Asociación entre variables de empuje Isométrico de media pierna (EIMP) con variables antropométricas y cualidades físicas en jugadores varones de Rugby Amateurs / Relationships between Isometric Mid-Thigh pull with anthropometric variables and physical qualities in Amateur Rugby players / Relações entre a puxada isométrica do meio da coxa com variáveis antropométricas e qualidades físicas em jogadores amadores de rugby

Objetivo: el objetivo de este estudio es describir el perfil de las variables del EIMP entre las dos posiciones de juego y determinar las posibles asociaciones con las características antropométricas y las cualidades físicas de un grupo de jugadores Rugby amateurs chilenos. Hipótesis: es por eso por lo que podemos plantear como hipótesis la existencia de asociaciones entre las variables de EIMP y las cualidades físicas de los jugadores de RU. Diseño metodológico: este estudio tiene un diseño de cohorte observacional, descriptivo y correlacional. Se investigó la asociación existente entre las variables de EIMP con las pruebas físicas y las variables antropométricas. Fueron evaluados treinta y dos jugadores de rugby varones de nivel amateurs chilenos (promedio ( DE, edad, 23,3 ( 5,4 años). Resultados: para la variable Masa Muscular se encontraron asociaciones grandes (r = 0.53) (p = 0.001) con la FM y asociaciones moderadas (r = 0,48) (r = 0,47) (r = 0,44) (r = 0,46) con F50, F100, F150 y F200 respectivamente. También se pueden observar las asociaciones grandes (R2 = 0,305) (R2 = 0,297) (R2 = 0,267) entre 1RM PB y F200, F100 y F150, respectivamente. Conclusión: en conclusión, este estudio puede demostrar la existencia de asociaciones estadísticamente significativas entre algunas de las variables antropométricas y físicos con las variables de Fuerza de EIMP en jugadores de RU amateurs chilenos.

OBJECTIVE: The objective of this study is to describe the profile of the EIMP variables between two playing positions and to determine its possible associations with anthropometric characteristics and physical qualities of a group of Chilean amateur rugby players. HYPOTHESIS: There are associations between the EIMP variables and the physical qualities of UR players. METHODOLOGICAL DESIGN: This study has an observational, descriptive and correlational cohort design. The association between the EIMP variables, from the physical tests, and the anthropometric variables was investigated. Thirty-two Chilean amateur-level male rugby players were evaluated (mean ( SD, age, 23.3 ( 5.4 years). RESULTS: For the Muscle Mass variable, large associations were found (r=0.53) (p=0.001) to FM, and moderate associations (r=0.48) (r=0.47) (r=0.44) (r =0.46) to F50, F100, F150, and F200 respectively. Large associations (R2=0.305) (R2=0.297) (R2=0.267) between 1RM PB and F200, F100, and F150, respectively, can also be observed. CONCLUSION: In conclusion, this study can demonstrate the existence of statistically significant associations between some of the anthropometric and physical variables and the EIMP Strength variables in Chilean amateur UR players.

OBJETIVO: O objetivo deste estudo é descrever o perfil das variáveis EIMP entre as duas posições de jogo e determinar as possíveis associações com as características antropométricas e qualidades físicas de um grupo de jogadores amadores de rugby chilenos. HIPÓTESE: É por isso que podemos hipotetizar a existência de associações entre as variáveis do EIMP e as qualidades físicas dos jogadores do RU. DESENHO METODOLÓGICO: Este estudo tem um desenho de coorte observacional, descritivo e correlacional. Investigou-se a associação entre as variáveis do EIMP com os testes físicos e as variáveis antropométricas. Trinta e dois jogadores de rugby masculinos de nível amador chileno foram avaliados (média ( DP, idade, 23,3 ( 5,4 anos). RESULTADOS: Para a variável Massa Muscular foram encontradas grandes associações (r=0,53ejercicio y cualidades físicos) (r=0,47) (r=0,44) (r=0,46) com F50, F100, F150 e F200 respectivamente. Grandes associações (R2=0,305) (R2=0,297) (R2=0,267) entre 1RM PB e F200, F100 e F150 respebaloncestotambém podem ser observadas. CONCLUSÃO: Em conclusão, este estudo pode demonstrar a existência de associações estatisticamente significativas entre algumas das variáveis antropométricas e físicas com as variáveis EIMP Força em jogadores amadores do RU chilenos.

Isometric resistance training effects on lower limb muscle activity / Efeitos do treino isométrico resistido sobre a atividade muscular dos membros inferiores / Efectos del entrenamiento de resistencia isométrica en la actividad muscular de los miembros inferiores

ABSTRACT Introduction The high muscular strength in the hip joint is the foundation of jumping ability. Isometric resistance training includes the process of takeoff and landing, recruiting a more extensive set of muscle groups. Objective Analyze the isometric resistance training effects on lower limb muscle activity, including the coactivation of the antagonist's muscles. Methods By mathematical statistics, weight-bearing isometric resistance training effects on lower extremity maximal muscle strength and explosive power were observed. Changes in coactivation and preactivation levels of lower extremity antagonist muscles data are evaluated and compared before and after isometric resistance training. Results The peak angular velocity of the joints at the hip and ankle in the isometric resistance training group is significantly higher than the control group. There was no significant difference in the peak angular velocity of the knee between the groups (P<0.05). Conclusion Isometric resistance training can shorten the return period, shorten the amortization period, and increase the energy conversion capacity in the muscle-tendon complex. Evidence level II; Therapeutic Studies - Investigating the results.

