Differences In Muscle Activity Research Articles

Bone and muscle differences in children and adolescents with type 1 diabetes: The mediating role of physical activity

Children with type 1 diabetes (T1D) experience an increased risk of fracture, which may be related to altered bone development. We aimed to assess differences in bone, muscle and physical activity (PA), and explore if better muscle and PA measures would mitigate bone differences between children and adolescents with T1D and typically developing peers (TDP). We matched 56 children and adolescents with T1D (mean age 11.9 yrs) and 56 TDP (11.5 yrs) by sex and maturity from 171 participants with T1D and 66 TDP (6-17 yrs). We assessed the distal radius and tibia with high-resolution peripheral quantitative computed tomography (HR-pQCT), and the radius and tibia shaft bone and muscle with pQCT. We also measured muscle function from force-related measures in neuromuscular performance tests (push-up, grip test, countermovement and long jump). We compared PA based on questionnaire scores and accelerometers between groups. Bone, muscle, and neuromuscular performance measures were compared using MANOVA. We used mediation to explore the role of PA and muscle in bone differences. Children and adolescents with T1D had 6–10 % lower trabecular density, bone volume fraction, thickness and number at both distal radius and tibia, and 11 % higher trabecular separation at the distal radius than TDP. They also had 3–16 % higher cortical and tissue mineral density, and cortical thickness at the distal radius, 5–7 % higher cortical density and 1–3 % higher muscle density at both shaft sites compared to TDP. PA mediated the between-group difference in trabecular number (indirect effect −0.04) at the distal radius. Children and adolescents with T1D had lower trabecular bone density and deficits in trabecular micro-architecture, but higher cortical bone density and thickness at the radius and tibia compared to TDP. They engaged in less PA but had comparable muscle measures to those of TDP. PA participation may assist in mitigating deficit in trabecular number observed in children and adolescents with T1D.

Impairments in peroneal muscle size and activation in individuals with patellofemoral pain in weight-bearing position.

Patellofemoral pain (PFP) is characterized by chronic pain in the anterior aspect of the knee during loading activities. Many studies investigating muscle morphology changes for individuals with PFP focus on the proximal joints, however, few studies have investigated muscles of the foot and ankle complex. This study aimed to explore the differences in peroneal muscle size and activation between individuals with PFP and healthy controls using ultrasound imaging in weight-bearing. A case-control study in a university lab setting was conducted. Thirty individuals with PFP (age: 20.23±3.30years, mass: 74.70±27.63kgs, height: 161.32±11.72cm) and 30 healthy individuals (age: 20.33±3.37years, mass: 64.02±11.00kgs, height: 169.31±9.30cm) participated. Cross-sectional area (CSA) images of the peroneal muscles were taken in non-weight bearing and weight-bearing positions. The functional activation ratio from lying to single-leg standing (SLS) was calculated. There was a statistically significant (p=0.041) group (PFP, healthy) by position (non-weight-bearing, weight-bearing) interaction for the peroneal muscle CSA with a Cohen's d effect size of 0.2 in non-weight-bearing position and 0.7 in weight-bearing position. The functional activation ratio for the healthy group was significantly more (p=0.01) than the PFP group. Peroneal muscles were found to be smaller in size in those with PFP compared to the healthy subjects in the weight-bearing SLS position. This study found that those with PFP have lower activation of peroneal muscles in functional position.

Neural Respiratory Drive During Different Dyspnea Relief Positions and Breathing Exercises in Individuals With COPD.

When the work load of the respiratory muscles increases and/or their capacity decreases in individuals with COPD, respiratory muscle activation increases to maintain gas exchange and respiratory mechanics, and perception of dyspnea occurs. The present study aimed to compare diaphragm and accessory respiratory muscle activation during normal breathing, pursed-lip breathing, and breathing control in different dyspnea relief positions, supine and side lying. A cross-sectional study design was used. Sixteen individuals with COPD age between 40-75 y were included. Pulmonary function was evaluated by spirometry, muscle activation by surface electromyography, and dyspnea by the modified Borg scale. Muscle activation was measured in the diaphragm, scalene, sternocleidomastoid, and parasternal muscles. The evaluation was made in the dyspnea relief positions (sitting leaning forward, sitting leaning forward at a table, leaning forward with back against a wall, standing leaning forward, and high lying), seated erect, supine, and side lying. There were significant differences between the 8 positions (P < .001). There was no significant difference in muscle activation between sitting leaning forward and sitting leaning forward at a table position with analyzing post hoc test results (P > .99 for each muscle). However, muscle activation was lower in these 2 positions than in the other positions (P < .001 for each muscle). Muscle activation was greater in the supine position than in the other positions (P < .001 for each muscle). No difference was observed in muscle activation between the seated erect, leaning forward with back against a wall, standing leaning forward, high-lying, or side-lying positions (P > .05 for each muscle with a minimum P value of .09). The use of sitting leaning forward and sitting leaning forward at a table positions together with breathing control may help people with COPD to achieve more effective dyspnea relief and greater energy efficiency.

