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1.
Sports Biomech ; 19(1): 1-25, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29781788

RESUMO

The use of isometric strength testing, particularly the isometric mid-thigh pull (IMTP) has increased dramatically over the last decade. The IMTP and isometric squat (ISqT) provide one aspect of performance monitoring with variables such as peak force and rate of force development being derived from the force-time curve. The reliability of some of these variables is conflicting in the literature, and the reporting of the reliability is not standardised across the research. The majority of research only reports intraclass correlation coefficients with very few studies reporting coefficient of variation and 90% confidence intervals. Additionally, methods used to calculate variables from the force-time curve differ across studies. An aim of muscle strength testing is to provide normative values for specific sports, allowing coaches to distinguish between performance levels or evaluate the effects of training on performance. This narrative review aims to evaluate studies that have researched the reliability and/or reported normative data for both tests. Additionally, the testing protocols and the force-time curve analysis techniques utilised are discussed, concluding with practical applications for coaches on the uses and limitations of these tests. Results demonstrate that peak force is the most reliable measure and can be used to determine maximum strength capabilities.


Assuntos
Teste de Esforço/métodos , Força Muscular/fisiologia , Coxa da Perna/fisiologia , Levantamento de Peso , Fenômenos Biomecânicos , Humanos , Contração Isométrica/fisiologia , Valores de Referência , Reprodutibilidade dos Testes , Esportes/fisiologia
2.
Clin Interv Aging ; 14: 1643-1648, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31564844

RESUMO

Purpose: Oral frailty or the loss of oral functionality can be a symptomatic precursor of overall frailty. Previous studies have suggested that decreased tongue pressure causes a decline in ingesting and swallowing function and poor nutrition. This study investigated what factor(s) contribute to tongue pressure, thereby leading to frailty. Patients and methods: For the purposes of the present study, 467 residents of Hirosaki city in northern Japan aged≥60 years who completed a questionnaire about frailty and underwent an intraoral assessment, which included number of teeth, presence or absence of periodontitis, tongue pressure, and oral diadochokinesis (ODK) were recruited. Results: Of the 467 participants with complete data sets, frailty was identified in 13 (7.5%) of 173 males and in 34 (11.6%) of 294 females. Significantly fewer teeth, lower tongue pressure, and a reduced diadochokinetic syllable rate were more prevalent among frail than among healthy residents. Multivariable logistic regression analysis revealed that age, body mass index, number of teeth, and tongue pressure significantly contributed to frailty, whereas ODK did not. Multiple regression analysis showed that tongue pressure was positively associated with muscle index and number of teeth. Conclusion: The results of the present study suggest that fewer teeth and lower tongue pressure, but not ODK function, are risk factors for developing overall frailty among older residents.


Assuntos
Fragilidade/diagnóstico , Contração Isométrica/fisiologia , Saúde Bucal , Língua/fisiologia , Idoso , Feminino , Fragilidade/fisiopatologia , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Pressão , Fatores de Risco
3.
Hum Mov Sci ; 67: 102516, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31539754

RESUMO

This study investigated motor responses of force release during isometric elbow flexion by comparing effects of different ramp durations and step-down magnitudes. Twelve right-handed participants (age: 23.1 ±â€¯1.1) performed trajectory tracking tasks. Participants were instructed to release their force from the reference magnitude (REF; 40% of maximal voluntary contraction force) to a step-down magnitude of 67% REF or 33% REF and maintain the released magnitude. Force release was guided by ramp durations of either 1 s or 5 s. Electromyography of the biceps brachii and triceps brachii was performed during the experimental task, and the co-contraction ratio was evaluated. Force output was recorded to evaluate the parameters of motor performance, such as force variability and overshoot ratio. Although a longer ramp duration of 5 s decreased the force variability and overshoot ratio than did shorter ramp duration of 1 s, higher perceived exertion and co-contraction ratio were followed. Force variability was greater when force was released to the step-down magnitude of 33% REF than that when the magnitude was 67% REF, however, the overshoot ratio showed opposite results. This study provided evidence proving that motor control strategies adopted for force release were affected by both duration and step-down magnitude. In particular, it implies that different control strategies are required according to the level of step-down magnitude with a relatively short ramp duration.


