Comparison Of Muscle Activity Research Articles

Comparing Muscle Activity and Onset Time of Cervical and Thoracoscapular Muscles during Shoulder Flexion and Abduction in Individuals with and without Forward Head Posture

Comparing Muscle Activity and Onset Time of Cervical and Thoracoscapular Muscles during Shoulder Flexion and Abduction in Individuals with and without Forward Head Posture

Comparison of muscle activity in school students while carrying backpacks and trolley bags.

Trolley bags have gained popularity among students, but there is limited research comparing them to backpack-style school bags. This study aimed to compare how carrying a backpack versus a trolley bag affects the activity of trunk and lower limb muscles in secondary school students. Electromyographic activity was measured in 25 students (13.4±1.1 years) as they walked on level ground and up/down stairs while carrying both types of bags. The activity of the gastrocnemius, tibialis anterior, semitendinosus, rectus femoris, lumbar erector spinae, and rectus abdominis muscles was assessed on both the dominant and non-dominant sides. The study found significantly reduced muscle activation in most of the targeted muscles when walking on level ground with the trolley bag and when going up/down stairs with the backpack. Lifting a trolley bag depends on the slope of the walking surface and is more efficient on level ground, while carrying a backpack is more efficient when going up and down stairs. Since it is not practical to switch bags when encountering stairs in schools, a bag with a mixed model design incorporating features of both trolley and backpack may be more beneficial and practical for students to use. Students, parents, and teachers should be aware of the injury risks associated with carrying different types of bags.

Rehabilitation strategies and magnetic resonance imaging techniques for shoulder injuries in sports

ObjectiveShoulder sleeve injuries are high-risk in men's tennis, with rehabilitation focusing on activating shoulder muscle groups to regain strength. Specific plans use electromyography and isokinetic instruments to compare muscle activity and torque pre- and post-rehabilitation. The goal is to explore training effects on rotator cuff injuries and assess routine MRI and MRI shoulder arthrography for diagnostic value in shoulder injuries. This aims to provide a reference for restoring shoulder function in male tennis players. MethodsTwenty college students (n = 20) with rotator cuff injuries from a university tennis program were selected as experimental subjects, matched based on gender and injury severity, and divided into experimental (n = 10) and control (n = 10) groups. A paired sample T-test assessed the impact of rehabilitation training on muscle recruitment and strength around the shoulder joint in the experimental group before and after training. This evaluated the influence of rehabilitation plans on shoulder muscle mobilization and strength. Another paired sample T-test compared indicators before and after the experiment, examining mechanisms underlying the effects of functional rehabilitation training on shoulder sleeve injuries in male tennis players. Results(1) Surface electromyography (EMG) results for internal/external rotation showed a significant increase in anterior, middle, and posterior deltoid EMG values (P < 0.05). Supraspinatus and infraspinatus muscles exhibited substantial increases (P < 0.01), while no significant change occurred in the teres minor muscle. (2) Adduction/abduction EMG tests at 60°/s, 90°/s, and 120°/s revealed significant increases (P < 0.01) in deltoid bundles and supraspinatus/infraspinatus muscles for both experimental and control groups. Teres minor muscle showed no significant change. (3) Isokinetic muscle strength tests indicated a significant peak torque increase (P < 0.01) during inward/outward rotation at 60°/s, 90°/s, and 120°/s for the experimental group compared to the control group. ConclusionA 10-week functional shoulder rehabilitation training program can enhance the strength, endurance, and neuromuscular recruitment of shoulder-related muscles in male tennis players with rotator cuff injuries. This approach, combined with the diagnostic capabilities of routine MRI and MRI shoulder arthrography, enables modifications in the body's ongoing adaptation to injuries. This, in turn, contributes to improved shoulder joint stability and effectively facilitates the functional recovery of the rotator cuff muscle group.

Examination of the relationship between masseter muscle activity during sleep and wakefulness measured by using a wearable electromyographic device.

