Medialis Muscle Activity Research Articles

Strategies for knee stabilising and pivot-shift avoidance in a step-down and cross-over task observed sub-acutely after anterior cruciate ligament reconstruction

BackgroundIndividuals with a recent anterior cruciate ligament reconstruction may demonstrate an altered movement strategy for protecting the knee and maintaining stability. Altered knee movement might lead to abnormal intra-articular load, potentially contributing to early knee osteoarthritis onset. A protective strategy may be particularly evident during active tasks that induce a pivot-shift manoeuvre, such as a step-down and cross-over task. In this study, we investigated whether knee joint mechanics and muscle activity differed between participants early (∼3 months) following reconstruction (n = 35) to uninjured controls (n = 35) during a step-down and cross-over task with a 45° change-of-direction. MethodsWe used motion capture, force plates and surface electromyography to compare time-normalised curves of sagittal and transverse-plane knee mechanics and muscle activity during the cross-over phase between groups using functional t-tests. We also compared knee mechanics between sides within the injured group and compared discrete outcomes describing the cross-over phase between groups. FindingsCompared to controls, the injured participants had greater knee flexion angle and moment, lower internal rotation moment, more preparatory foot rotation of the pivoting leg, a smaller cross-over angle, and a longer cross-over phase for both the injured and uninjured sides. The injured leg also had greater biceps femoris and vastus medialis muscle activity compared to controls and different knee mechanics than the uninjured leg. InterpretationIndividuals with anterior cruciate ligament reconstruction showed a knee-stabilising and pivot-shift avoidance strategy for both legs early in rehabilitation. These results may reflect an altered motor representation and motivate considerations early in rehabilitation.

A Comparative Study on Neuromuscular Control Patterns during Side Cutting Depending on Direction Prediction Presence or Absence and Gender

PURPOSE This study aimed to identify the lower limb muscle activity based on direction prediction presence or absence and gender during side cutting in healthy college students. METHODS The study participants included 14 healthy males and females (8 males; 6 females). All participants ran at full speed for a distance of 12m, and side-cutting was carried out at 45 degrees in a randomly indicated direction and in a fixed direction. Simultaneously, data regarding vastus medialis, vastus lateralis, semitendinosus, and biceps femoris muscle activity of the dominant leg were collected using an electromyography sensor, and data regarding vertical acceleration were collected using an inertial sensor attached to the pelvis. A sync webcam was used for obtaining the initial contact of side cutting and the stance period time. During the 10 milliseconds (pre-activation) prior to the initial contact and 50% of the stance phase (loading phase), vastus medialis, vastus lateralis, semitendinosus, and biceps femoris average muscle activity and hamstring to quadriceps ratio included as variables. RESULTS During the pre-activation and loading phase, the vastus medialis muscle activity of the male group was higher in the unexpected condition than in the expected condition. Furthermore, hamstring to quadriceps ratio was confirmed to be lower under unexpected condition compared to under expected condition during on loading phase. CONCLUSIONS The study results suggest that the risk of anterior cruciate ligament injury may increase with side cutting under unpredictable conditions. It is expected to provide useful information for identifying factors related to knee injury in the general population.

A Biomechanical Analysis of Wide, Medium, and Narrow Grip Width Effects on Kinematics, Horizontal Kinetics, and Muscle Activity on the Sticking Region in Recreationally Trained Males During 1-RM Bench Pressing.

Grip width has been found to affect lifting performance, especially around the sticking region; however, little is known about the kinetics and muscle activities that could explain these differences in performance. This study aimed to investigate the effects of grip width on the joint, barbell kinematics, and horizontal kinetics, analyzed in tandem with the effects of muscle activation around the sticking region in the one repetition maximum (1-RM) barbell bench press. Fourteen healthy bench press-trained males (body mass: 87.8 ± 18.4, age: 25 ± 5.4) performed 1-RM with a small, medium, and wide grip width. The participants bench pressed 109.8 ± 24.5 kg, 108.9 ± 26.4 kg, and 103.7 ± 24 kg with the wide, medium, and narrow grip widths. Furthermore, the wide grip width produced 13.1–15.7% lateral forces, while the medium and narrow grip widths produced 0.4–1.8 and 8.5–10.1% medially directed forces of the vertical force produced during the sticking region, respectively. Horizontal forces did not increase during the sticking region, and the resultant forces decreased during the sticking region for all grip widths. The wide and medium grip widths produced greater horizontal shoulder moments than the narrow grip width during the sticking region. Hence, the wide and medium grip widths produced similar shoulder and elbow joint moments and moment arm at the first located lowest barbell velocity. Furthermore, triceps medialis muscle activity was greater for the medium and narrow grip widths than the wide grip width. This study suggests that the sticking region for the wide and medium grip widths may be specific to the horizontal elbow and shoulder joint moments created during this region. Therefore, when the goal is to lift as much as possible during 1-RM bench press attempts among recreationally trained males, our findings suggest that bench pressing with a wide or medium grip width may be beneficial.