RESUMO Introdução A elevada força muscular na articulação do quadril é o que fundamenta a habilidade do salto. O treino resistido isométrico inclui o processo de decolagem e aterrissagem, recrutando um conjunto maior de grupos musculares. Objetivo Analisar os efeitos do treino isométrico resistido sobre a atividade muscular dos membros inferiores, incluindo a coativação dos músculos antagonistas. Métodos Por meio de estatísticas matemáticas, observa-se o efeito do treino isométrico resistido com sustentação de peso na força muscular máxima das extremidades inferiores e sua potência explosiva. Os dados das mudanças nos níveis de coativação e pré-ativação dos músculos antagonistas dos membros inferiores são avaliados e comparados antes e após o treino isométrico resistido. Resultados O pico de velocidade angular das articulações no quadril e tornozelo do grupo de treino isométrico resistido é significativamente maior do que no grupo controle. Não houve diferença significativa no pico de velocidade angular do joelho entre os dois grupos (P<0,05). Conclusão O treino isométrico resistido pode encurtar o período de retorno, encurtar o período de amortização e aumentar a capacidade de conversão de energia no complexo músculo-tendíneo. Nível de evidência II; Estudos terapêuticos - Investigação de resultados.

RESUMEN Introducción La elevada fuerza muscular en la articulación de la cadera es lo que fundamenta la capacidad de saltar. El entrenamiento de resistencia isométrica incluye el proceso de despegue y aterrizaje, reclutando un conjunto mayor de grupos musculares. Objetivo Analizar los efectos del entrenamiento de resistencia isométrica en la actividad muscular de las extremidades inferiores, incluyendo la coactivación de los músculos antagonistas. Métodos Mediante la estadística matemática, se observó el efecto del entrenamiento de resistencia isométrica con carga de peso sobre la fuerza muscular máxima de las extremidades inferiores y su potencia explosiva. Los datos de los cambios en los niveles de coactivación y preactivación de los músculos antagonistas de las extremidades inferiores se evalúan y comparan antes y después del entrenamiento de resistencia isométrica. Resultados La velocidad angular máxima de las articulaciones en la cadera y el tobillo en el grupo de entrenamiento de resistencia isométrica es significativamente mayor que en el grupo de control. No hubo diferencias significativas en la velocidad angular máxima de la rodilla entre los dos grupos (P<0,05). Conclusión El entrenamiento de resistencia isométrica puede acortar el periodo de retorno, reducir el periodo de amortización y aumentar la capacidad de conversión de energía en el complejo músculo-tendón. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.

Entrenamiento de handgrip isométrico de alta intensidad en adultos mayores pre-hipertensos y con diagnóstico de hipertensión arterial sistémica etapa I / Effects high intensity isometric handgrip training on blood pressure of hypertensive older people

Background: Moderate isometric handgrip exercise is an effective tool in the management of systemic hypertension. Aim: To evaluate the effectiveness of a high intensity isometric handgrip exercise protocol for the reduction of blood pressure in older people with pre or stage-1 hypertension. Material and Methods: Twenty-three participants aged 73.8 ± 6.6 years (range 61-90) completed eight weeks of high intensity isometric handgrip training 2 times per week, performing 32 contractions maintained for 5 seconds, with breaks of 5 seconds. Blood pressure (BP) was measured at baseline and at the end of the intervention. Results: Systolic blood pressure decreased from 141 ± 11 to 127 ± 10 mmHg (p < 0.01). The decrease in diastolic blood pressure was from 79 ± 7 to 74 ± 6 mmHg (p < 0.01). Conclusions: A blood pressure reduction was recorded in these participants after a period of high intensity isometric handgrip exercise.

Association of maximal voluntary isometric handgrip strength with age, gender and handedness in older people / Fuerza de agarre isométrica máxima en relación a la edad, sexo y dominancia de mano

ABSTRACT Background: Maximal voluntary isometric handgrip strength (MVIHS) is influenced by age, sex, and handedness. Aim: To assess the association of MVIHS with age, sex, and handedness in older adults. Material and Methods: MVIHS was measured using a digital dynamometer in 60 men and 60 women aged 73 ± 6 years. Weight, height and handedness were also recorded. For analysis purposes, participants were divided into two age groups (65 to 70.9 years of age and ≥ 71 years). Results: A negative correlation was observed between age and MVIHS in the non-dominant (r = −0.65 and −0.59 in men and women, respectively) and dominant hands (r = −0.71 and −0.64 in men and women, respectively). When age and MVIHS were correlated in the group aged 65-70 years, a significant correlation was observed in the non-dominant (r = −045 and −0.61 in men and women, respectively) and dominant hands (r = −0.47 and −0.64 in men and women, respectively). In the group aged ≥ 71 years, a stronger correlation with age was also observed in the non-dominant (r = −0.92 and −0.90 in men and women, respectively) and dominant hands (r = −0.95 and −0.90 in men and women, respectively). MVIHS was 2.8 to 8.9% lower in the non-dominant than in the dominant hand in all age groups. MVIHS was lower in women than in men in both age groups. Conclusions: MVIHS declines with age (especially after 71 years of age), is higher in men than women, and higher in the dominant than the non-dominant hand.