Comparison of trunk muscle activity during lumbar stabilization exercises on stable and unstable surfaces.

Lumbar stabilization exercises (LSE) provide dynamic trunk stability, promote muscle strength and endurance, and improve low back pain rehabilitation and performance. To clarify the differences in trunk muscle activity during LSEs on stable and different unstable surfaces. Fifteen healthy males performed three exercises (elbow-toe, hand-knee, and side bridge) on stable (floor) and unstable surfaces. Muscle activity of the bilateral rectus abdominis, internal oblique, external oblique, and erector spinae were recorded. Data were compared using the Friedman test. Pairwise comparisons were performed using Wilcoxon's signed rank test if significant differences were observed. In the elbow-toe exercise, muscle activity of the rectus abdominis and right internal oblique increased in the following order: floor, low-difficulty, and high-difficulty unstable surface. In the hand-knee exercise, muscle activity of the internal oblique on the lower-extremity elevated side, external oblique, and erector spinae on the upper-extremity elevated side were greater on unstable surface exercise performance. In the side bridge exercise, rectus abdominis muscle activity was highest on a high-difficulty unstable surface. Trunk muscle activity increased during exercise on unstable surfaces. Since the effects of unstable surfaces vary depending on muscle and exercise types, exercise difficulty and surface stability must be considered accordingly.

Influence of Amputation on Kinetic Chain Musculature Activity During Basic and Modified Core Exercises.

Core strength is vital for athletic performance, and many more exercises that involve the kinetic chain have been designed for able-bodied athletes. Disabilities that impair the kinetic chain can reduce the effectiveness of strength training. However, the impact of amputation on core strength training of people with disabilities and its underlying mechanism remains unclear. This study aimed to evaluate the muscle activation patterns and levels in athletes with amputation during 4 basic and modified weight-bearing core strength-training exercises. Fifteen elite athletes with unilateral amputation (170.6 [7.3]cm; 63.9 [11.9]kg; 25.9 [5.3]y) volunteered for this study. Surface electromyography was used to measure the muscle activity mainly in the lumbopelvic-hip complex-stabilizing muscles during 4 kinetic chain trunk exercises with and without modifications. The significance level was set at α = .05. The results showed a significant difference in muscle activation between different body sides (P < .05). Specifically, amputation on the support position resulted in a diagonal pattern of muscle activation, and amputation on the free distal segments resulted in a unilateral dominant pattern with higher activation in muscles on the nonamputated side (P < .05). Modifications led to significant decreases in muscle activation asymmetry index (P < .05). Amputation caused muscle activation asymmetry and 2 activation patterns. Modifications by enhancing proximal stability and adjusting distal loading effectively reduced the asymmetry of muscle activation. Coaches and clinicians can use these results to tailor exercises for athletes with disabilities in training and rehabilitation.

Differences on Thigh Muscles&amp;apos; Activity by Types of Squat

OBJECTIVES Thigh strength has many features in our life. Many people perform vary squat types to stimulate different thigh muscles. However, there is a lack of information on which squat is the most effective on targeted muscles. Therefore, the purpose of this study was to compare thigh muscles’ activity by squat types and suggest the correct squat for strengthening thigh.METHODS Total of 20 men and women (age: 23.9±1.5yrs, height: 173.3±6.6cm, weight: 75.1±13.2kg, BMI: 24.9±3.1kg/m&lt;sup&gt;2&lt;/sup&gt;) who had no musculoskeletal pathologies within last one year, and had weight training experience for more than 1 year were participated. Squat types were classified into standard (SS), narrow (NS), wide (WS), jump (JS), and Smith machine squats (SMS). Surface electromyography was used to collect the muscle activity of the thigh during three repetitions of each squat without weights. Time points during squat are defined as follows: E1 (start), E2 (maximum knee flexion, MKF), E3 (returned), P1 (from start to MKF), and P2 (from MKF to return). Repeated measured ANOVA was used to verify differences in lower limb muscle activity between squat types.RESULTS At the E2, significant differences were found in RF (p=.00) and ST (p=.00). In the P1, significant differences were found in RF (p=.00), VL (p=.00), and BF (p=.02). In the P2, significant differences were found in RF (p=.00), VM (p=.00), and ST (p=.01).CONCLUSIONS For more activity of both quadriceps and hamstrings, plyometric-based JS is the most effective squat, but by considering the performer's lack of exercise experience, postural control may not be performed correctly which may lead to injury. In addition, stable squat using the Smith machine should be considered and the intensity, number of repetitions, and weight should be carefully set according to type of squat.

