condition on feedlot performance and profitability. The objective of this study was to determine if a phenotypic relationship between HCW and FD with HS in Angus-influenced cattle. For this experiment, a total of 798 black, Angus-influenced cattle were used (245 steers, 553 heifers) that were fed near Greeley, CO. The HCW, FD, and HS data from each animal were recorded at harvest. Three general linear models were used to estimate the effects of HS on HCW and FD. Mean HCW and FD were 393.1 kg, (SD = 90.9) and 0.66 mm, (SD = 0.18), respectively, with an average HS of 2.08 (SD = 0.77). For all models, HCW and FD were fit as dependent variables, while lot and HS were included as fixed effects. Model 1 included all HS categories independently. Model 2 divided HS into 2 groups of normal (HS = 1 or 2) or remodeled (HS = 3+). For model 3 HS 3 was removed leaving only HS of 4 or 5 in the remodeled group. For both HCW and FD in Model 1, the overall effect of HS was not significant (P = 0.82 and P = 0.40, respectively). However, when comparing individual scores, animals with a HS = 4 were 15.0 kg lighter for HCW than individuals with a HS = 1 (P &amp;lt; 0.05). Conversely for FD, a non-significant difference (P = 0.74) of -0.33 mm was observed between animals with a HS = 4 versus a HS = 1. Grouping HS into 2 categories in Model 2 did change the outcome, yielding non-significant HCW and FD differences. However, when eliminating the HS = 3 data, a significant reduction in HCW of 16.9 kg (P = 0.05) was observed between the 2 HS groups, whereas non-significant effects on FD remained. These data suggest that at extreme levels of heart remodeling HCW may be extremely impacted negatively.

Enhancing Sports Injury Risk Assessment in Soccer Through Machine Learning and Training Load Analysis.

Sports injuries pose significant challenges in athlete welfare and team dynamics, particularly in high-intensity sports like soccer. This study used machine learning algorithms to assess non-contact injury risk in professional male soccer players from physiological and mechanical load variables. Twenty-five professional male soccer players with a first-time, non-contact muscle injury were included in this study. Recordings of external load (speed, distance, and acceleration/deceleration data) and internal load (heart rate) were obtained during all training sessions and official matches over a 4-year period. Machine learning model training and evaluation features were calculated for each of nine different metrics for a 28-day period prior to the injury and an equal-length baseline epoch. The acute surge in the values of each workload metric was quantified by the deviation of maximum values from the average, while the variations of cumulative workload over the last four weeks preceding injury were also calculated. Seven features were selected by the model as prominent estimators of injury incidence. Three of the features concerned acute load deviations (number of sprints, training load score-incorporating heart rate and muscle load- and time of heart rate at the 90-100% of maximum). The four cumulative load features were (total distance, high speed and sprint running distance and training load score). The accuracy of the muscle injury risk assessment model was 0.78, with a sensitivity of 0.73 and specificity of 0.85. Our model achieved high performance in injury risk detection using a limited number of training load variables. The inclusion, for the first time, of heart rate related variables in an injury risk assessment model highlights the importance of physiological overload as a contributor to muscle injuries in soccer. By identifying the important parameters, coaches may prevent muscle injuries by controlling surges of training load during training and competition.

Nonspherical humeral arthroplasty increases internal rotation: a biomechanical comparison of the native humeral head to nonspherical and spherical humeral implants