Antecedentes: La fuerza de agarre isométrica voluntaria máxima (FAIVM) puede verse influenciada por la edad, el sexo y la dominancia. Objetivo: Describir la FAIVM y su relación con la edad, el sexo y la dominancia en adultos mayores. Material y Métodos: La FAIVM, la masa corporal, la talla, y la dominancia fueron medidas mediante protocolos estandarizados en 60 hombres e igual número de mujeres que fueron divididos en dos grupos acorde a su edad (65 a 70,9 años, y ≥ 71 años, respectivamente). Resultados: Se observó una correlación entre la edad y la FAIVM de mano no-dominante (hombres: r = −0,65; mujeres: r = −0,59) y dominante (hombres: r = −0,71; mujeres: r = −0,64). Al correlacionar la FAIVM y la edad en el grupo de 65-70 años, una correlación significativa fue observada en la mano no-dominante (hombres, r = −0,45; mujeres, r = −0,61) y mano dominante (hombres, r = −0,47; mujeres, r = −0,64). En el grupo ≥ 71 años, la edad tuvo una mayor correlación con la FAIVM de la mano no-dominante (hombres, r = −0,92; mujeres, r = −0,90) y mano dominante (hombres, r = −0,95; mujeres, r = −0,90). Comparada con la mano dominante, la mano no-dominante presentó menores valores de FAIVM en todos los grupos, variando entre −2,8 a −8,9%. Comparadas con los hombres, las mujeres presentaron menor FAIVM en mano dominante y no-dominante, en ambos grupos de edad. Conclusión: La FAIVM disminuye con la edad, especialmente desde los 71 años; es mayor en hombres comparados con mujeres y es mayor en mano dominante comparada con mano no-dominante.

Decreased muscle strength is associated with proinflammatory cytokines but not testosterone levels in men with diabetes

The aim of this study was to compare muscle strength in male subjects with type 2 diabetes mellitus (DM2) with and without low plasma testosterone levels and assess the relationship between muscle strength, testosterone levels, and proinflammatory cytokines. Males (75) aged between 18 and 65 years were divided into 3 groups: control group that did not have diabetes and had a normal testosterone plasma level (>250 ng/dL), DnormalTT group that had DM2 with normal testosterone levels, and the DlowTT group that had DM2 and low plasma testosterone levels (<250 ng/dL). The age (means±SD) of the groups was 48.4±10, 52.6±7, and 54.6±7 years, respectively. Isokinetic concentric and isometric torque of knee flexors and extensors were analyzed by an isokinetic dynamometer. Plasma testosterone and proinflammatory cytokine levels were determined by chemiluminescence and ELISA, respectively. Glycemic control was analyzed by glycated hemoglobin (HbA1C). In general, concentric and isometric torques were lower and tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β plasma levels were higher in the groups with diabetes than in controls. There was no correlation between testosterone level and knee torques or proinflammatory cytokines. Concentric and isometric knee flexion and extension torque were negatively correlated with TNF-α, IL-6, and HbA1C. IL-6 and TNF-α were positively correlated with HbA1C. The results of this study demonstrated that muscle strength was not associated with testosterone levels in men with DM2. Low muscle strength was associated with inflammatory markers and poor glycemic control.

Time to task failure of the contralateral untrained limb after high load-low repetition eccentric and low load-high repetition resistance training

Abstract Aims: Cross-training is the process whereby training of one limb gives rise to enhancements in the performance of the opposite, untrained limb and may be dependent on type of muscle contractions performed. The aim of this study was to investigate whether unilateral resistance training using eccentric contraction is more effective than concentric resistance training to improve time to task failure in the contralateral untrained limb. Methods:Subjects completed 12 weeks of resistance training consisting of 36 sessions, using unilateral leg exercise. Sustained isometric knee extension performed at 50% of maxmal force until task failure for the contralateral untrained leg. Surface electromyography (EMG) signals were simultaneously recorded from contralateral untrained quadriceps (vastusmedialis, rectus femoris, and vastuslateralis). Results: Time to task failure of the contralateraluntrained leg and associated EMG activitiessignificantly increased after 12 weeks ofunilateral resistance training(p<0.05). However, percent increase in time to task failure and EMG amplitude after eccentric resistance training was significantly higher than concentric resistance training (p<0.05). Conclusion: This study concluded that unilateral eccentric resistancetraining is superior to concentric resistance training to increase time to task failure in the contralateral untrained limb.(AU)

Relationships between Isometric Muscle Strength, Gait Parameters, and Gross Motor Function Measure in Patients with Cerebral Palsy

