Activity Of Selected Muscles Research Articles

Effects of Extrinsic and Intrinsic Motivation on Selective Activation of Shoulder Girdle Muscles During the Barbell Bench Press Exercise

Background/Objectives: This study aimed to investigate the effects of intrinsic and extrinsic motivation on selective muscle activation of the shoulder girdle during the barbell bench press. Specifically, this research focused on how attentional focus on individual muscles, such as the anterior deltoid (AD), pectoralis major (PM), and triceps brachii long (TBL), could influence their electromyographic (EMG) activity during the exercise. Methods: Twelve male participants, with at least five years of strength training experience, performed bench press exercises under two conditions: with extrinsic motivation (no specific focus on muscle activity) and with intrinsic motivation (internal focus on specific muscles). Surface electromyography (sEMG) was used to measure muscle activity during three sets of bench presses at 60% of one repetition maximum (1RM). Participants were instructed to focus on the activation of specific muscles in a randomized sequence. Results: The intrinsic motivation condition significantly increased muscle activation compared to extrinsic motivation. Electromyographic activity of the AD, PM, and TBL muscles was notably higher when participants focused their attention on these muscles. AD activation increased from 71.78 ± 11.13%MVC (extrinsic) to 88.03 ± 8.84%MVC (intrinsic) (p = 0.0019), while PM and TBL activation also demonstrated significant increases under intrinsic focus. Conclusions: The study concludes that intrinsic motivation, or an internal focus on specific muscle activation, can significantly enhance EMG activity in target muscles during the bench press exercise. This finding has important implications for resistance training and rehabilitation, where focused muscle activation can be utilized to improve training outcomes and muscle engagement.

Transforming Stroke Recovery: The Bobath Concept in a Case Study of Middle Cerebral Artery Infarction

Stroke remains a major cause of long-term disability, necessitating effective rehabilitation strategies. This case study examines the rehabilitation of a 57-year-old male patient recovering from a middle cerebral artery (MCA) infarction, utilising the Model of Bobath Clinical Practice (MBCP). The patient underwent interventions based on the Bobath concept, focusing on selective activation of trunk muscles, core engagement, and pelvic alignment to enhance postural control. Assessments revealed significant improvements in both sitting and standing postures, with reductions in compensatory fixation strategies. The targeted therapeutic exercises facilitated better trunk control and lower limb weight-bearing, resulting in overall enhanced stability. The findings underscore the importance of individualised approaches in stroke rehabilitation aligned with Bobath principles. While the outcomes are promising, further research is needed to confirm the effectiveness of the MBCP model across varied patient populations. This study highlights the potential of the Bobath Concept in improving functional recovery and quality of life for stroke survivors.

A coactivation strategy in anticipatory postural adjustments during voluntary unilateral arm movement while standing in individuals with bilateral spastic cerebral palsy

Individuals with bilateral spastic cerebral palsy (BSCP) reportedly has problems with anticipatory postural adjustments (APAs) while standing. However, the use of coactivation strategy in APAs in individuals with BSCP has conflicting evidence. Hence, this study aimed to investigate postural muscle activities in BSCP during unilateral arm flexion task in which postural perturbations occur in the sagittal, frontal, and horizontal planes. We included 10 individuals with BSCP with level II on the Gross Motor Function Classification System (BSCP group) and 10 individuals without disability (control group). The participants stood on a force platform and rapidly flexed a shoulder from 0° to 90° at their own timing. Surface electromyograms were recorded from the rectus femoris, medial hamstring, tibialis anterior, and medial gastrocnemius. The control group showed a mixture of anticipatory activation and inhibition of postural muscles, whereas the BSCP group predominantly exhibited anticipatory activation with slight anticipatory inhibition. Compared with the control group, the BSCP group tended to activate the ipsilateral and contralateral postural muscles and the agonist–antagonist muscle pairs. The BSCP group had a larger disturbance in postural equilibrium, quantified by the peak displacement of center of pressure during the unilateral arm flexion, than those without disability. Individuals with BSCP may use coactivation strategy, mainly the anticipatory activation of postural muscle activity, during a task that requires a selective postural muscle activity to maintain stable posture.

