Muscle Activity In Patients Research Articles

An Electromyographic Analysis of Orbicularis Oris and Buccinator Muscle Activity in Patients with Complete Dentures Fabricated Using Two Neutral Zone Techniques—A Pilot Study

Several studies have evaluated electromyographic (EMG) activity of perioral muscles in patients using unsatisfactory old complete dentures and after the insertion of new clinically acceptable dentures; however, studies evaluating EMG activity of orbicularis oris (OO) and buccinator (BUC) muscles in patients wearing complete dentures fabricated using swallowing (SNZ) and phonetic neutral zone (PNZ) techniques are lacking in the literature. The purpose of this study was to evaluate differences in muscle activity of the superior orbicularis oris (SOO), inferior orbicularis oris (IOO) and BUC muscle during the use of unsatisfactory old complete dentures, in comparison with the satisfactory dentures fabricated using the two neutral zone techniques. Ten completely edentulous participants dissatisfied with their existing mandibular complete dentures participated in the study. Each patient received two sets of new dentures fabricated using the SNZ and PNZ techniques. Surface EMG activity of the OO and BUC muscles was recorded using a 4-channel Medelec premier plus electromyography machine while the patients still used their old dentures (group A) and with the SNZ (group B) and PNZ (group C) dentures. On the basis of participation in the study, five participants first received the SNZ dentures and five the PNZ type. After having worn the prosthesis for a minimum of 2 months, EMG recordings were repeated for the first set of dentures. The prostheses were then changed and the procedures repeated. The activity of OO and BUC muscles was recorded at rest, while pursing and laughing, and during pronunciation of various syllables. Results are expressed as mean ± SD and as absolute numbers and percentage. ANOVA with appropriate correction (Bonferroni or Tamhane) and Student's t-test were used for statistical analysis. A p-value < 0.05 was taken to indicate a significant difference. There was no statistically significant difference in the mean EMG activity of SOO, IOO, and BUC muscles at rest, or during pursing or laughing among the three groups. No significant difference was observed in the mean EMG activity of SOO and BUC muscle among the groups for all the syllables pronounced. For IOO, a statistically significant difference was observed among the groups for the words "baby" and "cheese." Within-group comparisons of the mean EMG activities of SOO and IOO during pronunciation and pursing showed no significant difference; however, at rest a statistically significant difference was observed in group B. OO and BUC muscle activities did not significantly differ, irrespective of the technique used for fabrication of complete dentures.

Deficient muscle activation in patients with Complex Regional Pain Syndrome and abnormal hand postures: An electromyographic evaluation

ObjectiveMotor abnormalities in Complex Regional Pain Syndrome (CRPS) are common and often characterized by a restricted active range of motion (AROM) and an increased resistance to passive movements, whereby the affected body part preferably adopts an abnormal posture. The objective of the present study was to obtain a better understanding of the factors that are associated with these abnormal postures and limitations of the AROM, and to investigate whether these motor impairments reflect dystonia. MethodsWe evaluated characteristics of surface EMG of the flexor carpi radialis and extensor carpi radialis muscles during active maintenance of various flexion–extension postures of the wrist of the affected and unaffected side in 15 chronic CRPS patients, and in 15 healthy controls. ResultsDeviant joint postures in chronic CRPS – at least in those patients with some range of active movement – were not characterized by sustained muscle contractions, and limitations of the AROM were not attributable to excessive co-contraction. Rather, the agonistic muscle and its antagonist were activated in normal proportions, albeit over a limited range. ConclusionsThe AROM limitations and abnormal postures that are often observed in chronic CRPS patients are not associated with excessive muscle activity and hence do not exhibit the characteristics typical of dystonia. SignificanceWe hypothesize that structural alterations in skeletal muscle tissue and pain-induced adaptations of motor function may contribute to the observed motor impairments. Our findings may have important clinical implications, since commonly prescribed treatments are aimed at reducing excessive muscle contraction.