PURPOSE: This study investigated the correlation between isometric muscle strength, gross motor function, and gait parameters in patients with spastic cerebral palsy and to find which muscle groups play an important role for gait pattern in a flexed knee gait. MATERIALS AND METHODS: Twenty-four ambulatory patients (mean age, 10.0 years) with spastic cerebral palsy who were scheduled for single event multilevel surgery, including distal hamstring lengthening, were included. Preoperatively, peak isometric muscle strength was measured for the hip flexor, hip extensor, knee flexor, and knee extensor muscle groups using a handheld dynamometer, and three-dimensional (3D) gait analysis and gross motor function measure (GMFM) scoring were also performed. Correlations between peak isometric strength and GMFM, gait kinematics, and gait kinetics were analyzed. RESULTS: Peak isometric muscle strength of all muscle groups was not related to the GMFM score and the gross motor function classification system level. Peak isometric strength of the hip extensor and knee extensor was significantly correlated with the mean pelvic tilt (r=-0.588, p=0.003 and r=-0.436, p=0.033) and maximum pelvic obliquity (r=-0.450, p=0.031 and r=-0.419, p=0.041). There were significant correlations between peak isometric strength of the knee extensor and peak knee extensor moment in early stance (r=0.467, p=0.021) and in terminal stance (r=0.416, p=0.043). CONCLUSION: There is no correlation between muscle strength and gross motor function. However, this study showed that muscle strength, especially of the extensor muscle group of the hip and knee joints, might play a critical role in gait by stabilizing pelvic motion and decreasing energy consumption in a flexed knee gait.

Skinfold thickness affects the isometric knee extension torque evoked by Neuromuscular Electrical Stimulation

BACKGROUND: Subcutaneous adipose tissue may influence the transmission of electrical stimuli through to the skin, thus affecting both evoked torque and comfort perception associated with neuromuscular electrical stimulation (NMES). This could seriously affect the effectiveness of NMES for either rehabilitation or sports purposes. OBJECTIVE: To investigate the effects of skinfold thickness (SFT) on maximal NMES current intensity, NMES-evoked torque, and NMES-induced discomfort. METHOD: First, we compared NMES current intensity, NMES-induced discomfort, and NMES-evoked torque between two subgroups of subjects with thicker (n=10; 20.7 mm) vs. thinner (n=10; 29.4 mm) SFT. Second, we correlated SFT to NMES current intensity, NMES-induced discomfort, and NMES-evoked knee extension torque in 20 healthy women. The NMES-evoked torque was normalized to the maximal voluntary contraction (MVC) torque. The discomfort induced by NMES was assessed with a visual analog scale (VAS). RESULTS: NMES-evoked torque was 27.5% lower in subjects with thicker SFT (p=0.01) while maximal current intensity was 24.2% lower in subjects with thinner SFT (p=0.01). A positive correlation was found between current intensity and SFT (r=0.540, p=0.017). A negative correlation was found between NMES-evoked torque and SFT (r=-0.563, p=0.012). No significant correlation was observed between discomfort scores and SFT (rs=0.15, p=0.53). CONCLUSION: These results suggest that the amount of subcutaneous adipose tissue (as reflected by skinfold thickness) affected NMES current intensity and NMES-evoked torque, but had no effect on discomfort perception. Our findings may help physical therapists to better understand the impact of SFT on NMES and to design more rational stimulation strategies.

Intensity of swimming exercise influences aortic reactivity in rats

Exercise is known to cause a vasodilatory response; however, the correlation between the vasorelaxant response and different training intensities has not been investigated. Therefore, this study evaluated the vascular reactivity and lipid peroxidation after different intensities of swimming exercise in rats. Male Wistar rats (aged 8 weeks; 250-300 g) underwent forced swimming for 1 h whilst tied to loads of 3, 4, 5, 6, and 8% of their body weight, respectively (groups G3, G4, G5, G6 and G8, respectively; n=5 each). Immediately after the test, the aorta was removed and suspended in an organ bath. Cumulative relaxation in response to acetylcholine (10−12-10−4 M) and contraction in response to phenylephrine (10−12-10−5 M) were measured. Oxidative stress was estimated by determining malondialdehyde concentration. The percentages of aorta relaxation were significantly higher in G3 (7.9±0.20), G4 (7.8±0.29), and G5 (7.9±0.21), compared to the control group (7.2±0.04), while relaxation in the G6 (7.4±0.25) and G8 (7.0±0.06) groups was similar to the control group. In contrast, the percentage of contraction was significantly higher in G6 (8.8 ±0.1) and G8 (9.7±0.29) compared to the control (7.1±0.1), G3 (7.3±0.2), G4 (7.2±0.1) and G5 (7.2±0.2%) groups. Lipid peroxidation levels in the aorta were similar to control levels in G3, G4 and G5, but higher in G6 and G8, and significantly higher in G8 (one-way ANOVA). These results indicate a reduction in vasorelaxing activity and an increase in contractile activity in rat aortas after high-intensity exercise, followed by an increase in lipid peroxidation.

