Electromyographic Reaction Time Research Articles

Internal consistency and test–retest reliability of an instrumented functional reaching task using wireless electromyographic sensors

The purpose of this study was to establish the internal consistency and test–retest reliability of the electromyographic and accelerometric data sampled from the prime movers of the dominant arm during an antigravity, within-arm’s length stand-reaching task without trunk restraint. Ten healthy young adults participated in two experimental sessions, approximately 7–10days apart. During each session, subjects performed 15 trials of both a flexion- and an abduction-reaching task. Surface EMG and acceleration using wireless sensors were sampled from the anterior and middle deltoid. Reliability was established using Cronbach’s alpha, intraclass correlation coefficients (ICC 2, k) and standard error of measurements (SEM) for electromyographic reaction time, burst duration and normalized amplitude along with peak acceleration. Results indicated high degrees of inter-trial and test–retest reliability for flexion (Cronbach’s α range=0.92–0.99; ICC range=0.82–0.92) as well as abduction (Cronbach’s α range=0.94–0.99; ICC range=0.81–0.94) reaching. The SEM associated with response variables for flexion and abduction ranged from 1.55–3.26% and 3.33–3.95% of means, respectively. Findings from this study revealed that electromyographic and accelerometric data collected from prime movers of the arm during the relatively functional stand-reaching task were highly reproducible. Given its high reliability and portability, the proposed test could have applications in clinical and laboratory settings to quantify upper limb function.

Tempo de reação eletromiográfica em idosas caidoras e não-caidoras após desequilíbrio postural

The electromyographic reaction time (ERT) reflects the magnitude and speed with which muscles are activated to perform movements, to prevent injuries, or to position a joint. This parameter can be used to analyze postural control performance after an external perturbation and can be correlated with the possibility of falls in older adults. The objective of this study was to determine the ERT of the internal oblique, rectus femoris, vastus lateralis, tibialis anterior, multifidus, gluteus maximus, biceps femoris, and lateral gastrocnemius muscles to balance threats in older adults with and without a history of falls. Twenty-nine physically active and noninstitutionalized women aged 60 years or older were divided into two groups: fallers (n=13; 72.4 ± 8.0 years) and non-fallers (n=16; 67.8 ± 6.8 years). The ERT of the muscles tested did not differ significantly between groups following forward or backward perturbations. The results suggest that the activation of the muscles tested in response to forward or backward perturbations is not a determinant factor of falls

Affordance Effects in Grasping Actions for Graspable Objects: Electromyographic Reaction Time Study

It is unclear whether affordance effects shorten the reaction time in the interaction between objects and actions. This study investigated affordance effects based on compatibility between perception of graspable objects and the act of grasping. The electromyographic reaction time (EMG-RT) was used as the response, and Go/NoGo (Experiment 1) and choice (Experiment 2) reaction-time tasks were performed using combinations of two types of stimulus image (tools and animals) and two types of response task (flexion and extension of all fingers). In Experiment 1, no interaction of stimulus images and response tasks occurred, but the EMG-RT for tools was statistically significantly delayed longer than that for animals. In Experiment 2, the EMG-RT of flexion of all fingers for tools was statistically significantly delayed compared with that for animals, showing interaction. Affordance effects based on compatibility of objects and actions are the basis on human-tool interaction. This interaction induces a goal-directed act and prolongs motor execution of grasping actions for them.

The Influence of Aging on Balance Function in Terms of the Foot Electromyographic Reaction Time

The Influence of Aging on Balance Function in Terms of the Foot Electromyographic Reaction Time

Effects of Factor of Forecast on Electromyographic Reaction Time due to Auditory Stimulation at Different Interstimulus Intervals

Effects of Factor of Forecast on Electromyographic Reaction Time due to Auditory Stimulation at Different Interstimulus Intervals

Influence of Varying the Interstimulus Intervals on Electromyographic Reaction Time during Exercise Using a Rhythmic Auditory Stimulus

Influence of Varying the Interstimulus Intervals on Electromyographic Reaction Time during Exercise Using a Rhythmic Auditory Stimulus

