RESUMEN
STUDY DESIGN: Controlled laboratory study. BACKGROUND: The hip abductor muscles are important hip joint stabilizers. Hip joint pain may alter muscle recruitment. Motion-mode (M-mode) ultrasound enables noninvasive measurements of the onset of deep and superficial muscle motion, which is associated with activation onset. OBJECTIVES: To compare (1) the onset of superficial and deep gluteus medius and gluteus minimus muscle motion relative to the instant of peak ground reaction force and (2) the level of swing-phase muscle motion during step-down between subjects with chronic hip pain and controls using M-mode ultrasound. METHODS: Thirty-five subjects with anterior, nontraumatic hip pain for more than 6 months (mean ± SD age, 54 ± 9 years) and 35 controls (age, 57 ± 7 years) were scanned on the lateral hip of the leading leg during frontal step-down onto a force platform using M-mode ultrasound. Computerized motion detection with the Teager-Kaiser energy operator was applied on the gluteus minimus and the deep and superficial gluteus medius to determine the time lag between muscle motion onset and instant of peak ground reaction force and the level of gluteus minimus motion during the swing phase. Time lags and motion levels were averaged per subject, and t tests were used to determine between-group differences. RESULTS: In participants with hip pain, gluteus minimus motion onset was 103 milliseconds earlier (P = .002) and superficial gluteus medius motion was 70 milliseconds earlier (P = .047) than those in healthy control participants. The level of gluteus minimus swing-phase motion was higher with pain (P = .006). CONCLUSION: Increased gluteus minimus motion during the swing phase and earlier gluteus minimus and superficial gluteus medius motion in individuals with hip pain suggest an overall increase of muscle activity, possibly a protective behavior.
Asunto(s)
Artralgia/fisiopatología , Dolor Crónico/fisiopatología , Cadera/fisiopatología , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , Adulto , Nalgas , Femenino , Humanos , Masculino , Persona de Mediana Edad , Movimiento , Tiempo de Reacción , UltrasonografíaRESUMEN
M-mode ultrasound imaging (US) reflects motion of connective tissue within muscles. As muscle contraction is accompanied by motion of muscle tissue, M-mode US may be used to measure non-invasively the onset of deep muscle activity. Isometric hip abduction was measured on nine healthy subjects in the deep region of the gluteus medius muscle and in gluteus minimus by fine-wire electromyography (EMG) and M-mode US. Following signal transformation with the Teager-Kaiser Energy Operator, EMG and M-mode US onsets of muscle activity were computer-processed. Correlation between log-transformed EMG and M-mode high-energy onsets was higher in gluteus medius (r 0.93) than in gluteus minimus (r 0.86). M-mode high-energy onsets followed EMG onset by median 33 (IQR 53) ms in gluteus medius, and by 17 (IQR 63) ms in gluteus minimus. 4% of gluteus medius and 23% of gluteus minimus M-mode onsets were detected before EMG onset. Using a higher onset threshold reduced the rate of onsets detected before EMG but also prediction accuracy. In voluntary activation, M-mode US high-energy onsets were closely related to EMG-measured onsets, but the time interval between both measures varied. The relationship of electrical and mechanical activation onsets appears to be influenced by modifying factors which may differ between muscles.
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Contracción Isométrica/fisiología , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , Ultrasonografía Doppler/métodos , Adulto , Electromiografía/métodos , Femenino , Cadera/diagnóstico por imagen , Cadera/fisiología , Humanos , Masculino , Contracción Muscular/fisiologíaRESUMEN
The clinical assessment of gluteus medius and minimus force sharing requires non-invasive measurements of individual activity levels. Do ultrasound measurements of change of muscle thickness substitute invasive electromyography (EMG)? Isometric hip abduction in 20-80% maximal voluntary isometric contraction (MVIC) was measured using dynamometry, M-mode ultrasound for gluteus medius and minimus thickness and EMG using (1) surface electrodes on gluteus medius, n = 15, (2) fine-wire electrodes in deep gluteus medius and minimus, n = 6. Gluteus medius thickened by 5.0 (SD 2.5) mm at 80% MVIC while gluteus minimus thickness was constant in the surface EMG study and decreased by 1.6 (SD 1.6) mm at the more ventral location in the fine-wire EMG study. Thickness change of gluteus medius enabled prediction of torque (r(2) 0.66) and of surface EMG amplitude (r(2) 0.57). Surface EMG enabled higher torque prediction (r(2) 0.84) than thickness change. Thickness change of gluteus minimus did not enable a practically relevant estimation of torque production. Ultrasound examination revealed a differential thickening behaviour of gluteus medius and minimus which enabled estimation of isometric torque production only for gluteus medius but with lower precision than surface EMG.