Purpose This study aimed to measure masseter muscle activity throughout the day in outpatients suspected of having awake bruxism (AB) and/or sleep bruxism (SB) and examine the relationship between AB and SB by comparing muscle activity during daytime wakefulness and nighttime sleep.Methods Fifty outpatients with suspected SB and/or AB participated in this study. A single-channel wearable electromyogram (EMG) device was used for EMG recording. The selected EMG bursts were divided into bursts during sleep (S-bursts) and bursts during awake state (A-bursts). The number of bursts per hour, average burst duration, and ratio of burst peak value to maximum voluntary contraction were calculated for both the S- and A-bursts. These values of the S- and A-bursts were then compared, and the correlations between them were analyzed. Additionally, the ratios of phasic and tonic bursts in the S- and A-bursts were compared.Results The number of bursts per hour was significantly higher for A-bursts than for S-bursts. No significant correlation was found between the numbers of S- and A-bursts. The ratio of phasic bursts was large and that of tonic bursts was small in both the S- and A-bursts. A comparison of the S- and A-bursts showed that the S-bursts had a significantly lower ratio of phasic bursts and higher ratio of tonic bursts than the A-bursts.Conclusions The number of masseteric EMG bursts during wakefulness did not show any association with that during sleep. It became clear that sustained muscle activity was not dominant in AB.

Muscle Activation During Squat on Different Surfaces

This study aimed to compare the vastus medialis and vastus lateralis muscle activations during squat exercises performed on different surfaces. Recreationally active 14 males (age: 20.43±1.28 years; height: 176.94±6.58 cm; body weight: 72.78±10.72 kg) participated in this study. A ground surface is used as a stable surface, a gymnastics mat and a Bosu ball are used as an unstable surface. Participants performed two sets of squats on three surfaces and ten repetitions of each set. Participants performed squat exercises with their body weight. Muscle activation measurements were made from the vastus medialis and vastus lateralis muscles during the squat movement on each surface. A one-way repeated-measures analysis of variances was used to statistically compare muscle activations between surfaces. As a result of statistical analysis, no significant differences were found in the vastus medialis and vastus lateralis muscle activations between surfaces (p&gt;0.05). In conclusion, it was determined that the vastus medialis and vastus lateralis muscle activation in the squat movement was not affected by the stability of the surfaces. Therefore, it can be suggested that the surfaces used in this study can be used interchangeably for vastus medialis (VM) and vastus lateralis (VL) muscle activation in the squat exercise.

EMG Analysis During Static Balance in Chronic Ankle Instability, Coper and Controls.

Patients with chronic ankle instability (CAI) consistently display postural control alterations, which may result from sensorimotor dysfunction. This study aimed to compare muscle activity in the lower extremity and postural control among individuals with CAI, copers and uninjured controls during a static balance test. A total of 57 physically active participants were categorized into three groups (CAI, copers and controls) and performed a single-leg balance test with two visual conditions: eyes open and eyes closed. Muscle activity in six lower extremity muscles and center of pressure (CoP) variables were recorded and analyzed. Patients with CAI exhibited greater muscle activity in the medial gastrocnemius and gluteus maximus compared to controls or copers, regardless of the visual condition. Copers displayed increased gluteus medius activity compared to controls. Additionally, all groups demonstrated increased muscle activity and CoP variables when visual feedback was disrupted. These findings suggest that patients with CAI may have less effective recruitment of motor units during static balance. On the other hand, greater muscle activity in the gluteus medius in copers may represent a coping mechanism to avoid further ankle injuries. Further research on muscle activity during dynamic postural control is warranted to explore sensorimotor alterations in patients with CAI.

Laptop use and muscle activity in adult females: Ground sitting has lower muscular demand than using a chair.