Sex differences in muscle activity and motor variability in response to a non-fatiguing repetitive screwing task

BackgroundMusculoskeletal disorders are more prevalent among women than among men, which may be explained by aspects of motor control, including neuromuscular requirements and motor variability. Using an exploratory approach, this study aimed to evaluate sex differences in neuromuscular responses and motor variability during a repetitive task performed on 3 days.MethodsThirty women and 27 men performed the non-fatiguing, repetitive, 1-h screwing task. For neuromuscular responses, the mean and difference values of static, median, and peak percentile muscle activity levels (normalized to a reference voluntary contraction force) and, for motor variability, the mean and difference values of relative and absolute cycle-to-cycle variability across days were compared between both sexes for each muscle. A mixed-design analysis of variance was used to assess differences between both sexes.ResultsThe non-fatiguing character of the screwing task was confirmed by the absence of decreased force levels in maximal voluntary contractions performed before and after the task and by absence of electromyographic signs of muscle fatigue. The static and median muscle activity levels tended to be higher among women (on average 7.86 and 27.23 %RVE) than men (on average 6.04 and 26.66 %RVE). Relative motor variability of the flexor and biceps muscles and absolute motor variability of both upper arm muscles were lower in women (on average 0.79 and 29.70 %RVE) than in men (on average 0.89 and 37.55 %RVE). The median activity level of both upper arms muscles tended to decrease within days among women (on average - 2.63 %RVE) but increase among men (on average + 1.19 %RVE). Absolute motor variability decreased within days among women (on average - 5.32 to - 0.34%RVE), whereas it tended to decrease less or increase within days among men (on average - 1.21 to + 0.25 %RVE).ConclusionWomen showed higher levels of muscle activity and lower initial relative and absolute motor variability than males when performing the same occupational task, implying women may have a higher risk for developing disorders and point to both sexes using different intrinsic motor control strategies in task performance. Clearly, biological aspects alone cannot explain why women would be at higher risk for developing disorders than men. Therefore, a wider range of individual and environmental factors should be taken into account for optimizing work station designs and organizations by taking into account sex differences.

Effects of Ergometer Exercise after Static Stretching and Strength Exercise on Muscle Activity of the Quadriceps Muscle

Purpose: This study aimed to investigate the effect of ergometer exercise after performing static stretching and strength exercise on the activity of the quadriceps muscle. In general, the effects of performing both the strength and stretching exercises before ergometer exercises were examined. Methods: The participants were divided into two exercise groups and performed static stretching and strength exercises and then ergometer exercise. Each exercise was performed for 4 weeks, three times a week, by each group to measure changes in the muscle activities of the rectus femoris, vastus lateralis, and vastus medialis. Measurements were made at weeks 0 and 4, and electromyography was used in a static posture. Results: Both the stretching and strength exercise groups showed significant increases in the rectus femoris, vastus lateralis, vastus medialis muscle activities after exercise. Conclusion: Stretching and strength exercises before ergometer exercise helps to increase muscle activities. Stretching is thought to be more effective for gaining muscle activity than muscle strength. However, no significant difference was found between the two groups.

Correction: Quadriceps neuromuscular function in women with patellofemoral pain: Influences of the type of the task and the level of pain.

[This corrects the article DOI: 10.1371/journal.pone.0205553.].