Effectiveness of an 8‐week exercise programme on pain and specificity of neck muscle activity in patients with chronic neck pain: A randomized controlled study

Although exercise can be effective for relief of neck pain, little is known about the effect of exercise on the neural control of neck muscles. A randomized controlled trial was conducted on 46 women with chronic neck pain to investigate the immediate effectiveness of an 8-week exercise programme on pain and directional specificity of neck muscle activity. At baseline, the patients completed questionnaires including the neck disability index (NDI) and performed a circular contraction of their head in the horizontal plane at 15 N force, with continuous change in force direction in the range 0-360°. Electromyography (EMG) was recorded from the sternocleidomastoid (SCM) and splenius capitis (SCap) muscles. Tuning curves of the EMG amplitude were computed, which depicts muscle activity over a range of force directions. The mean point of the tuning curves defined a directional vector, which determined the specificity of muscle activity. Patients were randomly assigned either to a training or control group. A significant between-group difference in the change in NDI was observed. A reduction in NDI was observed following training (pre: 18.2 ± 7.4; post: 14.1 ± 6.5; p < 0.01) but not for the control group (pre: 17.5 ± 6.3; post: 16.6 ± 7.4). The training group showed higher specificity of muscle activity post-intervention (pre: 18.6 ± 9.8%, post: 24.7 ± 14.3%; p < 0.05), whereas no change occurred for the control group (pre: 19.4 ± 11.9%, post: 18.2 ± 10.1%). An exercise programme that aims to enhance motor control of the cervical spine improves the specificity of neck muscle activity and reduces pain and disability in patients with neck pain.

Scapular Muscle Exercises Following Neck Dissection Surgery for Head and Neck Cancer: A Comparative Electromyographic Study

Shoulder pain and dysfunction can occur following neck dissection surgery for cancer. These conditions often are due to accessory nerve injury. Such an injury leads to trapezius muscle weakness, which, in turn, alters scapular biomechanics. The aim of this study was to assess which strengthening exercises incur the highest dynamic activity of affected trapezius and accessory scapular muscles in patients with accessory nerve dysfunction compared with their unaffected side. A comparative design was utilized for this study. The study was conducted in a physical therapy department. Ten participants who had undergone neck dissection surgery for cancer and whose operated side demonstrated clinical signs of accessory nerve injury were recruited. Surface electromyographic activity of the upper trapezius, middle trapezius, rhomboid major, and serratus anterior muscles on the affected side was compared dynamically with that of the unaffected side during 7 scapular strengthening exercises. Electromyographic activity of the upper and middle trapezius muscles of the affected side was lower than that of the unaffected side. The neck dissection side affected by surgery demonstrated higher levels of upper and middle trapezius muscle activity during exercises involving overhead movement. The rhomboid and serratus anterior muscles of the affected side demonstrated higher levels of activity compared with the unaffected side. Exercises were repeated 3 times on one occasion. Muscle activation under conditions of increased exercise dosage should be inferred with caution. Overhead exercises are associated with higher levels of trapezius muscle activity in patients with accessory nerve injury following neck dissection surgery. However, pain and correct scapular form must be carefully monitored in this patient group during exercises. Rhomboid and serratus anterior accessory muscles may have a compensatory role, and this role should be considered during rehabilitation.

Low-intensity kaatsu resistance exercises using an elastic band enhance muscle activation in patients with cardiovascular diseases

Muscle wasting results from sarcopenia due to aging and from cachexia caused by diseases such as chronic heart failure (CHF), chronic obstructive pulmonary disease (COPD), cancer, chronic kidney disease and other diseases (Thomas 2007). Above all, CHF is a disease of remarkable muscle wasting, and preventing it by exercise training is important. Nakajima et al. (2010) recently reported that low-intensity kaatsu resistance exercises safely increase the muscle strength/mass and endurance capacity in patients with ischemic heart disease. Kaatsu training using a low-intensity resistance exercise appears to be a promising and useful resistance method for cardiac rehabilitation. According to the American College of Sports Medicine guidelines, the conditions for inducing muscle hypertrophy and increasing muscle mass are as follows: (1) More than 65-70% work load of one repetition maximum (1-RM) is needed. (2) Three to four sets until exhaustion. (3) Frequency is two-three times per week. However, such high-intensity loads cannot be applied to patients with diseases, especially to patients with cardiovascular diseases and to elderly patients. In the past decade, several studies have reported that muscle hypertrophy can be produced with low-intensity (20–30% 1-RM) kaatsu training, regardless of age (Takarada et al. 2000; Abe et al. 2006; Fujita et al. 2007). As this type of exercise does not require lifting heavy weights, it might be a feasible method for cardiac rehabilitation requiring resistance exercise (Pollock et al. 2000; Balady et al. 2007). As an elastic band is inexpensive, compact, and easy to use compared with machines/free weights, elastic band resistance training is feasible for use in homebased training programs for older subjects or for patients with a lower level of activity (Zion et al. 2003; Ribeiro et al. 2009; Colado et al. 2010). We examined the effects of low-intensity kaatsu exercise using an elastic band for resistance on muscle activation in patients with cardiovascular diseases.

