Lower Muscle Activity Research Articles

Recruitment of the diaphragm and sternocleidomastoid muscle during increasing inspiratory pressure loads in healthy young adults

BackgroundInspiratory muscle training (IMT) is often employed to enhance improvement in inspiratory muscle strength. However, the relationship between inspiratory muscle recruitment patterns and increasing inspiratory load remains unclear. Furthermore, the effect of breathing instructions on diaphragm activity at various inspiratory loads is unknown. ObjectiveTo investigate the recruitment activity of the diaphragm and sternocleidomastoid (SCM) muscles under increased inspiratory pressure loading, with and without diaphragmatic breathing instructions, in healthy young adults. MethodsParticipants were invited to breathe, in random order, 6 sets of 10 breaths at inspiratory loads of 30% to 80% maximal inspiratory pressure (MIP), in 10% increments. The measurement process was repeated with a specific focus of diaphragmatic descent during inspiration. Concurrent recorded surface electromyography of the right SCM muscle and right hemi-diaphragm thickness measured by ultrasonography during each targeted breath. ResultsSixty-two adults (31 males, age: 23±3 years) participated in the study. Irrespective of breathing instructions, computed diaphragm thickening fraction (DTf) increased with increasing inspiratory load but peaked at 50%MIP and declined with increasing load to 80%MIP. SCM recruitment increased with increasing inspiratory load to 80%MIP. Forced inspiration with diaphragmatic breathing was associated with a higher DTf and lower SCM muscle activity. The above pattern was similar for both male and female participants. Female participants produced higher SCM activity compared with males but only at inspiration loads below 50%MIP. ConclusionsIn a cohort of young healthy adults, magnitude of diaphragmatic effort was greatest at 50% MIP but declined with increasing inspiratory load to 80%MIP. Forced inspiration combined with focused diaphragmatic breathing accentuated diaphragm contraction and reduced SCM muscle contribution. Our findings show that diaphragmatic muscle recruitment is non-linear and that the generic clinical prescription of an IMT program may need to be reconfigured.

Comparing total-body metabolic PET imaging signatures of lung cancer cachexia to other wasting conditions

Cancer cachexia (CC) is a debilitating wasting condition. While anorexia and muscle wasting are features of cachexia, CC is a distinct and poorly understood metabolic syndrome1. We harnessed preclinical models of lung cancer to study how glucose uptake changes during CC and performed comparative analyses with anorexia and muscle wasting. Lung K-rasG12D/+;Lkb1-/-(KL) mice suffering CC were imaged using [18F]fluorodeoxyglucose (FDG) PET at 15-19% weight loss alongside K-ras wild-type (WT) non-tumour bearing controls. Mice were injected with 12-18MBq of FDG, imaging 80-100 minutes post injection with the Mediso nanoScan® PET/MRI 1T. In non-tumour bearing male animals, we modelled anorexia, muscle wasting, and circulation of cachexia factor GDF15 as follows, respectively: fasted overnight for 20 hr, treated with dexamethasone 21-phosphate (dexa) (2mg/kg, i.p. daily, 21 days) and single injection of recombinant human GDF15 hormone (0.1 mg/kg s.c.). FDG ex vivo biodistribution showed increased uptake in myocardium (p<0.05), brain and liver (both p<0.01) of KL cachexic animals with no significant change in FDG blood pool. Like cachexic KL animals, FDG uptake in fasted animals increased in brain (p<0.0001), perhaps due to increased FDG blood pool. FDG uptake in skeletal muscles and brown adipose tissue decreased (both p<0.05) in fasted state suggesting lower muscle activity and decreased thermogenesis respectively. Dexa-induced muscle atrophy also resulted in decreased FDG uptake in gastrocnemius/soleus muscles (SUVmean 0.63 vehicle vs. 0.45 dexa, p<0.05) but no changes in skeletal muscle FDG uptake were noted in cachexic animals. In contrast to KL animals, GDF15 injection resulted in decreased FDG uptake in myocardium (p<0.05). Overall, the cachexic FDG signature showed differences to other wasting conditions in this mouse model, suggesting different underlying mechanisms. Total-body PET can reveal diverse metabolic wasting states. We aim to elucidate mechanisms of metabolic changes in cachexia to allow metabolic subtyping and personalised treatment options. Please click on the 'PDF' for the full abstract!