Engineered Graphene Material Improves the Performance of Intraneural Peripheral Nerve Electrodes.

Limb neuroprostheses aim to restore motor and sensory functions in amputated or severely nerve-injured patients. These devices use neural interfaces to record and stimulate nerve action potentials, creating a bidirectional connection with the nervous system. Most neural interfaces are based on standard metal microelectrodes. In this work, a new generation of neural interfaces which replaces metals with engineered graphene, called EGNITE, is tested. In vitro and in vivo experiments are conducted to assess EGNITE biocompatibility. In vitro tests show that EGNITE does not impact cell viability. In vivo, no significant functional decrease or harmful effects are observed. Furthermore, the foreign body reaction to the intraneural implant is similar compared to other materials previously used in neural interfaces. Regarding functionality, EGNITE devices are able to stimulate nerve fascicles, during two months of implant, producing selective muscle activation with about three times less current compared to larger microelectrodes of standard materials. CNAP elicited by electrical stimuli and ENG evoked by mechanical stimuli are recorded with high resolution but are more affected by decreased functionality over time. This work constitutes further proof that graphene-derived materials, and specifically EGNITE, is a promising conductive material of neural electrodes for advanced neuroprostheses.

Simulation of FES on the forearm with muscle-specific activation resolution.

Functional electrical stimulation (FES) is an established method of supporting neurological rehabilitation. However, particularly on the forearm, it still cannot elicit selective muscle activations that form the basis of complex hand movements. Current research approaches in the context of selective muscle activation often attempt to enable targeted stimulation by increasing the number of electrodes and combining them in electrode arrays. In order to determine the best stimulation positions and settings, manual or semi-automated algorithms are used. This approach is limited due to experimental limitations. The supportive use of simulation studies is well-established, but existing simulation models are not suitable for analyses of selective muscle activation due to missing or arbitrarily arranged innervation zones. This study introduces a new modeling method to design a person-specific digital twin that enables the prediction of muscle activations during FES on the forearm. The designed individual model consists of three parts: an anatomically based 3D volume conductor, a muscle-specific nerve fiber arrangement in various regions of interest (ROIs), and a standard nerve model. All processes were embedded in scripts or macros to enable automated changes to the model and the simulation setup. The experimental evaluation of simulated strength-duration diagrams showed good coincidence. The relative differences of the simulated amplitudes to the mean amplitude of the four experiments were in the same range as the inter-experimental differences, with mean values between 0.005 and 0.045. Based on these results, muscle-specific activation thresholds were determined and integrated into the simulation process. With this modification, simulated force-intensity curves showed good agreement with additionally measured curves. The results show that the model is suitable for simulating realistic muscle-specific activations. Since complex hand movements are physiologically composed of individual, selective muscle activations, it can be assumed that the model is also suitable for simulating these movements. Therefore, this study presents a new and very promising approach for developing new applications and products in the context of the rehabilitation of sensorimotor disorders.

Kinetics, Kinematics, and Muscle Activity Patterns During Back Squat With Different Contributions of Elastic Resistance.

Performing back squats with elastic bands has been widely used in resistance training. Although research demonstrated greater training effects obtained from adding elastic bands to the back squat, little is known regarding the optimal elastic resistance and how it affects neuromuscular performance. This study aimed to compare the force, velocity, power, and muscle activity during back squats with different contributions of elastic resistance. Thirteen basketball players performed 3 repetitions of the back squat at 85% of 1-repetition maximum across 4 conditions: (1)total load from free weightand (2)20%, (3)30%, and (4)40% of the total load from elastic band and the remaining load from free weight. The eccentric and concentric phases of the back squat were divided into upper, middle, and bottom phases. In the eccentric phase, mean velocity progressively increased with increasing elastic resistance, and muscle activity of the vastus medialis and rectus femoris significantly increased with the largest elastic resistance in the upper phase (P ≤ .036). In the concentric phase, mean power (P ≤ .021) and rate of force development (P ≤ .002) significantly increased with increasing elastic resistance. Furthermore, muscle activity of the vastus lateralis and vastus medialis significantly improved with the largest elastic resistance in the upper phases (P ≤ .021). Velocity, power, rate of force development, and selective muscle activity increased as the elastic resistance increased in different phases during the back-squat exercise.