Concurrent validity of the pressure biofeedback unit and surface electromyography in measuring transversus abdominis muscle activity in patients with chronic nonspecific low back pain

The Pressure biofeedback unit (PBU) is an assessment tool used in clinical practice and research aimed to indirectly analyze the transversus abdominis (TrA) muscle activity. The concurrent validity of the PBU in a clinically relevant sample is still unclear. The purpose of this study was to evaluate the concurrent validity and diagnostic accuracy of the PBU in measuring TrA muscle activity in patients with chronic nonspecific low back pain. This study was performed using a validation, cross-sectional design. Fifty patients with chronic nonspecific low back pain were recruited for this study. To test the concurrent validity both PBU measures (index test) and superficial electromyographic measures (reference-standard test) were compared and collected by a physical therapist in a series of voluntary contraction maneuvers of TrA muscle. Participants were on average 22 years old, weighed 63.7 kilos, 1.70 meters height and mean low back pain duration was 1.9 years. It was observed a weak and non-significant Phi coefficient (r=0.2, p<0.20). With regards to diagnostic accuracy tests, our results suggest a low sensitivity (60%) and specificity (60%) of the PBU. The positive predictive value was high (0.8) and negative predictive value was low (0.2). Concurrent validity of the PBU in measuring TrA muscle activity in patients with chronic nonspecific low back pain is poor given the low correlation and diagnostic accuracy with superficial EMG.

Trunk Extensor Muscle Activity during Exercises in Patients after Lumbar Fusion Surgery

Introduction The goal of postoperative rehabilitation after lumbar spine fusion (LSF) is to decrease pain and disability; however, back function should also be taken into account. Low trunk muscle strength has been reported in patients after LSF and it correlates with poor disability1. To increase the trunk muscle strength after fusion surgery the training should also include more intensive exercises. Exercises that are performed lumbar spine in a neutral position allow loading without the strain of fused segment. The purpose of present study was to determine trunk extensor muscle activity during different exercises and evaluate association between pain during loading and muscle activation in patients after LSF. Materials and Methods A total of 22 patients (50%women) with mean (SD) age of 59 (17) years who had undergone LSF 3 to 11 months earlier participated in the study. The indications for surgery were spondylolysis, degenerative olisthesis, spinal stenosis, and degenerative disk disease. Bilateral surface electromyography (EMG) activity of trunk extensor muscles (longissimus at the L1 level and multifidus at L5) was measured during dynamic upper limb exercise (bilateral shoulder flexion in the standing position). The load was individually adjusted using a pull machine so that each subject was able to perform 10 repetitions per set. In addition, lower limb exercise (right hip extension in the four-point kneeling position) with 10 repetitions and static back extension exercise (in the Biering-Sorensen test position) were studied. The starting and finishing points of the fifth repetition in the upper and lower limb exercises were determined from simultaneous EMG and video analysis, and this period was used for analysis. In static trunk extension exercise, the first 3 seconds were taken to analysis. The raw EMG signal was rectified and averaged. Then, the reference EMG activities obtained from maximal isometric trunk extension strength measurement (reference value) were used to normalize the EMG-activation levels collected for trunk muscle exercises. The intensity of back and leg pain during the past week and during the exercises was assessed by visual analogue scale (VAS, 0–100). Results The mean (SD) trunk extension strength was 341 (204) N. The highest activation in the longissimus was measured during the static back extension exercise. The activity on the right side was 104% and on the left side 83% when compared with the reference values. The corresponding values during bilateral shoulder flexion were 65 and 62%. The highest activity levels of the multifidus (62% on the right side and 64% on the left side) were also measured during the static back extension exercise. Activity levels of multifidus were 55% on the right side and 52% on the left side during bilateral shoulder flexion and 34% and 27% during right hip extension exercise. EMG activities of longissimus ( p &lt; 0.005) and left multifidus ( p &lt; 0.009) were higher during the static back extension than during the bilateral shoulder flexion exercise. The activation of longissimus and multifidus muscles was higher in the upper limb than in lower limb exercise (both p &lt; 0.003). The average intensities of back and leg pain during past week were 19 (19) mm and 15 (20) mm, respectively. In all participants during the reference and exercises measurements, back pain was less than 16 mm and leg pain was less than 9 mm. No significant correlation was found between strength and pain in back or leg during measurements. Back pain correlated only with right side multifidus activity during static back extension exercise ( r = −0.45, p &lt; 0.04). Conclusion Static back extension exercise elicited the highest longissimus and multifidus muscle activity. Bilateral shoulder flexion exercise in the standing position also elicited muscle activity that may be high enough to develop muscle endurance and strength characteristics. All studied exercises are feasible in the postoperative rehabilitation after lumbar fusion surgery because pain intensity remained at relatively low level. All studied exercises are performed in the lumbar spine in the neutral position, thus strain of fused segment is minimized. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared Tarnanen SP, et al. 2012, Submitted