Analysis of three different equations for predicting quadriceps femoris muscle strength in patients with COPD / Análise de três diferentes fórmulas de predição de força muscular do quadríceps femoral em pacientes com DPOC

AbstractObjective: To compare equations for predicting peak quadriceps femoris (QF) muscle force; to determine the agreement among the equations in identifying QF muscle weakness in COPD patients; and to assess the differences in characteristics among the groups of patients classified as having or not having QF muscle weakness by each equation.Methods: Fifty-six COPD patients underwent assessment of peak QF muscle force by dynamometry (maximal voluntary isometric contraction of knee extension). Predicted values were calculated with three equations: an age-height-weight-gender equation (Eq-AHWG); an age-weight-gender equation (Eq-AWG); and an age-fat-free mass-gender equation (Eq-AFFMG).Results: Comparison of the percentage of predicted values obtained with the three equations showed that the Eq-AHWG gave higher values than did the Eq-AWG and Eq-AFFMG, with no difference between the last two. The Eq-AHWG showed moderate agreement with the Eq-AWG and Eq-AFFMG, whereas the last two also showed moderate, albeit lower, agreement with each other. In the sample as a whole, QF muscle weakness (< 80% of predicted) was identified by the Eq-AHWG, Eq-AWG, and Eq-AFFMG in 59%, 68%, and 70% of the patients, respectively (p > 0.05). Age, fat-free mass, and body mass index are characteristics that differentiate between patients with and without QF muscle weakness.Conclusions: The three equations were statistically equivalent in classifying COPD patients as having or not having QF muscle weakness. However, the Eq-AHWG gave higher peak force values than did the Eq-AWG and the Eq-AFFMG, as well as showing greater agreement with the other equations.

ResumoObjetivo:Comparar diferentes fórmulas de predição do pico de força muscular do quadríceps femoral (QF); investigar a concordância entre elas para identificar fraqueza muscular de QF em pacientes com DPOC; e verificar as diferenças nas características nos grupos de pacientes classificados com presença ou ausência dessa fraqueza de acordo com cada fórmula.Métodos: Cinquenta e seis pacientes com DPOC foram avaliados quanto ao pico de força muscular do QF por dinamometria (contração isométrica voluntária máxima de extensão de joelho). Os valores preditos foram calculados com três fórmulas: uma fórmula composta por idade-altura-peso-gênero (F-IAPG); uma por idade-peso-gênero (F-IPG); e uma por idade-massa magra-gênero (F-IMMG).Resultados: A comparação da porcentagem do predito obtida pelas fórmulas mostrou a F-IAPG com maiores valores do que os valores de F-IPG e F-IMMG, sem diferença entre as duas últimas. A F-IAPG apresentou concordância moderada com F-IPG e F-IMMG, enquanto essas últimas também apresentaram concordância moderada, mas menor, entre si. Do total de pacientes, a fraqueza muscular de QF (< 80% do predito) foi identificada por F-IAPG, F-IPG e F-IMMG em 59%, 68% e 70% dos pacientes, respectivamente (p > 0,05). Idade, massa magra e índice de massa corpórea são características que diferenciam pacientes com e sem fraqueza muscular de QF.Conclusões: As três fórmulas foram estatisticamente equivalentes para classificar pacientes com DPOC como portadores ou não de fraqueza muscular de QF. Entretanto, a F-IAPG apresentou maiores valores de pico de força do que F-IPG e F-IMMG, assim como maior concordância com as outras fórmulas.

Influence of obstructive sleep apnea syndrome in the fluctuation of the submaximal isometric torque of knee extensors in patients with early-grade osteoarthritis

OBJECTIVE: The aim of this study was to investigate whether obstructive sleep apnea (OSA) alters the fluctuation of submaximal isometric torque of the knee extensors in patients with early-grade osteoarthritis (OA).METHOD: The study included 60 male volunteers, aged 40 to 70 years, divided into four groups: Group 1 (G1) - Control (n=15): without OA and without OSA; Group 2 (G2) (n=15): with OA and without OSA; Group 3 (G3) (n=15): without OA and with OSA; and Group 4 (G4) (n=15) with OA and with OSA. Five patients underwent maximal isometric contractions of 10 seconds duration each, with the knee at 60° of flexion to determine peak torque at 60°. To evaluate the fluctuation of torque, 5 submaximal isometric contractions (50% of maximum peak torque) of 10 seconds each, which were calculated from the standard deviation of torque and coefficient of variation, were performed.RESULTS: Significant differences were observed between groups for maximum peak torque, while G4 showed a lower value compared with G1 (p=0.005). Additionally, for the average torque exerted, G4 showed a lower value compared to the G1 (p=0.036). However, no differences were found between the groups for the standard deviation (p=0.844) and the coefficient of variation (p=0.143).CONCLUSION: The authors concluded that OSA did not change the parameters of the fluctuation of isometric submaximal torque of knee extensors in patients with early-grade OA.