With progressing technology in the portable computing field, laptops are now integral for work, home and social settings. Different working postures adopted by laptop users impose different loads on the relevant muscles, which can be associated with musculoskeletal discomfort in the various body regions. Some Arabic and Asian cultures adopted postures are not well investigated, particularly for the 20-30 years age-group. This study compared muscle activity in the cervical spine, arm, and wrist among different laptop workstation setups. In this cross-sectional study, 23 healthy female university students (age = 24.2±2.28 years, range 20-26 years) performed a standardized 10 minute typing task in four different laptop workstation setups: DESK, SOFA, GROUND sitting with back support, and laptop table (LAP-Tab). Differences between electromyography (EMG) muscle activity recorded in the trapezius (TR), cervical extensors (CE), deltoid (DEL), and wrist extensors (WE) were determined using one-way repeated ANOVA measures with a post-hoc Bonferroni test. Significantly higher muscle activity was observed respectively in the workstations of DESK > LAP-Tab > SOFA > GROUND. Significant differences were found between WE muscle activity and the three other muscle groups (p < 0.001). There was a significant interaction between workstations and muscle activity (F(9,264) = 3.81, p < 0.001, = 0.11), where the WE and DEL muscles showed respectively higher and lower muscle activity in all setups. Muscles showed variable activity in different workstations such that the GROUND workstation provided the minimum load, while the DESK workstation showed the maximum load on the measured muscle groups. These findings require further investigation in different cultural and gender specific groups.

Comparison of Muscle Activity around the Trunk and Hip according to Weight and Phase during Kettlebell Swing

Comparison of Muscle Activity around the Trunk and Hip according to Weight and Phase during Kettlebell Swing

Muscle activation patterns during active external rotation after reverse total shoulder arthroplasty: an electrophysiological study of the teres minor and associated musculature

Preoperative teres minor insufficiency has been identified as a risk factor for poor restoration of external rotation (ER) after reverse total shoulder arthroplasty (RTSA). However, there has been little investigation regarding muscle activation patterns generating ER. This prospective study sought to determine the timing and activation levels of the shoulder girdle musculature during ER in well-functioning RTSAs with an intact teres minor using a lateralized design. Patients who underwent RTSA ≥1 year previously with functional ER, an American Shoulder and Elbow Surgeons (ASES) score >70, superior rotator cuff deficiency, and an intact teres minor were identified. Electrophysiological and kinematic analyses were performed during ER in the modified neutral position (arm at side with 90° of elbow flexion) and in abduction (AB) (shoulder abducted 90° with 90° of elbow flexion). Dynamometer-recorded torque and position were pattern matched to electromyography during ER. The root-mean-square and integrated electromyography (in microvolts × milliseconds with standard deviation [SD]), as well as median frequency (MF) (in hertz with SD), were calculated to determine muscle recruitment. Pair-wise t test analysis compared muscle activation (P<.05 indicated significance). After an a priori power analysis, 16 patients were recruited. The average ASES score, visual analog scale pain score, and ASES subscore for ER in AB ("comb hair") were 87.7, 0.5, and 2.75 of 3, respectively. In AB, muscle activation began with the upper trapezius, middle trapezius, and latissimus dorsi, followed by the anterior deltoid activating to neutral. With ER beyond neutral, the teres major (9.6 μV × ms; SD, 9.2 μV × ms) initiated ER, followed by the teres minor (14.1 μV × ms; SD, 18.2 μV × ms) and posterior deltoid (11.1 μV × ms; SD, 9.3 μV × ms). MF analysis indicated equal contributions of the teres major (1.1 Hz; SD, 0.5 Hz), teres minor (1.2 Hz; SD, 0.4 Hz), and posterior deltoid (1.1 Hz; SD, 0.4 Hz) in ER beyond neutral. In the modified neutral position, the upper trapezius and middle trapezius were not recruited to the same level as in AB. For ER beyond neutral, the teres major (9.5 μV × ms [SD, 9 μV × ms]; MF, 1.1 Hz [SD, 0.5 Hz]), teres minor (11.4 μV × ms [SD, 15.1 μV × ms]; MF, 1.1 Hz [SD, 0.5 Hz]), and posterior deltoid (8.5 μV × ms [SD, 8 μV × ms]; MF, 1.2 Hz [SD, 0.3 Hz]) were activated in similar sequence and intensity as AB. No differences in muscle activation duration or intensity were noted among the teres major, teres minor, and posterior deltoid (P>.05). Active ER after RTSA is complex and is not governed by a single muscle-tendon unit. This study establishes a sequence, duration, and intensity of muscle activation for ER in well-functioning RTSAs. In both tested positions, the teres major, teres minor, and posterior deltoid function equally and sequentially to power ER.