Quadriceps neuromuscular function in women with patellofemoral pain: Influences of the type of the task and the level of pain

The present study aimed at investigating whether the neuromuscular system behaves differently (in terms of force and muscle activity generation) as a function of the task being performed (i.e. maximal voluntary efforts vs stair negotiation) and the presence of patellofemoral pain (PFP) and possible influences of pain intensity. Thirty-eight women with (n = 19) and without PFP (n = 19) had their knee strength (extension joint torque) measured during maximal voluntary isometric contractions (MVIC) and electromyography (EMG) data recorded during both MVIC and stair ascent tasks, which were performed before and after a loading protocol designed to exacerbate pain symptoms. Women with PFP displayed lower levels of vastus medialis (p = 0.002) and vastus lateralis (p = 0.032) EMG activation during MVIC assessments. Conversely, the PFP group showed higher levels of vastus medialis muscle activity during stair climbing (p = 0.007), which happened exclusively after the loading protocol. Similarly, women with PFP displayed lower knee extensor torque only during the MVIC tests performed after the loading protocol, which was moderately correlated with the increase in self-reported pain (p = 0.041, r = 0.37), whereas the changes in EMG activity during stair ascent were not correlated with changes in pain intensity (p = 0.215, r = 0.12). These results suggest that, in comparison to pain-free controls, women with PFP display lower levels of quadriceps EMG activation during maximal contractions, but higher activation during dynamic tasks (stair ascent). In addition, the moderate association between the decrease in knee extensor torque and increase in self-reported pain indicates that care should be taken by clinicians during quadriceps strength evaluation in women with PFP, as misleading outcomes may emerge if the intensity of knee pain is not considered during screening. Additionally, rehabilitation strategies should focus on both restoring neuromuscular control and increasing muscle strength.

Upper extremity muscle activity during household floor vacuuming with upright cleaners

Physical demands of household carpet vacuuming and associated risks for musculoskeletal problems have received little attention although the level of muscle exertions is often assumed to be similar to that of occupational vacuuming. The aim of this study was to quantitatively assess the level of muscle activities of the upper extremity during carpeted floor vacuuming with household upright vacuum cleaners. Eighteen participants conducted four different carpet vacuuming tasks with two different cleaner models. Electromyography data from seven upper extremity muscles were collected. Median muscle activity ranged from 4.5% to 47.5% of the maximum voluntary contraction capacity for female participants and from 2.7% to 23.6% for male participants. Normalized muscle activity levels were significantly higher in women compared to men across tasks and muscle groups. Study results suggest that home vacuuming with upright vacuum cleaners is physically intensive work, especially for female users who are less physically capable.

Effect of Fatigue on Electromyographic Activity Patterns of the Knee Joint Muscles in Anterior Cruciate Ligament Reconstructed and Deficient Patients during Landing Task

Lower extremity fatigue causes a number of neuromuscular alterations that may increase the risk of knee (re)injury. It has therefore been suggested that fatigue-resistance training be incorporated into injury prevention and rehabilitation programs. The purpose of this study was to determine the effects of fatigue on knee-muscle activity patterns after anterior cruciate ligament injury (ACL). Twelve healthy, 12 ACL reconstructed (ACLR) and 12 ACL deficient (ACLD) recreationally active male volunteers participated in this case-control study. Fatigue was induced via repetitive sets of double-leg squats and drop landings. Muscle activity was assessed via surface electromyography during a single-leg drop landing task pre- and post-fatigue. After fatigue, medial hamstring, lateral hamstring and vastus lateralis muscles turned on significantly earlier in ACLR compared to the control group. Significantly greater vastus medialis muscle activity was observed in ACLD compared to ACLR and control participants post-fatigue. Finally, fatigue decreased lateral gastrocnemius muscle activity in ACLD and control participants. It seems ACLR patients rely on earlier muscle pre-activation to establish knee joint stability upon landing after fatigue. This feed-forward strategy should be emphasized during post-operative rehabilitation in ACLR patients. Furthermore, according to our results, quadriceps and gastrocnemius muscles play an important role in establishing knee joint stability post impact in ACLD patients.

Muscle Fatigue Does Not Change the Effects on Lower Limbs Strength Caused by Aging and Parkinson's Disease.

