Masticatory Myoelectric Side Modular Ratio Asymmetry during Maximal Biting in Women with and without Temporomandibular Disorders.

There is no consensus on the role of electromyographic analysis in detecting and characterizing the asymmetries of jaw muscle excitation in patients with temporomandibular disorders (TMD). To analyze the TMD patients (n = 72) in comparison with the healthy controls (n = 30), the surface electromyography (sEMG) of the temporalis anterior muscle (TA) and masseter muscle (M) was recorded while a maximal biting task was performed. The differences in the asymmetry of the relationship between the masseter muscles were assessed in a module to determine the sensitivity (Sn) of binomial logistic models, based on the dominance of the TA or the M muscle, in accurately predicting the presence of TMD. All assumptions were met, and comparisons between the groups showed significant differences for the TA muscle ratio (p = 0.007), but not for the M muscle ratio (p = 0.13). The left side was predominant over the right side in the TMD group for both the TA (p = 0.02) and M muscles (p = 0.001), while the non-TMD group had a higher frequency of the right side. Binary logistic regression showed a significant model (χ2 = 9.53; p = 0.002) for the TA muscle with Sn = 0.843. The model for the M muscle also showed significance (χ2 = 8.03; p = 0.005) with Sn = 0.837. The TMD patients showed an increased TA muscle ratio and asymmetry of left dominance, compared to the healthy subjects. Both of the binomial logistic models, based on muscle dominance TA or M, were moderately sensitive for predicting the presence of TMD.

Balance Differences between North and South American Older Adults: A Cross-Sectional, Age and Sex Matched Study.

This study aimed to characterize the risk of falling in low-, moderate- and high-risk participants from two different geographical locations using a portable force-plate. A sample of 390 older adults from South and North America were matched for age, sex, height and weight. All participants performed a standardized balance assessment using a force plate. Participants were classified in low, moderate and high risk of falling. No differences were observed between South and North American men, nor comparing North American men and women. South American women showed the significantly shorter center of pressure path length compared to other groups. The majority of the sample was categorized as having low risk of falling (male: 65.69% and female: 61.87%), with no differences between men and women. Moreover, no differences were found between North vs. South Americans, nor between male and female groups compared separately. In conclusion, South American women had better balance compatible with the status of the 50-59 years' normative age-range. The prevalence of low falls risk was~61-65%; the prevalence of moderate to high risk was~16-19%. The frequency of fall risk did not differ significantly between North and South Americans, nor between males and females.

Test-Retest of a Novel Wii Board-Based Device to Assess Eccentric Knee Flexor Strength During the Nordic Hamstring Exercise.

This study aimed to assess the test-retest reliability of a Wii board-based device to assess the eccentric knee strength. Healthy participants (n = 20, 22.7 [3.4] y, 1.71 [0.09] m, 69 [13] kg) performed 2 assessments-days 1 and 2-of the Nordic hamstring exercise (3 trials per day, 3 min of rest between trials, and 48 h between trials) on a padded board with an attached Wii Balance Board (WBB). A ratchet inelastic strap made the contact between the participant's distal aspect of both legs and the inverted upper surface of the WBB. The means among 3 trials were used to extract the absolute strength and the left and the right limb strengths. No between-session differences were found (P range = .691-.981). The intraclass correlation coefficient range showed excellent results (.905-.926), as the Cronbach α test (above .94). The correlation was high (r > .91; .820 < r2 < .862). The Bland-Altman analysis returned high levels of agreement. The standard error of measurement ranged from 5.56 to 11.07 N and the minimal detectable change from 15.42 to 30.68 N. The percentage of standard error of measurement values were 2.95%, 3.74%, 2.88%, respectively, for absolute strength, right limb strength, and left limb strength. The adapted system showed an excellent cost-benefit relationship with optimal test-retest reliability. The findings suggest that the adapted system, using the WBB, is a reliable method for measuring the eccentric knee strength.

Validity and Test-Retest Reliability of a Novel Push Low-Cost Hand-Held Dynamometer for Knee Strength Assessment during Different Force Ranges.