運動強度と身体活動量が認知・脳機能に与える影響

The interactive effects of exercise intensity and physical activity level on the brain and cognition of young adults were investigated using the electromyographic reaction time (EMG-RT), the P3, and the NoGo P3, as well as the contingent negative variation (CNV) of event-related brain potentials. Participants (n＝26 : 24.0 ± 0.7 years) were divided on the basis of their regular physical activity level into active and inactive groups. Then, they performed a Go/NoGo reaction time task in the no exercise, control condition ; as well as after light, moderate, and hard cycling exercises. Results indicated that increases in P3 and NoGo P3 amplitude following moderate exercise were larger in the inactive group, suggesting that inactive individuals were more sensitive to exercise intensity than active individuals. Active individuals might be better able to sustain their attention during the Go/NoGo reaction time task, despite the exercise intensity. These findings are suggestive of a differential effect of exercise intensity on cognitive function that might be dependent on the level of regular physical activity. The effects of exercise intensity on EMG-RTs were observed across groups. However, the P3 latency was not affected by exercise intensity. These contradictory results are possible related to the nature of the cognitive task, such as its difficulty. Moreover, increases in CNV amplitudes following moderate exercise were larger than in other exercise conditions across groups, suggesting that motor preparation process is also facilitated by moderate, acute exercise. These findings provide additional evidence for the beneficial effects of acute aerobic exercise on the brain and cognition of young adults.

Influence of the Increase of Stimulus Number and the Difference of Stimulus Frequency on Electromyographic Reaction Time in Periodic Audio Stimulus

Influence of the Increase of Stimulus Number and the Difference of Stimulus Frequency on Electromyographic Reaction Time in Periodic Audio Stimulus

The effect of a single session submaximal aerobic exercise on premotor fraction of reaction time: An electromyographic study

Background Numerous studies investigating the effect of exercise on reaction time have yielded contradictory results. Most of the studies use computer based methods to measure reaction time instead of electromyography, yielding total reaction time rather than premotor time. In this study, we aimed to investigate the effect of a single session aerobic exercise on premotor fraction of reaction time in sedentary healthy individuals. Methods Twenty-two sedentary healthy subjects (11 subjects for the study group and 11 for the control group) enrolled in this study. Subjects in the exercise group performed a single session submaximal cycling exercise. Electromyographic reaction times were measured before and after the exercise session. In the control group, reaction time measurements were taken twice with an interval of 20 min. Findings In the exercise group, premotor fraction of reaction time values decreased considerably ( P = 0.01) after the exercise session. Interpretation A single bout of cycling exercise significantly improved premotor fraction of reaction time in healthy young sedentary subjects. Physical activity improves not only physical fitness but also cognitive functions. Electromyographic reaction time evaluations may be used in the sports medicine field where both aerobic fitness and short reaction time are indispensable demands.

What is the optimal repetition number in electromyographic reaction time studies?

To find out how many trials of electromyographic reaction time measurements are needed for reliable interpretation. The electromyographic reaction time values were obtained by surface electromyography from the flexor digitorum superficialis muscle of the 20 healthy volunteers. After five practice trials, the measurements were repeated 20 times. The differences between the 20 reaction time measurements were analyzed to find out the optimal repetition number of reaction time trials. The electromyographic reaction time values decreased upon repetition. The first consecutive five records were significantly longer than the second, third and fourth consecutive five records. However no difference was found among second, third and fourth consecutive five records. The results of our study indicate that before 15 test trials, 10 practice trials are needed for learning in simple electromyographic reaction time studies that use similar testing conditions with our study. However this conclusion needs verification with a study using a larger group of subjects.

Electromyographic Reaction Time in Auditory Stimulus of Movements of the Non-dominant Hand

Electromyographic Reaction Time in Auditory Stimulus of Movements of the Non-dominant Hand

Reaction time and movement time in patients with carpal tunnel syndrome: an electromyographic study

Objective. To measure the motor performance of the flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles using the parameters electromyographic muscle reaction time and movement time in patients with carpal tunnel syndrome during key turning function. Method. A total of 37 female patients with right hand pain were divided into two groups: 21 with an electrophysiologically confirmed diagnosis of carpal tunnel syndrome (Group I), and 16 with normal electrophysiological findings (Group II). The reaction time and movement time values obtained by surface electromyography of the right flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles were compared between groups. Results. Of the 21 patients in Group I, 15 had mild, four moderate, and two severe median nerve lesions. No significant difference between groups was found in the electromyographic reaction time and movement time values of the right flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles during key turning ( P>0.05). There was also no significant difference in electromyographic reaction time and movement time between six patients with severe or moderate carpal tunnel syndrome and 15 patients with mild carpal tunnel syndrome in Group I ( P>0.05). Sixteen patients in Group II did not have carpal tunnel syndrome. Conclusion. The results indicate that patients with and without carpal tunnel syndrome have similar values of reaction time and movement time of the flexor pollicis brevis, first dorsal interosseus, and flexor pollicis longus muscles during the pinch grasp function of the hand. Relevance Muscle reaction time and movement time, and hence the motor performance in electrophysiologically confirmed carpal tunnel syndrome patients appear to have similar parameters in patients with hand pain whose diagnosis were not confirmed with electrophysiologically.

