Neuromuscular adaptation to orthognathic surgery.
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Electromyography↗
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Results for “Neuromuscular adaptability”
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Neuromuscular adaptations during intensive strength training in middle-aged and elderly males and females.
Effects of progressive heavy resistance strength training combined with explosive types of exercises for 12 weeks on electromyographic activity (EMG), muscle cross-sectional area of the quadriceps femoris (QF), isometric maximal force and force-time curve of the leg extensor muscles were investigated in 9 middle-aged males and 9 females in the 50-year age group (M50; range 44-57), (F50; range 43-54), and in 10 elderly males and 11 females in the 70-year age group (M70; range 64-73), (F70; range 66-73). Great gradual increases took place in maximal force during the 12-week training period both in M50 (from 2834 +/- 452 N to 3941 +/- 772 N; p < 0.001) and in F50 (from 2627 +/- 725 N to 3488 +/- 1017 N; p < 0.001) as well as in M70 (from 2591 +/- 736 N to 3075 +/- 845 N; p < 0.01) and in F70 (from 1816 +/- 427 N to 2483 +/- 408 N; p < 0.001). Significant (p < 0.05-0.001) increases occurred also in the maximum integrated EMGs of the trained muscles in all groups primarily during the first 8 weeks of the training. Significant (p < 0.05-0.001) enlargements took place during the 12-week training period in the CSA of the QF muscle in all groups. Significant (p < 0.05-0.001) shifts occurred in all groups in the shape of the absolute force-time curves and the maximal rate of force production increased (p < 0.05-0.001) during the training as well. The present findings suggest that progressive heavy strength training combined with explosive types of exercises may lead to considerable increases not only in maximal strength but also in explosive force production characteristics of the trained muscles accompanied by adaptations in the nervous system as well as by muscular hypertrophy not only in middle-aged but in elderly males and females as well.
Adaptation, Physiological↗
[Post-polio syndrome; the limit of neuromuscular adaptation?].
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Adaptation, Physiological↗
Adaptation of neuromuscular activation patterns during treadmill walking after long-duration space flight.
The precise neuromuscular control needed for optimal locomotion, particularly around heel strike and toe off, is known to he compromised after short duration (8- to 15-day) space flight. We hypothesized here that longer exposure to weightlessness would result in maladaptive neuromuscular activation during postflight treadmill walking. We also hypothesized that space flight would affect the ability of the sensory-motor control system to generate adaptive neuromuscular activation patterns in response to changes in visual target distance during postflight treadmill walking. Seven crewmembers, who completed 3- to 6-month missions, walked on a motorized treadmill while visually fixating on a target placed 30 cm (NEAR) or 2 m (FAR) from the subject's eyes. Electronic foot switch data and surface electromyography were collected from selected muscles of the right lower limb. Results indicate that the phasic features of neuromuscular activation were moderately affected and the relative amplitude of activity in the tibialis anterior and rectus femoris around toe off changed after space flight. Changes also were evident after space flight in how these muscles adapted to the shift in visual target distance.
Adaptation, Physiological↗
Adaptation of neuromuscular junction to transmission of impulses after inactivation of acetylcholinesterase.
Adaptation of neuromuscular junction to transmission of impulses after inactivation of acetylcholinesterase. Acta Physiol. Pol., 1977, 28 (1): 23-30. Isolated preparation of rat diaphragm with phrenic nerve was incubated in paraoxon solutions which caused complete inactivation of acetylcholinesterase. This inactivation was associated with disturbances of neuromuscular transmission in the form of blockade of the tetanic response, post-tetanic inhibition of twitch responses and a decreased amplitude of the second response after the first one when two stimuli at a short interval were used. These disturbances were withdrawn somewhat during further incubation of the preparation, although it was kept in paraoxon solution which maintained complete inactivation of acetylcholinesterase. It is suggested that the observed recession of transmission disturbances may be caused by partial adaptation of blockade of the tetanic response, post-tetanic inhibition of twitch blockade of enzymatic hydrolysis of acetylcholine.
Acetylcholinesterase↗
Surgical treatment of the jaw deformities in hemifacial microsomia.
The surgical treatment of the mandibular and maxillary deformities in patients with hemifacial microsomia requires some form of mandibular lengthening. This is usually either via ramus interpositional bone grafting or end-on bone grafting. In a few cases, ramus lengthening may be completed by a sagittal split. Once the mandible has been reconstructed, the maxillary surgery can be completed. In previous forms of treatment, mandibular bone grafting was completed without regard to function and neuromuscular adaptation and a significant percentage of such procedures completed failed. Egil Harvold and his colleagues developed a method by which changes in form and function are co-ordinated by using a functional appliance resulting in neuromuscular adaptation. After the bone grafting is completed, as the second of six phases of treatment, a specially designed registration bite-block further facilitates neuromuscular adaptation by controlling mandibular movements (function), but in addition it protects the bone graft from excessive forces thereby aiding in osteogenesis (third phase). The theoretical basis, classification of deformities, and phases of treatment developed are presented and the surgery is described in detail. The results of a consecutive group of patients treated by these methods is then presented. While this form of treatment is not the only one possible, it is the only one that has been tested in the laboratory, proven in patient care, and stood the test of time.