Identification of the Biomechanical Response of the Muscles That Contract the Most during Disfluencies in Stuttered Speech.

Stuttering, affecting approximately 1% of the global population, is a complex speech disorder significantly impacting individuals' quality of life. Prior studies using electromyography (EMG) to examine orofacial muscle activity in stuttering have presented mixed results, highlighting the variability in neuromuscular responses during stuttering episodes. Fifty-five participants with stuttering and 30 individuals without stuttering, aged between 18 and 40, participated in the study. EMG signals from five facial and cervical muscles were recorded during speech tasks and analyzed for mean amplitude and frequency activity in the 5-15 Hz range to identify significant differences. Upon analysis of the 5-15 Hz frequency range, a higher average amplitude was observed in the zygomaticus major muscle for participants while stuttering (p < 0.05). Additionally, when assessing the overall EMG signal amplitude, a higher average amplitude was observed in samples obtained from disfluencies in participants who did not stutter, particularly in the depressor anguli oris muscle (p < 0.05). Significant differences in muscle activity were observed between the two groups, particularly in the depressor anguli oris and zygomaticus major muscles. These results suggest that the underlying neuromuscular mechanisms of stuttering might involve subtle aspects of timing and coordination in muscle activation. Therefore, these findings may contribute to the field of biosensors by providing valuable perspectives on neuromuscular mechanisms and the relevance of electromyography in stuttering research. Further research in this area has the potential to advance the development of biosensor technology for language-related applications and therapeutic interventions in stuttering.

Biomechanics of the lower limb in patients with mild knee osteoarthritis during the sit-to-stand task

BackgroundKnee osteoarthritis (KOA) is a prevalent and debilitating condition that markedly affects the sit-to-stand (STS) activity of patients, a prerequisite for daily activities. Biomechanical recognition of movements in patients with mild KOA is currently attracting attention. However, limited studies have been conducted solely on the observed differences in sagittal plane movement and muscle activation.AimThis study aimed to identify three-dimensional biomechanical and muscle activation characteristics of the STS activity in patients with mild KOA.MethodsA cross-sectional study was conducted to observe the differences between patients with mild KOA and a control group (CG). It was conducted to observe the differences in muscle activation, including root mean square (RMS%) and integrated electromyography (items), kinematic parameters like range of motion (ROM) and maximum angular velocity, as well as dynamic parameters such as joint moment and vertical ground reaction force (vGRF).ResultsPatients with mild KOA had a higher body mass index and longer task duration. In the sagittal plane, patients with KOA showed an increased ROM of the pelvic region, reduced ROM of the hip–knee–ankle joint, and diminished maximum angular velocity of the knee–ankle joint. Furthermore, patients with KOA displayed increased knee–ankle joint ROM in the coronal plane and decreased ankle joint ROM in the horizontal plane. Integrated vGRF was higher in both lower limbs, whereas the vGRF of the affected side was lower. Furthermore, patients showed a decreased peak adduction moment (PADM) and increased peak external rotation moment in the knee joint and smaller PADM and peak internal rotation moment in the ankle joint. The affected side exhibited decreased RMS% and iEMG values of the gluteus medius, vastus medialis, and vastus lateralis muscles, as well as a decreased RMS% of the rectus femoris muscle. Conversely, RMS% and iEMG values of the biceps femoris, lateral gastrocnemius, and medial gastrocnemius muscles were higher.ConclusionThe unbalanced activation characteristics of the anterior and posterior muscle groups, combined with changes in joint moment in the three-dimensional plane of the affected joint, may pose a potential risk of injury to the irritated articular cartilage.

Comparison of muscle activity of the lower limbs while running on different treadmill models.