The effect of squats on muscle activity in standing, kneeling, and half-kneeling positions: A cross-sectional study.

Kneeling and half-kneeling training are common positions used in physical therapy. however, research on lower extremity muscle activity is lacking compared to the ergonomic aspects and trunk muscle activity. The purpose of this study is to investigate the effects on lower extremity muscle activity during squats in kneeling and half-kneeling positions. The study was designed as a cross-sectional study with a single group of healthy adults. Participants were instructed to perform squats while assuming 3 positions (standing, kneeling, and half-kneeling). Surface electromyography data were recorded 3 times from the rectus femoris (RF), gluteus maximus (GMax), gluteus medius (GMed), and biceps femoris (BF) on the participant's dominant side, and the mean values were analyzed. The participants performed squats for 9 seconds, with 4 seconds of the descent phase, 1 second of the maintenance phase, and 4 seconds of the ascent phase. A metronome was used to ensure precise timing. The study included 30 participants (19 males and 11 females). The muscle activities of the RF, GMed, and BF showed statistically significant differences among the 3 positions, being highest in the half-kneeling position (HKP), followed by the standing position (SP) and kneeling position (KP). The muscle activity of the GMax was significantly higher in the HKP than in the SP and KP (P < .05). The co-contraction ratio was significantly higher with KP than with the SP and HKP (P < .05). In the SP and KP, there were statistically significant differences between the ascent and descent phases of the RF, GMax, GMed, and BF (P < .05). In the HKP, there were statistically significant differences between the ascent and descent phases of the RF, GMax, and GMed (P < .05). The results of this study indicate that squats in the HKP (especially during the ascent phase) require the highest muscle activity, whereas squats in the KP (especially during the descent phase) can be performed with the lowest muscle activity. It can be concluded that these findings could serve as selective indicators for squat exercises and in enhancing postural control, muscle strength, and lower extremity stabilization.

Amplitude of Lower Limb Muscle Activation in Different Phases of the Illinois Test in Parkinson's Disease Patients: A Pilot Study.

Background: Parkinson's disease (PD) is a neurodegenerative disorder with high prevalence in men and is characterized by symptoms such as tremors and gait difficulties. This study aimed to determine muscle activation in patients with PD by considering sex differences. Methods: This pilot study used analytical, quantitative, observational, and case-control methods. Surface electromyography was used to assess muscle activity during a variant of the Illinois agility test. The study population comprised an experimental group of patients with PD (N = 30) and a control group of healthy individuals without the disease (N = 10). Results: The Illinois agility test revealed significant differences in completion times between the groups. The Parkinson's disease group took longer overall (p = 0.004), especially for standing up (p < 0.001) and sitting down (p = 0.002), than the control group. In the control group, sex influenced gastrocnemius muscle activation, with women showing higher activation (rs = -0.87). Women also had greater rectus femoris activation during standing and sitting, with higher activation on the right side when standing (rs = -0.66) and the left side when sitting (rs = -0.87). In the control group, men exhibited greater activation of the right biceps femoris (rs = 0.87). However, in the Parkinson's disease group, sex did not affect muscle activation. Conclusions: Patients with Parkinson's showed lower muscle activation than healthy individuals while standing up, sitting down, and walking.

Effects of time-dependent acupuncture on back muscle endurance in women with chronic nonspecific low back pain: A randomized crossover trial.