Adolescent↗
Adaptations of neuromuscular facilitation technice.
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Acclimatization↗
Specific adaptations of neuromuscular control and knee joint stiffness following sensorimotor training.
The aim of this study was to examine how fixations of the ankle joint during sensorimotor training (SMT) influence adaptations in mechanical stiffness and neuromuscular control of the knee joint. Sixty-three healthy subjects were randomly assigned to three training groups that differed in their degree of ankle joint fixation, which was either barefooted, with an ankle brace or with a ski boot. Mechanical knee joint stiffness and reflex control of m. vastus medialis, m. vastus lateralis, m. biceps femoris, and m. semitendinosus were tested during force controlled anterior tibial displacements. This force was applied as both a fast and a slow stimulus. After the training period the group that trained barefooted showed an increase in mechanical stiffness of the knee joint from 79 +/- 21 (Mean +/- SD) N/mm to 110 +/- 38 N/mm (p < 0.05) in the fast stimulus. The training group that trained with ski boots was able to improve knee joint stiffness from 67 +/- 26 N/mm to 96 +/- 47 N/mm (p < 0.05) in the slow stimulus. These improvements correspond with an enhanced activity of the hamstring muscles (m. biceps femoris and m. semitendinosus). From a more functional point of view, specific adaptations due to the fixation of the ankle joint may be helpful in the prevention and rehabilitation of knee joint injuries.
Adaptation, Physiological↗
Concepts related to adaptation of neuromuscular function and craniofacial morphology.
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Adaptation, Physiological↗
Low frequency depression of H-reflexes in humans with acute and chronic spinal-cord injury.
We measured low-frequency depression of soleus H-reflexes in individuals with acute (n=5) and chronic (n=7) spinal-cord injury and in able-bodied controls (n=7). In one acute subject, we monitored longitudinal changes in low-frequency depression of H-reflexes over 44 weeks and examined the relationship between H-reflex depression and soleus-muscle fatigue properties. Soleus H-reflexes were elicited at 0.1, 0.2, 1, 5, and 10 Hz. The mean peak-to-peak amplitude of ten reflexes at each frequency was calculated, and values obtained at each frequency were normalized to 0.1 Hz. H-reflex amplitude decreased with increasing stimulation frequency in all three groups, but H-reflex suppression was significantly larger in the able-bodied and acute groups than in the chronic group. The acute subject who was monitored longitudinally displayed reduced low-frequency depression with increasing time post injury. At 44 weeks post injury, the acute subject's H-reflex depression was similar to that of chronic subjects, and his soleus fatigue index (assessed with a modified Burke fatigue protocol) dropped substantially, consistent with transformation to faster muscle. There was a significant inverse correlation over the 44 weeks between the fatigue index and the mean normalized H-reflex amplitude at 1, 5, and 10 Hz. We conclude that: (1) the chronically paralyzed soleus muscle displays impaired low-frequency depression of H-reflexes, (2) attenuation of rate-sensitive depression in humans with spinal-cord injury occurs gradually, and (3) changes in H-reflex excitability are generally correlated with adaptation of the neuromuscular system. Possible mechanisms underlying changes in low-frequency depression and their association with neuromuscular adaptation are discussed.
Acute Disease↗
Tai Chi and vestibular rehabilitation improve vestibulopathic gait via different neuromuscular mechanisms: preliminary report.