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Nalgas , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , Adulto , Electromiografía , Femenino , Humanos , Masculino , Contracción Muscular/fisiología , Torque , UltrasonografíaRESUMEN
The hip abductors gluteus medius (Gmed) and minimus (Gmin) differ slightly in function and how they are affected by hip joint pathology. A separate assessment of Gmed and Gmin is feasible by ultrasound (US) imaging. B-mode and M-mode US can be used to measure muscle thickness. Two B- and two M-mode scans of Gmed and Gmin thickness were taken in relaxation on 16 asymptomatic volunteers, repeated within 4 days on 11 subjects. Three types of intra-rater reliability of muscle thickness measurements were examined: (1) within-session reliability comparing two scans from the same session, (2) between-days reliability comparing thickness from two scanning occasion within 4 days and (3) reliability of taking thickness measurements by re-measuring the same US scans after 1 week. Thickness measurements on B- and M-mode images provided ICC3,1 >0.96 for within-session reliability. ICC3,k >0.89 for between-days reliability and ICC3,1 >0.85 for re-reading the same scans were estimated. Minimal detectable changes >1.0 mm within-session, >2.4 mm between-days and >1.7 mm for re-reading scans indicated that small thickness changes are not detectable. The investigation suggests a slight advantage for fascia recognition in B-mode and the advantage of visual control of muscle relaxation in M-mode.
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Electromiografía/métodos , Articulación de la Cadera/fisiología , Músculo Esquelético/diagnóstico por imagen , Ultrasonografía Doppler/métodos , Adulto , Nalgas , Femenino , Voluntarios Sanos , Humanos , Masculino , Contracción Muscular/fisiología , Músculo Esquelético/fisiología , Variaciones Dependientes del Observador , Rango del Movimiento Articular/fisiología , Valores de Referencia , Muestreo , Adulto JovenRESUMEN
UNLABELLED: PURPOSE This study aimed to develop a new unsupported upper limb exercise test (UULEX) for patients with chronic obstructive pulmonary disease (COPD). METHODS: The reproducibility of the UULEX was assessed in nine patients with COPD who performed the test on three occasions. A comparison of the UULEX and a supported incremental upper limb exercise test (SULEX) using an arm ergometer also was performed with 18 patients who had COPD. RESULTS: There were no significant differences in the maximum values for each cardiorespiratory variable and sensation of dyspnea between the three repetitions of the UULEX, and all the variables showed high reproducibility. During the supported test, maximum values for the cardiorespiratory variables were significantly higher, but the ratio of minute ventilation to carbon dioxide output was lower than during the unsupported exercise test. There were significant correlations for cardiorespiratory responses, arm muscle fatigue, and sensation of dyspnea between the two tests. CONCLUSIONS: The findings suggest that the new UULEX test is a reproducible and acceptable exercise test for patients with COPD that can be used as a simple method to evaluate upper limb function in these patients. Further studies are required to determine the external validity of the test and its sensitivity to interventions such as pulmonary rehabilitation.
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Prueba de Esfuerzo/métodos , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Anciano , Análisis de Varianza , Brazo/fisiopatología , Disnea/fisiopatología , Tolerancia al Ejercicio , Femenino , Humanos , Masculino , Persona de Mediana Edad , Consumo de Oxígeno , Reproducibilidad de los ResultadosRESUMEN
OBJECTIVE: To examine for differences in joint position sense (JPS) between knees with reconstructed anterior cruciate ligaments (ACLs) and uninjured knees by using a functional weight-bearing measurement method. DESIGN: Two-way repeated-measures in a convenience sample. SETTING: An Australian university rehabilitation laboratory. PARTICIPANTS: Nine subjects presenting at 12 to 16 months after unilateral ACL reconstruction using the semitendinosus/gracilis graft who were recruited from 2 orthopedic surgeons. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: JPS of the reconstructed and uninjured knees was examined by using the Peak Motus motion measurement system to record target joint angles and to calculate reproduced angles after limb movement into flexion and extension, performed in a weight-bearing position. RESULTS: There were no significant differences in JPS between reconstructed and uninjured knees (P=.68) or between the flexion and extension tasks (P=.47). CONCLUSION: There was no deficit in knee JPS 12 to 16 months after ACL reconstruction, as measured by a functional weight-bearing method. Further studies should examine the clinical utility of the method as a way to evaluate functional aspects of knee joint proprioception.