Effects of proprioceptive neuromuscular facilitation on the initiation of voluntary movement and motor evoked potentials in upper limb muscles

To better understand the mechanisms behind proprioceptive neuromuscular facilitation (PNF), an important method in motor rehabilitation, we investigated the effects of assuming a PNF posture relative to a neutral posture on the initiation of voluntary movement (Experiment 1) and the excitability of the motor cortex (Experiment 2) using a wrist extension task. The initiation of voluntary wrist movement was operationalized in terms of the electromyographic reaction time (EMG-RT), and the excitability of the motor cortex in terms of motor evoked potentials (MEPs). Compared to the neutral position, we found that (1) the facilitation position changed the muscle discharge order enhancing the movement efficiency of the joint, (2) the facilitation position led to a reduction in EMG-RT, the magnitude of which depended on the proximity of the muscle to the movement joint, and (3) MEP amplitude increased and MEP latency decreased in the facilitation position as a function of the proximity of the muscle to the joint. These findings corroborate the presumed effects of PNF and provide insights into the neurophysiological mechanisms underlying the PNF method.

Muscular response to sudden load. A tool to evaluate fatigue and rehabilitation.

Subjects were exposed to fatiguing and restorative interventions to assess their response to sudden loads. To investigate the erector spinae and rectus abdominis response characteristics to "sudden load" and the effect of fatigue and rehabilitation. Unexpected loads which people often experience, can lead to high forces in the spine and may be a cause of low back injury. Muscle responses to sudden load were mediated by fatigue, walking, expectation, method of load application, exposure to vibration, and cognitive-behavioral rehabilitation in patients with chronic low back pain. A novel technique, perfected in this work, called wavelet analysis, was used to analyze these data. Reaction time was affected by fatigue and expectation. Vibration exposure significantly increased the muscle response time. Walking was able to ameliorate that effect. Back muscles responded differently, depending on whether loads were applied to the back through the hands or through the trunk. Electromyographic reaction time and magnitude decreased in patients after a 2-week rehabilitation program. Sudden loads can exacerbate fatigue effects. Walking after driving reduces the risk to the back caused by handling unpredictable loads. Vibration exposure guidelines should be more conservative. Patients have longer response times than healthy subjects, but patients can improve their response to sudden loads via rehabilitation. Patients exhibit a flexion-extension oscillation at 5 Hz in response to a sudden load, suggesting that the 5-Hz, seated, natural frequency observed during whole-body vibration may result from neurophysiologic control limits.

Inter-relationships among anticipatory EMG activity, Hoffmann reflex amplitude and EMG reaction time during voluntary standing movement

In order to understand the process of executing a voluntary standing movement, the parameters latency (AEA-LT), duration (AEA-DUR) and amplitude (AEA-AMP) of the anticipatory electromyographic (EMG) activity (AEA) in the tibialis anterior muscle, Hoffmann (H) reflex amplitude in the soleus muscle (Sol) prior to the onset of EMG activity in that muscle, and EMG reaction time (EMG-RT) were measured during heel raising from the standing position. The following results were obtained: the three parameters of AEA correlated with EMG-RT in each subject; the average values for all nine normal subjects were r = 0.856 for AEA-DUR, r = 0.448 for AEA-LT and r = -0.215 for AEA-AMP; for the group the mean value of AEA-DUR correlated significantly with that of EMG-RT (r = 0.983, P less than 0.01), while no such significant correlation was observed for AEA-LT; the average value of the AEA-DUR in three slower EMG-RT performers (SLOW-PFM) was significantly longer (P less than 0.05) than that in three faster ones (FAST-PFM), while no significant difference in the AEA-LT was observed; and lastly the total area of the anticipatory suppression of the Sol H reflex amplitude in the SLOW-PFM was greater than that in the FAST-PFM. These results suggest that AEA-DUR, representing postural responses, rather than AEA-LT, reflecting cognitive processes, may have had a close link with EMG-RT, and that the increased suppression in Sol H reflex amplitude originated from the increased anticipatory postural requirement, thus bringing about the EMG-RT delay.

Movement Precuing Altered Reaction Time of Elbow Flexion and Forearm Supination

Electromyographic reaction time (EMG-RT) of the biceps brachii muscle for elbow flexion and forearm supination was investigated in 10 healthy subjects under two conditions of movement precuing and nonprecuing with a constant foreperiod. Analysis showed that the precuing significantly reduced EMG-RT of both movements, especially the supination, and confirmed previous finding that the supination had an advantage in initiation over the flexion when the movement pattern was prepared in advance. When not prepared, on the contrary, EMG-RT of supination significantly prolonged as compared with flexion.