Reliability of new software in measuring cervical multifidus diameters and shoulder muscle strength in a synchronized way; an ultrasonographic study

OBJECTIVES: This study was conducted with the purpose of evaluating the inter-session reliability of new software to measure the diameters of the cervical multifidus muscle (CMM), both at rest and during isometric contractions of the shoulder abductors in subjects with neck pain and in healthy individuals.METHOD: In the present study, the reliability of measuring the diameters of the CMM with the Sonosynch software was evaluated by using 24 participants, including 12 subjects with chronic neck pain and 12 healthy individuals. The anterior-posterior diameter (APD) and the lateral diameter (LD) of the CMM were measured in a resting state and then repeated during isometric contraction of the shoulder abductors. Measurements were taken on separate occasions 3 to 7 days apart in order to determine inter-session reliability. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and smallest detectable difference (SDD) were used to evaluate the relative and absolute reliability, respectively.RESULTS: The Sonosynch software has shown to be highly reliable in measuring the diameters of the CMM both in healthy subjects and in those with neck pain. The ICCs 95% CI for APD ranged from 0.84 to 0.94 in subjects with neck pain and from 0.86 to 0.94 in healthy subjects. For LD, the ICC 95% CI ranged from 0.64 to 0.95 in subjects with neck pain and from 0.82 to 0.92 in healthy subjects.CONCLUSIONS: Ultrasonographic measurement of the diameters of the CMM using Sonosynch has proved to be reliable especially for APD in healthy subjects as well as subjects with neck pain.

Neural adaptations in isometric contractions with EMG and force biofeedback

This study aimed to evaluate the quadriceps femoris neural adaptations during isometric contractions using force and electromyogram (EMG) signals as visual biofeedback. Forty-two participants were randomly assigned to three groups: EMG group, tested with EMG biofeedback; Force group, tested with force biofeedback; and Control group, tested without biofeedback. Evaluations were performed pre (baseline) and post-tests to determine the maximum force and EMG amplitude during maximal voluntary isometric contraction (MVIC). The tests consisted of series of MVICs in which the participants were encouraged to surpass the force or EMG thresholds determined at baseline. The vastus lateralis EMG amplitude and knee extensor force increased significantly in all groups when compared the baseline and post-test evaluations values ​​(p < .05). EMG percentage gain was significantly different between Force and Control groups (p < .01), while force percentage gain was not different between groups. Force biofeedback was more effective in producing neural adaptations.

Este estudo avaliou as adaptações neurais do quadríceps durante contrações isométricas usando os sinais de força e eletromiografia (EMG) como biofeedback. Quarenta e dois sujeitos foram distribuídos em três grupos: EMG, testado com biofeedback da EMG; Força, testado com biofeedback de força; e Controle, testado sem biofeedback. As avaliações foram realizadas pré/pós-testes para determinar a máxima força e amplitude EMG durante contrações isométricas voluntárias máximas (CIVM). Os testes consistiram em séries de CIVM onde os sujeitos foram encorajados a ultrapassar os limiares de força e EMG inicialmente determinados. A amplitude EMG do vasto lateral e a força extensora do joelho aumentaram significativamente em todos os grupos quando comparadas as avaliações pré e pós-testes (p < 0,05). A porcentagem de ganho EMG foi significativamente diferente entre os grupos Força e Controle (p < 0,01), enquanto que a porcentagem de ganho da força não foi diferente entre os grupos. O biofeedback de força foi mais efetivo em produzir adaptações neurais.

Este estudio evaluó las adaptaciones neurales de cuádriceps durante contracciones isométricas usando los signos de fuerza y ​​electromiografía (EMG) como biofeedback. Cuarenta y dos sujetos fueron divididos en tres grupos: EMG, probado con biofeedback EMG; Fuerza, probado con biofeedback de fuerza; y control, probado sin biofeedback. Las avaluaciones se realizaron pre/post pruebas para determinar la máxima fuerza y amplitud EMG durante contracciones isométricas voluntarias máximas (CIVM). Las pruebas consistieron en series de CIVM en que los sujetos fueron encorajados a cruzar el umbral de fuerza y EMG ​​ inicialmente determinados. La amplitud EMG del vasto lateral y fuerza de los extensores de la rodilla aumentó significativamente en todos los grupos al comparar las avaluaciones pre y post pruebas (p < 0,05). El porcentaje de ganancia EMG fue significativamente diferente entre los grupos Fuerza y ​​control (p < 0,01), mientras que el porcentaje de aumento de la fuerza no fue diferente entre los grupos. Biofeedback de fuerza fue más eficaz en producir adaptaciones neurales.

Fadiga muscular entre séries de exercícios isocinéticos em mulheres jovens / Muscle fatigue between isokinetic exercises sets in young women

OBJETIVO: Avaliar o efeito de dois Intervalos de Recuperação (IR) no pico de torque (PT) e no trabalho total (TT) isocinético em mulheres jovens. MÉTODOS: 17 mulheres, destreinadas, (27,2 ± 4,1 anos; 56,8 ± 6,9 kg; 162,6 ± 7,0 cm) realizaram três séries de 10 extensões isocinéticas do joelho a 60° e 180°/s, com um e dois minutos de IR. A análise estatística foi a ANOVA dois x três [IR (um e dois minutos) x série (1ª, 2ª e 3ª)] com α < 0.05. RESULTADOS: Um minuto de IR não foi suficiente para manter o PT e o TT ao longo das séries (p<0,05) a 60º (redução de 15,7% no PT e 19,8% no TT) e 180º/s (redução de 3,6% no PT e de 5,6% no TT). Dois minutos foram suficientes apenas a 180º/s. Contudo, a 60°/s, dois minutos de IR possibilitou um maior PT na segunda e na terceira série em relação a um minuto (p<0,05). CONCLUSÃO: Dois minutos são suficientes para manutenção do PT em um protocolo de treinamento isocinético a 180º/s, mas não a 60º/s em mulheres jovens.

