Muscle Onset Times Research Articles

Push-up 동작 시 신체기울기에 따른 견관절 주변근의 수축 개시시간 변화

PURPOSE: The purpose of this study was to investigate recruiting order and onset time around shoulder muscle during the push-up according to the body tilting angle. METHODS: Twenty healthy young adult subjects were recruited for this study. They had no neurological and musculoskeletal disease. We used the sEMG for recording onset time of shoulder muscles. Shoulder Muscles were anterior deltoid(AD), posterior deltoid(PD), pectoralis major(PM), upper trapezius(UT). Body tilting angle were measured at 0 degree, 30 degree and 60 degree by using tilting table. Muscles contraction onset time were set by the push-up performed 3 times respectively. Mean of 3 measurements were used. And initiate onset time was decided by the Mean <TEX>${\pm}2$</TEX> SD in the threshold, more than 25ms. RESULTS: There were significant difference at 0 degree, 30 degree and 60 degree(p<.05). Muscles onset time were same order at 0 degree, 30 degree. UT occurred first of all contraction at 0 degree and 30 degree. And then contracted AD, PD, PM. But, at 60 degree, AD was the first contraction, and PM, UT, PD. CONCLUSION: Muscle recruitment order and onset time according to the body tilting was shown the difference when you do push-up. Therefore, this result, shoulder muscle recruitment pattern of according to the body tilting is different and it has to make effective shoulder exercise program.

Association between wrist extensor muscle onset timing and motor control accuracy in acute and chronic stroke patients

Association between wrist extensor muscle onset timing and motor control accuracy in acute and chronic stroke patients

Delayed wrist extensor muscle onset timing in acute and chronic people with stroke

Delayed wrist extensor muscle onset timing in acute and chronic people with stroke

Muscle Activation and Onset Times of Hip Extensors during Various Loads of a Closed Kinetic Chain Exercise

The aim of this study was to determine the muscle activity and onset time of hip extensors during a closed kinetic chain exercise (deadlift) at sub-maximal loads of 30%, 40%, 50%, and 75% of one repetition maximum (1RM). Twelve healthy males with at least three years of resistance training experience volunteered for the study. Biceps femoris (BF) and gluteus maximus (GM) muscle activity, onset time, peak and mean power were measured during the concentric phase of the deadlift. There was no main effect (p > 0.05) or no interaction effect for the onset time in BF and GM and for each load BF and GM had similar muscle activity. Increasing the external load during deadlift had no adverse effect on the relative onset time and it did not promote BF onset to occur before GM onset, thus both muscles were simultaneously activated, which should not compromise a delay in GM.

Effect of abduction and external rotation of the hip joint on muscle onset time during prone hip extension with knee flexion.

[Purpose] This study investigated the effect of hip position on muscle onset time during prone hip extension with knee flexion. [Subjects] The study included 21 healthy male volunteers. [Methods] Muscle onset times of the right gluteus maximus, right hamstrings, bilateral lumbar erector spinae, and bilateral lumbar multifidus were measured using surface electromyography during right hip extension with knee flexion in the prone position. Measurements were made with the hip in 3 positions: (1) neutral, (2) abduction, and (3) abduction and external rotation. [Results] Gluteus maximus onset relative to the hamstrings was significantly earlier with hip abduction and with hip abduction and external rotation compared with that with the hip in the neutral position. Gluteus maximus onset relative to the hamstrings was significantly earlier with hip abduction and external rotation compared with that with hip abduction. The bilateral multifidus and left lumbar erector spinae onset times relative to the hamstrings were significantly earlier with hip abduction and external rotation compared with those with hip abduction and with the hip in the neutral position. [Conclusion] Abduction and external rotation of the hip during prone hip extension with knee flexion is effective for advancing the onset times of the gluteus maximus, bilateral multifidus, and contralateral lumbar erector spinae.

Muscle Activation Amplitude and Onset Time in Patients with Chronic Nonspecific Low Back Pain During Trunk Rotation

Muscle Activation Amplitude and Onset Time in Patients with Chronic Nonspecific Low Back Pain During Trunk Rotation

Effect of abdominal drawing-in maneuver during hip extension on the muscle onset time of gluteus maximus, hamstring, and lumbar erector spinae in subjects with hyperlordotic lumbar angle.