Assuntos
Articulação do Cotovelo/fisiologia , Contração Isométrica/fisiologia , Músculo Esquelético/fisiologia , Braço/fisiologia , Eletromiografia , Humanos , Masculino , Desempenho Psicomotor/fisiologia , Amplitude de Movimento Articular/fisiologia , Fatores de Tempo , Adulto Jovem
4.
Med Sci Sports Exerc ; 51(9): 1961-1970, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31415444

RESUMO

PURPOSE: The purpose of this study was to compare the development and etiology of neuromuscular fatigue of the knee extensor muscles at different muscle-tendon unit (MTU) lengths during repeated maximal voluntary isometric contractions (MVIC) between boys and men. METHODS: Twenty-two prepubertal boys (9-11 yr) and 22 men (18-30 yr) performed three knee extensor fatigue protocols at short (SHORT), optimal (OPT), and long (LONG) MTU lengths, consisting of repeating 5-s MVIC interspersed with 5-s passive recovery periods until torque reached 60% of the initial MVIC torque. The etiology of neuromuscular fatigue was identified using noninvasive methods such as surface electromyography, near-infrared spectroscopy, magnetic nerve stimulation and twitch interpolation technique. RESULTS: The number of repetitions was significantly lower in men at OPT (14.8 ± 3.2) and LONG (15.8 ± 5.8) than boys (39.7 ± 18.4 and 29.5 ± 10.2, respectively; P < 0.001), whereas no difference was found at SHORT between both age groups (boys, 33.7 ± 15.4; men, 40.9 ± 14.2). At OPT and LONG boys showed a lower reduction in the single potentiated twitch (Qtwpot) and a greater decrease in the voluntary activation level than men. At SHORT, both populations displayed a moderate Qtwpot decrement and a significant voluntary activation reduction (P < 0.001). The differences in maximal torque between boys and men were almost twice greater at OPT (223.9 N·m) than at SHORT (123.3 N·m) and LONG (136.5 N·m). CONCLUSIONS: The differences in neuromuscular fatigue between children and adults are dependent on MTU length. Differences in maximal torque could underpin differences in neuromuscular fatigue between children and adults at OPT and SHORT. However, at LONG these differences do not seem to be explained by differences in maximal torque. The origins of this specific effect of MTU length remain to be determined.


Assuntos
Contração Isométrica/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Tendões/fisiologia , Adolescente , Adulto , Criança , Eletromiografia , Humanos , Joelho/fisiologia , Magnetismo , Músculo Esquelético/inervação , Torque , Adulto Jovem
5.
J Sports Sci ; 37(23): 2667-2675, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31418319

RESUMO

This study aimed to evaluate responsiveness (ability to detect change) of isometric force-time measures to neuromuscular fatigue in resistance-trained participants using two differing protocols that modified both the instructions provided to participants and the duration of the test. Both protocols were completed at two knee joint angles in the isometric squat test. Ten participants volunteered to take part in this study (age: 27.0 ± 4.5 years, strength training experience: 7.7 ± 2.6 years). Isometric peak force (ISqTpeak) and isometric explosive force (ISqTexp) test protocols were assessed at two joint angles (knee angle 100° and 125°) pre-high intensity strength training, immediately post strength training, 24-h post, 48-h post and analysed for peak and RFD performance. Participants completed eight sets of three repetitions of the back-squat exercise as the high-intensity strength training. Results showed the highest standardised response means (SRM) detected was peak force using the ISqTpeak 100, SRM -1.97 compared to an SRM of -1.31 for RFD 200 ms in the ISqTexp 125. Peak force was the most responsive variable using the ISqTpeak protocol, whereas the ISqTexp protocol was most responsive for RFD measures. Therefore, ISqTpeak and ISqTexp test protocols should not be used interchangeably to evaluate RFD variables.


Assuntos
Contração Isométrica/fisiologia , Fadiga Muscular/fisiologia , Treinamento de Resistência/métodos , Levantamento de Peso/fisiologia , Adulto , Teste de Esforço/métodos , Feminino , Humanos , Articulação do Joelho/fisiologia , Masculino , Força Muscular/fisiologia , Mialgia/etiologia , Mialgia/fisiopatologia , Treinamento de Resistência/efeitos adversos , Adulto Jovem
6.
Int J Sports Med ; 40(12): 789-795, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31466083

RESUMO

We investigated the effects of sling-based, suspended push-up training on muscle size and function of upper limb and abdominal muscles. Eight men conducted suspended push-ups to failure 3 sets/session, 3 sessions/week, for 8 weeks. The maximum number of push-ups during training gradually and significantly increased from the first to last training session (+92%), suggesting improved muscle endurance. After the training, muscle thickness of the elbow extensors (+16%) and flexors (+3%), as well as abdominal muscles (rectus abdominis: RA,+27%; external oblique: EO,+14%) significantly increased. No changes occurred in maximum isometric strength of elbow extension or flexion, nor in 1-repetition maximum bench press. In a follow-up experiment, electromyograms (EMGs) of RA, EO and internal oblique (IO) during suspended push-ups to failure were measured and normalized to those during maximum voluntary contraction of each muscle (% EMGmvc) in six men. EMG significantly increased when reaching failure in all muscles (RA: 46-88%, EO: 32-50%, IO: 19-52%, start-end), and was particularly high in RA. These results suggest that suspended push-up training can augment size of not only upper limb but also abdominal muscles, likely attributable to high muscle activities during exercise; however, this does not necessarily improve maximum strength after training thus warrants careful interpretation/application.


