Duration Of Muscle Activity Research Articles

バイトプレーンの装着がそしゃく筋筋電図に及ぼす影響 Ｉ タッピング運動時の筋活動について

The purpose of this study is to examine the influence of the insertion of bite plane on masticatory muscle activity during tapping movement, and find out useful parameters for examination and diagnosis of stomatognathic dysfunction. The subjects in this study were twenty normal subjects with intact dentition and no signs of mandibular dysfunction as the control group, and twelve subjects with unilateral temporomandibular joint pain during jaw opening or closing movement as the patient group. Electromyographic activity in the bilateral anterior temporal and masseter muscles and mandibular movement using the Mandibular Kinesiograph were recorded simultaneously during tapping movement. The usefulness of the 61 items used in this study was evaluated. The results were summarized as follows: 1. In the patient group, a significant correlation between the jaw opening degree during tapping movement and the maximal jaw opening one without pain was recognized. 2. The total muscle activity in the patient group decreased significantly by the insertion of the bite plane. 3. Many subjects of the patient group showed a significant difference between the right and left activity of each muscle. 4. A significant difference between the two groups was found in the duration of muscle activity before and after Silent period, those coefficients of variation and the difference between those durations of the right and left muscle activity. This study suggests that the above factors are very useful parameters for examination and diagnosis of temporomandibular joint dysfunction.

Selected temporal aspects of coordination during fluent speech of young stutterers.

The purpose of this study was to compare the onsets, offsets, and durations of respiratory, articulatory, and laryngeal behaviors associated with the perceptually fluent speech of young stutterers (n = 8) to those of their normally fluent peers (n = 8). Simultaneous recordings of the targeted behaviors were made using noninvasive, minimally intrusive instrumentation. Specific temporal parameters of coordination--onsets, offsets, and durations of muscle activity and structural movement--were assessed within a particular component of the speech production system (e.g., onset of lower lip closing relative to lower lip opening muscle activity) as well as between different components (e.g., onset of rib cage deflation relative to onset of vocal fold contact for voicing). Results indicated that there were neither statistically significant nor apparent differences between the perceptually fluent speech of young stutterers and that of their normally fluent peers in terms of selected temporal characteristics of coordination. Findings suggest that the molar temporal characteristics of coordination for young stutterers' fluent speech production(s) are not appreciably different from those of their normally fluent peers and further, any temporal characteristics of stutterers' fluent speech that do differ from normal are probably brief, as well as subtle, in nature.

The electromyographical basis of inaccurate motor performance.

The aim of this study was to investigate the electromyographical basis of inaccurate movement by identifying the variate and invariate characteristics of a ballistic, isometric precision-grip skill. Our results have shown that in most subjects investigated, IEMG, discharge rate and the patterns of muscle synergy were variate movement parameters while the sequence of muscle activation, the relative duration of muscle activity and the time to peak force (rise-time) remained essentially invariate. Based on these results, we can conclude that inaccurate performance of this skill, in most of the subjects investigated, was more dependent upon changes in muscle IEMG than in alterations in the temporal sequencing of muscle activity. It was apparent that from trial to trial, subjects had more difficulty in reproducing the appropriate levels of muscle contraction and synergy than in reproducing the required periods of action.

DURATION OF MUSCLE ACTIVITY DURING STANDING IN NORMALLY AND SLOWLY DEVELOPING CHILDREN

Research in motor control indicates that there are fixed patterns of activity which occur in certain muscle groups involved in standing in adults. The purpose of this study was to assess patterns of duration of muscle activity during quiet standing with and without superimposed arm movement in young children with normal and delayed motor development. Thirty-three children 4, 6, 8 and 10 years of age were screened for level of motor development and classified as either normally or slowly developing. Children performed two tasks: standing and standing with a superimposed 90 degree shoulder abduction movement. Using surface electrodes, EMG activity was monitored in Gastrocnemius, Tibialis Anterior and Erector Spinae muscle groups. The percentage of time activity was present in individual muscle groups was analyzed as a function of age and developmental level. Results indicated that quiet standing in children with delayed motor development was characterized by greater duration of activity in trunk than in leg muscles while in normal children, there was a more equal distribution of muscle activity between the legs and trunk. Both groups of children accommodated superimposed arm movement by increasing the percentage of time Erector Spinae activity was present. Patterns of duration of muscle activity in the legs were, however, different for the two groups of children.