Treadmill running is a common method of exercise and to study human locomotion. Research has examined the kinematics and kinetics of overground and treadmill running, but there has been less focus on the levels of muscle activity during treadmill running. We investigated if muscle activity is different while running overground compared to running on a variety of treadmills. A total of 11 healthy individuals ran at 3 speeds (2.6, 3.6, 4.5 m/s) under 4 different running conditions (3 treadmills, overground). The three treadmills included a typical home exercise treadmill, a midsize commercial research treadmill, and a large, instrumented research treadmill. Surface EMG of the tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF) and biceps femoris (BF) muscles were measured for each running condition. The integrated EMG was computed for each running condition for the stance and swing phase, as well as 100 ms before and after the heel-strike. Friedman analysis revealed significant effects during the stance phase for GM and RF at all speeds, such that muscle activation was lower on the treadmills relative to overground. During the stance phase at faster speeds, the muscle activity was higher for the TA and lower for the BF while running on the different treadmills compared to overground running. Before heel-strike, the TA was significantly less active during treadmill compared to overground running at 2.6 m/s and the RF showed significantly higher activity at 3.6 m/s and 4.5 m/s while running on the different treadmills. Summarizing, differences were mainly observed between the different treadmill conditions relative to overground running. Muscle activation differences between the different treadmill conditions were observed at faster running speeds for RF during the pre-heel-strike phase only. Different types of treadmills with different mechanical properties affects the muscle activity during stance phase as well as in preparation to heel-strike. Additionally, the muscle activity is greater during overground compared to treadmill running during the stance phase for the GM, BF, and RF.

Forward Head Posture and Its Effect on Muscle Activation

Forward head posture (FHP), which is defined as a forward displacement of the head on the cervical spine, is a common postural disorder. It is suggested that this malalignment alters the loads on the spine, affects the length-tension relationship in muscles, and changes muscle activation. Therefore, the aim of this review is to investigate the results of studies on the examination of the changes exerted by FHP on muscle activation. Although there are many methods used to assess FHP, there is no standard clinical method for accurate measurement of this angle. Photographic measurement is the most widely used, valid, and reliable assessment method. Craniovertebral angle (CVA) is the most widely used value to assess FHP in photographic measurements. A CVA of less than 48-50° is defined as FHP, although there are differences regarding the norm value of the CVA. There are many studies on the assessment of differences in the activation of the neck and shoulder muscles by making FHP and non-FHP classifications according to the CVA to show the changes in muscle activation in individuals with FHP. Although many studies have shown increased sternocleidomastoideus and upper trapezius activation, there are also others indicating no difference. Similar conflicting results exist for the lower trapezius and serratus anterior muscles. Although there are conflicting results regarding muscle activation in studies, it seems likely that muscle activation is altered in individuals with FHP. It may be recommended that physiotherapists conduct interventions by considering these differences in muscle activation in individuals with FHP.

Assessing mouse, trackball, touchscreen and leap motion in ship vibration conditions: A comparison of task performance, upper limb muscle activity and perceived fatigue and usability

A variety of interaction devices are increasingly used for human-computer interaction (HCI) tasks in ship vibration conditions, but have seldom been well assessed. This study aimed to examine task performance, upper limb muscle activity, and perceived fatigue and device usability for four typical interaction devices (i.e., mouse, trackball, touchscreen, and Leap Motion) under simulated ship vibration conditions. A two-factor within-subjects design was employed in this study, where participants performed basic HCI tasks with the four interaction devices under three conditions (i.e., static condition, and low and high vibration conditions). The results showed that vibration condition significantly reduced task performance, especially for Leap Motion. Differences in task performance, upper arm and shoulder muscle activities, perceived fatigue and device usability were found among interaction devices. Mouse and touchscreen achieved the best task performance, compared with trackball and Leap Motion, while both touchscreen and Leap Motion achieved larger upper limb muscle activities, compared with trackball and mouse. Relevance to industryThe findings provide important implications for the use and configuration of interaction devices, and for the development of prevention interventions for risks of musculoskeletal disorders in using interaction devices under ship vibration conditions.

Does dual‐tasking affect the ability to generate anticipatory postural adjustments in young adults?