Chronic nonspecific low back pain (CNLBP) is a leading cause of disability and remains a major burden for many public health systems. Acupuncture is a nonpharmacological treatment for CNLBP that can be effective in improving low back pain; nevertheless, its effect on improving back muscle endurance in patients with CNLBP and its duration of effect have not been studied. The goal of this study was to assess the impact of acupuncture on lower back muscle activity in CNLBP patients. This was a single-blind, randomized, crossover experimental study. Thirty female patients were randomized into Group A (15 patients) or Group B (15 patients). Patients in Group A were assigned to receive real acupuncture (RA) in the first phase and sham acupuncture (SA) in the second phase, while those in Group B received SA first and then RA, with a 1-week washout period between phases. Two-way repeated ANOVA was used to evaluate the effect of group and time on isokinetic parameters, Surface electromyography (sEMG) data, and blood data. Significant interaction effects were identified between group * time on the isokinetic parameters of the lumbar extensor muscles, sEMG values of the erector spinae, blood lactate levels, and blood ammonia levels (all p< 0.05). Compared with those of the SA group, the isokinetic parameters of the lumbar extensor muscles, sEMG values of the erector spinae, blood lactate levels, and blood ammonia levels of the RA group were significantly different (all p< 0.05). RA improves lumbar extensor endurance in patients with CNLBP and lasts approximately 9 minutes. RA can improve blood circulation to reduce blood lactic acid and blood ammonia produced during exercise.

The Influence of the Type of Breathing on the Masticatory Muscle Patterns in Children.

Background and Objectives: The aim was to compare the activity of the masseter muscles in children with different types of breathing. Materials and Methods: A cross-sectional study was conducted including patients aged 6-12 years with mixed dentition, who came for oral care at the Master's Degree in Pediatric Dentistry program at the Complutense University of Madrid (UCM), according to inclusion and exclusion criteria. The sample was divided into three groups: nasal breathers without dental alterations (control group), oral breathers with dental malocclusion, and oral breathers with previous orthodontic treatment. An electromyography was performed, and statistic methods were conducted with a 95% confidence to contrast hypothesis. Results: A total of 122 children were analyzed and distributed into three groups. The electrical muscle activity of masseters was significantly different between the study groups (p < 0.001 for all comparisons). Pairwise comparisons revealed a significantly higher electrical muscle activity in the control group (nasal breathers) during chewing compared to both groups of oral breathers (p < 0.001 for both comparisons). Orthodontic treatment decreased electrical muscle activity during isometric contraction in oral breathers compared to nasal breathers (p < 0.001), but did not significantly affect electrical muscle activity during chewing. Higher decompensation values were obtained in oral breathers without previous orthodontic treatment compared the other study groups (p < 0.001 for both comparisons), although electrical muscle activity values were similar in both groups of oral breathers (p > 0.05 for both comparisons). Conclusions: Differences in electrical muscle activity between nasal and oral breathers can be confirmed. Oral breathers with and without orthodontic treatment showed lower electrical muscle activity of masseters during chewing than nasal breathers, while at isometric contraction, only oral breathers with previous orthodontic treatment showed lower electrical activity. Higher decompensation values were found in oral breathers without previous orthodontic treatment, in comparison to the control group and oral breathers with previous orthodontic treatment.

Commercial infant products influence body position and muscle use

The musculoskeletal and motor development of infants is affected by their environment, which varies from being held, lying on a firm flat surface, to seated in various nursery products. Nursery products can alter the body position of infants, particularly the position of the head/neck and trunk, which may inhibit an infant's ability to breathe. With U.S. infants spending an increasing amount of time in seated products, the purpose of this study was to assess muscle activation and body position in four commercial infant products (carrier, bouncer, rocker, and swing) during supine and prone positioning, compared to a firm flat surface. Thirteen healthy infants (age: 4.2 ± 1.4 months; 7 M/6F) were enrolled in this IRB-approved in-vivo biomechanics study. Surface electromyography sensors recorded muscle activity of the erector spinae, cervical paraspinals, quadriceps, and abdominal muscles and retro-reflective markers tracked movements to determine head-neck, trunk, and torso-pelvis flexion/extension in the sagittal plane. While supine, infants exhibited increased head-neck and trunk flexion of up to 21° and 27° above the playmat, respectively, in all seated products. While prone, high abdominal muscle activation compared to the playmat indicates that infants will fatigue faster in seated products. Additionally, the lower muscle activation levels exhibited in younger infants (< 4 months) compared to older infants (≥ 4 months) indicates that younger infants rely on the product design to maintain body position. However, offering infants a variety of environments to move within is important to avoid motor delay, therefore future work should explore how long-term use may impact an infant's development.