The aim of this study was to determine the impact of aging and Parkinson’s disease (PD) on lower limb muscle strength before and after muscle fatigue. One hundred thirty-five individuals were distributed over seven groups according to their age (20, 30, 40, 50, 60, 70 years old) and disease. Participants performed maximum voluntary isometric contractions (MVIC) in a leg press device followed by the muscle fatigue protocol (repeated sit-to-stand task). Immediately after muscle fatigue (less than 2 min), the MVIC were repeated. The peak force, peak rate of force development (first 50, 100, 200 ms), and root mean square and peak values of the vastus lateralis and vastus medialis muscle activity during MVIC were calculated before and after muscle fatigue. We found more pronounced reductions in lower limb muscle strength parameters (lower limb force, RFD-100 and RFD-200 - p<0.05) in individuals over 50 years of age and with PD. In addition, there was an inverse relation between aging and lower limb muscle strength parameters. The main findings were the lack of changes in peak force, RFDs and muscle activity of the vastus lateralis and vastus medialis after muscle fatigue according to aging and PD, and similar lower limb muscle strength parameters (before and after muscle fatigue) and effect of muscle fatigue in PD compared to the aged groups (60 and 70 years old groups).

Biomechanical differences between cases with suspected chronic exertional compartment syndrome and asymptomatic controls during running

Chronic exertional compartment syndrome (CECS) has been hypothesised, following clinical observations, to be the result of abnormal biomechanics predominantly at the ankle. Treatment of CECS through running re-education to correct these abnormalities has been reported to improve symptoms. However no primary research has been carried out to investigate the movement patterns of those with CECS. This study aimed to compare the running kinematics and muscle activity of cases with CECS and asymptomatic controls.20 men with bilateral symptoms of CECS of the anterior compartment and 20 asymptomatic controls participated. Barefoot and shod running 3D kinematics and muscle activity of the left and right legs; and anthropometry were compared.Cases displayed less anterior trunk lean and less anterior pelvic tilt throughout the whole gait cycle and a more upright shank inclination angle during late swing (peak mean difference 3.5°, 4.1° and 7.3° respectively). Cases demonstrated greater step length and stance time, although this was not consistent across analyses. There were no consistent differences in Tibialis anterior or Gastrocnemius medialis muscle activity. Cases were heavier (mean difference 7.9kg, p=0.02) than controls with no differences in height (p>0.05)These differences only partially match the clinical observations previously described. However, no consistent differences were found at the ankle joint suggesting that current running re-education interventions which focus on adjusting ankle kinematics are not modifying pathological aspects of gait. The longer step length is a continuing theme in this population and as such may be a key component in the development of CECS.

The effect of a hybrid assistive limb(®) on sit-to-stand and standing patterns of stroke patients.

[Purpose] The Hybrid Assistive Limb® (HAL®) robot suit is a powered exoskeleton that can assist a user’s lower limb movement. The purpose of this study was to assess the effectiveness of HAL® in stroke rehabilitation, focusing on the change of the sit-to-stand (STS) movement pattern and standing posture. [Subjects and Methods] Five stroke patients participated in this study. Single leg HAL® was attached to each subject’s paretic lower limb. The subjects performed STS three times both with and without HAL® use. A tri-axial accelerometer was used to assess the STS movement pattern. Forward-tilt angle (FTA) and the time required for STS were measured with and without HAL® use. Surface electromyography (EMG) of STS and standing were recorded to assess the vastus medialis muscle activities of the paretic limb. [Results] The average FTA without HAL® use was 35° and it improved to 43° with HAL® use. The time required for STS was longer for all subjects with HAL® use (without HAL® use: 3.42 s, with HAL® use: 5.11 s). The integrated EMGs of HAL® use compared to those without HAL®, were 83.6% and 66.3% for STS and standing, respectively. [Conclusion] HAL® may be effective in improving STS and standing patterns of stroke patients.

Effect of armrest positioning and workspace constraints on muscle activity for touchless gestural controls

The recent development of affordable technologies now allow touchless gestural controls to be integrated in common computing environments, however, ergonomic issues (user fatigue, in particular) have not been solved. This experiment investigates shoulder muscle activity for different traditional supported or user-preferred touchless gesture interaction scenarios and quantifies the location that touchless gestural control users would like to position armrests in different gestural workspaces. A custom hand/finger-based gestural control system was developed using a motion tracking system. Users browed an online shopping website while a prototype office chair allowed them to positon armrests easily in a wide space in front of themselves. Results show that median muscle activity of the upper trapezius, medial deltoid, and anterior deltoid are significantly affected by armrest configuration. User-preferred armrest positions generally reduced muscle activity compared to traditional positions, but this reduction was greatest when the gesture space is constrained over the desktop. In those conditions, average user preferred positioning of the armrest was higher and closer to the sternum of the user.