AbstractThe aim of this study was to investigate how additional cognitive tasks (Stroop test and counting backwards task) influence young adults' ability to generate appropriate postural responses while standing on a continuously oscillating platform. Twenty young adults (25.95 ± 2.97 years) stood on a moving platform which was translated in the anterior–posterior direction at three different frequencies (0.10, 0.25 and 0.50 Hz) in three dual‐task conditions (counting backwards task, a Stroop task or no additional cognitive task). Postural muscle onset latencies and tonic activity levels of the leg muscles were measured through surface electromyography; the number of steps taken and cognitive errors made were recorded. Results showed no significant differences in muscle activity between dual and single‐tasking conditions nor between the two dual tasking conditions. Cognitive errors were made in the counting backwards task but not the Stroop task. A frequency effect was identified with participants showing greater tonic activity in rectus femoris (p = 0.012), gastrocnemius medialis (p = 0.016) and bicep femoris (p = 0.043) at 0.5 Hz, as well as earlier muscle activation in tibialis anterior, gastrocnemius medialis and bicep femoris (p &lt; 0.001) at 0.50 Hz. Transition and steady state muscle onset latencies were only significantly different for gastrocnemius medialis at 0.25 Hz (p = 0.001). Dual tasking did not seem to influence anticipatory postural adjustments in young adults; however, perturbation intensities did. The differences observed in the number of cognitive errors made could be indicative of the regional cortical activations and overlapping demand for resources interfering with balance control, though cortical activation was not recorded. Future research should include detailed cognitive behavior, including cortical activations and task reaction times to better understand the allocation of attentional resources during perturbed balance dual tasking.

Usability of the novel ankle training equipment with spring resistance-based plantar press exercises in the standing position: A focus on chronic stroke patients with hemiplegic gait.

To improve gait disability in patients with chronic stroke, ankle muscle strengthening and calf muscle stretching exercises are required. However, currently available ankle training equipment limit ankle exercises based on the position. Recently developed ankle training equipment enables spring resistance-based plantar press exercises to be performed in the standing position with weight support. To conduct a usability test of the ankle training equipment in the standing position by stroke patients with hemiplegic gait and verify its effects on ankle movements. The ankle training equipment was applied to five patients with chronic stroke and hemiplegic gait. In the standing position, the patients performed forefoot and rearfoot press exercises in the affected side with a day's interval at 20 repetitions maximum (RM). During the exercises, surface electromyography (sEMG) was used to measure the maximum voluntary isometric contraction (%MVIC) of the leg muscles. The System Usability Scale (SUS) was used to assess the ankle training equipment. Wilcoxon signed-rank test was used to evaluate the differences in muscle activity between the two exercises. Forefoot and rearfoot press exercises increased the %MVIC in the biceps femoris. Additionally, the tibialis anterior and medial gastrocnemius activity was significantly different between the two exercises. The SUS was 78.75% (SD 12.7). The usability test of the passive-control foot press trainer (PFPT) that with improvements in the structure and functions for convenience, it could be commercialized. PFPT could be an alternative to the ankle rehabilitation robot that necessitates a sitting position.

Changes in the Activation Level of the Floor of the Mouth Muscles during Pressing and Swallowing Tasks According to the Degree of Tongue Pressure.

The suprahyoid muscles play an important role in protecting the airway by elevating both the hyoid bone and larynx superior-anteriorly during swallowing. However, providing systematic external resistance when performing exercises to improve suprahyoid muscle strength is practically difficult. This study attempted to confirm whether systematic resistance can be provided to the suprahyoid muscles using the Iowa Oral Performance Instrument (IOPI)-a representative tongue pressure measurement device. Thirty-one healthy adults participated in this study (20.6 ± 0.96 y, 19 females). The participants performed 16 exercise tasks using the IOPI three times each in random order (Anterior/posterior tongue × pressing/swallowing task × 40/60/80/100% maximum tongue pressure). Furthermore, the floor of the mouth (FOM) muscle activity during exercise was simultaneously measured using surface electromyography. During the pressing task, there were significant differences in FOM maximal muscle activity among the four exercise intensities for both the anterior and posterior oral tongue. For the swallowing task, a significant difference was found in FOM muscle activity among the four exercise intensities for the anterior tongue. For the posterior tongue, significant differences were identified among all conditions except for the comparison between 80% and 100% maximum tongue pressure. Significant correlations between the degree of tongue pressure and maximal FOM muscle activity were found in both the pressing and swallowing tasks at the anterior and posterior oral tongue. Overall, these results indicate that objective and systematic external resistance can be applied using the IOPI-a standard tongue pressure measurement device-during the program to improve suprahyoid muscle function.