BackgroundNonspherical humeral head implants more closely resemble native humeral anatomy than spherical components and may better replicate native shoulder range of motion (ROM) and kinematics. The purpose of this study was to compare shoulder ROM and kinematics of a commercially available nonspherical humeral head implant with the native humeral head and a height matched, custom manufactured spherical implant. MethodsSix fresh frozen cadaveric shoulder specimens were used with a custom shoulder testing system. The native shoulder was tested in multiple positions under anatomic muscle loading. Each specimen was tested for ROM and glenohumeral joint kinematics by measuring the humeral head apex and humeral head center (HHC) translation per degree of rotation using a MicroScribe digitizer. Measurements were then repeated after implantation of a spherical and, subsequently, a nonspherical humeral head prothesis. ResultsThe nonspherical implant had significantly more internal rotation (IR) compared to the spherical implant at 0° abduction (10.6 ± 6.2° more IR, P = .004, 95% confidence interval [CI]: −13.3, 34.5), 30° abduction (5.7 ± 2.8°, P = .009, 95% CI: −12.6, 24.0) and 60° abduction (6.8 ± 2.7°, P = .002, 95% CI: −8.3, 22.1) in the scapular plane, and 60° abduction (6.9 ± 2.0°, P = .031, 95% CI: −12, 25.6) in the coronal plane. The nonspherical implant had more IR than the native head at 60° of abduction in the scapular plane (7.0 ± 2.2° P = .002, 95% CI: −10.3, 24.3). The spherical head had less IR than the native head at 0° abduction (7.2 ± 4.8°, P = .031, 95% CI: 32.5, 18.1). There were no differences in humeral head apex translation per degree of rotation noted between the spherical implant or nonspherical implant and the native shoulder. The nonspherical head had less HHC translation than the native shoulder at 30° abduction in the forward flexion plane (P = .007); otherwise, there were no statistically significant differences in HHC translation between the native shoulder, the spherical head, and the nonspherical head. There was no significant difference observed between the average difference in anterior-posterior and superior-inferior radius of curvature of the nonspherical implants (2.0 ± 0.7 mm) and the native humeral heads (1.9 ± 1.3 mm) [P = .926]. ConclusionThe results of this biomechanical study suggest that the commercially available nonspherical humeral head has improved IR when compared to a custom, height controlled spherical implant and offers ROM and kinematics similar to the native humeral head in a cadaveric model.

The straight head of rectus femoris: An underdiagnosed cause of chronic pain post hip replacement

Groin pain following hip arthroplasty has a spectrum of aetiologies. Although mild post-operative pain at six months to a year is common, other causative factors should be considered where pain is severe or persistent. The rectus femoris (RF) muscle is the most common of the quadriceps tendons to be injured or strained. Pathologies are known to occur in athletic adults and children and include tendinopathy, tear, and avulsion, but the RF is rarely attributed to hip pain post-arthroplasty. However, tendinopathy may occur as a result of altered biomechanics and muscle loading. We performed a retrospective analysis of 100 patients, at our tertiary orthopedic hospital, who presented with chronic pain post hip arthroplasty. We identified three patients with RF straight (direct) head tendinopathy and one patient with RF straight (direct) head calcific tendinopathy. Established causes of chronic post-operative pain include septic/aseptic loosening, pseudotumor, iliopsoas bursitis/impingement, and bursitis. In this report, we describe the scanning technique, sonographic appearances, and our institutional experience of post-arthroplasty pathologies of the RF straight (direct) head which is an underreported cause of chronic pain following hip replacement. We also recommend including the RF straight (direct) head in routine US protocols of the post-operative hip.

Rehabilitation-Specific Predictors of Pain Intensity and Physical Activity Levels in Individuals With Acetabular Dysplasia 6 Months After Periacetabular Osteotomy.

Individuals with acetabular dysplasia often report hip joint instability, pain, and poor hip-related function. Periacetabular osteotomy (PAO) is a surgical procedure that aims to reposition the acetabulum to improve joint congruency and improve pain and function. We aimed to examine the influence of presurgery clinical measures on functional recovery following PAO and the associations among clinical outcomes after PAO. We screened 49 potential participants, 28 were enrolled, and 23 completed both study visits (pre-PAO and 6 months post-PAO). We evaluated dynamometer-measured hip and thigh strength, loading patterns during a squat and countermovement jump (CMJ), pain intensity, and device-measured physical activity (PA) levels (light, moderate-to-vigorous PA [MVPA], and daily steps). We used linear regression models to examine the influence of muscle strength (peak torque; limb symmetry index [LSI]) and loading patterns before PAO on pain intensity and PA levels in individuals 6 months following PAO. Additionally, we used Pearson correlation coefficient to examine cross-sectional associations among all variables 6 months following PAO. Lower extremity muscle strength and loading patterns during the squat and CMJ before PAO did not predict pain intensity or device-measured PA levels in individuals 6 months following PAO (p > 0.05). Six months following PAO, higher knee extensor LSI was associated with higher time spent in MVPA (r = 0.56; p = 0.016), higher hip abductor LSI was associated with both lower pain (r = 0.50; p = 0.036) and higher involved limb loading during the squat task (r = 0.59; p = 0.010). Lastly, higher hip flexor LSI was associated with higher CMJ takeoff involved limb loading (r = 0.52; p = 0.021) and higher involved hip extensor strength was associated with higher CMJ landing involved limb loading (r = 0.56; p = 0.012). Six months after PAO, higher hip and thigh muscle strength and strength symmetry were associated with lower pain, higher PA levels, and greater normalized limb loading during dynamic movement tasks.