The objective was to assess the instrumental validity and the test-retest reliability of a low-cost hand-held push dynamometer adapted from a load-cell based hanging scale (tHHD) to collect compressive forces in different ranges of compressive forces. Three independent raters applied 50 pre-established compressions each on the tHHD centered on a force platform in three distinct ranges: ~70 N, ~160 N, ~250 N. Knee isometric strength was also assessed on 19 subjects in two sessions (48 h apart) using the tHHD anchored by an inelastic adjustable strap. Knee extension and flexion were assessed with the participant seated on a chair with the feet resting on the floor, knees, and hips flexed at 90°. The isometric force peaks were recorded and compared. The ICC and the Cronbach's α showed excellent consistency and agreement for both instrumental validity and test-retest reliability (range: 0.89-0.99), as the correlation and determination coefficients (range: 0.80-0.99). The SEM and the MDC analysis returned adequate low values with a coefficient of variation less than 5%. The Bland-Altman results showed consistency and high levels of agreement. The tHHD is a valid method to assess the knee isometric strength, showing portability, cost-effectiveness, and user-friendly interface to provide an effective form to assess the knee isometric strength.

Validity of a portable hanging scale to assess the isometric muscle strength during knee movement.

Inexpensive and practical equipment to assess muscle strength can disseminate objective measures, which can provide valid information to implement effective treatment and exercise training. The purpose of the study was to examine the instrumental validity of the hanging scale (HS) to assess the muscle strength during knee flexion and extension by comparing the peak force values to a standard equipment (laboratory-grade load cell [LLC]). Knee isometric strength was assessed on thirty-two subjects (16 women and 16 men, 22 [5] years, 171 [9] cm, 69 [15] kg, 23 [4] kg/m2). The knee flexion was tested by placing the volunteer's body in prone with the knee flexed at 90°. Knee extension was assessed with the volunteer seated on a chair with the feet resting on the floor, knees, and hips flexed at 90°. No differences were observed comparing the isometric peak forces between a laboratory-grade load cell and a HS (p > 0.05). The intraclass correlation coefficient (ICC)1,1 returned values above 0.90. The Cronbach's α test also returned values above 0.90 for all comparisons. Bland-Altman results showed high levels of agreement with low risk of bias. The HS appears to be a valid method to assess the knee isometric strength. The portability, the cost-effectiveness and the simple user-friendly system provides an effective way to assess the knee isometric strength.

Scapular Retraction under Adduction Load: An Alternative to Overhead Exercises to Activate Infraspinatus, Upper, and Lower Trapezius in Subjects with and without Shoulder Pain.

Exercises for lower trapezius (LT) often use overhead positions, causing compressive forces to the subacromial space. Scapular retraction would be an alternative to activate LT muscle. The present study aimed to assess the excitation levels of infraspinatus, upper trapezius, and lower trapezius muscles during a scapular retraction exercise under progressive adduction loads in subjects with and without painful shoulder. Electromyography of infraspinatus (IS), upper trapezius (UT), and LT was recorded during scapular retraction under progressive adduction loads of 42 participants, divided into two groups: with (SP, n = 26) and without shoulder pain (nSP, n = 16). The adduction loads of 20%, 30%, 40%, and 50% of the maximal voluntary contraction (MVC) were applied using a load cell. Normalized electromyography and the ratio between UT and LT (UT:LT) were used for statistical analysis. No differences were observed between groups, but a condition effect occurred for all muscles: UT showed higher values at 50% vs. 20% of MVC (p = 0.004); LT showed higher values on 40% and 50% of MVC (p = 0.001; 0.006). Higher values for IS were noted at 40% of MVC (vs. 20% of MVC; p = 0.04) and at 50% of MVC (vs. 20% of MVC; p = 0.001, vs. 30% of MVC, p = 0.001; vs. 40% of MVC; p = 0.001). UT:LT showed lower values at 50% of MVC (vs. 20% of MVC; p = 0.001 and vs. 30% of MVC; p = 0.016). Scapular retraction with adduction loads at 40-50% is an alternative to overhead exercises aiming to activate the LT and the IS muscles. The exercise ensures higher levels of LT and IS excitation without increasing UT excitation.