Assistive Technology for Real-Time Fall Prevention During Walking: Evaluation of the Effect of an Intelligent Foot Orthosis

Abstract We present an intelligent foot orthosis (IFO) designed to prevent lateral falls during walking by employing a magnetorheological (MR) fluid brake. This study aims to demonstrate the feasibility of evaluating effectiveness of the proposed orthosis in fall prevention. Seventeen healthy adults underwent four conditions: (1) without IFO, (2) with IFO and current-OFF, (3) with IFO current-ON, and (4) with IFO and control-ON. Gait was assessed by three-dimensional motion capture and with ground reaction force. Postural changes on the frontal plane were measured, and the mediolateral center of gravity and center of pressure inclination angle (ML COG-COP IA) was calculated. Additionally, tibialis anterior (TA) and peroneus longus (PL) muscle activity during walking were measured using surface electromyography. Results indicate a significant increase in ML COG-COP IA in (3). No significant differences were found in muscle activity between conditions. The study suggests that the posture's deviation from the lateral fall direction in (3) is primarily due to wearing the IFO, emphasizing human postural control over muscle activity. A negative correlation between ML COG-COP IA and TA muscle activity under (4), implies that individuals with lower TA muscle activity may benefit more from IFO fall prevention. In conclusion, the study demonstrates the feasibility of preventing lateral falls in human walking using the proposed orthosis with an MR fluid brake. The general efficacy of the orthosis in lateral fall prevention is suggested, emphasizing the need for further development.

An Ergonomic Golf Grip Leads to Lower Forearm Muscle Activity - A Prospective Case Series of 30 Right-Handed Amateur and Professional Golfers

BackgroundThe elbow is a common site for overuse injuries in golfers. Tendinopathies, such as medial and lateral epicondylitis, are frequently diagnosed in amateur and professional golfers. The aim of our study was to determine the effect of an ergonomic golf grip on forearm muscle activity during the five phases of the golf swing.MethodsThirty right-handed golfers with a mean age of 32 years (range, 18–70 years) and a mean handicap of 15 (range, 0–43) performed 10 golf swings with a standard and ergonomic golf grip respectively. The mean and maximum muscle activity of the Musculus (M.) extensor carpi radialis brevis (ECRB), M. flexor carpi ulnaris (FCU), M. pronator teres (PT) and M. biceps brachii (BB) of the lead and trail arms were assessed during the five phases of the golf swing using surface electromyography (EMG). Subgroup analyses were performed regarding sex, playing ability (handicap < 10 vs. ≥10), weekly playing time (≤ 5 h, 5–20 h, > 20 h) and preexisting elbow pain during golfing (VAS < 2 vs. VAS ≥ 2). Significance was set at p < 0.05.ResultsAn ergonomic golf grip resulted in a reduction in muscle activity in at least one but up to three consecutive phases of the golf swing for the ECRB, FCU and PT of the lead arm and for the PT of the trail arm. Amateurs, a playing time < 20 h per week and golfers without preexisting elbow pain were factors that were associated with greater reductions in muscle activity.ConclusionForearm muscle activity can be decreased using an ergonomic golf grip, indicating the possible role of an ergonomic golf grip as a preventive measure against overuse syndromes such as medial and lateral epicondylitis.Trial registration numberThis study was retrospectively registered at the German Clinical Trials Register DRKS-ID: DRKS00033732 (01/03/2024).