Use of expiratory change in bladder pressure to assess expiratory muscle activity in patients with large respiratory excursions in central venous pressure

Expiratory muscle activity may cause the end-expiratory central venous pressure (CVP) to greatly overestimate right atrial transmural pressure. We recorded CVP and expiratory change in intra-abdominal pressure (ΔIAP) in 39 patients who had a respiratory excursion in CVP from end-expiration to end-inspiration (CVP(ee)-CVP(ei)) ≥ 8 mmHg. Uncorrected CVP was measured at end-expiration, and corrected CVP was calculated as uncorrected CVP-ΔIAP. In 13 patients measurements were repeated during relaxed breathing. The CVP(ee)-CVP(ei) was 15.2 ± 6.3 mmHg (range 8-34 mmHg), and ΔIAP was 7.4 ± 6.0 mmHg (range 0-30 mmHg). Uncorrected CVP was 18.3 ± 6.1 mmHg, and corrected CVP was 10.9 ± 3.9 mmHg. There was a significant positive correlation between CVP(ee)-CVP(ei) and ΔIAP (r = 0.814). However, some patients with a large CVP(ee)-CVP(ei) had negligible ΔIAP. In a subset of 13 patients with active expiration who had a relaxed CVP tracing available for comparison, the difference between uncorrected CVP and relaxed CVP was much greater than the difference between corrected CVP and relaxed CVP (7.3 ± 3.0 vs. 1.1 ± 0.7 mmHg, p < 0.001). Patients with large respiratory excursions in CVP often have significant expiratory muscle activity that will cause their CVP to overestimate transmural right atrial pressure. The magnitude of expiratory muscle activity can be assessed by measuring ΔIAP. Subtracting ΔIAP from the end-expiratory CVP usually provides a reasonable estimate of the CVP that would be obtained if exhalation were passive.

Reproducibility of the pressure biofeedback unit in measuring transversus abdominis muscle activity in patients with chronic nonspecific low back pain

The Pressure Biofeedback Unit (PBU) is often used by clinicians and researchers to indirectly evaluate transversus abdominis (TrA) muscle activity. The purpose of this study was to evaluate the inter and intra-examiner reproducibility of the PBU in measuring TrA muscle activity in fifty patients with chronic nonspecific low back pain. This study was performed using a test-retest design with a seven day interval. An Intraclass Correlation Coefficient (ICC(2,1)) of 0.74 (95% CI 0.54 to 0.85) and 0.76 (95% CI 0.58 to 0.86) was observed for the intra and inter-examiner reproducibility, respectively. The intra-examiner agreement (Limits of Agreement - LOA = 2.1 to -1.8 mmHg) and the inter-examiner agreement (LOA = 2.0 to -1.9 mmHg) were within the limits of agreement on 95% of occasions. The reproducibility of PBU in measuring TrA muscle activity in patients with chronic nonspecific low back pain ranged from satisfactory to excellent.