BackgroundThe abdominal drawing-in maneuver (ADIM) is used to prevent abnormal movements of the lumbar spine and pelvis during therapeutic exercises. This study compared the effects of ADIM on the muscle onset time of the hamstring, gluteus maximus, and erector spinae muscles during prone hip extension exercise in subjects with or without hyperlordotic lumbar angle. Forty healthy adults (18 male, 22 female) were recruited for this study.MethodsThe lumbar lordotic angles and pelvic tilt angles of the subjects were measured using the Avaliação postural analysis software. The subjects were divided into two groups: the lumbar hyperlordotic angle (LHLA) and lumbar normal lordotic angle (LNLA) groups. The muscle contraction onset time of the hamstring, gluteus maximus, and erector spinae were assessed using surface electromyography.ResultsDuring ADIM application, the muscle contraction onset time of the gluteus maximus was significantly increased in the LHLA group compared with the LNLA group.ConclusionsADIM application during prone hip extension was more effective for gluteus maximus onset time in the LHLA group. Therefore, ADIM during prone hip extension may be useful for gluteus maximus training in individuals with lumbar hyperlordosis.

Task-specificity of bilateral anticipatory activation of the deep abdominal muscles in healthy and chronic low back pain populations

Study designCross-sectional study of lumbopelvic muscle activation during rapid limb movements in chronic low back pain (CLBP) patients and healthy controls. IntroductionControversy exists over whether bilateral anticipatory activation of the deep abdominal muscles represents a normal motor control strategy prior to all rapid limb movements, or if this is simply a task-specific strategy appropriate for only certain movement conditions. ObjectiveTo assess the onset timing of the transversus abdominis/internal oblique muscles (TrA/IO) during two rapid limb movement tasks with different postural demands – bilateral shoulder flexion in standing, unilateral hip extension in prone lying – as well as differences between CLBP and controls. MethodsTwelve CLBP and 13 controls performed the two tasks in response to an auditory cue. Surface EMG was acquired bilaterally from five muscles, including TrA/IO. ResultsIn both groups, 50% of bilateral shoulder flexion trials showed bilateral anticipatory TrA/IO activation. This was rare, however, in unilateral hip extension for which only the TrA/IO contralateral to the moving leg showed anticipatory activation. The only significant difference in lumbo-pelvic muscle onset timing between CLBP and controls was a delay in semitendinosus activation during bilateral shoulder flexion in standing. ConclusionOur data suggest that bilateral anticipatory TrA/IO activation is a task-specific motor control strategy, appropriate for only certain rapid limb movement conditions. Furthermore, the presence of altered semitendinosus onset timing in the CLBP group during bilateral shoulder flexion may be reflective of other possible lumbo-pelvic motor control alterations among this population.

Changes in onset times of muscular activity during a side hop task

IntroductionRecovery of functional muscle force after anterior cruciate ligament (ACL) injury is critical prior returning to sport. Beside restored muscle power, adequately timed motor control is crucial. Since fatigue alters neuromuscular control and is suggested to increase ACL injury risk, we hypothesized that the development of fatigue during a standardized 30-second hop test would modify the onset times of EMG activity in healthy individuals. MethodsEight healthy participants (4 males, 4 females; aged 26±6years) performed a 30-second one-legged side hop test across a distance of 40cm using their non-dominant leg. Synchronized kinetics (Arsalis force plates sampled with 1kHz) and surface electromyography (Noraxon TeleMyo 8-channel EMG system sampled with 1.5kHz) signals were recorded. Successful hops, defined as jumping side-to-side across the two parallel lines without touching the marked area, were identified by video analysis. The technique described by Santello and McDonagh (1998) was used to obtain the onset times of muscular activity from corresponding electromyographic signals of vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF) and semitendinosus (ST). Vertical ground reaction force exceeding 10N indexed landing events. Preceding muscular activity onset times were expressed in milliseconds (ms). To discriminate between non-fatigued and fatigued conditions, the first and last five successful hops of the test were compared with paired samples t-tests. ResultsAveraged onset times of muscular activity before landing during the first five hops were as follows: 56±11ms in VM, 55±11ms in VL, 77±14ms in BF and 86±13ms in ST. The last five hops showed significantly earlier onset times for VM (74±15ms, P=0.020) and VL (66±12ms, P=0.046), but not for BF (90±12ms, P=0.143) and ST (91±20ms, P=0.455). Males and females displayed similar onset times for all muscles in all conditions. DiscussionIn the course of a 30-second side hop task healthy individuals display earlier activation onset times of knee extensor muscles prior to landing. This strategy likely stiffens the knee joints and may help anticipate impact loads under fatigue. The reason why this was not observed in knee flexor muscles is unclear. However, assuming that the main role of the quadriceps is to deliver the knee extension power while hamstrings account more for the stabilization, the effect of fatigue could be identified more easily in the former muscle group. Further research is needed to elucidate if the evaluation of muscle onset timing may be of interest for the return to sports decision after ACL injury.