Neuromotor variability partially explains different endurance capacities of expert pianists

During fatiguing piano tasks, muscle fatigue develops differently between expert pianists. Differences in neuromotor strategies employed could explain a slower rate of fatigue development. The objective was to compare muscle activation and kinematic variabilities between ShortDuration (i.e., pianists with less endurance) and LongDuration groups. Results from 49 pianists showed that EMG activation variability of most shoulder and upper limbs muscles was greater for the ShortDuration group with time during two piano fatiguing tasks, namely Digital and Chord tasks. Segment acceleration variability, assessed using inertial measurement units, was also greater with time for the ShortDuration group at the right arm during the Digital task, and at the thorax and head during the Chord task. Finally, thorax lateroflexion variability increased with time for the LongDuration group (but not the ShortDuration group) during the Digital task. During the Chord task, wrist flexion variability was higher for the LongDuration group compared to the ShortDuration group. These results showed a direct effect of time on the pianists’ acceleration variability and EMG activation variability. In contrast, a protective effect of fatigue development could be attributed to kinematic variability. Results also suggest a higher risk of injury among pianists in the ShortDuration group.

Comparison of Muscle Activity and Muscle Thickness According to Knee Flexion Angle during Supine Bridge Exercises using the Abdominal Drawing-in Maneuver on an Unstable Surface

Comparison of Muscle Activity and Muscle Thickness According to Knee Flexion Angle during Supine Bridge Exercises using the Abdominal Drawing-in Maneuver on an Unstable Surface

Comparison of Muscle Activity and Muscle Thickness According to Knee Flexion Angle during Supine Bridge Exercises using the Abdominal Drawing-in Maneuver on an Unstable Surface.

This study evaluated changes in deep trunk muscle thickness and lower extremity muscle activities during bridge exercises with the abdominal drawing-in maneuver. Bridge exercises were conducted on an unstable surface at different knee flexion angles (60º, 90º and 120º), with the aim of identifying more effective angles for bridge exercises. This study included 21 healthy adults, aged 20-27 years. Biceps femoris (BF), rectus abdominis, and rectus femoris activity was measured using surface electromyography. The thicknesses of the transverse abdominis (TrA), external oblique (EO) and internal oblique (IO) muscles were measured. BF (p = 0.000, partial η2 = 0.670) activity increased considerably as the knee flexion angle decreased. TrA (p = 0.000, partial η2 = 0.883) and IO (p = 0.000, partial η2 = 0.892) thickness significantly increased, while EO (p = 0.000, partial η2 = 0.893) thickness decreased as the knee flexion angle decreased. When performing bridge exercises using the abdominal drawing-in maneuver on an unstable surface, the knee flexion angles should be at 120º and 60º to increase trunk stability and lower extremity muscle activity, respectively.

Ergonomic Analysis of a Novel Shelf Stocking Cart

This study investigated the potential for an ergonomic intervention, specifically a prototype height-adjustable stocking cart to reduce the physical demands experienced when stocking shelves. This study compared muscle activity, kinematics, and subjective preferences when participants used the prototype cart versus a traditional, manual stocking method. Nine males and three females participated in this study. A traditional stocking method was compared to the prototype cart method for two types of dry grocery products as they were moved to three different destination shelf heights. EMG data, kinematic data, and subjective feedback generally favored the cart prototype over the traditional method. Bilaterally, anterior deltoid muscle activity was reduced for the cart condition when transferring products to the lower and higher shelves; trapezius activity was reduced for only the higher shelf; right side erector spinae activity was reduced for the lower shelf. The cart primarily benefited the anterior deltoid and trapezius descendens through reduced shoulder flexion. There were interaction effects of cart and shelf height on shoulder and spine kinematics. Questionnaire data showed that participants favored using the prototype. Study results support the continued development of the prototype cart toward a commercially available ergonomic aid for shelf stockers.

Muscle activity between dentate and edentulous patients rehabilitated with dental prostheses: A systematic review.