Assuntos
Músculos Abdominais/anatomia & histologia , Músculos Abdominais/fisiologia , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/fisiologia , Condicionamento Físico Humano/métodos , Extremidade Superior/fisiologia , Adolescente , Adulto , Eletromiografia , Humanos , Contração Isométrica/fisiologia , Masculino , Força Muscular/fisiologia , Adulto Jovem
7.
J Athl Train ; 54(9): 945-952, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31454288

RESUMO

CONTEXT: Upper extremity (UE) musculoskeletal injuries are common in baseball athletes due to the increased demand placed on the UE. The link between risk factors for UE musculoskeletal injuries and baseball athletes' perceived UE function and pain, as measured by the Kerlan-Jobe Orthopaedic Clinic (KJOC) questionnaire, is unclear. OBJECTIVE: To (1) describe the musculoskeletal characteristics of the UE (posture, range of motion, flexibility, and isometric strength) in a population of baseball athletes and (2) determine the predictive capability of UE musculoskeletal characteristics for the KJOC score in these athletes. DESIGN: Cohort study. SETTING: Athletic training room. PATIENTS OR OTHER PARTICIPANTS: A total of 37 male National Collegiate Athletic Association Division I baseball athletes (age = 20.10 ± 1.27 years, height = 186.96 ± 7.64 cm, mass = 90.60 ± 10.69 kg). INTERVENTION(S): Athletes self-reported all shoulder musculoskeletal injuries and completed the KJOC questionnaire. Postural assessment consisted of forward head and shoulder posture. Flexibility tests characterized glenohumeral internal and external rotation, posterior shoulder tightness, and pectoralis minor length. Strength tests involved the lower and middle trapezius, rhomboid, glenohumeral internal and external rotation, pectoralis major, serratus anterior, supraspinatus, and upper trapezius. MAIN OUTCOME MEASURE(S): All 10 KJOC questions were summed for an overall score out of 100. Questions 1 through 5 were summed for a pain score; questions 6 through 10 were summed for a function score. All data were assessed for normality. A stepwise multiple regression model was fit to determine if the predictor variables assessed could predict the KJOC score. We set the α level a priori at .05. RESULTS: For the KJOC total score, a 1-year history of shoulder injury accounted for 7.80% of the variance in the KJOC total score (P = .07). For KJOC questions 1 through 5, a history of UE injury in the year before testing and posterior shoulder tightness accounted for 14.40% of the variance in the KJOC total score (P = .047). CONCLUSIONS: The link between a history of UE musculoskeletal injuries and the KJOC score highlights the need for continued focus on self-perceived pain and function after UE musculoskeletal injury.


Assuntos
Beisebol/lesões , Ortopedia/métodos , Lesões do Ombro/fisiopatologia , Inquéritos e Questionários/normas , Adolescente , Adulto , Atletas , Estudos de Coortes , Humanos , Contração Isométrica/fisiologia , Masculino , Força Muscular/fisiologia , Amplitude de Movimento Articular/fisiologia , Lesões do Ombro/diagnóstico , Adulto Jovem
8.
IEEE Int Conf Rehabil Robot ; 2019: 240-245, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31374636

RESUMO

Ankle dorsiflexion produced by Tibialis Anterior (TA) muscle contraction plays a significant role during human walking and standing balance. The weakened function or dysfunction of the TA muscle often impedes activities of daily living (ADL). Powered ankle exoskeleton is a prevalent technique to treat this pathology, and its intelligent and effective behaviors depend on human intention detection. A TA muscle contraction strength monitor is proposed to evaluate the weakness of the ankle dorsiflexion. The new method combines surface electromyography (sEMG) signals and sonomyography signals to estimate ankle torque during a voluntary isometric ankle dorsiflexion. Changes in the pennation angle (PA) are derived from the sonomyography signals. The results demonstrate strong correlations among the sonomyography-derived PA, the sEMG signal, and the measured TA muscle contraction force. Especially, the TA muscle strength monitor approximates the TA muscle strength measurement via a weighted summation of the sEMG signal and the PA signal. The new method shows an improved linear correlation with the muscle strength, compared to the correlations between the muscle strength and sole sEMG signal or sole PA signal, where the R-squared values are improved by 4.21 % and 1.99 %, respectively.


