Tiempos de activación muscular frente a una desestabilización en pacientes con enfermedad de Parkinson en etapas iniciales / Muscle activation times facing to a perturbation in patients with early-stage Parkinson's disease

Objetivos: La enfermedad de Parkinson (EP) genera alta incidencia de caídas, sin embargo, existe poca evidencia de inestabilidades en etapas iniciales. Esta investigación buscó comparar los tiempos de activación muscular en pacientes con EP inicial frente a una alteración postural vs. un grupo control. Materiales y métodos: Se evaluó la actividad electromiográfica (EMG) de 10 pacientes con EP (61,3 ± 3,8 años) en etapas iniciales y grupo control de 10 adultos (62,2 ±3,0 años). Los participantes fueron tratados mediante una alteración de la superficie, la cual generó una respuesta de estabilización. La prueba se realizó en 2condiciones: ojos abiertos (OA) vs. ojos cerrados (OC). Se analizó el tiempo de activación de músculos del tronco (erector espinal) y extremidad inferior (sóleo, tibial anterior, peroneo lateral largo, recto femoral, bíceps femoral, glúteo medio y aductor mayor) usando EMG de superficie. Resultados: El grupo con EP mostró tiempos de respuestas más rápidas en comparación con l grupo control en el músculo sóleo en OC (p=0,04). Este mismo músculo mostró diferencias al comparar OA vs. OC solo en el grupo con EP (p=0,04), mostrando un menor tiempo de respuesta en la condición OC. Al comparar el músculo erector espinal el grupo con EP mostró tiempos de respuesta más lentos en la condición de OA (p=0,02) y OC (p=0,04) con relación al grupo control. Conclusiones: Los tiempos de activación muscular muestran que las personas con EP responden con un retraso en la activación en la musculatura del tronco, mientras que a nivel distal responden más rápido que los sujetos controles. En las etapas tempranas las respuestas más lentas a nivel de tronco podrían explicar el inicio de las alteraciones del equilibrio en estos pacientes.(AU)

Objectives: Parkinson's disease (PD) generates a high incidence of falls, however, there is little evidence of instabilities in the initial stages. This investigation sought to compare the muscle activation times in patients with initial PD against a postural disturbance vs. a control group. Materials and methods: The electromyographic activity (EMG) of 10 patients with PD in early stages (61.3 ±3.8 years) and a control group of 10 adults (62.2 ±3.0 year) was evaluated. The participants were subjected to a surface disturbance, which generated a stabilization response. The test was performed under 2conditions: eyes open (OA) v/s eyes closed (OC). Trunk (spinal erector) and lower extremity (soleus, tibialis anterior, femoral biceps, femoral rectus, adductor magnus, gluteus medius) muscle activation time was analyzed using surface EMG. Results: The PD group showed faster response times compared to the control group in the soleus muscle in OC (P=.04). This same muscle showed differences when comparing OA vs. OC only in the PD group (P=.04), showing a shorter response time in the OC condition. When comparing the spinal erector muscle, the PD group showed slower response times in the OA (P=.02) and OC (P=.04) conditions compared to the control group. Conclusions: Muscle activation times show that people with PD respond slower in the trunk muscles, while activation times decrease at the distal level. In the early stages, the slower responses at the trunk level could explain the onset of instability postural in these patients.(AU)

[Muscle activation times facing to a perturbation in patients with early-stage Parkinson's disease]. / Tiempos de activación muscular frente a una desestabilización en pacientes con enfermedad de Parkinson en etapas iniciales.

OBJECTIVES: Parkinson's disease (PD) generates a high incidence of falls, however, there is little evidence of instabilities in the initial stages. This investigation sought to compare the muscle activation times in patients with initial PD against a postural disturbance vs. a control group. MATERIALS AND METHODS: The electromyographic activity (EMG) of 10 patients with PD in early stages (61.3 ±3.8 years) and a control group of 10 adults (62.2 ±3.0 year) was evaluated. The participants were subjected to a surface disturbance, which generated a stabilization response. The test was performed under 2conditions: eyes open (OA) v/s eyes closed (OC). Trunk (spinal erector) and lower extremity (soleus, tibialis anterior, femoral biceps, femoral rectus, adductor magnus, gluteus medius) muscle activation time was analyzed using surface EMG. RESULTS: The PD group showed faster response times compared to the control group in the soleus muscle in OC (P=.04). This same muscle showed differences when comparing OA vs. OC only in the PD group (P=.04), showing a shorter response time in the OC condition. When comparing the spinal erector muscle, the PD group showed slower response times in the OA (P=.02) and OC (P=.04) conditions compared to the control group. CONCLUSIONS: Muscle activation times show that people with PD respond slower in the trunk muscles, while activation times decrease at the distal level. In the early stages, the slower responses at the trunk level could explain the onset of instability postural in these patients.