BACKGROUND: Vestibular rehabilitation (VR) is a well-accepted exercise program intended to remedy balance impairment caused by damage to the peripheral vestibular system. Alternative therapies, such as Tai Chi (TC), have recently gained popularity as a treatment for balance impairment. Although VR and TC can benefit people with vestibulopathy, the degree to which gait improvements may be related to neuromuscular adaptations of the lower extremities for the two different therapies are unknown. METHODS: We examined the relationship between lower extremity neuromuscular function and trunk control in 36 older adults with vestibulopathy, randomized to 10 weeks of either VR or TC exercise. Time-distance measures (gait speed, step length, stance duration and step width), lower extremity sagittal plane mechanical energy expenditures (MEE), and trunk sagittal and frontal plane kinematics (peak and range of linear and angular velocity), were measured. RESULTS: Although gait time-distance measures were improved in both groups following treatment, no significant between-groups differences were observed for the MEE and trunk kinematic measures. Significant within groups changes, however, were observed. The TC group significantly increased ankle MEE contribution and decreased hip MEE contribution to total leg MEE, while no significant changes were found within the VR group. The TC group exhibited a positive relationship between change in leg MEE and change in trunk velocity peak and range, while the VR group exhibited a negative relationship. CONCLUSION: Gait function improved in both groups consistent with expectations of the interventions. Differences in each group's response to therapy appear to suggest that improved gait function may be due to different neuromuscular adaptations resulting from the different interventions. The TC group's improvements were associated with reorganized lower extremity neuromuscular patterns, which appear to promote a faster gait and reduced excessive hip compensation. The VR group's improvements, however, were not the result of lower extremity neuromuscular pattern changes. Lower-extremity MEE increases corresponded to attenuated forward trunk linear and angular movement in the VR group, suggesting better control of upper body motion to minimize loss of balance. These data support a growing body of evidence that Tai Chi may be a valuable complementary treatment for vestibular disorders.
Biomechanical Phenomena↗
Role of muscular exercise in amyotrophic lateral sclerosis.
The general, systemic, and specific neuromuscular adaptation to physical exercise and training in healthy individuals is reviewed with application to individuals with neuromuscular disease in general and ALS in particular. A pilot study utilizing patients with ALS suggests the cardiopulmonary response to acute exercise is similar to normal individuals. However, a case study of a training response suggests the success of neuromuscular adaptation will be dependent upon the degree of motor neuron involvement.
Adult↗
Adaptation of neuromuscular synergies during intentional constraints of space-time relationships in human gait.
Tight frequency-to-amplitude relationships are observed in spontaneous human steady gait. They can be modified, if required; that flexibility forms a fundamental basis of the intentional adaptive capabilities of locomotion. In the present experiments, the processes underlying that flexibility were investigated at both the level of joint kinematics and the level of neuromuscular synergies. Subjects (N = 4) walked at the same speed either with a preferred or a nonpreferred frequency-to-amplitude relationship (i.e., constrained, short steps at a high frequency [COS condition] or constrained, long steps at a low frequency [COL condition]); their swing and stance phases were separately analyzed. In the COS condition, increases in EMG activity were specifically required during the swing phase. In the COL condition, several muscles required increases in EMG activity during the stance phase, but decreases of the hamstring muscles were needed during the swing phase. Whereas, in preferred walking, modification of the frequency affects the EMG patterns globally (the gain increasing with the frequency in both the stance and swing phases), the present results show that changing the frequency in a constrained manner either affects the swing phase specifically or affects both phases, but in the opposite direction. That finding indicates that a separate control is needed in both the swing and the stance phases.
Adult↗
Reconsidering the motor recovery plateau in stroke rehabilitation.
Termination of motor rehabilitation is often recommended as patients with cerebrovascular accident (CVA) become more chronic and/or when they fail to respond positively to motor rehabilitation (commonly termed a "plateau"). Managed-care programs frequently reinforce this practice by restricting care to patients responding to therapy and/or to the most acute patients. When neuromuscular adaptation occurs in exercise, rather than terminating the current regimen, a variety of techniques (eg, modifying intensity, attempting different modalities) are used to facilitate neuromuscular adaptations. After presenting the concepts of the motor recovery plateau and adaptation, we similarly posit that patients with CVA adapt to therapeutic exercise but that this is not indicative of a diminished capacity for motor improvement. Instead, like traditional exercise circumstances, adaptive states can be overcome by modifying regimen aspects (eg, intensity, introducing new exercises). Findings suggesting that patients with chronic CVA can benefit from motor rehabilitation programs that apply novel or different parameters and modalities. The objectives of this commentary are to (1) to encourage practitioners to reconsider the notion of the motor recovery plateau, (2) to reconsider chronic CVA patients' ability to recover motor function, and (3) to use different modalities when accommodation is exhibited.
Activities of Daily Living↗
Functional processes when wearing the SII appliance during the day.
In 20 subjects the neuromuscular activity during the day was divided into six different activities and recorded. In the case of typical application of the SII appliance for 4 hours in the afternoon and the free organization of this time by the patient himself, most of the time fell into the area "intellectual activity" followed by the area "manual activity". Since the term "functional orthodontics" naturally describes the function, this should be realized most impressively when wearing such an appliance during the day. During the day there are mouth opening and closing movements of varying frequency with quite different amplitudes. Conversation as well as reading a text aloud can be considered favorable in terms of neuromuscular adaptation. Obviously, the relatively short habituation period soon results in the patient not needing the bars as guiding bars any more (this is in contrast to investigations during nocturnal sleep). In other words, the patient needs them only for a brief time to influence the muscles in such a way that the neuromuscular masticatory pattern is virtually independent of the bars. Only during intellectual and practical activity does the patient rest on the inclined plane with the help of the bars and execute small movements. Consequently, wearing the SII appliance during the day can be regarded as extremely important to the success of treatment. Important neuromuscular influences occur while doing homework as well as during intellectual activity. Wearing the appliance during the day corresponds to neuromuscular programming, so that the term "functional orthodontic appliance" is completely correct. Since there are only about 600 biting actions during the night, a functional orthodontic appliance should definitely be worn for a certain time during the day too, in order not to jeopardize the neuromuscular adaptation.