Assuntos
Tornozelo/fisiologia , Eletromiografia , Amplitude de Movimento Articular/fisiologia , Ultrassom , Adulto , Humanos , Contração Isométrica/fisiologia , Modelos Lineares , Masculino , Músculo Esquelético/fisiologia , Processamento de Sinais Assistido por Computador
9.
IEEE Int Conf Rehabil Robot ; 2019: 1147-1152, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31374784

RESUMO

Proprioceptive deficits are frequent and disabling symptoms of neurological diseases such as Multiple Sclerosis (MS). These deficits are poorly understood partly because of the limited sensitivity and reproducibility of clinical measures. However, their assessment is crucial in planning and evaluating rehabilitative treatments. Therefore, we designed a device and a protocol for assessing proprioceptive deficits by evaluating the position and force control performance. We focused on bimanual tasks, as most daily life activities require the combined use of both hands while MS induces coordination problems and often affects the two arms differently. Specifically, without being able to see their arms, subjects had (1) to reach with their hands a target positions holding objects of equal or different weights; (2) to exert equal isometric forces with the two hands in upward direction against rigid constraints at the same or different heights. For a first proof of concept of the feasibility we enrolled seven MS subjects with different levels of upper limb impairment and seven sex and age matched controls. We found that the ability to exert symmetric forces with both arms was significantly altered in all MS subjects, while position control decreased only for higher level of impairment. These preliminary findings suggest that in people with MS the ability to exert bilaterally required levels of force might be affected earlier compared to the ability to control hand position.


Assuntos
Esclerose Múltipla/fisiopatologia , Mãos/fisiologia , Humanos , Contração Isométrica/fisiologia , Desempenho Psicomotor/fisiologia , Extremidade Superior/fisiologia
10.
BMC Musculoskelet Disord ; 20(1): 360, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31391035

RESUMO

BACKGROUND: Strength testing of the serratus anterior muscle with hand held dynamometry (HDD) in supine subjects has low reproducibility, and is influenced by compensatory activity of other muscles like the pectoralis major and upper trapezius. Previously, two manual maximum voluntary isometric contraction tests of the serratus anterior muscle were reported that recruited optimal surface electromyography (sEMG) activity in a sitting position. We adapted three manual muscle tests to make them suitable for HHD and investigated their validity and reliability. METHODS: Twenty-one healthy adults were examined by two assessors in one supine and two seated positions. Each test was repeated twice. Construct validity was determined by evaluating force production (assessed with HHD) in relation to sEMG of the serratus anterior, upper trapezius and pectoralis major muscles, comparing the three test positions. Intra- and interrater reliability were determined by calculating intra-class correlation coefficients (ICC) smallest detectable change (SDC) and standard error of measurement (SEM). RESULTS: Serratus anterior muscle sEMG activity was most isolated in a seated position with the humerus in 90° anteflexion in the scapular plane. This resulted in the lowest measured force levels in this position with a mean force of 296 N (SEM 15.8 N). Intrarater reliability yielded an ICC of 0.658 (95% CI 0.325; 0.846) and an interrater reliability of 0.277 (95% CI -0.089;0.605). SDC was 127 Newton, SEM 45.8 Newton. CONCLUSION: The results indicate that validity for strength testing of the serratus anterior muscle is optimal with subjects in a seated position and the shoulder flexed at 90° in the scapular plane. Intrarater reliability is moderate and interrater reliability of this procedure is poor. However the high SDC values make it difficult to use the measurement in repeated measurements.


Assuntos
Dinamômetro de Força Muscular , Força Muscular , Músculo Esquelético/fisiologia , Ombro/fisiologia , Adulto , Eletromiografia , Feminino , Voluntários Saudáveis , Humanos , Contração Isométrica/fisiologia , Masculino , Reprodutibilidade dos Testes , Lesões do Ombro/diagnóstico , Postura Sentada , Decúbito Dorsal , Adulto Jovem
11.
Fisioterapia (Madr., Ed. impr.) ; 41(4): 192-199, jul.-ago. 2019. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-183095

RESUMO

Antecedentes y objetivos: Los músculos del abdomen, y en especial el transverso abdominal, tienen un papel fundamental en el control lumbopélvico. La maniobra de ahuecamiento abdominal es una técnica para potenciar la contracción del transverso. El objetivo del estudio es comparar mediante ecografía el cambio de grosor de la musculatura abdominal durante 2 técnicas de contracción: la contracción isométrica y la maniobra de ahuecamiento abdominal. Materiales y métodos: A una muestra de 23 voluntarios, previamente instruidos en la maniobra de ahuecamiento abdominal y la contracción isométrica, se le realizó una ecografía de la musculatura abdominal en ambos tipos de contracción y en reposo. Se midió el grosor de cada músculo y se calculó la fracción de contracción. Se analizó la existencia de diferencias significativas en la activación de la musculatura abdominal entre ambas técnicas y se evaluó la fiabilidad del análisis de imagen ecográfica. Resultados: Se observó un aumento significativo en el cambio de grosor del transverso con la maniobra de ahuecamiento (media ± DE = 2,01 ± 0,61 cm), en comparación con la contracción isométrica (media ± DE = 1,70 ± 0,65 cm). El oblicuo externo también presentó resultados mayores durante esta maniobra, mientras que el cambio de grosor del oblicuo interno fue mayor durante la contracción isométrica. El análisis de la fiabilidad interobservador fue excelente en todos los casos. Conclusiones: La maniobra de ahuecamiento abdominal produce un aumento de grosor del músculo transverso y del oblicuo externo mayor que la contracción isométrica. La ecografía es una herramienta fiable para valorar la activación de la musculatura abdominal