Effect of Six Months of Using Thermoplastic Polyurethane and Rubber Military Boots on Lower Limb Muscle Activities During Running

Background: The age of boots is a significant factor that can impact the risk of injury during daily activities. Conversely, military personnel rely on their footwear to meet the physical demands of their daily professional tasks. Objectives: This study aimed to evaluate how wearing thermoplastic polyurethane (TPU) and rubber military boots for six months affects lower limb muscle activity during running. Methods: Thirty healthy male participants were provided with two new pairs of rubber and TPU military boots and instructed to wear them for six months. Electromyography signals were recorded during a pre-test and after six months while the participants ran at a speed of 3.2 m/s. Statistical analysis was conducted using a two-way ANOVA with repeated measures, with a significance level of 0.05. Results: The results did not show a significant overall effect of "boots" or "time" on muscle activities during running. However, there were significant boot-by-time interactions for muscle activities during different phases of the running cycle. These interactions were observed for the tibialis anterior (P = 0.037, η2p = 0.146), gastrocnemius medialis (P = 0.023, η2p = 0.172), and gluteus medius (P = 0.038, η2p = 0.144) activities during the loading phase, tibialis anterior activity at the mid-stance phase (P = 0.003, η2p = 0.278), and gastrocnemius medialis activity during the push-off phase (P = 0.046, η2p = 0.135). Conclusions: Wearing military boots appears to affect muscle activities, particularly the tibialis anterior, in healthy males. These findings underscore the importance of careful boot selection for running activities. Understanding the reasons behind differences in muscle activity between TPU and rubber military boots can inform further research and the development of specialized footwear tailored to specific operational needs.

27. OBJECTIVE ANALYSIS OF ERGONOMICS IN ROBOTIC MICROSURGERY

Abstract Introduction This study compares the surgeon's ergonomics during the performance of microsurgical procedures using a robotic platform and conventional techniques. The study evaluates the differences in the surgeons' muscle activity. Methods Four surgeons with expertise in microsurgery participated in this study. They performed various microsurgical and supermicrosurgical procedures, including vascular and lymphatic-venous anastomoses. The procedures were performed by both robotic and conventional techniques. Muscle activity of five muscle groups was recorded bilaterally using a wireless electromyography system. For analysis, derivation of the evolution of mean frequencies and amplitudes was calculated to quantify muscle fatigue. Results Less muscle activity was observed with the use of the robot for the upper trapezius. In contrast, the brachioradialis shows higher muscle activity in robotic surgery. The erector spinae, medial trapezius and abductor did not show significant differences in terms of median but in terms of distribution. As for muscle fatigue, it is less dispersed among subjects in robotic surgery and tends to be less accentuated than with the conventional surgical technique. Conclusion According to muscle activity indicators, ergonomics differs in conventional and robotic surgery depending on the muscle group. However, preliminary results show less muscle fatigue in robotic surgery.

Sex related differences in neuromuscular fatiguability between prepubertal children and young adults