The Mechanical Power Output of A Tettigoniid Wing Muscle During Singing and Flight

ABSTRACT The mesothoracic wings of tettigoniid insects are used in song production and flight; the metathoracic wings in flight only. In Neoconocephalus triops the wing stroke frequency during flight is about 25 Hz ; the frequency during singing about 100 Hz. The twitch duration of mesothoracic, first tergocoxal (Tcxl) wing muscles is only about one-half the duration of the upstroke or downstroke portion of the wing cycle. During tethered flight the Tcxl muscles are activated on each cycle with short bursts of action potentials, each burst typically containing four action potentials. Activating the muscles with brief, tetanizing bursts increases the duration of muscle activity and the mechanical power output per wing cycle above that obtainable with single twitch contractions of the muscle. The mechanical power output was determined for mesothoracic Tcxl muscles undergoing sinusoidal length change and stimulated phasically in the length cycle. At 25 Hz, the power at optimum muscle strain and optimum stimulus phase was 5 Wkg-1 at 30 °C for muscles activated with a single stimulus per cycle and about 33 W kg-1 for muscles activated with bursts of stimuli in the normal pattern of flight. The maximum power output at 100 Hz, the singing frequency, was 18 W kg-1. This was achieved with a single stimulus per wing cycle. From published values of oxygen consumption by tettigoniids during singing, it is concluded that the efficiency of conversion of metabolic to mechanical power during singing is about 3 %.

Electromyographic and kinematic measures of articulatory coordination in a deaf speaker

Variability in production and disruption of interarticulator timing is reported for a deaf speaker. Acoustic, electromyographic, and movement records were obtained from a deaf subject and a hearing control, producing multiple repetitions of nonsense syllables (e.g., ə bib ɑ b) with stress on either V1 or V2. Electromyographic recordings were obtained from genioglossus, geniohyoid, and anterior belly of digastricus. Temporal patterns of lip closure were recorded using an electrical conductance technique. Infrared LEDs were attached to the jaw and monitored using a modified SELSPOT optical tracking system. Tokens were sorted into perceptually correct versus error patterns according to listener judgments, and formant frequency measures obtained. The deaf speaker differed from the normal control in several ways. She was unable to consistently execute changes in stress across different syllables and did not differentiate high versus low vowels in either genioglossus or relative jaw position. Timing of geniohyoid was variable and did not accompany stress changes. While activity of digastricus paralleled jaw movement, the duration of muscle activity continued well beyond maximum displacement of the jaw, perhaps contributing to laryngeal instability. [Work supported by NINCDS.]

Kinematic and electromyographic patterns of Olympic race walkers.

The performance of two Olympic race walkers was studied during free-speed, fast, and race walking. Measurements of the stride and temporal components of gait, as well as the simultaneous displacement patterns of the body segments, and the electromyographic activity of muscles of the trunk and upper and lower limbs were recorded during the three walking speeds. During the testing, the race walkers achieved an average speed of 12.5 km/hr as compared to the 8.7 km/hr average speed achieved by normal men of the same age during fast walking. Race walking was characterized by an increase in cadence and stride length beyond that of normal controls (in a prior study) during fast walking, with stride lengths averaging 125% of stature during race walking, and 115% during normal fast walking. In the two race walkers the amplitudes of most of the movement patterns of the trunk and upper and lower limbs were exaggerated during race walking as compared to normal controls' fast walking. Several mechanisms were used by the race walkers to minimize the vertical excursion of the center of gravity of the body during race walking. All of the muscles monitored in the race walkers showed an increase in the amplitude of electromyographic activity during race walking as compared to fast walking; duration of muscle activity was also usually increased during race walking. Several suggestions for prevention of injuries associated with race walking are made.