Foot center of pressure manipulation and gait therapy influence lower limb muscle activation in patients with osteoarthritis of the knee

Background Foot center of pressure (COP) manipulation has been associated with improved gait patterns. The purpose of this study was to determine lower limb muscle activation changes in knee osteoarthritis patients, both immediately after COP manipulation and when COP manipulation was combined with continuous gait therapy (AposTherapy). Methods Fourteen females with medial compartment knee osteoarthritis underwent EMG analyzes of key muscles of the leg. In the initial stage, trials were carried out at four COP positions. Following this, gait therapy was initiated for 3 months. The barefoot EMG was compared before and after therapy. Results The average EMG varied significantly with COP in at least one phase of stance in all examined muscles of the less symptomatic leg and in three muscles of the more symptomatic leg. After training, a significant increase in average EMG was observed in most muscles. Most muscles of the less symptomatic leg showed significantly increased peak EMG. Activity duration was shorter for all muscles of the less symptomatic leg (significant in the lateral gastrocnemius) and three muscles of the more symptomatic leg (significant in the biceps femoris). These results were associated with reduced pain, increased function and improved spatiotemporal parameters. Conclusions COP manipulation influences the muscle activation patterns of the leg in patients with knee osteoarthritis. When combined with a therapy program, muscle activity increases and activity duration decreases.

Inverse relationship between the complexity of midfoot kinematics and muscle activation in patients with medial tibial stress syndrome

Medial tibial stress syndrome is a common overuse injury characterized by pain located on the medial side of the lower leg during weight bearing activities such as gait. The purpose of this study was to apply linear and nonlinear methods to compare the structure of variability of midfoot kinematics and surface electromyographic (SEMG) signals between patients with medial tibial stress syndrome and healthy controls during gait. Fourteen patients diagnosed with medial tibial stress syndrome and 11 healthy controls were included from an orthopaedic clinic. SEMG from tibialis anterior and the soleus muscles as well as midfoot kinematics were recorded during 20 consecutive gait cycles. Permuted sample entropy and permutation entropy were used as a measure of complexity from SEMG signals and kinematics. SEMG signals in patients with medial tibial stress syndrome were characterized by higher structural complexity compared with healthy controls ( p < 0.001) while it was the opposite for the midfoot kinematics ( p = 0.01). Assessing the complexity of midfoot kinematics and SEMG activation pattern enabled a precise characterization of gait in patients with medial tibial stress syndrome. The reported inverse relationship in foot kinematics and SEMG complexity most likely point towards separated control processes governing gait variability.

Electromyographic investigation of unstable patella before and after its realignment operation

Background:Patellar dislocations are either due to superolateral contracture of the soft tissue or imbalance of the power between the vastus medialis (VM) and the vastus lateralis (VL). The imbalance of muscle power as an etiology of patellar dislocation has not been studied. Hence, we studied the recurrent, habitual and permanent dislocations of the patella with an electromyogram (EMG) of the vastus medialis, vastus lateralis, and pes anserinus, before and after realignment operations, to document the muscle imbalance and effectiveness of the realignment operation.Materials and Methods:An electromyographic investigation was carried out on the vastus medialis and vastus lateralis in nine recurrent, 20 habitual, and 13 permanent dislocations of the patella, before and after their realignment operations. Pes anserinus transposition, which acted as a medial stabilizer of the patella, was also investigated with an EMG study, to understand its role on patellar stability at 0°, 30°, 60°, 90°, 120°, 150°, and full flexion of the knee. The age of the patients varied from nine to 30 (mean 15) years. There were 24 males and 18 females. Twenty-six patellar dislocations were on the right and 16 were on the left side.Results:Electromyographic pictures reveal subnormal activity of the vastus medialis in all types of dislocations and similar activities of the vastus lateralis in permanent and habitual dislocations recorded pre operatively, which recovered to almost normal values postoperatively, at the mean one-year follow-up. Pes anserinus, which was used for medial stabilization of the patella after its realignment, maintained normal EMG activity before and after the operation.Conclusion:This study is significant for understanding the imbalance of muscle activities in patients with an unstable patella, which can be rectified without recurrence after pes anserinus transposition.