Introduction and objectives: The abdominal muscles, and especially the transversus abdominis, play a fundamental role in lumbopelvic control. Abdominal drawing-in maneuvre is a specific technique to transversus contraction. The objective of the study was to compare the thickness changes of the abdominal muscles with ultrasonography, during two techniques of abdominal contraction: isometric contraction and abdominal drawing-in maneuvre. Materials and methods: A sample of 23 volunteers, trained to do abdominal drawing-in maneuvre and isometric contraction were explored with ultrasonography during muscle contraction and rest. Muscle thickness and contraction fraction were calculated. Differences in the activation of the abdominal muscles between both techniques and the reliability of the ultrasound image analysis were analyzed. Results: During the abdominal drawing-in maneuvre a significant increase in thickness change of the transverse was observed (mean ± SD = 2.01 ± 0.61 cm) compared with the isometric contraction (mean ± SD=1.70 ± 0.65 cm). The external oblique also showed greater results during this maneuvre, while the change in internal oblique thickness was greater during the isometric contraction. The interobserver reliability analysis was excellent. Conclusions: The abdominal drawing-in maneuvre produces an increase in the thickness of the transverse muscle and the external oblique greater than the isometric contraction. Ultrasound is a reliable tool to assess the activation of the abdominal muscles


Assuntos
Humanos , Masculino , Feminino , Adulto , Determinação de Necessidades de Cuidados de Saúde , Contração Isométrica/fisiologia , Contração Muscular/fisiologia , Músculos Abdominais/diagnóstico por imagem , Músculos Abdominais/fisiologia , Voluntários Saudáveis , Estudos Transversais , Estudantes de Ciências da Saúde/estatística & dados numéricos , Ultrassonografia/instrumentação
12.
Sensors (Basel) ; 19(14)2019 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-31330807

RESUMO

Injuries caused by the overstraining of muscles could be prevented by means of a system which detects muscle fatigue. Most of the equipment used to detect this is usually expensive. The question then arises whether it is possible to use a low-cost surface electromyography (sEMG) system that is able to reliably detect muscle fatigue. With this main goal, the contribution of this work is the design of a low-cost sEMG system that allows assessing when fatigue appears in a muscle. To that aim, low-cost sEMG sensors, an Arduino board and a PC were used and afterwards their validity was checked by means of an experiment with 28 volunteers. This experiment collected information from volunteers, such as their level of physical activity, and invited them to perform an isometric contraction while an sEMG signal of their quadriceps was recorded by the low-cost equipment. After a wavelet filtering of the signal, root mean square (RMS), mean absolute value (MAV) and mean frequency (MNF) were chosen as representative features to evaluate fatigue. Results show how the behaviour of these parameters across time is shown in the literature coincides with past studies (RMS and MAV increase while MNF decreases when fatigue appears). Thus, this work proves the feasibility of a low-cost system to reliably detect muscle fatigue. This system could be implemented in several fields, such as sport, ergonomics, rehabilitation or human-computer interactions.


Assuntos
Técnicas Biossensoriais , Fadiga Muscular , Músculo Esquelético/fisiopatologia , Músculo Quadríceps/fisiopatologia , Adulto , Algoritmos , Eletromiografia , Humanos , Contração Isométrica/fisiologia , Masculino , Contração Muscular/fisiologia , Adulto Jovem
13.
J Sports Sci ; 37(21): 2452-2458, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31303128

RESUMO

Hamstring strain injury (HSI) rates are higher for males vs. females. This cross-sectional study investigated if inherent differences in biceps femoris long head (BFLH) fascicle length (Lf) exist between recreationally active males and females (i.e., individuals without specific training practice history). Twenty-four young healthy participants (12 males; 12 females) had their BFLH muscle architecture (Lf, pennation angle [θp], and muscle thickness [MT]) measured using B-mode ultrasonography. Eccentric and isometric knee flexion strength were also assessed. BFLH Lf did not differ between sexes when expressed in absolute terms (males, 81.5 ± 14.7 mm; females, 73.6 ± 15.9 mm, P = 0.220, effect size (ES) = 0.52) or relative to femur length (0.140 ≤ P ≤ 0.220, ES = 0.63). Similarly, BFLH θp did not differ between sexes (P = 0.650) but BFLH MT was 18.9% larger for males vs. females (P = 0.024, ES = 0.99). Isometric and eccentric knee flexion strength was greater for males vs. females in absolute terms ([both] P < 0.001, 2.00 ≤ ES ≤ 2.27) and relative to body mass ([both] P < 0.001, 1.93 ≤ ES ≤ 2.13). In conclusion, factors other than BFLH Lf seem likely to be implicated in higher male vs. female HSI rates.