Selective zygomaticus muscle activation by ball electrodes in synkinetically reinnervated patients after facial paralysis.

Although many different treatments were developed for facial palsy, only a few therapeutic options are available for facial synkinesis. Electrical stimulation of specific muscles via implants could be useful in restoring facial symmetry in synkinetic patients. A challenge in developing stimulation devices is finding the right stimulation location, type, and amplitude. This work assesses the ability to selectively stimulate the zygomaticus muscle (ZYG) in patients with oral-ocular synkinesis to elicit a visually detectable response of the ipsilateral corner of the mouth (COM), without causing a reaction of the orbicularis oculi muscle (OOM). We aimed to assess how close to the COM the stimulation should be delivered in order to be selective. A total of 10 patients (eight females, two males) were enrolled. Facial function was graded according to the Sunnybrook facial grading system. Needle EMG was used to test the activities of the muscles, during volitional and "unintended" movements, and the degree of synkinesis of the ZYG and OOM. Two ball electrodes connected to an external stimulator were placed on the paretic ZYG, as close as possible to the COM. Independent of the waveform with which the stimulation was presented, a selective ZYG response was observed within 4.5 cm of the horizontal plane and 3 cm of the vertical plane of the COM. When the distance between the electrodes was kept to ≤2 cm, the amplitude necessary to trigger a response ranged between 3 and 6 mA when the stimulation was delivered with triangular pulses and between 2.5 and 3.5 mA for rectangular pulses. The required amplitude did not seem to be dependent on the applied phase duration (PD), as long as the PD was ≥5 ms. Our results show that selective stimulation of the ZYG presenting synkinetic ZYG-OOM reinnervation can be achieved using a broad PD range (25-1,000 ms) and an average amplitude ≤6 mA, which may be further decreased to 3.5 mA if the stimulation is delivered via rectangular rather than triangular waves. The most comfortable and effective results were observed with PDs between 50 and 250 ms, suggesting that this range should be selected in future studies. [https://drks.de/search/de/trial/DRKS00019992], identifier (DRKS00019992).

Immediate neck hypoalgesic effects of craniocervical flexion exercises and cervical retraction exercises among individuals with non-acute neck pain and a directional preference for retraction or extension: preliminary pretest-posttest randomized experimental design

ABSTRACT Background Selective deep neck flexor muscle activation through craniocervical flexion exercises has been considered to be different from cervical retraction exercises. Objective To compare the immediate analgesic effect of craniocervical flexion versus cervical retraction exercises in individuals with nonacute, directional preference (DP) for cervical retraction or extension Methods A two-arm, assessor-blinded, pretest-posttest randomized experiment was conducted. Participants were randomly assigned to either craniocervical flexion or cervical retraction exercises and those who were confirmed at the post-intervention examination to have a DP for cervical retraction or extension were analyzed. The primary outcome measure was pressure pain thresholds at the C2 and C5-C6 levels. Results A total of 10 (mean age = 20.6 years) and nine participants (mean age = 19.4 years) undertook craniocervical flexion and retraction exercises, respectively. One-way analysis of variance demonstrated no statistically significant (p > 0.05) interaction effect regardless of the neck level. In the pre-post change percentages, retraction exercises provided greater analgesic effects compared to craniocervical flexion exercises at the C2 (Hedges’ g = 0.679) and C5-C6 levels (g = 0.637). Conclusion This study showed a comparable or greater immediate neck analgesic effect from cervical retraction exercises compared to craniocervical flexion exercises in individuals with a DP for cervical retraction or extension.