Synchronous analysis of ankle coronal plane tilt angle and peripheral associated muscle load in semi-squat landing of paratroopers

Objective: To investigate the relationship between ankle stability and associated muscle load around the ankle and the effect of a parachute ankle brace (PAB) on ankle inversion and associated muscle load around the ankle during landing through the simulated paratrooper semi-squat landing field experiment. Methods: In August 2021, 37 male paratroopers were randomly selected as the study objects to perform parachute landing training in the semi-squat posture on the 1.5 m and 2.0 m jump platforms with or without PAB, respectively. The coronal plane tilt angle of ankle joint and the percentage of maximum voluntary contraction (MVC%) of associated muscles around ankle joint during the process were measured and correlation analysis was conducted. And the effect of wearing PAB on the coronal plane tilt angle of ankle joint and the associated muscles around the ankle joint was analyzed. Results: During the semi-squat landing, the MVC% of the tibialis anterior muscle, lateral gastrocnemius muscle and peroneus longus muscle were positively correlated with the ankle coronal plane tilt angle in paratroopers wearing and without wearing PAB, and the correlations were statistically significant (P<0.05). At the same height, compared with those without PAB, the coronal plane tilt angle of the ankle joint decreased during semi-squat landing in paratroopers PAB, and the differences were statistically significant (P<0.05). At the landing moment of the same height, compared with those without PAB, the MVC% of lateral gastrocnemius muscle decreased and the MVC% of peroneus longus muscle increased in paratroopers wearing PAB, and the differences were statistically significant (P<0.05). After the landing moment until the standing stage (100-200 ms) at 1.5 m height, the MVC% of the tibialis anterior muscle decreased in paratroopers wearing PAB compared with those without PAB, and the differences were statistically significant (P<0.05). In the post-standing stage (200 ms) at 2.0 m height, the MVC% of the tibialis anterior muscle decreased in paratroopers wearing PAB compared with those without PAB, and the difference was statistically significant (P<0.05) . Conclusion: Wearing PAB can reduce the ankle coronal plane tilt angle, improve ankle stability, reduce the muscle load of the lateral gastrocnemius muscle at the moment of landing, and reduce the load of the tibialis anterior muscle after landing, but increase the peroneus longus muscle load at the moment of landing.

DIAGNOSTICS OF POSTURAL DISORDERS IN CHILDREN USING COMPUTER PHOTOMETRY

Actuality of the research. Literary and statistical data show that the level of morbidity among children in Ukraine remains high. Important to note that musculoskeletal system and connective tissue diseases take the fifth place among the morbidity structure, while the postural disorders and scoliosis remain the most urgent problem in school­age children. The aim of study is to check the computer photometry method efficiency for postural disorders diagnostics in school­age children with different levels of motor activity. Research methodology. In order to improve the dynamic control over the posture state, to increase the study objectification, to reduce the examination time and simplify the statistical material processing, a software complex for diagnosing posture disorders using the computer photometry method was used. Results. It was found that 25% of examined school­age children had postural disorders. Most often, postural disorders were observed within the age of 10­13 years, while in girls, postural disorders were registered 10% more often than in boys. Systematic exercise does not automatically guarantee the correct posture formation. In children­athletes, more pronounced indicators of angular anthropometric parameters asymmetry were registered, as a result of asymmetric back muscles load distribution. Children who did not exercise were more prone to kyphotic posture developing. Conclusions. As instrumental diagnostics, the computer photometry method has high level of informativeness and reliability, helps to maximize the data objectification and is effective in postural disorders detecting during as screening and as mass examinations.