Assuntos
Músculos Isquiotibiais/anatomia & histologia , Estudos Transversais , Feminino , Músculos Isquiotibiais/diagnóstico por imagem , Músculos Isquiotibiais/lesões , Músculos Isquiotibiais/fisiologia , Humanos , Contração Isométrica/fisiologia , Joelho/fisiologia , Masculino , Força Muscular/fisiologia , Fatores de Risco , Fatores Sexuais , Ultrassonografia
14.
Eur J Appl Physiol ; 119(9): 1971-1979, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31273453

RESUMO

BACKGROUND: Children have been hypothesized to utilize higher-threshold (type-II) motor units (MUs) to a lesser extent than adults. Two recent studies, using a cycling-based EMG-threshold (EMGTh) protocol, supported the hypothesis, showing children's EMGTh intensities to be higher than adults'. Conclusions, however, were hampered by children's low EMGTh detection rates. Insufficiently high contractile forces at exhaustion were postulated as the reason for non-detection, predominantly in children. An intermittent isometric contraction test (IICT) protocol facilitates higher contractile forces prior to exhaustion and was shown effective in EMGTh testing of adults. PURPOSE: Determine whether an IICT protocol would enhance EMGTh detection in children, and consequently increase the magnitude of the previously observed child-adult EMGTh differences. METHODS: 18 boys and 21 men completed one-repetition-maximum (1RM) isometric knee-extension test. The IICT protocol followed, commencing at 25%1RM and comprising five isometric contractions per load, incremented by ~ 3%1RM to exhaustion. Vastus lateralis surface EMG was recorded and EMGTh, expressed as %1RM, was defined as the onset of the EMG-response's steeper segment. RESULTS: EMGTh was detected in 88.9% of boys and 95.2% of men, and occurred at higher relative intensities in boys (56.4 ± 9.2%1RM) than in men (46.0 ± 6.8%1RM). This 10.4% difference was 57% greater than the corresponding, previously reported cycling-based age-related difference. CONCLUSIONS: With the boys' detection rate nearly on par with the men's, the IICT protocol appears to overcome much of the intensity limitation of cycling-based protocols and provide a more sensitive EMGTh detection tool, thus extending the previously observed boys‒men difference. This difference adds supports to the notion of children's more limited type-II MU recruitment capacity.


Assuntos
Contração Isométrica/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Adulto , Criança , Eletromiografia/métodos , Humanos , Articulação do Joelho/fisiologia , Masculino , Músculo Quadríceps/fisiopatologia , Adulto Jovem
15.
BMC Musculoskelet Disord ; 20(1): 320, 2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31286912

RESUMO

BACKGROUND: Muscle strength measurements using hand-held dynamometry (HHD) can be affected by the inadequate strength of the tester and lack of stabilization of the participants and the device. A portable HHD anchoring system was designed that enabled the measurement of isometric knee extensor muscle strength in a supine position. This can be used with individuals who are unable to assume the sitting position required for the measurement of knee extensor strength in conventional isokinetic dynamometry (IKD). The aim of this study was to evaluate the reliability and validity of knee extensor strength measurements using this device. METHODS: The maximal knee extensor isometric strength of the dominant leg in healthy adults aged 20 to 40 years was tested. Three trials of three contractions were assessed by two raters using the portable dynamometer anchoring system whilst the participant was in the supine position. After the three measurement trials, peak knee extensor torque was evaluated using IKD. The intraclass correlation coefficient (ICC) and 95% limits of agreement (LOA) for intra- and inter-rater reliability were obtained. RESULTS: Thirty-nine participants (19 male and 20 female, aged 30.08 ± 4.16 y), completed the three measurement trials. The ICC for intra-rater reliability was 0.98 for the maximum measurements of knee extensor strength (95% confidence interval [CI]: 0.96-0.98) and 0.98 (95% CI: 0.96-0.99) for inter-rater reliability. The mean difference (%) between the maximum knee extensor strength measurements of each trial was 1.02% (LOA range: - 11.13 to 13.16%) for intra-rater and - 1.44% (LOA range: - 13.98 to 11.08%) for inter-rater measurements. The Pearson correlation coefficient of the maximum voluntary peak torque measurements with the portable dynamometer anchoring system and IKD was 0.927. CONCLUSIONS: The portable dynamometer anchoring system is a reliable and valid tool for measuring isometric knee extensor strength in a supine position. Future clinical feasibility studies are needed to determine if this equipment can be applied to people with severe illness or disabilities. TRIAL REGISTRATION: KCT0003041 .