Comparison of muscle activity of hamstrings as knee flexors and hip extensors and effect of tibial and hip rotation on the contribution of hamstrings

BackgroundLimited studies have compared the muscle activity of the medial and lateral hamstrings as knee flexors with tibial internal and external rotation and hip extensors with hip internal and external rotation. In particular, hamstring activity during hip extension with hip rotation has rarely been investigated. ObjectiveThis study aimed to compare the muscle activity of the medial and lateral hamstrings as knee flexors and hip extensors and to compare the activity of these muscles according to tibial rotation during isometric knee flexion and hip rotation during isometric hip extension. MethodsA total of 23 healthy adults participated in the study. The electromyographic (EMG) activity of the hamstrings was measured during maximal isometric knee flexion and maximal isometric hip extension. In addition, tibial rotation was applied actively during maximal isometric knee flexion, whereas hip rotation was applied actively during maximal isometric hip extension. ResultsEMG activity during maximal isometric knee flexion with tibial internal and external rotation was significantly higher than that during maximal isometric hip extension with hip internal and external rotation, respectively. For EMG activity according to tibial and hip rotation, there was no significant difference between tibial internal and external rotation during maximal isometric knee flexion, whereas there was a significant difference between hip internal and external rotation during maximal isometric hip extension. ConclusionHamstring activity was higher for knee flexors than for hip extensors. However, hip rotation during maximal isometric hip extension is an effective intervention for selective muscle activation of the medial and lateral hamstrings.

Appropriate Resistance Intensity for Activation of Infraspinatus and Control of Anterior Translation of the Humeral Head

Background In general, external rotation (ER) exercises are commonly used in rotator cuff retraining programs to improve stabilization ability. ER exercises at 90° of shoulder abduction are common and effective in strengthening the infraspinatus (ISP). However, if the ISP is weak during ER at 90° shoulder abduction, the posterior deltoid muscle (PD) is overactivated, which can lead to anterior translation of the humeral head. Therefore, the selective activation of ISP muscles is an important factor in rehabilitation. Objectives We investigated the muscle activities of the ISP, PD, and middle trapezius (MT), the ratio of the ISP to PD muscle activities, and the anterior translation of the humeral head in response to three resistance intensities during sitting external rotation (SITER) exercises. Methods A total of 12 healthy women recorded changes in the anterior translation of the humeral head using a load cell, the muscle activities of the ISP, PD, and MT, the ratio of the ISP to PD muscle activities using surface electromyography (EMG) during SITER under three different intensities [low (10-20%) medium (45-55%) high (60-70%)]. Results The ISP, PD, and MT amplitudes were highest at high intensity, followed by medium and low intensities during SITER (p < 0.001). The muscle activity ratio was significantly highest at medium intensity compared with low and high intensities (p = 0.031). The anterior translation of the humeral head was highest at high intensity, followed by medium and low intensities during SITER (p < 0.001). Conclusions Medium intensity (45-55%) was the most appropriate intensity during the SITER exercise. However, anterior gliding of the humeral head was the lowest at low intensity. Therefore, during ER exercises, we should think about how to control the anterior gliding of the humeral head.

Selective Neural Electrical Stimulation of an Injured Facial Nerve Using Chronically Implanted Dual Cuff Electrodes.

Facial nerve (FN) injury can lead to debilitating and permanent facial paresis/paralysis (FP), where facial muscles progressively lose tone, atrophy, and ultimately reduce to scar tissue. Despite considerable efforts in the recent decades, therapies for FP still possess high failure rates and provide inadequate recovery of muscle function. In this pilot study, we used a feline model to demonstrate the potential for chronically implanted multichannel dual-cuff electrodes (MCE) to selectively stimulate injured facial nerves at low current intensities to avoid stimulus-induced neural injury. Selective facial muscle activation was achieved over six months after FN injury and MCE implantation in two domestic shorthaired cats (Felis catus). Through utilization of bipolar stimulation, specific muscles were activated at significantly lower electrical currents than was achievable with single channel stimulation. Moreover, interval increases in subthreshold current intensities using bipolar stimulation enabled a graded EMG voltage response while maintaining muscle selectivity. Histological examination of neural tissue at implant sites showed no appreciable signs of stimulation-induced nerve injury. Thus, by selectively activating facial musculature six months following initial FN injury and MCE implantation, we demonstrated the potential for our neural stimulator system to be safely and effectively applied to the chronic setting, with implications for FP treatment.