Should I prescribe exercise to a patient with an immobilized shoulder? An electromyographic study in patients with unilateral shoulder pain and healthy volunteers

Background There is limited evidence about exercise performance during postoperative immobilization. This study aimed to quantify the muscle activity in the immobilized shoulder girdle in an abduction and neutral rotation position during a battery of contralateral activities and ipsilateral exercises of the upper limb in healthy volunteers and patients with unilateral shoulder pain (USP). Methods Thirty participants were included and grouped as without ( N = 17) or with USP ( N = 13). Muscle activity (percentage of maximum voluntary isometric contraction (%MVIC)) of the serratus anterior (SA), upper trapezius (UT), lower trapezius (LT) and infraspinatus muscles was assessed during five contralateral activities (during comfortable speed, fast speed and comfortable speed with additional load) and seven ipsilateral exercises. Results No differences in % MVIC were found between healthy volunteers and patients with USP on immobilized upper limb exercises and with the contralateral shoulder girdle. General muscle activity was low (&lt;15% MVIC) to moderate (21–40% MVIC). This similarity was maintained at different speeds and with additional load. Adapted lawnmower exercise showed a favorable UT/LT activation ratio. Conclusion The study results support the use of all evaluated shoulder exercises, as they have shown low muscle activity, which is important for early rehabilitation phases.

Evaluation of a passive back-support exoskeleton during in-bed patient handling tasks

This study evaluated the effects of a back-support exoskeleton on the trunk and hip joint angles, lower back muscle activity and heart rate during four patient handling tasks: assisting a patient from sitting to lying, laterally repositioning the patient and turning the patient in two directions. Eight participants performed these tasks with and without the exoskeleton. Results demonstrated a significant reduction in the lower back muscle activity, but less pronounced effects for other tasks involving minimal trunk flexion. Hip flexion angles were reduced for all tasks when the exoskeleton was worn. The amount of reduction in the muscle activity and changes in the trunk and hip angles varied by task. The exoskeleton did not affect the heart rate across all tasks. The exoskeleton appeared to be more effective in tasks requiring substantial trunk flexion, indicating its potential benefits for reducing lower back muscle strain during such activities.

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.

Shoulder Rotation Affects Trapezius Muscle Activity During Shoulder Horizontal Abduction.

Shoulder horizontal abduction exercise in the prone position is effective for strengthening the lower trapezius muscle. However, this exercise is difficult for patients with acute pain or those undergoing initial rehabilitation because of the postural characteristics of the exercise. This study aimed to (1) investigate the effect of a shoulder horizontal abduction exercise when performed with a different amount of shoulder rotation on the trapezius muscle activation and scapular anterior/posterior tilt angle and (2) evaluate the effect of shoulder rotation on the acromiohumeral distance while sitting. Fifteen healthy men performed shoulder horizontal abduction exercise in three shoulder positions (internal rotation, neutral rotation, and external rotation). During exercises, we measured trapezius muscle activity using an electromyography system and scapular anterior/posterior tilt angle using an inclinometer application. We also measured the acromiohumeral distance using real-time ultrasonography before the exercises. Increases in lower trapezius and middle trapezius muscle activities and a decrease in scapular anterior tilt occurred in shoulder external rotation compared with other positions (p<0.001). Shoulder external rotation also significantly increased acromiohumeral distance in the sitting position (p<0.05). We propose that shoulder external rotation effectively and safely increases middle and lower trapezius muscle activities during the sitting shoulder horizontal abduction exercise.