Minimal Detectable Change in Quadriceps Strength and Voluntary Muscle Activation in Patients With Knee Osteoarthritis

Minimal Detectable Change in Quadriceps Strength and Voluntary Muscle Activation in Patients With Knee Osteoarthritis

KINETIC AND KINEMATIC ANALYSIS OF STANCE WITH AND WITHOUT ARM SUPPORT IN INCOMPLETE SPINAL CORD INJURED SUBJECTS

There is a lack of studies concerning standing stability in subjects with incomplete spinal cord injury (SCI). The aims of this study were to analyze the changes of center of pressure (COP), joint moment, joint angle, and muscle activities in patients with incomplete SCI during quiet stance with and without arm support. Ten cervical–thoracic cord incompletely injured patients (mean age: 47.8 ± 13.4 years old) participated in this study. They performed quiet standing with each leg on separate force plate (AMTI, USA) for 5 s with and without holding the walker to obtain the kinetic data. The kinematic data of joint angles were recorded by Motion Analysis System (Vicon 250, Oxford, UK). The electromyographic activities of trunk muscles and quadriceps were recorded by surface electrodes. The results indicated that the COP sway area and the normalized COP sway area significantly (P &lt; 0.01) increased from 94.9 ± 61.3 mm2 to 254.6 ± 91.8 mm2 and from 0.0013 ± 0.0007 to 0.0037 ± 0.0012, respectively, in patients with incomplete SCI, while standing with arms released from walker. The ankle and knee moments also increased significantly (P &lt; 0.05) during stance without support. However, the joint angles and recorded muscle activities were not significantly different between those with and without support. The conclusion was that the proprioceptive feedback of postural sway, and the motor control strategies of knee–ankle muscles would be important for patients with incomplete SCI during stance without arm support.

¿Qué respuesta fisiológica desencadena la aplicación de la técnica de estimulación nerviosa eléctrica transcutánea?

Purpose To analyze the physiological effects of the application of the transcutaneous electrical nerve stimulation (TENS) technique on patients, to provide guidance for successful implementation in clinical practice. TENS technique involves the application of a pulsed electric current, traditionally used for pain control. Different TENS programming parameters should be adjusted, taking into account that the different programming options will activate various physiological mechanisms. Extensive studies in animals and in healthy subjects have been conducted recently, in order to elucidate the physiological effects produced in the body when TENS is applied. Material and methods We conducted a comprehensive review of published scientific literature on the use of the TENS technique and its physiological effects. Relevant trials were identified through a search of various databases and reference books on the subject, from the Library of the CEU-Cardenal Herrera University of Valencia. Results We found 97 references that met the inclusion criteria. Conclusions TENS produces its analgesic effect by activation of afferents of deep tissues by stimulation of primary Aβ large diameter afferent fibers. The physiological mechanisms of action of TENS at low and high frequency are different, although both occur at peripheral, spinal and supraspinal level, and are based primarily on the activation of different opioid receptors. With the proper combination of parameters, TENS reduces pain from the first minute of application. Regarding the duration of analgesic effect after a treatment session, it is known the importance of using higher intensities for greater duration of post-session effect. The daily repeated application of TENS with the same parameters will lead to the development of tolerance. Although there has been speculation about a vascular effect of the application of TENS, it only has an effect on peripheral circulation when applied at intensity sufficient to achieve significant muscle contractions; in any case the effect is reduced in the area of application. The application of TENS can positively influence muscle activity in patients with motor deficits in stroke and other neurological disorders.