Effects of the abdominal drawing-in maneuver on hamstring rotational activity and pelvic stability in females.

The medial hamstring (MH) and lateral hamstring (LH) can be selectively trained through tibial internal and external rotation during prone knee flexion. However, no study has identified how a combined tibial rotation and lumbo-pelvic stability strategy influences MH and LH muscle activities. To investigate the combined effects of tibial rotation and the abdominal drawing-in maneuver (ADIM) on MH and LH muscle activities as well as pelvic rotation during prone knee flexion. Fifteen female volunteers performed prone knee flexion with tibial internal and external rotation, with and without the ADIM. Under each condition, MH and LH muscle activities were measured by surface electromyography (EMG), and the pelvic rotation angle by a smartphone inclinometer application. The results showed increased MH (without the ADIM: p< 0.001, effect size (d) = 2.05; with the ADIM: p< 0.001, d= 1.71) and LH (without the ADIM: p< 0.001, d= 1.64; with the ADIM: p= 0.001, d= 1.58) muscle activities under internal and external tibial rotation, respectively. However, addition of the ADIM led to increased MH (internal tibial rotation: p= 0.001, d= 0.67; external tibial rotation: p= 0.019, d= 0.45) and LH (internal tibial rotation: p= 0.003, d= 0.79; external tibial rotation: p< 0.001, d= 1.05) muscle activities combined with reduced pelvic rotation (internal tibial rotation: p< 0.001, d= 3.45; external tibial rotation: p< 0.001, d= 3.01) during prone knee flexion. These findings suggest that the ADIM could be useful for reducing compensatory pelvic rotation and enhancing selective muscle activation in the MH and LH, according to the direction of tibial rotation, during prone knee flexion.

New Strategies for Controlling Pelvic Transverse Rotation and Selective Activation of Hip Muscles during Prone Hip Extension with Knee Flexion

Background : Prone hip extension with knee flexion (PHEKF) is a commonly used exercise for strengthening the gluteal muscles. However, PHEKF exercise is associated with a risk of increased hamstring and erector spinae activities, lumbar rotation to compensate for gluteal muscle weakness. Therefore, PHEKEF with isometric hip 30 abduction was evaluated in this study using Thera-Band to reduce pelvic transverse rotation compensation and effectively strengthen gluteal muscle strength. Objectives : The purpose of this study was to investigate the activity of the gluteus maximus (GMax), gluteus medius (GMed), erector spinae (ES) and hamstring (HAM) muscles and pelvic transverse rotation during PHEKF in three conditions. Methods : Fifteen healthy women participated in the study. The pelvic transverse rotation was measured using a smart phone-based measurement tool. The surface electromyography was attached the GMax, GMed, ES and HAM muscles. Then, the maximum voluntary isometric contraction was measured. The PHEKF exercise was performed in three different conditions (PHEKF, PHEKF with 30º hip abduction, and PHEKF with 30º isometric hip abduction [IHA]) by randomly. A one-way repeated measures ANOVA was performed to determine the difference in pelvic transverse rotation angle and muscle activity between the condition. Results : The GMax and GMed amplitudes were highest in PHEKF with 30° IHA, followed by 30º and 0° hip abduction during PHEKF (GMax, p < 0.001; GMed, p < 0.001). HAM and ipsilateral ES amplitudes were not significantly different among the three conditions (ipsilateral ES, p = 0.268; HAM, p = 0.577). In the pelvic transverse rotation angle and contralateral ES, the PHEKF with 30° IHA showed significantly lower than PHEKE with 30° abduction (the pelvic transverse rotation angle, p < 0.05; contralateral ES, p < 0.05). Conclusions : The results of these studies can examine that the PHEK with 30º IHA was effective to control pelvic transverse rotation and increase the contribution of the selective muscles activities of GMax and GMed muscles.