Assuntos
Articulação do Joelho/fisiologia , Dinamômetro de Força Muscular , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Adulto , Estudos Transversais , Feminino , Voluntários Saudáveis , Humanos , Contração Isométrica/fisiologia , Masculino , Reprodutibilidade dos Testes , Decúbito Dorsal/fisiologia , Adulto Jovem
16.
Eur J Appl Physiol ; 119(9): 2065-2073, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31332518

RESUMO

PURPOSE: To investigate the effects of acute experimental knee joint pain on maximum force generation and rate of force development (RFD) of the quadriceps muscle during isometric and dynamic muscle activations. METHODS: The right knee of 20 healthy people was injected with hypertonic saline to create an acute pain experience. Measurements of maximum knee extensor torque during isometric, concentric, and eccentric contractions were undertaken using a Biodex dynamometer. The RFD was also examined during the isometric contractions. Quadriceps muscle activity was obtained using electromyography (EMG). The outcome measures were obtained at baseline, during pain, and after knee pain had resolved. RESULTS: Maximum joint torque and peak EMG were significantly reduced during pain, but there were no differences across the three types of contraction. The maximum RFD and rate of EMG rise were also reduced during pain, primarily at 50-100 ms post-contraction onset. The RFD and EMG rise were largely unaffected at later time periods following contraction onset (150-200 ms). CONCLUSIONS: Acute joint pain has a similar impact on isometric and isokinetic contractions despite differences in neural control strategies. Joint pain also impairs rapid muscle activation and the RFD. These findings are important for people with musculoskeletal pain as it likely contributes to impairments in joint function in these populations.


Assuntos
Contração Isométrica/fisiologia , Joelho/fisiologia , Contração Muscular/fisiologia , Força Muscular/fisiologia , Dor/fisiopatologia , Músculo Quadríceps/fisiologia , Adolescente , Adulto , Eletromiografia/métodos , Exercício/fisiologia , Feminino , Humanos , Articulação do Joelho/fisiologia , Masculino , Pessoa de Meia-Idade , Movimento/fisiologia , Torque , Adulto Jovem
17.
Muscle Nerve ; 60(4): 437-442, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31325319

RESUMO

BACKGROUND: Reliable measurement of functional recovery is critical in translational peripheral nerve regeneration research. Behavioral functional assessments such as volitional grip strength testing (vGST) are limited by inherent behavioral variability. Isometric tetanic force testing (ITFT) is highly reliable but precludes serial measurements. Combining elements of vGST and ITFT, stimulated grip strength testing (sGST) involves percutaneous median nerve stimulation to elicit maximal tetanic contraction of digital flexors, thereby allowing for consistent measurement of maximal grip strength. METHODS: We measured side-to-side equivalence of force using sGST, vGST, and ITFT to determine relative reliability and repeatability. We also performed weekly force measurements following median nerve repair. RESULTS: sGST demonstrated greater reliability and inter-trial repeatability than vGST and similar reliability to ITFT, with the added benefit of serial measurements. CONCLUSIONS: sGST is a valid method for assessing functional recovery that addresses the limitations of the currently available modalities used in translational peripheral nerve regeneration research.


Assuntos
Força da Mão/fisiologia , Contração Isométrica/fisiologia , Nervo Mediano/fisiopatologia , Regeneração Nervosa , Recuperação de Função Fisiológica , Animais , Comportamento Animal , Estimulação Elétrica , Masculino , Nervo Mediano/lesões , Nervo Mediano/fisiologia , Nervo Mediano/cirurgia , Ratos , Ratos Endogâmicos Lew , Reprodutibilidade dos Testes , Nervo Ulnar/cirurgia
18.
J Pak Med Assoc ; 69(7): 1000-1005, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31308571

RESUMO

OBJECTIVE: To estimate the test-retest reliability of measurements in shoulder internal and external rotators' isometric peak torque using a new dynamometer, and to compare it with isokinetic dynamometer. METHODS: The validity study was conducted in September-October 2016 at Pontificia Universidad Catolica de Chile and the Clinica Las Condes, Santiago, Chile. It comprised of asymptomatic university students who were randomly tested twice within a two-week period while in a supine position at 90° of shoulder abduction, using the novel functional electromechanical pulley dynamometer. Concurrent validity was assessed through comparing the values with the gold standard isokinetic dynamometer in the same position. SPSS 17 was used for data analysis. RESULTS: Of the 24 subjects, 5(21%) were males and 19(79%) were females. The overall mean age was 23.1±2.2 years, body mass index 23.6±2.13 kg/m2 and Shoulder Pain and Disability Index score was 3.9±6.4. There was no statistically non-significant difference in terms of test-retest trials and between the devices (p>0.05). Absolute reliability was 24.3% for internal rotation and 27.9% for external rotation. Both dynamometer systems were very highly correlated for internal rotators peak torque (0.93) and highly correlated for external rotators peak torque (0.84). CONCLUSIONS: Compared to the gold standard, the new device was found to be a valid instrument in measuring maximal voluntary isometric peak torque in internal and external rotation.