The effects of ephedrine on the onset time of non-depolarizing muscular relaxant

Background Ephedrine,as a kind of sympathomimetic agent,can accelerate the delivery of non-depolarizing muscle relaxant to the neuromuscular junction by increasing cardiac output,thus shortening the onset time of muscle relaxant.Objective To review the advances of ephedrine use in shortening the onset time of non-depolarizing muscle relaxant and provide reference for clinical anesthesia.Content This article mainly elaborates the mechanism of ephedrine on shortening the onset time of non-depolarizing muscle relaxant,dosage,medication timing and adverse reactions.Trend Ephedrine has been proved to provide a practical way for shortening the onset time of non-depolarizing muscle relaxant in clinical anesthesia. Key words: Ephedrine; Non-depolarizing muscular relaxant; Dosage ; Medication occasion; Onset time

Sex Differences in Neuromuscular Recruitment Are Not Related to Patellar Tendon Load

Although male volleyball players report a greater prevalence of patellar tendinopathy than female players, it remains unknown whether higher patellar tendon loading generated during landing by male players is related to sex-specific neuromuscular recruitment patterns. This study aimed to investigate the relationship between neuromuscular recruitment patterns and patellar tendon loading during landing and to determine whether there were any significant differences in lower limb neuromuscular recruitment patterns displayed by male and female volleyball players during landing. The neuromuscular recruitment patterns and patellar tendon loading of 20 male and 20 female volleyball players performing a lateral stop-jump block movement were recorded and calculated. Pearson product-moment correlations were conducted to determine whether neuromuscular recruitment patterns were related to the peak patellar tendon force or patellar tendon force loading rate generated at landing. Independent t-tests were applied to a subset of data for 13 males and 13 females matched for jump height to identify any between-sex differences in neuromuscular recruitment patterns. Later onset of rectus femoris (r = 0.312), vastus medialis (r = 0.455), and biceps femoris (r = 0.330) were significantly correlated with a higher patellar tendon force loading rate, although these correlation values were weak. Male volleyball players displayed significantly earlier biceps femoris and semitendinosus onset, and significantly earlier peak semitendinosus activity compared with their female counterparts. Although male and female volleyball players displayed significantly different muscle onset times, these patterns were not strongly related to patellar tendon loading at landing. It is likely that a multitude of factors, including the frequency of patellar tendon loading, more strongly contributes to developing patellar tendinopathy than neuromuscular recruitment patterns in isolation.

Determining the Activation of Gluteus Medius and the Validity of the Single Leg Stance Test in Chronic, Nonspecific Low Back Pain