OBJECTIVE: To examine the effect of two rest interval (RI) on isokinetic Peak Torque (PT) and total work (TW) produced by young women. METHODS: 17 untrained women (27.2 ± 4.1 yrs; 56.8 ± 6.9 kg; 162.6 ± 7.0 cm) performed three sets of 10 unilateral isokinetic knee extension repetitions at 60° and 180°/s with one and two minutes of RI. Statistical evaluation was performed using a two x three ANOVA [RI (one and two minutes) x set (1st, 2nd, 3rd)] with α < 0.05. RESULTS: One minute was not enough to keep PT and TW between sets (p<0.05) at 60º (reduction of 15.7% in PT and 19.8% in TW) and 180º/s (reduction of 3.6% in PT and 5.6% in TT). Two minutes was enough only at 180º/s. However, two minutes of RI was greater (p<0.05) than one minutes at 60°/s for PT during the 2nd and 3rd sets. CONCLUSION: Two minutes is sufficient to keep PT within typical isokinetic resistance training protocols at 180º/s, but not at 60º/s in young women.

Progress in isokinetic technology in testing and training for assessment of muscle function / 法医学杂志

Isokinetic technology in testing and training is the most advanced practical technique in the evaluation of muscle function. This method is a continuous dynamic test in the full range of the joint motion which has strong pertinence at the aspect of assessing muscle strength, and is an objective and quantitative method for reflecting each point's muscle strength in the range of the joint motion. This article reviews the key concepts, brief history of development and influencing factors of isokinetic technology in testing and training, introduces the progress in the field of rehabilitation medicine and sport science, etc., and discusses the future exploration in forensic science.

Respostas hemodinâmicas a um protocolo de treinamento isométrico de preensão manual / Hemodynamic responses to an isometric handgrip training protocol / Respuestas hemodinámicas a un protocolo de entrenamiento isométrico de prensión manual

FUNDAMENTO: No passado, os exercícios isométricos foram proscritos para cardiopatas. Contudo, evidências recentes sugerem que um protocolo de treinamento isométrico de preensão manual (PTIM) - quatro séries de dois minutos a 30 por cento da força máxima - provoca efeitos favoráveis sobre a modulação autonômica e reduz os níveis de pressão arterial sistólica (PAS) e diastólica (PAD) de repouso. OBJETIVO: Visando obter subsídios para uma ampla aplicabilidade clínica, quantificamos as principais respostas hemodinâmicas durante uma sessão de PTIM em pacientes de um programa de exercício supervisionado. MÉTODOS: Quarenta e um pacientes (36 homens) realizaram o PTIM com medidas da frequência cardíaca (FC) e da PA antes, durante cada uma das duas séries feitas com o braço esquerdo e um minuto após a finalização. As medidas foram colhidas mediante um sinal de eletrocardiograma em um tensiômetro oscilométrico digital Tango+, previamente validado para condições de exercício físico. RESULTADOS: PTIM foi adequadamente realizado e sem a ocorrência de reações clínicas adversas. Observou-se um pequeno aumento dos níveis de PAS e de PAD, respectivamente, 16 e 7 mm Hg (p < 0,05) e um incremento ainda menor da FC - 3 bpm - (p < 0,05), quando compararam-se os dados obtidos aos 80 segundos da última série com os de pré-exercício. Um minuto pós-esforço, os valores de FC, de PAS e PAD já haviam praticamente retornado aos níveis iniciais. CONCLUSÃO: PTIM foi bem tolerado por pacientes em programas de exercício, gerando uma repercussão hemodinâmica transiente e modesta, sem induzir a rápida inativação vagal cardíaca característica dos exercícios dinâmicos e curtos.

BACKGROUND: In the past, isometric exercises were proscribed for heart disease. However, recent evidence suggests that an isometric handgrip training (IHT) protocol - four sets of two minutes at 30 percent of maximum strength - produces favorable effects on the autonomic modulation and reduces resting systolic (SBP) and diastolic (DBP) blood pressure. OBJECTIVE: Aiming at obtaining support for broad clinical applicability, we quantified the main hemodynamic responses during an IHT session in patients from a supervised physical exercise program. METHODS: Forty-one patients (36 men) underwent the IHT with measurements of heart rate (HR) and BP before, during each of the two series performed with the left arm and one minute after completion. Measurements were obtained by an electrocardiogram signal in a digital Tango + oscillometric tensiometer, previously validated for physical exercise conditions. RESULTS: The IHT was appropriately carried out, with no clinical adverse reactions. There was a small increase in SBP and DBP levels, respectively, of 16 and 7 mmHg (p <0.05) and an even smaller increase in HR - 3 bpm - (p <0.05) when we compared the data obtained at 80 seconds of the last series with the pre-exercise CONCLUSION: IHT was well tolerated by patients undergoing exercise programs, resulting in a transient and modest hemodynamic effect, without inducing rapid cardiac vagal inactivation, characteristic of dynamic and short exercises.