Adequate muscle activity is important for the success of oral rehabilitation: it maintains the integrity of the stomatognathic system and is responsible for chewing movements needed to break, crush and grind food. To compare muscle activity using electromyography (EMG) while clenching or chewing soft and/or hard foods among individuals with natural dentition (ND) and edentulous patients rehabilitated with dental prostheses. This review was conducted until March, 2023, and the research question was "Is the muscle activity of edentulous patients rehabilitated with dental prostheses similar to that of dentate individuals?" A search strategy was conducted in PubMed/MEDLINE, The Cochrane Library, Web of Science, Lilacs, Embase and manual journal searches. Ten studies were included in the analysis. Most of them reported that individuals with ND had significant higher muscle activity (clenching or chewing) than complete dentures (CD) users. However, no difference was observed between patients with full mouth implant-supported fixed dental prosthesis (ISFDP) and ND. Additionally, two studies compared patients with mandibular ISFDP with maxillary CD and individuals with ND and found no differences; however, one study concluded that patients with ISFDP with CD (maxillary or mandibular) had lower muscle activity than individuals with ND. Only one study reported a higher muscle activity in patients with full-mouth ISFDP than in individuals with ND. Bimaxillary CD users had lower muscle activity than individuals with ND. During rehabilitation, the muscle activity of patients with full-mouth ISFDP and mandibular ISFDP with maxillary CD is similar to individuals with ND.

The Effect on Muscle Activity of Reaching Beyond Arm's Length on a Mobile Seat: A Pilot Study for Trunk Control Training for People After Stroke

ObjectiveThis pilot study compared muscle activity during lateral reaching tasks between mobile and stable sitting using a novel therapy chair in people after stroke and healthy controls. DesignObservational pilot study. SettingThis study was conducted in a rehabilitation center for people after stroke and at the university's movement laboratory for healthy participants. ParticipantsA total of eleven people after stroke and fifteen healthy people (N=26) took part. InterventionsLateral reaching exercises to the ipsilateral and contralateral sides were performed on a mobile and a stable seat. Main Outcome MeasureMuscular activity of the multifidus, erector spinae and external oblique was measured bilaterally. A within-subject linear mixed model was applied to analyze the effects of seat condition, task, muscle side, and group. ResultsA seat condition effect was found for the multifidus and external oblique that was dependent on the muscle side and task. During ipsilateral reaching, the activity of the multifidi decreased for people after stroke on the mobile seat, while increasing for healthy participants. The erector spinae showed no condition effect. Decreased activity of the external oblique was found for both groups on the mobile seat. ConclusionsMobile sitting influences muscular activity. However, these preliminary results should be further investigated in order to generate recommendations for rehabilitation.

Poster 103: Proximal Shoulder Muscle Recruitment with Blood Flow Restriction Exercise Under Various Occlusion Conditions: Is More Pressure Really Better?