ObjectivesTo determine the activation of the gluteus medius in persons with chronic, nonspecific low back pain compared with that in control subjects, and to determine the association of the clinical rating of the single leg stance (SLS) with chronic low back pain (CLBP) and gluteus medius weakness. DesignCohort-control comparison. SettingAcademic research laboratory. ParticipantsConvenience sample of people (n=21) with CLBP (>12wk) recruited by local physiotherapists, and age- and sex-matched controls (n=22). Subjects who received specific pain diagnoses were excluded. InterventionsNot applicable. Main Outcome MeasuresBack pain using the visual analog scale (mm); back-related disability using the Oswestry Back Disability Index (%); strength of gluteus medius measured using a hand dynamometer (N/kg); SLS test; gluteus medius onset and activation using electromyography during unipedal stance on a forceplate. ResultsIndividuals in the CLBP group exhibited significant weakness in the gluteus medius compared with controls (right, P=.04; left, P=.002). They also had more pain (CLBP: mean, 20.50mm; 95% confidence interval [CI], 13.11–27.9mm; control subjects: mean, 1.77mm; 95% CI, −.21 to 3.75mm) and back-related disability (CLBP: mean, 18.52%; 95% CI, 14.46%–22.59%; control subjects: mean, .68%; 95% CI, −.41% to 1.77%), and reported being less physically active. Weakness was accompanied by increased gluteus medius activation during unipedal stance (R=.50, P=.001) but by no difference in muscle onset times. Although greater gluteus medius weakness was associated with greater pain and disability, there was no difference in muscle strength between those scoring positive and negative on the SLS test (right: F=.002, P=.96; left: F=.1.75, P=.19). ConclusionsIndividuals with CLBP had weaker gluteus medius muscles than control subjects without back pain. Even though there was no significant difference in onset time of the gluteus medius when moving to unipedal stance between the groups, the CLBP group had greater gluteus medius activation. A key finding was that a positive SLS test did not distinguish the CLBP group from the control group, nor was it a sign of gluteus medius weakness.

DIFFERENCES IN THE MUSCLE ONSET TIMING BETWEEN LANDING POSTURES DECIDED BEFORE AND DURING JUMP-LANDING

BackgraoundJump-landing is a well-studied movement that causes sports injuries.ObjectiveThe purpose of this study was to clarify the differences in the onset timing of the muscles during jump-landing among landing postures...

LOWER EXTREMITY MUSCLE ONSET TIMES DURING THE TRANSITION FROM DOUBLE-LEG STANCE TO SINGLE-LEG STANCE IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTED SUBJECTS

BackgroundDeficits in neuromuscular control are believed to increase re-injury risk after anterior cruciate ligament reconstruction (ACLR). Previous studies mainly focused on muscles at the operated knee, less on muscles around...

Gender differences between muscle activation and onset timing of the four subdivisions of trapezius during humerothoracic elevation

The aim of this study was to provide a description of gender differences of the normal muscle activation patterns of the four subdivisions of the trapezius (clavicular, descending, transverse, ascending) during arm elevation. Surface EMG was collected from these four subdivisions from twenty-two healthy subjects (12 females, 10 males) during arm elevation in the scapular plane. Percent activation (RMS) of each subdivision was compared between genders across arm angles and elevation phase and onset time of each subdivision was compared between genders. Females demonstrated significantly higher % activation levels for each subdivision (p<.05), except transverse trapezius (p=.36). A statistically significant difference for onset time was observed between gender for the descending trapezius, with a slower onset time for females (p<.05). Findings from this study support the theory that subdivisions within descending trapezius are preferentially activated and demonstrate that gender differences are present within the fourth subdivision of trapezius. As subjects were without shoulder pathology, the observed gender differences may be explained by normal motor control variations. However, as coordinated activation of trapezius is required for normal shoulder motion, it is recommended to include all four subdivisions of trapezius and address gender differences in future studies.

An Investigation Into the Onset, Pattern, and Effects of Pain Relief on Lumbar Extensor Electromyography in People With Acute and Chronic Low Back Pain

ObjectiveThe aim of this study was to use an experimental pain relief model to determine the effect of pain relief on lumbar muscle function in people with low back pain. MethodsA test-retest design was used with all data collection being completed within a therapy setting. Twenty people with acute and 20 with chronic low back pain were recruited from general practitioner and therapist referrals. Participants completed spinal movements and lifting. Electromyography (EMG) was used to measure the pattern of muscle activity, onset of muscle activation, and peak activation of bilateral lumbar multifidus and iliocostalis. Movements were investigated before and after pain relief, through the self-administration of oral analgesia. ResultsElectromyography profiles and peak values were reliable across 3 trials, and EMG profiles correlated well with kinematic profiles. Specific EMG profiles were commonly associated with specific kinematic values, and on the whole, the EMG profiles were unaffected by pain relief. Muscle onset times and peak muscle amplitudes were not affected by pain relief in either acute or chronic low back pain. ConclusionThis study showed that the EMG activities from the lumbar region, including lumbar multifidus and iliocostalis, are reliable, and specific EMG profiles are identifiable. Pain relief as achieved in this study did not affect the pattern of EMG activity, onset of muscle activation, or peak activation values.