Activities of Daily Living↗
Morphological adaptations of neuromuscular junctions depend on fiber type.
The neuromuscular junction (NMJ) forms the communicative link between motoneurons and muscle fibers. The properties of motoneurons and muscle fibers are matched in different types of motor units, which are recruited selectively to accomplish various motor behaviors. Motor units and muscle fibers can be classified based upon structural and functional properties, reflecting the essential match between motoneuron and muscle fiber. Using a three-color immunofluorescence technique combined with confocal microscopy, we examined the three-dimensional structure of pre- and postsynaptic elements of NMJs on different fiber types in the rat diaphragm muscle. On type I and IIa fibers, comprising slow-twitch and fast-twitch fatigue-resistant motor units, the structure of NMJs is far less complex than on type IIx6 and IIb fibers comprising fast-twitch fatigue-intermediate and fast-twitch fatigable motor units. We also found a greater extent of overlap between pre- and postsynaptic elements of NMJs on type I and IIa fibers. This review focuses on these normal phenotypic differences in NMJ properties and on the adaptations that occur under various conditions of altered use.
Adaptation, Physiological↗
Molecular adaptations of neuromuscular disease-associated proteins in response to eccentric exercise in human skeletal muscle.
The molecular events by which eccentric muscle contractions induce muscle damage and remodelling remain largely unknown. We assessed whether eccentric exercise modulates the expression of proteinases (calpains 1, 2 and 3, proteasome, cathepsin B+L), muscle structural proteins (alpha-sarcoglycan and desmin), and the expression of the heat shock proteins Hsp27 and alphaB-crystallin. Vastus lateralis muscle biopsies from twelve healthy male volunteers were obtained before, immediately after, and 1 and 14 days after a 30 min downhill treadmill running exercise. Eccentric exercise induced muscle damage as evidenced by the analysis of muscle pain and weakness, creatine kinase serum activity, myoglobinaemia and ultrastructural analysis of muscle biopsies. The calpain 3 mRNA level was decreased immediately after exercise whereas calpain 2 mRNA level was increased at day 1. Both mRNA levels returned to control values by day 14. By contrast, cathepsin B+L and proteasome enzyme activities were increased at day 14. The alpha-sarcoglycan protein level was decreased immediately after exercise and at day 1, whereas the desmin level peaked at day 14. alphaB-crystallin and Hsp27 protein levels were increased at days 1 and 14. Our results suggest that the differential expression of calpain 2 and 3 mRNA levels may be important in the process of exercise-induced muscle damage, whereas expression of alpha-sarcoglycan, desmin, alphaB-crystallin and Hsp27 may be essentially involved in the subsequent remodelling of myofibrillar structure. This remodelling response may limit the extent of muscle damage upon a subsequent mechanical stress.
Actins↗
Resistance training and human cervical muscle recruitment plasticity.
This study examined cervical neuromuscular adaptations to resistance training. The ResX group performed conventional resistance training plus head-extension exercise. Another group performed only conventional resistance training, and the control group performed no resistance exercise. Muscle use during head extension was determined by quantifying shifts in T2 in serial-transaxial magnetic resonance images of the neck. ResX was the only group that showed a training effect. Training decreased (P < 0.05) the cross-sectional area (CSA) of cervical muscle used to perform submaximal head extension by 31%. This reflected a decrease (P < 0.05) in relative use of the splenius capitis, semispinalis capitis, and semispinalis cervicis and multifidus muscles by about one-third; their percentage of CSA showing contrast shift was reduced from 60 to 40% on average. This same exercise evoked no contrast shift in the levator scapulae, longissimus capitis and cervicis, and scalenus medius and anterior muscles posttraining, yet 20% or more of their CSA was engaged pretraining. The relative CSA of cervical musculature that was used to perform maximal head extension was increased (P < 0.05) 16% by training. The findings suggest functional redundancy of neck musculature that can be modified by training; submaximal tasks can be performed despite cessation of recruitment of individual muscles, yet recruitment can be increased for maximal efforts. These results also suggest that neuromuscular adaptations to training require a specific cervical exercise.
Adaptation, Physiological↗