Minimal Detectable Change in Quadriceps Strength and Voluntary Muscle Activation in Patients With Knee Osteoarthritis

Kean CO, Birmingham TB, Garland SJ, Bryant DM, Giffin JR. Minimal detectable change in quadriceps strength and voluntary muscle activation in patients with knee osteoarthritis. Objective To examine the test-retest reliability and quantify the minimal detectable change (MDC) in quadriceps strength and voluntary activation in patients with knee osteoarthritis (OA). Design Repeated measures over a 1-week interval. Setting Tertiary care center. Participants A convenience sample of patients (N=20) diagnosed with knee OA. Intervention Isokinetic and isometric quadriceps strength testing and voluntary quadriceps activation testing using interpolated twitch technique. Main Outcome Measures Peak isokinetic and isometric knee extension torque (Nm) and percentage of voluntary quadriceps activation (%). Results The mean differences with 95% confidence intervals between the 2 test sessions for quadriceps isokinetic strength, isometric strength, and percent of voluntary activation were −4.34Nm (−14.01 to 5.34Nm), 1.56Nm (−5.56 to 8.68Nm), and 1.34% (−.53 to 3.22%), respectively. The intraclass correlation coefficients for all measures ranged from .93 to .98. The standard errors of measurement (SEMs) for quadriceps isokinetic and isometric strength were 14.57Nm and 10.76Nm, respectively. The SEM for percentage of voluntary activation was 2.84%. Based on these values, the MDCs were 33.90Nm, 25.02Nm, and 6.60% for quadriceps isokinetic strength, isometric strength, and percentage of voluntary activation, respectively. Conclusions Maximal quadriceps isokinetic strength, isometric strength, and percentage of voluntary activation measures demonstrate excellent test-retest reliability in patients with knee OA. In addition to research applications, the present findings suggest these measures are appropriate for use when evaluating change in neuromuscular function of the quadriceps in individual patients.

Electromyographic evaluation of masticatory, neck, and trunk muscle activity in patients with posterior crossbites

This study investigated the pattern of masticatory, neck, and trunk muscle activity in patients with posterior crossbites and associated mandibular displacement. The test group consisted of 75 patients [45 males mean age 19.5 years, SD 5.6 years, and 30 females mean age 20.4 (SD 3.2) years]. Of this group, 25 patients presented a left posterior crossbite, 25 a right posterior crossbite, and the remaining 25 patients a bilateral posterior crossbite. A control group of 25 subjects (19 males and 6 females aged 22.5 ± 5.8 years) without any crossbite were included. Surface electromyographic (sEMG) activity was recorded bilaterally, in the mandibular rest position and during maximum voluntary clenching (MVC), at the following sites: anterior and posterior temporal, masseter, sternocleidomastoid (SCM), upper and lower trapezius, and cervical muscles. In the mandibular rest position, patients with unilateral crossbites showed a significant difference (P < 0.05) in sEMG activity of the anterior temporal muscle, with the greatest activity being detected on the side to which the mandible displaced. Control subjects demonstrated significantly lower (P < 0.05) sEMG activity but only in the SCM muscle when compared with patients with bilateral posterior crossbites; no such differences were detected in relation to unilateral crossbites. During MVC, control subjects showed significantly lower (P < 0.01) sEMG activity in both the SCM and the posterior cervical muscles compared with patients demonstrating both unilateral and bilateral crossbites. The findings of the present study indicate that the presence of a crossbite can affect electromyography activity of masticatory, neck, and trunk muscles.

Reflexive Quadriceps Muscle Inhibition following Chronic ACL Injury or Reconstruction

BACKGROUND: Vastus medialis muscle atrophy occurs frequently as a result of ACL injury or reconstructive surgery. Atrophy is theorized to be the result of reflex inhibition. Recording the vastus medialis H-reflex amplitude in patients with chronic ACL injury might reflect the changes in the reflexive component of muscle activation. PURPOSE: The purpose of this study was to examine the vastus medialis muscle activation in patients with chronic ACL injury or long after reconstructive surgery. METHODS: Thirty participants (15 healthy, 15 post ACL reconstruction) participated in this study. EMG units were used to elicit and record the H-reflex (from femoral nerve using 0.5 ms pulses at 0.2 pps of H-maximum). Vastus medialis H-reflexes were recorded unilaterally (right leg in healthy participants, involved leg in patients) while standing during 0°, 30°, and 60° knee flexion. Four traces of the maximum vastus medialis H-reflex amplitude were recorded and averaged. Split plot ANOVAs examined the statistical differences with the global a set at 0.05. RESULTS: H-reflex amplitude was significantly less in the patient group than in healthy group (p = 0.003). The mean H-reflex amplitudes were 4.85, 5.83, and 6.70 mV for the healthy and the mean H-reflex amplitudes for patients were 2.4, 3.5, and 3.7 mV at 0°, 30°, and 60° knee flexion. This reduction in H-reflex amplitude was associated with decreased muscle strength. CONCLUSIONS: Results indicated that there was reflexive muscular inhibition of the vastus medialis muscle in patients with chronic ACL injury or reconstruction. This inhibition may be the underlying cause of quadriceps muscle atrophy in this patient population.