Objectives: Blood Flow Restriction (BFR) training provides partial occlusion at the proximal upper and lower extremities and has been shown to improve muscular strength and hypertrophy following an injury or surgery. By eliciting hypoxic intramuscular conditions, we can stimulate adaptive processes in skeletal muscle in a similar manner to high intensity resistance training but at substantially lower and safer exercise workloads (20-30%1RM). While much of the literature has focused on tissues distal to the site of occlusion, recent findings (Lambert et al 2021, Bowman et al 2020) have observed proximal benefits (increased muscle mass, work capacity, and performance) to upper extremity BFR in the shoulder region during rotator cuff training in both general population adults and pitching athletes. These findings were partially attributed to increased muscle activation (via electromyography, EMG) observed while extremities were under occlusion. However, only one standardized occlusion pressure (50%LOP) was utilized during these investigations as typical in current literature. The purpose of the present study was to compare muscle activation (EMG amplitude, EMGa) of the shoulder region during BFR training at variable occlusion pressures in order to optimize application and muscle-specific targeting of BFR for rehabilitation and preventative shoulder training. Methods: Institutional review board approval was first obtained. Fifteen healthy subjects (7 males and 8 females; age 29.4 ± 4.26 y.o.) from a sports medicine physical therapy clinic were recruited and consented to participate in this study. Individuals were excluded if they had any pre-existing shoulder pathology in the dominant limb, active participation in a structured upper body weight regimen, or any history of vascular compromise that may render use of BFR inappropriate. Each participant underwent 4 different experimental sessions, which included performing 3 common exercises for the shoulder to failure on the dominant limb; dumbbell scaption, cable external rotation (ER) @ 0°, and cable internal rotation (IR) @ 0°. Exercises were completed with BFR using an automated tourniquet system (Delfi Medical Innovations®) at a different pre-assigned occlusion pressure (0, 25, 50, 75% LOP) each session. Load was determined using 20% of a one-repetition maximum (1RM) for each exercise utilizing a maximal voluntary isometric contraction (MVIC) test. EMGa data utilizing surface electrodes (Delsys, Natick, MA, US) were recorded from target shoulder muscles proximal to the occlusive cuff during testing - anterior deltoid, middle deltoid, posterior deltoid, infraspinatus, teres minor, and upper trapezius muscles. Repetitions to failure (RTF) and assessments of discomfort (VAS, 0-10) with each exercise at the various occlusive pressures were also collected for analysis. Raw EMGa measures were averaged across the first 30 contractions for IR and scaption as well as the first 20 contractions for ER following normalization to 5 calibration contractions at 0% LOP. A mixed model ANOVA repeated on occlusion pressure was performed followed by a Bonferroni post hoc test for pairwise comparisons. Type I error set at ∝=0.05. Results: EMG findings are presented in Figure 1 demonstrating a significant effect of occlusion level on shoulder muscle activation for all exercises (p&lt;0.05). Of note, continued significant increases in EMGa were not observed above 50%LOP with the exception of the teres minor during IR (Figure 1A) or the posterior deltoid during scaption (Figure 1C). As shown in Figure 2, significant decreases in repetitions to failure relative to 0%LOP were observed at 75%LOP for all exercises as well as at 50%LOP for scaption (p&lt;0.05). Also shown in Table 1, a linear increase in discomfort was observed for all exercises with increasing LOP (p&lt;0.01). Conclusions: There appears to be several distinct differences in muscle activation about the shoulder complex based on the exercise as well as occlusive pressure; including a common trend of heightened EMG activity being concurrent with an increase in LOP. These findings may indicate that added occlusion leads to greater muscle utilization, enhancing exercise selection and prescription dependent on the targeted muscle group. However, based on these data, there may be an element of diminishing returns past 50% LOP for the exercises and musculature studied, ultimately limiting efficacy past this occlusion stimulus when considering discomfort or total achievable exercise volume. While limited to the population study, these findings paired with those found in general and athletic populations may be used to establish BFR guidelines which may be suitable for shoulder rehabilitation or injury prevention.

EMG Validation of a Subject-Specific Thoracolumbar Spine Musculoskeletal Model During Dynamic Activities in Older Adults.

Musculoskeletal models can uniquely estimate in vivo demands and injury risk. In this study, we aimed to compare muscle activations from subject-specific thoracolumbar spine OpenSim models with recorded muscle activity from electromyography(EMG) during five dynamic tasks. Specifically, 11 older adults (mean = 65years, SD = 9) lifted a crate weighted to 10% of their body mass in axial rotation, 2-handed sagittal lift, 1-handed sagittal lift, and lateral bending, and simulated a window opening task. EMG measurements of back and abdominal muscles were directly compared to equivalent model-predicted activity for temporal similarity via maximum absolute normalized cross-correlation (MANCC) coefficients andfor magnitude differences via root-mean-square errors (RMSE), across all combinations of participants, dynamic tasks, and muscle groups. We found that across most of the tasksthe model reasonably predicted temporal behavior of back extensor muscles (median MANCC = 0.92 ± 0.07) but moderate temporal similarity was observed for abdominal muscles (median MANCC = 0.60 ± 0.20). Activation magnitude was comparable to previous modeling studies, and median RMSE was 0.18 ± 0.08 for back extensor muscles. Overall, these results indicate that our thoracolumbar spine model can be used to estimate subject-specific in vivo muscular activations for these dynamic lifting tasks.