Muscle excitation, force response, and efficiency during explosive force production after diacutaneous fibrolysis on lateral gastrocnemius of recreational athletes.

OBJECTIVE: Fibrous adhesions impair normal muscle mechanics. The present study aimed to assess lateral gastrocnemius muscle excitation, isometric force response, and neuromuscular efficiency during explosive force in plantarflexion before and after diacutaneous fibrolysis. METHODS: Thirty-five recreational athletes were allocated in the intervention group (n = 20) treated with diacutaneous fibrolysis, while the sham group (n = 15) was treated with placebo diacutaneous fibrolysis. Force response synchronized with surface electromyography during a plantarflexion task was collected. RESULTS: Differences between Pre- and Post-diacutaneous fibrolysis were observed for all variables, except for the placebo group. CONCLUSIONS: Diacutaneous fibrolysis was effective to increase force, muscle excitation, and neuromuscular efficiency on lateral gastrocnemius.

Validity of an Inexpensive Hanging Scale During Isometric Shoulder Movements.

CONTEXT: Strength assessment is essential to prescribe exercise in sports and rehabilitation. Low-cost valid equipment may allow continuous monitoring of training. OBJECTIVE: To examine the validity of a very low-cost hanging scale by comparing differences in the measures of peak force to a laboratory grade load cell during shoulder abduction, flexion, extension, and internal and external rotations. DESIGN: Analytical study. PARTICIPANTS: Thirty-two healthy subjects (18 women, age 26 [10] y, height 172 [8] cm, mass 69 [13] kg, body mass index 23 [4] kg/m2). MAIN OUTCOME MEASURES: The dependent variable was the maximal peak force (in kilogram-force). The independent variable was the instrument (laboratory grade load cell and hanging scale). RESULTS: No differences were observed while comparing the results. The intraclass correlation coefficients1,1 ranged from .96 to .99, showing excellent results. The Cronbach alpha test also returned >.99 for all comparisons. The SEM ranged from 0.02 to 0.04 kgf, with an averaged SD from 0.24 to 0.38 kgf. The correlation was classified as high for all tested movements (r > .99; P < .001), with excellent adjusted coefficients of determination (.96 < r2 < .99). Bland-Altman results showed high levels of agreement with bias ranging from 0.27 to 0.48. CONCLUSIONS: Hanging scale provides valid measures of isometric strength with similar output measures as laboratory grade load cell.

Effects of 8 weeks of masticatory muscles focused endurance exercises on women with oro-facial pain and temporomandibular disorders: A placebo randomised controlled trial.

BACKGROUND: Exercises are used to treat temporomandibular disorders (TMD), but they are often assessed with other therapies. Local endurance exercises may alter the resistance to fatigue and pain. OBJECTIVE: To assess the effects of an 8-week protocol of local endurance exercises of masticatory muscles on muscle excitation, force response, perceived pain and over muscle efficiency. DESIGN: Randomised controlled trial. SETTING: Ambulatory care. SUBJECTS: In a placebo randomised controlled trial, 46 women with TMD and oro-facial pain were randomised into intervention group and placebo group. The intervention group received a protocol of biting endurance exercises, controlled by biofeedback. The placebo group received a placebo (simulated laser therapy). MAIN OUTCOME MEASURES: The primary outcomes were collected at baseline, 4 weeks and 8 weeks. Pain was assessed through visual analogue scale (VAS) and pressure pain thresholds (PPT). Bite force was collected by a load cell synchronised with surface electromyography of masticatory muscles, bilaterally. RESULTS: Pain scores decreased for both groups, but the intervention group showed lower values at 8 weeks. No differences were noted between groups for PPT, but the results increased for both overtime. Time until fatigue and muscle efficiency were higher in the intervention group vs placebo group in both within- and between-subject analysis. Force increased from 4 to 8 weeks in the PG, without differences between groups. Temporal muscle excitation was higher on 8 weeks compared with baseline for the intervention group, without differences between groups. CONCLUSION: Eight-week exercise protocol of muscle endurance alleviates the pain and improves the resistance to fatigue and muscle efficiency in TMD subjects.