The Effects of Sensorimotor Training on Anticipatory Postural Adjustment of the Trunk in Chronic Low Back Pain Patients

[Purpose] This study aimed to examine the effects of sensorimotor training on the anticipatory postural adjustment (APA) of chronic low back pain (CLBP) patients. [Subjects and Methods] Fourteen CLBP patients were randomly assigned to Group II (ordinary physical therapy, n=7) and Group III (sensorimotor training, n=7). In addition, a normal group (Group I) consisting of seven subjects was chosen as the control group. The two CLBP groups received their own treatment five times per week, for four weeks, for 40 minutes each time. Changes in pain and functional performance evaluation were examined by the visual analogue scale (VAS) and the Oswestry Disability Index (ODI). In order to look at the change in APA, muscle onset time was examined using electromyography (EMG). [Results] Group III showed significant changes in both VAS and ODI. According to comparison of the results for muscle onset time, there were significant decreases in Group III's transversus abdominis muscle (TrA) and external oblique muscle (EO) in the standing and sitting positions. There were significant differences between Group II and III in terms of the TrA in the sitting position. [Conclusion] Sensorimotor training makes patients capable of learning how to adjust muscles, thereby alleviating pain and improving muscle performance.

Neuromuscular changes of abdominal and lumbar muscles following exercise for chronic non-specific low back pain

Low back pain (LBP) is a prevalent physical, social, economic problem in developed countries. Past research has shown exercise to be a favourable treatment, but the most successful mode of exercise for LBP is unknown. This study compared 8 weeks of specific, general forms of exercise in chronic non-specific low back pain (CNSLBP) individuals. Surface electromyography (sEMG) was used to measure the abdominal, lumbar muscle onset times of the central nervous system (CNS) in a rapid unilateral arm movement. Self-reported disability, pain were also measured. It was hypothesised that there would be a decrease in muscle onsets following specific exercise, no change in onsets following general exercise. Neither hypothesis was supported, as neuromuscular changes were observed following both general, specific exercise with no between-group differences identified. Muscle onsets were found to change in the direction of the prime mover. This change was proposed to be an adaptation of the CNS to produce more coordinated neuromuscular responses following each intervention. Contrary to past research, no delays in muscle onsets in LBP were identified. Side-specific changes were also found in muscle onsets, with the contralateral side activating prior to the ipsilateral side. Disability was reduced after specific exercise only, but pain was reduced following both interventions. A possible rationale for the lack of treatment effects observed in this study includes common adaptations of the CNS underpinning the success of any form of appropriately prescribed exercise. Moreover, muscle onsets may be a neuromuscular marker of this adaptation. Future studies are required to replicate these findings, further investigate the relationship between pain, neuromuscular responses of the CNS. Low back pain (LBP) is a prevalent physical, social, economic problem in developed countries. Past research has shown exercise to be a favourable treatment, but the most successful mode of exercise for LBP is unknown. This study compared 8 weeks of specific, general forms of exercise in chronic non-specific low back pain (CNSLBP) individuals. Surface electromyography (sEMG) was used to measure the abdominal, lumbar muscle onset times of the central nervous system (CNS) in a rapid unilateral arm movement. Self-reported disability, pain were also measured. It was hypothesised that there would be a decrease in muscle onsets following specific exercise, no change in onsets following general exercise. Neither hypothesis was supported, as neuromuscular changes were observed following both general, specific exercise with no between-group differences identified. Muscle onsets were found to change in the direction of the prime mover. This change was proposed to be an adaptation of the CNS to produce more coordinated neuromuscular responses following each intervention. Contrary to past research, no delays in muscle onsets in LBP were identified. Side-specific changes were also found in muscle onsets, with the contralateral side activating prior to the ipsilateral side. Disability was reduced after specific exercise only, but pain was reduced following both interventions. A possible rationale for the lack of treatment effects observed in this study includes common adaptations of the CNS underpinning the success of any form of appropriately prescribed exercise. Moreover, muscle onsets may be a neuromuscular marker of this adaptation. Future studies are required to replicate these findings, further investigate the relationship between pain, neuromuscular responses of the CNS.