Penyuluhan Fisioterapi K3 Dalam Upaya Melakukan Preventif Dan Promotive Low Back Pain Di Penjahit Sartika Express Samarinda, Kalimantan Timur

Introduction: Jobs in long static positions, such as tailors, can cause musculoskeletal disorders (MSDs). MSDs are caused by unergonomic work postures, long work durations, and monotonous movements, resulting in loss of productivity and health problems. In Indonesia, the prevalence of musculoskeletal diseases is around 7.30%. Tailors often experience stiff posture and static muscle loads, causing muscle pain and stiffness in the waist and lower back. Objective: To provide preventive and promotional services and understanding of low back pain to tailors at Sartika Express, Samarinda, East Kalimantan. Method: This counseling is carried out by a health promotion method about low back pain which is carried out with presentations and using flyer media to facilitate education, this aims to understand the tailors, after that conduct a question and answer session to find out the condition and complaints of the tailors and then, educate with exercises and management that can be done independently. Conclusion: The counseling process went well, the tailors were able to follow and understand the exercises that had been taught, this activity got results in the form of understanding related to the exercises that had been taught from 0% to 100% after the counseling was carried out so that it could help the tailors prevent low back pain

Effects of laptop screen height on neck and shoulder muscle fatigue and spine loading for office workers.

Due to the unfavourable neck-shoulder muscle loads caused by poor posture, the people who use the laptop for a long time may face the risk of neck and shoulder injuries. The purpose of this study investigates the impact of the screen height on the muscle activation of head flexion, neck and shoulder, and the cervical spine torque to provide the favorite screen height for laptop user. Twelve healthy young participants completed a15-minute task of the reading at the four different screen heights. sEMG signals of the splenius capitis (SC) and upper trapezius (UT) were measured and calculated the root mean square (RMS) and mean power frequency (MPF) to determine muscle fatigue. The different height of laptop users was simulated and the forces on the spine of users at different screen heights were analyzed by Jack. Adjusting the height of the laptop screen can effectively reduce head flexion and muscle activity of SC and UT, and has a positive effect on reducing fatigue of SC, but has no significant effect on UT. Adjusting the height of the laptop screen can delay the occurrence of SC muscle fatigue to a certain extent. The joint analysis of sEMG spectrum and amplitude reports that the screen heights of D15 and D45 have the highest and the lowest frequency of fatigue, respectively. At the same time, the moment of spineT1/T2 and spineL4/L5 decrease with the increase of screen height.

Loading Recognition for Lumbar Exoskeleton Based on Multi-Channel Surface Electromyography From Low Back Muscles.

Lumbar exoskeleton is an assistive robot, which can reduce the risk of injury and pain in low back muscles when lifting heavy objects. An important challenge it faces involves enhancing assistance with minimal muscle energy consumption. One of the viable solutions is to adjust the force or torque of assistance in response to changes in the load on the low back muscles. It requires accurate loading recognition, which has yet to yield satisfactory outcomes due to the limitations of available measurement tools and load classification methods. This study aimed to precisely identify muscle loading using a multi-channel surface electromyographic (sEMG) electrode array on the low back muscles, combined with a participant-specific load classification method. Ten healthy participants performed a stoop lifting task with objects of varying weights, while sEMG data was collected from the low back muscles using a 3x7 electrode array. Nineteen time segments of the lifting phase were identified, and time-domain sEMG features were extracted from each segment. Participant-specific classifiers were built using four classification algorithms to determine the object weight in each time segment, and the classification performance was evaluated using a 5-fold cross-validation method. The artificial neural network classifier achieved an impressive accuracy of up to 96%, consistently improving as the lifting phase progressed, peaking towards the end of the lifting movement. This study successfully achieves accurate recognition of load on low back muscles during the object lifting task. The obtained results hold significant potential in effectively reducing muscle energy consumption when wearing a lumbar exoskeleton.