A mixed methods approach to describe the efficacy of lift assist device use to reduce low back musculoskeletal disorder risk factors during three common patient extrication scenarios

This mixed-method study evaluated the efficacy of lift assist device use (Binder®, Eagle®, Maxi Air®) relative to manual lifting/care-as-usual in reducing low back muscle activity and perceived exertion during simulated patient extrication tasks. User feedback was recorded to identify factors that might influence use. Twenty paramedics performed a floor to stretcher lift, lateral transfer, and confined space extrication care-as-usual and with lift assist devices. Use of a lift assist reduced low back muscle activity during floor to stretcher and confined space tasks by 34–47%. Paramedics perceived exertion decreased from ‘somewhat hard’ to ‘light’ or ‘very light’ when using an assistive device. Paramedics noted that ease of use, patient comfort, task time, patient acuity, among other considerations would influence use decisions. Lift assist devices were efficacious at reducing low back muscle activity and perceived exertion during floor to stretcher and patient extrication tasks.

Muscle activity and hypoalgesia in blood flow restricted versus unrestricted effort-matched resistance exercise in healthy adults.

This study assessed muscle activity (root mean square, RMS, and median frequency, MDF) to evaluate the acute response to blood flow restriction (BFR) resistance exercise (RE) and conventional moderate intensity (MI) RE. We also performed exploratory analyses of differences based on sex and exercise-induced hypoalgesia (EIH). Fourteen asymptomatic individuals performed four sets of unilateral leg press with their dominant leg to volitional fatigue under two exercise conditions: BFR RE and MI RE. Dominant side rectus femoris (RF) and vastus lateralis (VL) muscle activity were measured using surface electromyography (sEMG) through exercise. RMS and MDF were calculated and compared between conditions and timepoints using a linear mixed model. Pressure pain thresholds (PPT) were tested before and immediately after exercise and used to quantify EIH. Participants were then divided into EIH responders and nonresponders, and the differences on RMS and MDF were compared between the two groups using Hedges' g. RMS significantly increased over time (RF: p = 0.0039; VL: p = 0.001) but not between conditions (RF: p = 0.4; VL: p = 0.67). MDF decreased over time (RF: p = 0.042; VL: p < 0.001) but not between conditions (RF: p = 0.74; VL: p = 0.77). Consistently lower muscle activation was found in females compared with males (BRF, RF: g = 0.63; VL, g = 0.5. MI, RF: g = 0.72; VL: g = 1.56), with more heterogeneous findings in MDF changes. For BFR, EIH responders showed greater RMS changes (Δ RMS) (RF: g = 0.90; VL: g = 1.21) but similar MDF changes (Δ MDF) (RF: g = 0.45; VL: g = 0.28) compared to nonresponders. For MI, EIH responders demonstrated greater increase on Δ RMS (g = 0.61) and decrease on Δ MDF (g = 0.68) in RF but similar changes in VL (Δ RMS: g = 0.40; Δ MDF: g = 0.39). These results indicate that when exercising to fatigue, no statistically significant difference was observed between BFR RE and conventional MI RE in Δ RMS and Δ MDF. Lower muscle activity was noticed in females. While exercising to volitional fatigue, muscle activity may contribute to EIH.

The Use of Virtual Reality in Stable Sitting Trunk Rehabilitation for Stroke Patients: A Pilot Study

INTRODUCTION: Virtual reality (VR) holds promise for stroke rehabilitation. However, many existing VR systems requires users to stand while playing, posing a potential falling risk for stroke patients. This study investigated the effects of a custom-developed VR system that focus on trunk rehabilitation in stable sitting position on muscle activities, postural control, and physiological cost compared to conventional trunk exercises in stroke patients. MATERIALS AND METHODS: A cross-sectional observational pilot study was conducted involving 12 paretic stroke subjects performing four exercises: two Conventional Trunk Exercises (CTE) and two VR-based Trunk Exercises (VRTE) using customized Tilt-The-Maze (self-paced) or Catch-The-Mole (game-paced) games. Muscle activity was measured using electromyography (EMG). Postural control data in the Anterior-Posterior (AP) and Medio-Lateral (ML) axes was recorded using a force plate, while the physiological cost was measured via a heart rate sensor during the exercises. RESULTS: The results indicated low muscle activity and light-intensity cardiovascular responses in all CTE and VRTE exercises. Game-paced VRTE recorded slightly higher Center of Pressure (CoP) velocity in the AP and ML axes versus CTE (AP:4.40±1.80 vs. 4.02±1.20 cm/s; ML:6.40±2.54 vs. 5.42±2.21 cm/s). In contrast, the self-paced VRTE showed an insignificant impact on postural control than both CTE and game-paced VRTE. CONCLUSION: The game-paced VRTE induced comparable effects on muscular activation, postural control, and physiological cost to that of CTE in stroke patients. The findings suggest the stable-sitting VR system as a supplementary approach to the existing trunk rehabilitation protocols for stroke patients.