Effects of Intended Scapular Posterior Tilt Motion on Trapezius Muscle Electromyography Activity.

The intended scapular motion is a strategy to strengthen the lower trapezius (LT). However, few studies have explored the effects of the intended scapular posterior tilt motion on selective LT activation. Thus, the present study investigated the effect of the intended scapular posterior tilt on the electromyography (EMG) activity of trapezius muscles during prone shoulder horizontal abduction (PSHA). Eighteen asymptomatic men performed three types of PSHA: (1) preferred PSHA, (2) PSHA with the intended scapular posterior tilt, and (3) PSHA with the intended scapular posterior tilt and trunk extension. EMG activity of the upper trapezius (UT), middle trapezius (MT), and LT were measured during PSHAs. Scapular posterior tilt angle, with and without the intended scapular posterior tilt, were measured using inclinometer. The results indicated that LT muscle activity increased when scapular posterior tilt was applied with and without trunk extension (14–16%), compared to the preferred condition, during PSHA (p < 0.05). However, the addition of trunk extension to PSHA with the intended scapular posterior tilt increased the UT muscle activity (28%) and the UT/LT (29%) and UT/MT (31%) ratios (p < 0.05). The scapular posterior tilt angle was higher (15%) when applying the intended scapular posterior tilt (p = 0.020). These findings suggest that the intended scapular posterior tilt may be a useful strategy for selective LT muscle activation.

Effects of the Additional Scapular Posterior Tilt Movement on Selective Muscle Activation of the Lower Trapezius during Prone Shoulder Extension

Effects of the Additional Scapular Posterior Tilt Movement on Selective Muscle Activation of the Lower Trapezius during Prone Shoulder Extension

Selective Facial Muscle Activation with Acute and Chronic Multichannel Cuff Electrode Implantation in a Feline Model.

Facial paralysis is a debilitating condition with substantial functional and psychological consequences. This feline-model study evaluates whether facial muscles can be selectively activated in acute and chronic implantation of 16-channel multichannel cuff electrodes (MCE). Two cats underwent acute terminal MCE implantation experiments, 2 underwent chronic MCE implantation in uninjured facial nerves (FN) and tested for 6 months, and 2 underwent chronic MCE implantation experiments after FN transection injury and tested for 3 months. The MCE were wrapped around the main trunk of the skeletonized FN, and data collection consisted of EMG thresholds, amplitudes, and selectivity of muscle activation. In acute experimentation, activation of specific channels (ie, channels 1-3 and 6-8) resulted in selective activation of orbicularis oculi, whereas activation of other channels (ie, channels 4, 5, or 8) led to selective activation of levator auris longus with higher EMG amplitudes. MCE implantation yielded stable and selective facial muscle activation EMG thresholds and amplitudes up to a 5-month period. Modest selective muscle activation was furthermore obtained after a complete transection-reapproximating nerve injury after a 3-month recovery period and implantation reoperation. Chronic implantation of MCE did not lead to fibrosis on histology. Field steering was achieved to activate distinct facial muscles by sending simultaneous subthreshold currents to multiple channels, thus theoretically protecting against nerve damage from chronic electrical stimulation. Our proof-of-concept results show the ability of an MCE, supplemented with field steering, to provide a degree of selective facial muscle stimulation in a feline model, even following nerve regeneration after FN injury. N/A.

Retraining selective trunk muscle activity: A key to more successful rehabilitation outcomes for hemiparetic stroke patients.

Hemiparetic patients lose the ability to move their trunk selectively, abdominals are affected and neither voluntary nor reflex activity is present. To investigate if the inclusion of specific exercises for the trunk muscles in a rehabilitation program for chronic hemiparetic patients could lead to an additional improvement. A multiple-participant single-subject design was replicated in patients with hemiplegia. The study was conducted in two cycles: for the first cycle (A), patients received conventional rehabilitation program, then for the second cycle (B), six months later, the same subjects received conventional rehabilitation therapy plus an additional specific selective trunk muscles training. Trunk Impairment Scale (TIS), Berg Balance Scale (BBS), 10 meters distance walk test (10 MWT), Functional Independence Measure (FIM) and instrumental gait analysis were performed before and after both treatment cycles. Significant changes were observed in TIS and 10 MWT after the two treatment cycles. However, after treatment cycle B, BBS and FIM score showed an additional improvement. Whereas, after treatment cycle A gait analysis did not relevantly changed, but after cycle B a significant improvement was registered in velocity, cadence and percentage of stance in the gait cycle. In our patients, the training for selective activation of the trunk muscles had led to a consistent improvement of gait analysis parameters, and hemiparesis-related disability in stance and activities of daily living.