Introduction&#x0D; Prepubertal children compared to adults manifest neuromuscular differences in a lower voluntary activation and fatigability, as well as a potentially lesser use of larger motor units innervating fast-twitch-fibers (Dotan et al., 2012). While children tend to fatigue more on a central than peripheral level, these trends vary based on exercise modality and muscle group (Ratel et al., 2015; Souron et al., 2022). Furthermore, females incline to fatigue less than males, but research on sex differences in children remains limited (Hunter, 2014). Therefore, the aim of this study was to investigate neuromuscular age and sex differences in a sustained isometric contraction until failure.&#x0D; Methods&#x0D; 16 prepubertal children (9.2 ± 0.9y) and 16 adults (23.4 ± 2.4y; m = f) performed a maximal voluntary isometric contraction (MVCpre), a failure-task at 60%MVCpre, followed by another MVCpost of knee extensors. Surface electromyography for rectus femoris (RF), vastus medialis (VM), and vastus lateralis muscles (VL) was analysed at 0, 25, 50, 75, and 100% of the individual time to failure (TTF). Linear models and Cohen’s d effect sizes were used to quantify age and sex differences of TTF, MVCpre-post, as well as root mean square (RMS) and median frequency (MDF) of each muscle throughout the fatiguing trial.&#x0D; Results&#x0D; Trivial differences were observed in TTF across age, sex, and age*sex-interaction (d ≤ 0.78). Children displayed a larger decline in MVCpre-post (d = 1.24), whereas sex and age*sex interactions were minimal (d ≤ 0.63).&#x0D; Initially (0% TTF), children had a lower activation in RF, VL and VL (d &gt; 1.32), whereas age-differences across the failure-task were found for RMS VL, MDF RF, VL and VM (d ≥ 0.15), with no prominent sex-differences (d ≤ 0.14). Sex*age-interaction yielded detectable results only in RMS VM (d = -0.36).&#x0D; Conclusion&#x0D; The lower ability to generate an MVCpost combined with a smaller change in EMG parameters in children could be due to more central rather than peripheral fatigue. This is also supported by the lower initial activation in adults, suggesting that larger, more fatigable motor units are initially preserved, which may not be available in children.&#x0D; The small to large effects in neuromuscular fatigability between age and sex groups indicate the need for more in-depth research (tracking of motor units, change of voluntary activation and twitch properties) particularly with regard to sex-related disparities.&#x0D; References&#x0D; Dotan, R., Mitchell, C., Cohen, R., Klentrou, P., Gabriel, D., &amp; Falk, B. (2012). Child-adult differences in muscle activation—A review. Pediatric Exercise Science, 24(1), 2–21. https://doi.org/10.1123/pes.24.1.2&#x0D; Hunter, S. K. (2014). Sex differences in human fatigability: Mechanisms and insight to physiological responses. Acta Physiologica, 210(4), 768–789. https://doi.org/10.1111/apha.12234&#x0D; Ratel, S., Kluka, V., Vicencio, S. G., Jegu, A.-G., Cardenoux, C., Morio, C., Coudeyre, E., &amp; Martin, V. (2015). Insights into the mechanisms of neuromuscular fatigue in boys and men. Medicine &amp; Science in Sports &amp; Exercise, 47(11), 2319–2328. https://doi.org/10.1249/MSS.0000000000000697&#x0D; Souron, R., Carayol, M., Martin, V., Enzo, P., Duché, P., &amp; Gruet, M. (2022). Differences in time to task failure and fatigability between children and young adults: A systematic review and meta-analysis. Frontiers in Physiology, 13, Article 1026012. https://doi.org/10.3389/fphys.2022.1026012

Bilateral Activity of Spine Extensors and Rotators during Asymmetric Lumbar Stabilization Exercises Executed in Prone, Quadruped, and Standing-Prone Positions

(1) Background: Most daily activities and sport gestures involve asymmetric movement patterns of the upper and lower extremities, transferring asymmetric mechanical loadings to the spine. Therefore, asymmetric lumbar stabilization exercises are frequently prescribed in athletic programs and preventive/rehabilitation interventions. This study analyzed the bilateral activity of the thoracic erector spinae (ES), lumbar multifidus (MF), external oblique (EO), and internal oblique (IO) during asymmetric lumbar stabilization exercises executed in prone, quadruped, and standing-prone positions, rising an upper and/or lower limb in all possible combinations. A limited subset of these data has been previously published in earlier studies. (2) Methods: Surface EMG signals were bilaterally recorded from the selected muscles using wireless EMG sensors. (3) Results: ES, MF, and oblique muscles’ activity was significantly higher in prone, standing-prone, and quadruped positions, respectively, and was maximized by specific limb rise combinations (up to 69%, 64%, 34%, and 24% maximum-voluntary-isometric-contraction for ES, MF, EO, and IO). The bilateral difference in muscle activation was significantly higher in the quadruped position and revealed different strategies used to stabilize the body in response to the different exercise conditions. (4) Conclusions: The study results can provide deeper insights into the stabilizing function of the lumbar and oblique muscles and aid in designing optimal progressions for lumbar stabilization exercises.

Biomechanical risk factors for ACL injury differ between the sexes when performing a high-intensive exergame