Pain, balance, grip strength and gait parameters of older adults with and without post-chikungunya chronic arthralgia.

OBJECTIVE: To compare the levels of pain, grip strength, balance and gait in older adults with and without post-Chikungunya chronic arthralgia (PCCA). METHODS: Sixty-two older adults, 30 with and 32 without PCCA participated in the study. Pain level was assessed using a Visual Analogue Scale (VAS). Gait during a 10-m walk was assessed using inertial sensors. Semi-static balance was assessed during an eyes-closed bipedal balance test on a force platform, and grip strength was assessed using a hand dynamometer. RESULTS: Participants with PCCA presented severe levels of pain (VAS > 7.5), poorer balance, lower grip strength, walked slower, with lower cadence and stride length and higher stride time and stride length variability than participants without PCCA (P < 0.001 for all variables). CONCLUSIONS: Older adults with PCCA had high levels of pain, impaired balance and gait and lower grip strength compared to older adults without PCCA.

Pilates experience vs. muscle activation during abdominal drawing-in maneuver.

The purpose of this study was to compare the activation of deep abdominal and spine stabilizer muscles of subjects with and without Pilates experience. Twenty-three subjects were divided into a no-experience group (n = 13) and an experienced group (n = 10). The subjects performed three 12-s drawing-in maneuver trials at 50% TrA/IO maximal voluntary contraction (MVC). The experienced group presented greater activation of both muscles than the no-experience group (62% vs. 32% MVC for the TrA/IO, and 52% vs. 12% MVC for the LD, p < 0.001). The no-experience group had higher variability among trials and did not reach 50% MVC for the TrA/IO, while the experienced group was able to reach and keep the TrA/IO activation at or above 50% MVC. Pilates experience and muscle activation were strongly associated. Pilates trained subjects were able to sustain concomitant abdominal and low back muscle contraction during the drawing-in maneuver, while subjects with no Pilates experience were not able to reach the same levels of abdominal activation and did not present significant low back muscle co-activation.

Immediate electromyographic changes of the upper limb muscles following cervical manipulation in a patient with essential tremor: a case report / Alterações eletromiográficas imediatas dos músculos dos membros superiores após manipulação cervical em uma paciente com tremor essencial: estudo de caso

Introduction and Objective: The purpose of this case report is to evaluate upper limb muscle electric behavior by surface electromyography before and after cervical manipulation in a patient with essential tremor. Methods: In 2009, essential tremor was diagnosed by a neurologist in a 25-year-old woman. Previous treatment included Paroxetine for a number of months, without alteration of her symptoms. The patient was assessed by surface electromyography of the upper limb muscles (flexor and extensor of the wrist, long heads of biceps and triceps) before and after being subjected to high-velocity, low-amplitude spinal manipulation to her mid cervical spine (C3-C4 level, 1 manipulation/side). Results: There was an increase of the median frequency rate and a decrease of the electrical activity of these muscles. Conclusion: This case study showed the cervical manipulation technique acutely modifying the electromyographic activity, increasing the median frequency, and decreasing the muscle recruitment of the upper limb. It suggests improved motor control during the tasks.

Introdução e Objetivo: O objetivo neste estudo de caso foi avaliar o comportamento elétrico dos músculos do membro superior, por eletromiografia, antes e após manipulação cervical em paciente com tremor essencial. Métodos: Uma mulher (25 anos) apresentou-se com tremor essencial, diagnosticado em 2009 por neurologista. Foi empregado tratamento prévio com Paroxetina por meses, sem diminuição dos sintomas. A paciente foi avaliada por eletromiografia dos músculos dos membros superiores (flexores e extensores do punho, cabeça longa do bíceps e do tríceps) antes e após manipulação de alta velocidade e baixa amplitude na cervical média (nível C3-C4, 1 manipulação para cada lado). Resultados: Observou-se aumento na frequência mediana e diminuição na atividade elétrica dos músculos avaliados. Conclusão: A técnica de manipulação cervical modificou de forma imediata a atividade eletromiográfica, aumentando a frequência mediana e diminuindo o recrutamento dos músculos do membro superior para a paciente estudada, sugerindo melhor controle motor durante a atividade proposta.