Age- and Parkinson-related differences in trunk and lower-limb muscle activation during four balance tasks: A case-control pilot study

BackgroundPoor postural control has been reported in people with Parkinson's disease, which could be explained by the changes in muscular activation patterns related to antigravitational muscles. This study aims to measure the muscle activation of antigravitational muscles during balance tasks in individuals, with and without Parkinson's. MethodsSixteen (16) participants (9 with Parkinson's), aged ≥65 yrs., performed 2 × 30-s trials of 4 balance tasks (bipodal and semi-tandem opened eyes and closed eyes) on a force platform (center of pressure measurement); while surface electromyography measurements were obtained bilaterally on the multifidus at L5, biceps femoris and medialis gastrocnemius. Electromyography amplitude analysis was processed by the Root Mean Square (250 ms window epochs) and normalized by the peak of activation during the balance task, to determine each muscle's activity level. FindingsThe Parkinson's group reported lower muscle activation than control across tasks (in mean for multifidus = 8%, biceps femoris = 16%, gastrocnemius = 7%), although not statistically significant. Parkinson's reported significantly poorer postural control than control, mainly for the center of pressure sway ellipse area (p = 0.016) from challenge balance tasks such as semi-tandem. InterpretationPoor postural control was confirmed in the Parkinson's group, but not significantly associated by the changes from muscle activation of trunk and lower limbs, during balance performance.

Investigation of muscle activation during kinetic chain based exercises in individuals with and without forward head posture.

The Band Pull-Apart (BPA) exercise is used to strengthen the periscapular muscles. It was recently stated that the lower extremity and trunk movements should be included in the shoulder rehabilitation programs to optimize an effective energy transfer throughout the kinetic chain. The aim of this study is to investigate the effects of kinetic chain based BPA exercise on the muscle activations of the sternocleidomasteideous (SCM) and the trapezius muscles in individuals with and without forward head posture (FHP). Eighteen individuals with FHP and 18 individuals without FHP were included. Photographic measurements were made to identify individuals with FHP. The muscle activations of SCM, Upper Trapezius (UT), Middle Trapezius (MT), and Lower Trapezius (LT) were measured with surface EMG. BPA exercise was performed in the standing, unipedal standing, squat, unipedal squat, and Bulgarian split squat (BSS). There was no Group × Exercise interaction for the SCM, UT, MT, LT muscle activations, or for the UT/MT and UT/LT ratios (p> 0.05). While there was a difference in the activation of all muscles between individuals with and without FHP (p< 0.05), both ratios were similar (p> 0.05). There was a statistically significant difference between exercises for SCM, MT, and LT muscle activations (p< 0.000 for these muscles), UT/MT (p< 0.000) and UT/LT ratios (p= 0.004). SCM muscle activation in squat was lower than activation in standing (Mean Difference (MD) = 2.5% Maximal Voluntary Isometric Contractions (MVIC); p= 0.004) and in unipedal standing (MD = 2.1% MVIC; p= 0.002). MT muscle activation in squat was higher than activation in standing (MD = 9.7% MVIC), unipedal standing (MD = 7.8% MVIC), unipedal squat (MD = 6.9% MVIC) and BSS (MD = 9.4% MVIC; p< 0.000 for these positions). LT muscle activation in the squat was higher than activation in the standing (MD = 8.5% MVIC) and unipedal squat (MD = 8.1% MVIC; p< 0.004 for these positions). UT/MT ratio in the squat was lower than standing (MD = 0.3), unipedal standing (MD = 0.2) and BSS (MD = 0.3; p< 0.000 for these positions). UT/LT ratio in squat was lower than unipedal squat (MD = 0.5) and BSS (MD = 0.6; p= 0.002; for these positions). Performing the BPA exercise in the squat position is suggested in cases where lower SCM and UT muscle activation, lower UT/MT, and UT/LT ratios and higher MT and LT muscle activations are needed for individuals with and without FHP.