Parameters of some reflexes of human jaw elevator muscles

Because of the potential diagnostic value in mandibular joint dysfunction, the similarities and differences in 3 open-close-clench (OCC) cycles, at ad libitum, 1 s and 2 s , were investigated. The response to chin taps with the jaw elevator muscles both relaxed (CTRL) and clenched (CTCL) were also studied from surface electromyographs over the masseter and anterior temporalis muscles of 10 normal adults. In OCC cycles, there were positive correlations between total cycle length and the inactive component and the duration of muscle activity (clench) after inhibition induced by tooth contact. Negative correlations were found between the duration of muscle activity before tooth contact and the clench and inactive components. The inactive and clench components changed most with variations in cycle duration and the latency between tooth contact and resultant inhibition varied little. For chin tap responses, there were no significant differences between masseter and temporalis muscles. The latency between mallet contact and inhibition in CTCL responses was the same as the latency in OCC cycles but shorter than the equivalent sum of latency and activity in the CTRL responses. If a common mechanism exists for the three reflexes, their parameters suggest that OCC and CTCL reflexes are facilitated with respect to CTRL.

Work-induced potassium changes in skeletal muscle and effluent venous blood assessed by liquid ion-exchanger microelectrodes

Using liquid ion-exchanger semimicroelectrodes with a side pore, we measured changes of extracellular potassium concentration (Ke+) in adult rabbit and cat gastrocnemius muscles and in venous effluent blood flowing from the cat gastrocnemius muscle during various bouts of activity induced by sciatic nerve stimulation. 1. Isometric tetanic contractions (at 50 Hz) of various durations caused transient accumulation of Ke+ which was non-linearly related to the duration of muscle activity. The peak values of Ke+ in response to muscle stimulation were analogous in rabbits and cats, attaining values, e.g. after a 20-sisometric tetanus, between 8-9 mEq/1K+ in both species. 2. Potassium concentration in venous effleunt blood (K+ven) was transiently increased after isometric tetani. Since blood flow was measured at the same time, it was possible to calculate the amount of K+ lost by the muscle after tetani of various durations. A 32 g gastrocnemius muscle of the cat, for example, loses 9.36 +/- 1.52 muEqK+ after a 20-s isometric tetanus, which corresponds roughly to 0.5% of the total muscle potassium content. The loss of K+ in this muscle was 29.3 pEq K+ /impulse/100 g fresh muscle tissue. 3. There was no evident difference between the amount of K+ released during isometric tetani, or tetanic contractions performed under isotonic conditions. Single twitches evoked by indirect stimulation at 1 HZ for several minutes also induced a small rise in K+ven. 4. If the loss of K+ from the muscle into the blood stream is transiently prevented by arterio-venous occlusion installed immediately before a 10-s isometric tetanus, most K+ is released subsequently when blood flow is renewed, if the occlusion lasts for 20-25 s. It is not until blood flow is occuded for 40-60 s that most K+ is apparently resorbed and only a minor portion is released and is to be found in the venous blood. 5. The transient accumulation of muscle extra-cellular potassium may locally affect nerve endings, skeletal and smooth muscle cells.

Relation between facial morphology and activity of the masticatory muscles.

SummaryThe relation between muscle activity and facial morphology was studied in twenty‐five boys and twenty‐seven girls, aged 9–11 years. The activity in the anterior and posterior parts of the temporal muscle, the masseter muscle and the upper lip was recorded bilaterally with the mandible in postural position and during chewing, swallowing and maximal bite. The electromyograms were analysed in respect of maximal mean voltage amplitude and the duration of muscle activity. Facial morphology was studied with the aid of profile roentgenograms and model analysis. The activity in postural position was found to be greater in the posterior than in the anterior part of the temporal muscle. The average mean voltage amplitude in the temporal and masseter muscles was greatest during maximal bite, smaller during chewing and smallest during swallowing. In the orbicularis oris muscle the activity was greater during the opening phase of the chewing cycle than during the closing phase.In postural position the activity in the anterior and posterior parts of the temporal muscle were positively correlated. The amplitudes in the anterior and posterior parts of the temporal muscle and in the masseter muscle were positively correlated during chewing, swallowing and maximal bite. The amplitudes in these muscles during chewing were positively correlated with those in the same muscles during maximal bite. During swallowing the amplitude in the upper lip was negatively correlated with that in the anterior part of the temporal muscle.The clearest correlations between muscle activity and facial morphology were found during chewing and maximal bite. During these functions the amplitudes in the temporal and masseter muscles were large in cases with a tendency to parallelism between the jaws bases and between the mandibular occlusal line and the mandibular line. These cases with considerable muscle activity are characterized by rectangular shape of the face in profile and small lower face height.