反応時間と筋電図による各種スポーツ種目の上肢運動特性の解析

The electromyographic reaction time (EMG-RT) of biceps brachii muscle as an indicator of initiation of rapid forearm movement is reportedly different between flexion(F) and the supination (S), the EMG-RT of S being faster than that of F on both hands. Moreover, the EMG-RT difference between. F and S. (DFS) is considered to reflect the motor control system. The study undertaken here measured EMG-RTs of F and S among athletes of 12 different events which may or may not involue usage of their upper limbs (tennis, runnirig, soccer, fencing, table tennis, badminton, kendo, volleyball, gymnastics, shot put, discuss throw and javelin throw; 191 right handed subjects, 159 males and 32 females), and investigated the differences in the motor control systems between these sporting events. All subjects were asked to perform bilateral F and S responses by both forearms simultaneously to a peep sound as fast as possible. From results of different DFS_S, six sporting events (kendo, discuss throw, javelin throw, tennis, shot put and table tennis) were examined in EMG activities of both upper limbs in the movement specialities of these sporting events. Obtained results may be summaried as follows : 1. The DFS_S of' preferred hand were different among twelve sporting events but those of nonpreferred hand were not. 2: Twelve sporting events were possibly classified into three types. The first group was the type in which significantly dif'ferent DFS_s on the preferred hand was observed but not on the non-preferred hand (running, soccer, fencing, table tennis, badminton, volleyball and gymnastics). The second group was the type in which significantly different DFS_s was observed not only in the preferred hand but also in the non-preferred hand (tennis and shot put). The third group was the type in which no significantly different DFS_s was observed in both hands (kendo, discuss throw and javelin throw). 3. From EMG analyses of both upper limbs' movement specialities, specific EMG activities were observed in respective three types. From these results, presence of different motor control systems among 12 sporting events were suspected. The reasons of such different motor control systems were examined on the viewpoint of differential effects depending on motor learning of each sporting event and were discussed on the viewpoint of neuropsychological and motor behavioral mechanisms.

下肢肢位変化による反応時間とH波の変動性

Postural changes and the difference of attitudes influence the reaction time of a limb muscle. The present study is a modification and extension of previous studies on influense of the position changes in the hip joint on the electromyographic reaction time (EMG-RT) and on the H-reflex of the soleus muscle in normal human subjects. Primarily, the aim of this study was to explore the relevant neurophysiological mechanism which control reaction time. In experiment I (Exp. I), the EMG-RT from the 20 subjects (16 males and 4 females) who reacted the plantar flexion at peep sound (1000 Hz, 100 db, 100 msec duration) were recorded from the soleus muscle at three different positions of the hip joint (neutral, externally and internally rotated positions). In experiment II (Exp. II), H-reflexes were elicited in the soleus muscle at the static three hip joint positions. In this case, H-reflexes were recorded under two conditions; one where the subjects' hip joint position was changed passively by the experimentor (20 subjects) and the other where the subjects voluntarily changed their hip joint position (10 subjects). In this way, obtained H-reflexes were measured from peak to peak. Those amplitudes of H-reflex were examined as an indicator of activation of alpha-motoneurons pool. Major results may be summarized as following: 1. The EMG-RT of internally rotated position was longer than that of neutral position, and the EMG-RT of externally rotated position was shorter than that of neutral position (Exp. I). 2. In both conditions, the H-reflex amplitudes of internally rotated position were smaller than those of neutral position, and the H-reflex amplitudes of externally rotated position were larger than those of neutral position (Exp. II). 3. Especially, this tendency was remarkable when the subjects voluntarily changed their hip joint position (Exp. II). From these results, the relevant neurophysiological mechanisms which control reaction time were discussed, and the scheme for an explanation of the relationship between the changes of reaction time and the excitabilities of alpha-motoneurons pool was suggested.

Effects of Postural Change of the Shoulder on EMG Reaction Time of Triceps Brachii

Postural dependence of electromyographic reaction time (EMG-RT) of triceps brachii in normal subjects was examined at neutral (N) and facilitating (F) positions. EMG-RT was faster at F than at N; moreover, the slower one's EMG-RT, the larger the difference of EMG-RTs. F position of arms causes the shifting of EMG-RT through two biasing systems. The action of one system arises from either arm and acts on both arms, as the facilitation and its intensity depend on one's EMG-RT. The other system arises from one arm, and facilitates the ipsilateral arm but inhibits the contralateral arm; its intensity is independent of one's EMG-RT. The amount of the shift is determined by the added contribution of those two actions.