TRX와 저항운동 시 상체와 하체 및 복부의 근활성도 비교

The purpose of this study was to investigate exercise intensity of TRX and each muscles by comparing muscle activity occurred through resistance training and TRX. The exercise of this study consisted of the upper body(bench press, low row), lower body(squat, leg curl) an abdominal muscle(crunch) using TRX and weight machine. In exercises for upper body, the TRX chest press with descending phase showed significantly higher triceps brachii muscle than 80%/1RM the bench press with same phase conducted on the flat ground. There was no difference of the muscle activity between seated row and TRX low row. In exercises for lower limb, 80%/1RM squat with ascending and descending phase showed significantly greater rectus femoris, vestus lateralis, and vestus medialis muscle activities than TRX squat. There was no difference of the muscle activities between leg curl row and TRX leg curl. In exercises for abdominal muscles, there was no difference of the muscle activities between crunch and TRX crunch. There is significant difference between the TRX squat and 80%/1RM squat. However, the other muscle activity was not significantly different between TRX and weigh t machine exercise. It shows that TRX is not only effective for core muscle strength, but also upper and lower body strength. But performing TRX squat that it makes little instability, it needs to be modified into alternate conformation such as one leg squat increasing instability much more.

Cutaneous reflex modulation and self-induced reflex attenuation in cerebellar patients.

Modulation of cutaneous reflexes is important in the neural control of walking, yet knowledge about underlying neural pathways is still incomplete. Recent studies have suggested that the cerebellum is involved. Here we evaluated the possible roles of the cerebellum in cutaneous reflex modulation and in attenuation of self-induced reflexes. First we checked whether leg muscle activity during walking was similar in patients with focal cerebellar lesions and in healthy control subjects. We then recorded cutaneous reflex activity in leg muscles during walking. Additionally, we compared reflexes after standard (computer triggered) stimuli with reflexes after self-induced stimuli for both groups. Biceps femoris and gastrocnemius medialis muscle activity was increased in the patient group compared with the control subjects, suggesting a coactivation strategy to reduce instability of gait. Cutaneous reflex modulation was similar between healthy control subjects and cerebellar patients, but the latter appeared less able to attenuate reflexes to self-induced stimuli. This suggests that the cerebellum is not primarily involved in cutaneous reflex modulation but that it could act in attenuation of self-induced reflex responses. The latter role in locomotion would be consistent with the common view that the cerebellum predicts sensory consequences of movement.

Effect of caffeine ingestion on torque and muscle activity during resistance exercise in men

We examined the effect of caffeine ingestion on muscle torque production and muscle activity at different contraction speeds in trained men. 10 men (mean age ± SD=22 ± 1.1 years) volunteered to participate. A double-blind, randomized cross-over design was used. Sixty minutes postingestion of caffeine (6 mg kg(-1) ) or placebo, participants completed 6 repetitions of isokientic knee extension at 3 angular velocities (30°s(-1) , 150°s(-1) , 300°s(-1) ) from which peak torque was determined. Electromyographic activity of the vastus medialis was also collected. Repeated measures analysis of variance indicated that muscle torque production was significantly higher (P=0.02) with caffeine compared with placebo. A significant (P=0.02) substance by velocity interaction for muscle activity indicated significantly higher vastus medialis muscle activity in the presence of caffeine versus placebo, and this difference was amplified as angular velocity increased. Acute caffeine ingestion improves muscle performance and increases muscle activity during short-duration maximal dynamic contractions.