Assuntos
Contração Isométrica/fisiologia , Dinamômetro de Força Muscular , Força Muscular/fisiologia , Ombro/fisiologia , Torque , Adulto , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Rotação , Adulto Jovem
19.
Gait Posture ; 73: 101-107, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31319373

RESUMO

BACKGROUND: Muscular parameters have been considered to influence gait of older adults, but it is still unclear which specific lower limb muscular parameters correlate with kinematics of overground and obstacle crossing in older adults. RESEARCH QUESTION: What lower limb muscular parameters correlate and explain kinematics of overground walking and obstacle crossing ability in the elderly? METHODS: Muscle structure was evaluated in 15 older individuals (75.4 ±â€¯5 years) through measures of architecture (muscle thickness, fascicle length, and pennation angle) and muscle quality (echo intensity) from lower limb muscles (vastus lateralis, biceps femoris, rectus femoris, tibialis anterior, and gastrocnemius medialis). Muscle function was assessed through isometric strength of hip, knee and ankle joint muscles. Gait kinematics (toe and heel clearances, step length and gait speed) was evaluated during walking with and without obstacle crossing at preferred and maximal gait speeds. Correlation and regression analyses were performed considering a significance level of 0.05. RESULTS: Isometric strength did not correlate with gait kinematics and gait speed. Tibialis anterior thickness correlated with lead limb toe clearance, and vastus lateralis thickness with gait speed and step length. Vastus lateralis echo intensity correlated with step length and gait speed. SIGNIFICANCE: Tibialis anterior and vastus lateralis muscles deserve attention in physical training to improve gait of older adults. Specifically, tibialis anterior should receive more attention on exercise programs aiming at improvement of obstacle crossing, and knee extensors when aiming at improving gait speed and step length.


Assuntos
Marcha/fisiologia , Contração Isométrica/fisiologia , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Caminhada/fisiologia , Idoso , Idoso de 80 Anos ou mais , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Estudos Transversais , Eletromiografia , Feminino , Humanos , Masculino , Músculo Esquelético/anatomia & histologia
20.
Gait Posture ; 73: 74-79, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31302335

RESUMO

BACKGROUND: Lower extremity movement asymmetries may lead to re-injury and knee osteoarthritis after anterior cruciate ligament (ACL) reconstruction surgery. However, there is no consensus regarding the effect of quadriceps strength asymmetry on lower extremity movement asymmetry after ACL reconstruction. RESEARCH QUESTION: What is the relationship between quadriceps strength asymmetry and asymmetries in lower extremity kinematics and kinetics during walking in individuals who underwent ACL reconstruction surgery?. METHODS: Isometric quadriceps strength, kinematic, and kinetic data during walking were collected from 24 men with unilateral ACL reconstruction. Knee joint angles and moments were reduced. Pearson correlation coefficients between asymmetry in selected knee biomechanics and isometric quadriceps strength asymmetry were determined. RESULTS: The isometric quadriceps strength of the injured leg was significantly lower than that of the uninjured leg (P < 0.001). Knee flexion angles and knee extension moments were smaller in the injured leg than that in the uninjured leg during both loading response (P = 0.007, P = 0.047) and mid-stance phases (P = 0.005, P = 0.028). Isometric quadriceps strength asymmetry was significantly correlated with asymmetry in the peak knee flexion angle during loading response and mid-stance phases (r = -0.48, P = 0.017, r = -0.48, P = 0.017). Isometric quadriceps strength asymmetry was also significantly correlated with asymmetry in the peak knee extension moment during the mid-stance phase (r = -0.44, P = 0.033). SIGNIFICANCE: Individuals with ACL reconstruction demonstrate knee movement asymmetry in the sagittal plane. Isometric quadriceps strength asymmetry is significantly correlated with asymmetry in knee flexion angles during the early stance phase and knee extension moments during the mid-stance phase. Rehabilitation programs should emphasise eccentric exercise to beneficially modify quadriceps neuromuscular control.


Assuntos
Lesões do Ligamento Cruzado Anterior , Reconstrução do Ligamento Cruzado Anterior , Articulação do Joelho/fisiologia , Força Muscular/fisiologia , Músculo Quadríceps/fisiologia , Caminhada/fisiologia , Adulto , Lesões do Ligamento Cruzado Anterior/fisiopatologia , Lesões do Ligamento Cruzado Anterior/cirurgia , Fenômenos Biomecânicos , Humanos , Contração Isométrica/fisiologia , Traumatismos do Joelho/fisiopatologia , Traumatismos do Joelho/cirurgia , Masculino , Suporte de Carga/fisiologia , Adulto Jovem
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