Simulation of Lower Limb Muscle Moment and Total Muscle Fiber Force Using OpenSim for Knee Osteoarthritis

Computational modelling is a tool that provide accurate readings and simulation by using a combination of trusted and tested mathematical models of materials and system dynamics. Existing study in gait analysis mostly focus on extrinsic parameter such as kinetics and kinematics measures. The analysis of gait especially for disease such as knee osteoarthritis (OA) can provides insight into muscle properties, activation pattern and potential impact on the knee stability and function. This study aims to simulate and compare muscle activation properties in normal individual and individuals with knee osteoarthritis (OA) during gait phases. This study used musculoskeletal modeling software, OpenSim, to analyze the total fiber force and moment of several key muscles (such as medial gastrocnemius, vastus lateralis, and rectus femoris) relative to knee flexion moments. The motion analysis data of three subjects (one normal subject and two knee OA patients) were used in this study. The results shows that total muscle fiber force and muscle moment for medial gastrocnemius and vastus lateralis muscle were higher among individual with knee osteoarthritis. Meanwhile, rectus femoris muscle behaved differently where both parameters were smaller among knee OA patient. These simulated findings suggest that muscle mechanism changed due to knee osteoarthritis disease. The muscles force and moment were observed in this study gave some insight on the devastating effect of the disease on the lower limb joint muscle. Thus, further study is still warranted to investigate the risk of muscle injury and alteration of gait on individual with knee osteoarthritis. It is highly recommended to repeat this study with larger number of subjects for a better data interpretation.

Electromyographic and Kinematic Comparison of the Leading and Trailing Fore- and Hindlimbs of Horses during Canter.

This study compared muscle activity and movement between the leading (Ld) and trailing (Tr) fore- (F) and hindlimbs (H) of horses cantering overground. Three-dimensional kinematic and surface electromyography (sEMG) data were collected from right triceps brachii, biceps femoris, middle gluteal, and splenius from 10 ridden horses during straight left- and right-lead canter. Statistical parametric mapping evaluated between-limb (LdF vs. TrF, LdH vs. TrH) differences in time- and amplitude-normalized sEMG and joint angle-time waveforms over the stride. Linear mixed models evaluated between-limb differences in discrete sEMG activation timings, average rectified values (ARV), and spatio-temporal kinematics. Significantly greater gluteal ARV and activity duration facilitated greater limb retraction, hip extension, and stifle flexion (p < 0.05) in the TrH during stance. Earlier splenius activation during the LdF movement cycle (p < 0.05), reflected bilateral activation during TrF/LdH diagonal stance, contributing to body pitching mechanisms in canter. Limb muscles were generally quiescent during swing, where significantly greater LdF/H protraction was observed through greater elbow and hip flexion (p < 0.05), respectively. Alterations in muscle activation facilitate different timing and movement cycles of the leading and trailing limbs, which justifies equal training on both canter leads to develop symmetry in muscular strength, enhance athletic performance, and mitigate overuse injury risks.

Comparison of Muscle Activity between the Horizontal Bench Press and the Seated Chest Press Exercises Using Several Grips.

This study aims to compare muscle activity in the pectoralis major, anterior deltoid, and triceps brachii in the horizontal bench press exercise with a prone grip at 150% and 50% of the biacromial width and the seated chest press exercise with two types of grips (a neutral grip at ~150% of the biacromial width and a prone grip at ~200% of the biacromial width). Twenty physically active adults performed a set of 8 repetitions at 60% of the one repetition maximum. The results showed that the clavicular portion of the pectoralis major had significantly greater muscle activity in the seated chest press exercise with a neutral grip (~30% of the maximal voluntary isometric contraction (MVIC)) than in the lying bench press exercise with a prone grip at 150% of the biacromial width (~25% MVIC). The muscle activity of the anterior deltoid was not significantly different across any exercise or grip evaluated (~24% MVIC). The muscle activity of the triceps brachii was significantly higher in the lying bench press exercise with a grip at 50% biacromial width (~16% MVIC) than at 150% of the biacromial width (~12% MVIC). In conclusion, all exercises and grips showed similar muscle activity, and the selection of these exercises should not be based exclusively on the grounds of muscle activation but rather on the load capacity lifted, the level of technique of the participant, and/or the transference to the specific sporting discipline or event.