Introduction&#x0D; Incidence rates in anterior cruciate ligament (ACL) injuries, which are linked to multiple factors, are higher in females than males (Sutton &amp; Bullock, 2013). However, the main contributors to the difference in risk are biomechanical factors such as increased knee valgus (KV), knee internal rotation (KIR), or decreased hip flexion (HF; Seyedahmadi et al., 2022). Returning back to sports after an injury requires extensive rehabilitation as well as training of dual-task situations in order to be physically and cognitively prepared. Exergaming represents a dual task including a cognitive and a motor component and may be used as training modality during rehabilitation. It is known that performing a dual-task leads to altered landing movement patterns in healthy athletes (Dai et al., 2018). Before an exergame for rehabilitation after ACL injury can be implemented and tailored to the specific needs of female and male athletes, the movement patterns of males and females need to be understood. Therefore, the aim of this study was to identify biomechanical differences between males and females when performing a high-intensive exergame.&#x0D; Methods&#x0D; Using 3D-motion capture (Vicon) kinematics were measured in 18 healthy athletes (9 male, 9 female) during a 25-min exergame (Sphery Racer, ExerCube). The exergame included nine different exercises of which 8 were used for analysis. The exercises were separated into neutral (squat, jump, burpee) and side-specific exercises (low-touch, mid-touch, high-touch, punch, lunge). For analysis, the maximal KV, maximal KIR, and the minimal HF were extracted during 10-30° knee flexion. These maximal values were then compared between the sexes, the exercises, and both legs with a linear mixed model, for each the neutral and the side-specific exercises.&#x0D; Results&#x0D; A main effect of sex was only found for side-specific exercises in KIR (F(1, 16) = 6.1, p = .02) with females exhibiting higher values. For KV and HF in side-specific exercises as well as all variables in neutral exercises, no significant main effect for sex was found. However, there was a main effect of exercise in KV; KIR, and HF in neutral (p &lt; .001) as well as in side-specific exercises (p &lt; .001).&#x0D; Discussion/Conclusion&#x0D; Differences in KIR between males and females primarily exist during touches and punches. Therefore, exergames should incorporate this fact to counteract increased risk for knee injuries in females.&#x0D; References&#x0D; Dai, B., Cook, R. F., Meyer, E. A., Sciascia, Y., Hinshaw, T. J., Wang, C., &amp; Zhu, Q. (2018). The effect of a secondary cognitive task on landing mechanics and jump performance. Sports Biomechanics, 17(2), 192–205. https://doi.org/10.1080/14763141.2016.1265579&#x0D; Seyedahmadi, M., Minoonejad, H., Karimizadeh Ardakani, M., Heidari, Z., Bayattork, M., &amp; Akbari, H. (2022). What are gender differences in lower limb muscle activity during jump-landing tasks? A systematic review and meta-analysis. BMC Sports Science, Medicine &amp; Rehabilitation, 14(1), Article 77. https://doi.org/10.1186/s13102-022-00469-3&#x0D; Sutton, K. M., &amp; Bullock, J. M. (2013). Anterior cruciate ligament rupture: Differences between males and females. The Journal of the American Academy of Orthopaedic Surgeons, 21(1), 41–50. https://doi.org/10.5435/jaaos-21-01-41

Predicting Dysphonia by Measuring Surface Electromyographic Activity of the Supralaryngeal Muscles.

This study set out to investigate whether individuals with dysphonia, as determined by either self-assessment or clinician-based auditory-perceptual judgment, exhibited differences in perilaryngeal muscle activities using surface electromyography (sEMG) during various phonatory tasks. Additionally, the study aimed to assess the effectiveness of sEMG in identifying dysphonic cases. A total of 77 adults (44 women, 33 men, Mage = 30.4 years) participated in this study, with dysphonic cases identified separately using either a 10-item Voice Handicap Index (VHI-10) or clinician-based auditory-perceptual voice quality (APVQ) evaluation. sEMG activities were measured from the areas of suprahyoid and sternocleidomastoid muscles during prolonged vowel /i/ phonations at different pitch and loudness levels. Normalized root-mean-square value against the maximal voluntary contraction (RMS %MVC) of the sEMG signals was obtained for each phonation and compared between subject groups and across phonatory tasks. Additionally, binary logistic regression analysis was performed to determine how the sEMG measures could predict the VHI-10-based or APVQ-based dysphonic cases. Participants who scored above the criteria on either the VHI-10 (n = 29) or APVQ judgment (n = 17) exhibited significantly higher RMS %MVC in the right suprahyoid muscles compared to the corresponding control groups. Although the RMS %MVC value from the right suprahyoid muscles alone was not a significant predictor of self-evaluated dysphonic cases, a combination of the RMS %MVC values from both the right and left suprahyoid muscles significantly predicted APVQ-based dysphonic cases with a 69.66% fair level. This study found that individuals with dysphonia, as determined by either self-assessment or APVQ judgment, displayed more imbalanced suprahyoid muscle activities in voice production compared to nondysphonic groups. The combination of the sEMG measures from both left and right suprahyoid muscles showed potential as a predictor of dysphonia with a fair level of confidence. https://doi.org/10.23641/asha.25112804.