Developing a Framework for Predicting Upper Extremity Muscle Activities, Postures, Velocities, and Accelerations During Computer Use: The Effect of Keyboard Use, Mouse Use, and Individual Factors on Physical Exposures

Prediction models were developed based on keyboard and mouse use in combination with individual factors that could be used to predict median upper extremity muscle activities, postures, velocities, and accelerations experienced during computer use. In the laboratory, 25 participants performed five simulated computer trials with different amounts of keyboard and mouse use ranging from a highly keyboard-intensive trial to a highly mouse-intensive trial. During each trial, muscle activity and postures of the shoulder and wrist and velocities and accelerations of the wrists, along with percentage keyboard and mouse use, were measured. Four individual factors (hand length, shoulder width, age, and gender) were also measured on the day of data collection. Percentage keyboard and mouse use explained a large amount of the variability in wrist velocities and accelerations. Although hand length, shoulder width, and age were each significant predictors of at least one median muscle activity, posture, velocity, or acceleration exposure, these individual factors explained very little variability in addition to percentage keyboard and mouse use in any of the physical exposures investigated. The amounts of variability explained for models predicting median wrist velocities and accelerations ranged from 75 to 84% but were much lower for median muscle activities and postures (0–50%). RMS errors ranged between 8 to 13% of the range observed. While the predictions for wrist velocities and accelerations may be able to be used to improve exposure assessment for future epidemiologic studies, more research is needed to identify other factors that may improve the predictions for muscle activities and postures.

Physical workloads of the upper‐extremity among workers of the Colombian flower industry

We report the prevalence of symptoms of common upper-limb disorders and describe comprehensively mechanical workloads in a sample of workers of the Colombian flower industry. One hundred fifty eight workers from eight flower manufacturers were assessed. Assessments included Borg self-reported exertion and working practices, medical examinations, video-based observations and kinematic and surface muscular activity assessments of upper-limb. Point prevalence of signs and symptoms of CTS, epicondylitis, and De Quervain's disease was 32.9%, 15.2%, and 13.3%, respectively. All tasks are executed on average in wrist extension, ulnar deviation, and high elbow flexion. Average median muscle activity across tasks ranged between 3.6% and 27.3%. Forearm muscles were mainly active. The occurrence of signs and symptoms of upper-extremity musculoskeletal disorders was high among the sample. The classification and cutting task showed the highest mechanical demands. Interventions in this working population are required and should be directed to allow for muscular rest on regular basis.

Reduced plantar cutaneous sensation modifies gait dynamics, lower-limb kinematics and muscle activity during walking

Peripheral neuropathy is the most common long-term complication in diabetes and is involved in changes in diabetic gait and posture. The regression of nerve function leads to various deficits in the sensory and motor systems, impairing afferent and efferent pathways in the lower extremities. This study aimed to examine how reduced plantar-afferent feedback impacts the gait pattern. Cutaneous sensation in the soles of both feet was experimentally reduced by means of intradermal injections of an anaesthetic solution, without affecting foot proprioception or muscles. Ten subjects performed level walking at a controlled velocity before and after plantar anaesthesia. Muscle activity of five leg-muscles, co-contraction ratios for the knee and ankle joint, ground reaction forces (GRF), spatiotemporal characteristics, joint angles and moments of the hip, knee and ankle were analysed. The intervention significantly lowered plantar sensation, reducing it to the level of sensory neuropathy. Spatiotemporal gait characteristics remained unchanged. The ankle joint was more dorsiflexed which coincided with increased tibialis anterior and decreased gastrocnemius medialis muscle activity during foot flat to mid-stance. In addition, the knee joint was more flexed accompanied by increased biceps femoris activity and higher internal knee-extension moment. With regard to gait dynamics, a delay of the first peak of the vertical GRF was observed. Increased soleus and tibialis anterior muscle activity were found during the end of stance. Short-term loss of plantar sensation affects lower-limb kinematics and gait dynamics, particularly during the first half of stance, and contributes to modified muscle-activation patterns during locomotion.

시각 통제 균형훈련이 뇌졸중 환자의 균형 및 근 활성도에 미치는 영향

This study aims to examine effects of vision control balance training applied to stroke patients on their balance. 26 stroke patients, the subjects of this study, were divided into an affected side 1/2 vision control group (9), a non-affected side 1/2 vision control group (9), and a non-vision control group (8). After vision control standing on Posturo-med, all of the three groups received balance training 20 minutes four times per week for 8 weeks watching themselves 1M away from a mirror. To measure their balance abilities, measurements were made on their time of balance maintenance and muscle activity prior to the intervention, four 4 after the intervention, and 8 weeks after the intervention. Vision control balance training applied to stroke patients resulted in increase in their time of balance maintenance and significant improvement in vastus medialis muscle activity (p<0.05). This study result is that vision control balance training is considered an effective exercise method for balance training of stroke patients.