Current Issues Related to Biomechanics in Engineering

Motion capture was employed by Eadweard Muybridge and Etienne-Jules Marey. Industry standard for computing joint kinematics is motion capture. Kinematic analysis is a technique used in biomechanics and mechanical engineering to quantify stiff body motion. A joint moment can be computed in one of two ways: bottom-up or top-down. Joint moments measure muscle and joint tension indirectly. Researchers predicted joint moments using kinematic-based characteristics and machine learning outside of the biomechanics lab.Ankle osteoarthritis causes significant biomechanical issues in the foot and lower leg. Patients' 3D multi-segment kinematic foot models were studied. The technique used is Openpose, which recognises the human body from a single photograph.Falling fear is linked to decreased activity, despondency, and anxiety in the elderly. They adopt a hip approach to manage their GRFs and balance. The lateral ankle technique corrects minor foot placement problems by swiftly moving the pressure point. Angular momentum is affected by foot placement and ground reaction forces. Changing the body's centre of mass along a curved trajectory implies large changes in both ground reaction force impulses and ground reaction force.Lens stiffness and a ciliary muscle anterior/inward displacement produce presbyopia. By 55, the majority of folks have lost their ability to accommodate. Cataracts become common around this time, reaching over 70% by 75. The circumferential and meridional stiffnesses rose with anisotropy from pole to equator, but dropped with distance. The Holzapfel model accurately fits the data from inflation and uniaxial mechanical tests.Anatomical motions of the femur during knee flexion were examined. The data revealed morphological and physiological knee kinematic characteristics. The data led to several hypotheses about axial femoral condyle rotation. This review discusses lower limbs, foot positioning, lens capsule, femoral condyle, muscle activation, collagen fibre, knee joint, and walking speed. The purpose is to provide a general overview on the subject matter.

Evacuation safety effects of a lightweight elevator-type evacuation device using carbon material: Focus on plantar pressure and muscle strength.

Elevator-type evacuation devices have proven to be feasible in high-rise buildings through studies on safety performance and evacuation time. However, there is a lack of research on safety using biosignal analysis in the elderly population. A carbon material is used in this study to reduce the weight of an evacuation elevator. The impact on the human body is evaluated by conducting a satisfaction survey involving elderly and youth groups and quantitatively analyzing biological signals, including electromyography (EMG) and plantar pressure, during five repeated uses of the proposed device. The study involves 12 healthy adults in their 20s and 20 elderly individuals with no experience in using an evacuation elevator. The EMG and left and right plantar pressures are analyzed to evaluate the physical factors affected by repeated use. The experiment results showed that the normalization of EMG to maximum voluntary contraction showed a significant decrease with repeated use, especially in the right tibialis anterior muscle. Moreover, plantar pressure shows a significant difference, which decreased with repetition, and the left and right balance gradually tilted to the left. This suggests that with more repeated use, muscle tension decreases owing to adaptation, resulting in lower muscle activity and plantar pressure. Particularly, the tibialis anterior muscle experiences significant muscle activity, indicating increased load, but without any apparent danger. In the future, it will be necessary to evaluate elevators for disabled individuals.