骨格性下顎前突症患者における嚥下時筋活動様式の特徴

The present study investigated the pattern of muscle activity during swallowing in patients with mandibular prognathism.The subjects comprised 12 mandibular prognathism patients (5 males, 7 females, average age of 20.8 years old), and 12 volunteers (2 males, 10 females, average age of 23.8 years old) with individual normal occlusion and no abnormalities of deglutition function as a control.Electromyographic (EMG) activity was recorded from the masseter and suprahyoid muscles bilaterally, mentalis on the midline and orbicularis oris and infrahyoid muscles on the right side.Each subject was asked to perform the following: (1) maximum clenching for 5 seconds at 10-second intervals, (2) maximum jaw opening for 5 seconds at 10-second intervals, and (3) swallow 4 ml of half-solid nutrient made of 0.8% agar powder. The first two tasks were repeated four times and the last one was repeated five times.Peak amplitudes of masseter and suprahyoid EMGs during maximum clenching and jaw opening were first obtained. For analysis of swallowing, mean values of duration of EMG, mean values of amplitude, and root mean square (RMS) of EMGs of orbicularis oris, mentalis and infrahyoid muscles, and those of %peak (swallow activity/peak activity) amplitude of masseter and suprahyoid EMGs were calculated and compared between the patient group and the normal group. Morphological characteristics of the patients were also compared between the groups using lateral cephalograms.The duration of activity in all muscles recorded except the infrahyoid was significantly longer in the patient group than in the control. Peak amplitude and RMS of mentalis muscles were significantly larger in the control than in the patient group. %peak amplitude of masseter and suprahyoid muscles were both significantly larger in the patient group than in the control. On the contrary, there were no significant differences in all the variables of infrahyoid muscles.The present study successfully showed the pattern of orofacial muscle activity in patients with mandibular prognathism in terms of peak amplitude and duration. Although the activities of orofacial muscles recorded in this study are reflexively controlled at the lower brainstem during swallowing, these are also known to be voluntary muscles and therefore they are likely to adapt the activity patterns to their morphologic characteristics.

Kontrolliertes Biofeedbacktraining zur Behandlung der Spätfolgen nach Kinderlähmung

PURPOSE: Does biofeedback controlled exercises change muscle activity in patients with post polio syndrome? PATIENTS AND METHOD: 26 patients with postpolio syndrome (age 63 years, 17 female, 9 male, 15 with walkers) were treated by EMG-controlled exercises of the m. obliquus abdominis internus combined with a baseline physiotherapy. Before, during and after this therapy the surface EMG-activity of 8 muscles of trunk and tigh was evaluated. RESULTS: EMG-amplitude of the m. obliquus abdominis internus increased immediatly after the therapy by 0,33 μV in stand and by 0,86 μV in gait. To the same point of time in stand the amplitude of m. vastus medialis reduced from 23,35 to 17,02 μV (p=0,033) and the amplitude of m. bizeps femoris from 15,1 μV to 12,65 μV (p=0,009). No changes could be occurred during the steps. DISCUSSION: The increase of EMG-activity of m. obliquus abdominis internus in combination with the tendency of reduced activity of the tigh musculature shows the positive effect of training and confirms the results of Feldman and Soskolne , who verify an increased strength by progressive resistance exercises 3 times a week in patients with spinal cord diseases, but EMG controls are necessary to prevent overload . CONCLUSION: Stabilization of trunk musculature by EMG controlled exercises is possible and release muscles of the lower limb.