Retraining selective trunk muscle activity: A key to more successful rehabilitation outcomes for hemiparetic stroke patients.

Retraining selective trunk muscle activity: A key to more successful rehabilitation outcomes for hemiparetic stroke patients.

Selective activation of Forearm muscles for improving Wrist Joint Stability

The wrist movements has important role in the daily life activities. Flexion, ExtensionandAbduction and Adduction are acceptable movements in the wrist. The Strength training of extensionis necessary for prevention of wrist sprains due to flexion movements because flexionforce is morethan extension Aim of this study was to improve the muscle strength by human resistive trainingand inspecting selective activation of forearm muscles in the above movements. 10 subjects wererecruited for performing maximum Isometric contraction at human resistive training and Flexorcarpiulnaris, Flexor carpi radialis,Extensor carpi radialislongusExtensor carpi ulnarisand abductorpollicislonguswereselected for investigation. Surface electromyography was used to get thecontraction level. Ourresult showed co activation of investigated muscles were less in synergistic thanagonist function (FCU:during Abduction 45%, ECU: during Abduction 37%, FCR:during adduction43%, ECRL: during adduction 29%, APL: during flexion 23%) (P<0.0001).In the APL investigation, there was significant difference observed in the interaction effect (P=0.054, F(3, 9)=140.29,ηp2 =0.205). In the isometric training, biomechanical stability of radio carpal and midcarpal wasimproved due to strengthening of forearm muscles.

DEEP NECK FLEXORS IMPACT RECTUS ABDOMINIS MUSCLE ACTIVITY DURING ACTIVE STRAIGHT LEG RAISING.

Active straight leg raising (ASLR) is commonly performed to test fundamental movement competency. Head control or positioning can affect the abdominal muscle activity during movements. To investigate whether abdominal muscle activity differs when the head is extended or when deep neck flexor (DNF) muscles are selectively activated during the ASLR. Cross-sectional. Participants were included based on the following criteria: 1) age>17 years; 2) no spinal or lower extremity pain in the prior month; 3) the vertical line of the malleolus in an elevated the lower limb resides below the knee joint line of a non-moving lower limb during ASLR and above during a passive straight leg raising in each lower limb; and 4) no history of diagnosed spinal deformities or central nervous system disorders. Participants with > 39% reference voluntary contraction in the sternocleidomastoid muscle during the craniocervical flexion test (CCFT) of 24 mmHg target were excluded from the analyses. Right ASLR was repeated in each of the following three head conditions in a random order: 1) neutral head position, 2) head extended by 25 °, and 3) CCFT maintained with a 24 mmHg target. Among the three head conditions, the relative latency for the onset of the right rectus femoris (RF) muscle during the right ASLR and the muscle activity amplitude for 50ms were compared after the onset of RF muscular activity in the following muscles: left rectus abdominis (RA), bilateral external obliques, bilateral internal obliques, and left gluteus maximus muscles. Data from 31 participants (21 women and 10 men, mean age=22.5 years) were analyzed. The relative latency of the left RA (Hedges' g = 0.39, p=.038) was higher in the CCFT condition (mean±SD=112.1ms±86.0ms) than that in the neutral head condition (82.9ms±58.6ms). However, no difference (all p>.05) was observed in other measures between the groups. In people with impaired movement competency in ASLR, head extension did not alter the abdominal muscle activities in ASLR. However, selective activation of the DNF muscles delayed the onset of RA muscle activity during the ASLR. 4.