Progress on the evaluation of limbs muscle function / 法医学杂志

Evaluation of limbs muscle function is one of the difficult tasks in forensic clinical medicine. Recently, there are more and more cases needed to be evaluated on the limbs muscle function in forensic clinical appraisal. Thus the assessment methods for muscle function have been concerned increasingly. This paper introduces the classification of muscle function and the type of muscle contraction, reviews the assessment methods for muscle function and their application value, such as manual muscle test, simple instrumental muscle test, isokinetic muscle test and electrophysiological test. It has also proposed to evaluate the muscle function with multiple methods comprehensively.

Respostas cardiovasculares durante avaliação muscular isocinética em claudicantes / Cardiovascular responses during isokinetic muscle assessment in claudicant patients

FUNDAMENTO: A dinamometria isocinética tem tido crescente importância para avaliação da função muscular em indivíduos com claudicação intermitente. No entanto, ainda há escassez de informações sobre as respostas cardiovasculares desses doentes durante este tipo de avaliação. OBJETIVO: Avaliar e comparar as respostas cardiovasculares na avaliação da força e resistência muscular de dois exercícios comumente utilizados para de pacientes com CI (flexão plantar/dorsiflexão e flexão/extensão de joelhos). MÉTODOS: Dezessete claudicantes com doença estável há pelo menos 6 meses compuseram a amostra avaliada no dinamômetro isocinético. Frequência cardíaca, pressão arterial e duplo produto foram mensurados não invasivamente em repouso e no pico do esforço, em protocolos específicos para avaliação de força e resistência muscular. RESULTADOS: Com exceção da pressão arterial diastólica, a frequência cardíaca, pressão arterial sistólica e o duplo produto aumentaram durante o exercício em comparação ao repouso (p < 0,05). A frequência cardíaca e o duplo produto sofreram maior elevação durante o exercício de extensão/flexão de joelho, em comparação ao exercício de flexão plantar/dorsiflexão (P < 0,05). Maiores incrementos na frequência cardíaca foram observados durante o protocolo de avaliação da resistência em comparação ao da avaliação da força muscular. CONCLUSÃO: Os testes isocinéticos de avaliação da força e resistência musculares em pacientes com CI promovem aumento da frequência cardíaca, da pressão arterial sistólica e do duplo produto durante sua execução. Estes aumentos são maiores nos testes de resistência muscular e nos que envolvem maior massa muscular, sugerindo que testes de força de pequenos grupamentos musculares promovem menor sobrecarga cardiovascular nesses pacientes.

BACKGROUND: Isokinetic dynamometry is becoming increasingly important for the assessment of muscle function in individuals with intermittent claudication. However, there is still little information available about the cardiovascular responses of these patients during this type of assessment. OBJECTIVE: To assess and compare the cardiovascular responses recorded during the assessment of muscle strength and endurance for two exercises commonly used in patients with IC (plantar flexion/dorsiflexion and knee flexion/extension). METHODS: The sample consisted of 17 claudicant patients with stable disease for at least 6 months. During the isokinetic dynamometer testing, non-invasive measurements of heart rate, blood pressure and double product at rest and at peak exertion were obtained according to specific protocols established for muscle strength and endurance assessment. RESULTS: Except for diastolic blood pressure, heart rate, systolic blood pressure and double product values rose during the exercise compared to the resting stage (p < 0.05). Elevations in heart rate and double product values were higher during knee extension/flexion than during plantar flexion/dorsiflexion (p < 0.05). Increases in heart rate were also higher during the endurance assessment protocol than during muscle strength assessment. CONCLUSION: Isokinetic strength and endurance testing in patients with IC results in elevation of heart rate, systolic blood pressure and double product values during the exercises. These increases are higher during the muscle endurance exercises and in those involving greater muscle mass, suggesting that strength testing of small muscle groups causes less cardiovascular overload in these patients.

Low-frequency fatigue at maximal and submaximal muscle contractions

Skeletal muscle force production following repetitive contractions is preferentially reduced when muscle is evaluated with low-frequency stimulation. This selective impairment in force generation is called low-frequency fatigue (LFF) and could be dependent on the contraction type. The purpose of this study was to compare LFF after concentric and eccentric maximal and submaximal contractions of knee extensor muscles. Ten healthy male subjects (age: 23.6 ± 4.2 years; weight: 73.8 ± 7.7 kg; height: 1.79 ± 0.05 m) executed maximal voluntary contractions that were measured before a fatigue test (pre-exercise), immediately after (after-exercise) and after 1 h of recovery (after-recovery). The fatigue test consisted of 60 maximal (100 percent) or submaximal (40 percent) dynamic concentric or eccentric knee extensions at an angular velocity of 60°/s. The isometric torque produced by low- (20 Hz) and high- (100 Hz) frequency stimulation was also measured at these times and the 20:100 Hz ratio was calculated to assess LFF. One-way ANOVA for repeated measures followed by the Newman-Keuls post hoc test was used to determine significant (P < 0.05) differences. LFF was evident after-recovery in all trials except following submaximal eccentric contractions. LFF was not evident after-exercise, regardless of exercise intensity or contraction type. Our results suggest that low-frequency fatigue was evident after submaximal concentric but not submaximal eccentric contractions and was more pronounced after 1-h of recovery.