Scapular Muscle Rehabilitation Exercises in Overhead Athletes With Impingement Symptoms

Background: Previous research has identified some specific exercises to correct scapular muscle balance and onset timing in healthy subjects. However, evidence for their effectiveness in overhead athletes with impingement symptoms has been lacking until now. Hypothesis: A 6-week exercise program consisting of previously selected exercises is able to improve muscle activation and onset timing during shoulder elevation. This program may also change pain and functionality levels in overhead athletes with mild impingement symptoms. Study Design: Case series; Level of evidence, 4. Methods: Forty-seven overhead athletes with mild impingement symptoms (25 men and 22 women) were enrolled in this study. Before and after the 6-week training program, the Shoulder Pain and Disability Index (SPADI) score was individually obtained and maximum voluntary isometric contraction (MVIC) values were determined by surface electromyography. Mean muscle activation levels, muscle ratio data, and muscle onset timing were assessed for the upper (UT), middle (MT), and lower (LT) trapezius and serratus anterior (SA) muscle during arm elevation in the scapular plane. Results: Forty participants completed the exercise program. The SPADI scores significantly decreased from 29.86 ± 17.03 during initial assessment to 11.7 ± 13.78 during postmeasurements (P < .001). The 3 trapezius muscle parts showed increased MVIC values and decreased activation levels during arm elevation, whereas this was not the case for the SA muscle. After the training program, UT/SA significantly decreased, whereas UT/MT and UT/LT did not change (P < .05). No differences in muscle timing between pre- and postmeasurements could be identified. The LT showed significant earlier activation compared with UT (−0.47; P < .001) and MT (−0.49; P < .001). The serratus anterior showed significant earlier activation compared with the UT (−0.74; P < .001), MT (−0.76; P < .001), and LT muscles (F = 0.27; P = .046). Conclusion: This is the first longitudinal study to demonstrate that previously selected exercises (1) improve pain and function based on SPADI scores, (2) reduce relative trapezius muscle activation, and (3) alter UT/SA ratios. However, they were unable to change the timing of the scapular muscles during arm elevation when compared before and after a 6-week training program in overhead athletes with mild impingement symptoms.

Influence of Infrapatellar and Suprapatellar Straps on Quadriceps Muscle Activity and Onset Timing During the Body-Weight Squat

The use of knee braces for the treatment of patellofemoral pain syndrome (PFPS) is widely documented, yet the mechanism by which such braces alleviate knee pain remains unclear. This study attempted to clarify this issue by simplifying the brace to the level of only straps. The effectiveness of an infrapatellar strap for PFPS remains controversial, and the use of a suprapatellar strap has not yet been studied. Quadriceps muscle activity and onset timing parameters were measured with surface electromyography (EMG) during a body-weight squat in 19 healthy subjects during 4 different knee-strapping conditions (infra, supra, both, and none). No differences in normalized mean or peak EMG activity in any part of the quadriceps were found. The onset timing of the vastus lateralis (VL) was significantly delayed when using an infrapatellar strap (p < 0.05) or both straps (p < 0.05) and marginally delayed when using a suprapatellar strap (p < 0.10) in comparison with the no-strap (control) condition. No differences in the vastus medialis oblique (VMO) onset timing or VMO-VL onset timing difference were found among the strapping conditions, although an improvement in timing was noted with the suprapatellar condition. The results provide novel evidence that the application of an infrapatellar strap, suprapatellar strap, or both straps improves quadriceps muscle timing imbalances by delaying VL onset. Because the largest delay in VL onset occurred when wearing both straps, the combined application of an infrapatellar and suprapatellar strap may be the most beneficial in managing patellofemoral pain. Knee straps, unlike braces, are cost effective, nonrestrictive, and can be universally fitted to any knee and based on the results deserve further study in the patellofemoral pain population.