Riesgo de caídas en personas mayores: comparación de resultados pre y postaplicación de un programa de ejercicios multicomponentes basado en subsistemas de la estabilidad postural / Comparison of the risk of falls in older people before and after to application of a multicomponent exercise program based on subsystems of postural stability

Antecedentes y objetivo: Los programas de ejercicios de componentes múltiples han demostrado una adecuada efectividad en personas mayores. Sin embargo, no siempre muestran beneficios directos sobre la estabilidad y el riesgo de caídas. Esto implica la necesidad de aplicar estos programas de ejercicios con un fuerte componente de entrenamiento de la estabilidad postural. El objetivo fue comparar el riesgo de caídas antes y después de la aplicación de un programa de ejercicios de componentes múltiples basado en componentes específicos de estabilidad postural. Materiales y métodos: Mediante un estudio cuasi experimental, participaron 72 personas mayores de 60 años y más, las que fueron evaluadas basalmente con las siguientes pruebas clínicas: Five Times Sit to Stand(FTST); Estación unipodal (EUP); Timed Up and Go (TUG); Self-Selected Walking Speed (SSWS) y Falls Efficacy Scale (FES). Posteriormente se realizó una intervención de 12 sesiones de 45min/3 veces por semana, que consistió en un programa de ejercicios de componentes múltiples con 6 estaciones de ejercicios de acondicionamiento físico y estabilidad. Un mes después los voluntarios fueron evaluados nuevamente. Resultados: Se observaron mejoras significativas en las pruebas FTST (p<0,0001); EUP derecha (p=0,006), EUP izquierda (p=0,010) y TUG (p<0,0001). No hubo cambios significativos en las pruebas SSWS (p=0,938) y FES (0,767). Conclusiones: El entrenamiento de componentes múltiples basados en subsistemas de la estabilidad, postural podría estar asociado a una mejora significativa en el rendimiento de las pruebas de EUP, TUG y FTST, y con ello a una posible reducción del riesgo de caídas.

Background and objective: Multicomponent Exercise Programs have shown adequate effectiveness in older people. However, they do not always show direct benefits on balance and risk of falls. This implies the need to apply these exercise programs with a strong a strong postural stability training component. The objective was to compare the risk of falls before and after the application of an Multicomponent Exercise Program based on specific components of postural stability. Material and methods: Through a quasi-experimental research, 72 people aged 60 years and over participated, who were evaluated based on the following clinical tests: Five Times Sit to Stand (FTST); Unipedal Stance Test (UST); Timed Up and Go (TUG); Self-Selected Walking Speed (SSWS) and Falls Efficacy Scale (FES). Subsequently, an intervention of 12 45-minute sessions was carried out three times per week, which consisted of a Multicomponent Exercise Program with 6 specific stations of physical conditioning and stability exercises. A month later the volunteers were evaluated again. Results: Significant improvements were observed in the FTST tests (P<.0001); Right EUP (P=.006), Left EUP (P=.010) and TUG (P<.0001). There were no significant changes in the SSWS tests (P=.938), and FES (.767). Conclusions: The multicomponent training plan based on postural stability subsystems could be associated with the best significant performance in the EUP, TUG and FTST tests, and with it to a possible reduction of the risk of falls.

Effect of exercise duration on pro-oxidants and pH in exhaled breath condensate in humans

Exercise promotes pulmonary oxidative imbalance. In this regard, some evidence has been obtained from the study of exhaled breath condensate (EBC) during urban races, in which the factors involved in the occurrence of this process are still not characterized. In this paper, under laboratory conditions, both the role of time of exercise on the generation of pro-oxidants (H2O2, NO2-) and pH have been assessed in EBC of 16 under-trained subjects who completed three tests of cycloergometric exercise at low intensity (30 % of VO2 max) with a duration of 10, 30, and 90 min. Samples were obtained as follows: immediately before and at 80 min post exertion in each test. In the 90-min test, an increase in H2O2, NO2- concentration in EBC at 80 min post exertion with no changes in the pH was observed. Total O2 consumption and total ventilation weakly correlated with the changes in H2O2 and NO2-. In conclusion, the concentration of pro-oxidants in the EBC depends on the duration of the exercise when it is performed at low intensity under laboratory conditions (AU)

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Effect of exercise duration on pro-oxidants and pH in exhaled breath condensate in humans.

Exercise promotes pulmonary oxidative imbalance. In this regard, some evidence has been obtained from the study of exhaled breath condensate (EBC) during urban races, in which the factors involved in the occurrence of this process are still not characterized. In this paper, under laboratory conditions, both the role of time of exercise on the generation of pro-oxidants (H2O2, NO2 (-)) and pH have been assessed in EBC of 16 under-trained subjects who completed three tests of cycloergometric exercise at low intensity (30 % of VO2 max) with a duration of 10, 30, and 90 min. Samples were obtained as follows: immediately before and at 80 min post exertion in each test. In the 90-min test, an increase in H2O2, NO2 (-) concentration in EBC at 80 min post exertion with no changes in the pH was observed. Total O2 consumption and total ventilation weakly correlated with the changes in H2O2 and NO2 (-). In conclusion, the concentration of pro-oxidants in the EBC depends on the duration of the exercise when it is performed at low intensity under laboratory conditions.

Concordance of the location of the innervation zone of the tibialis anterior muscle using voluntary and imposed contractions by electrostimulation.

BACKGROUND: The innervation zone (IZ) corresponds to the location of the neuromuscular junctions. Its location can be determined by using arranged surface linear electrode arrays. Typically, voluntary muscle contractions (VC) are used in this method. However, it also may be necessary to locate the IZ under clinical conditions such as spasticity, in which this type of contraction is difficult to perform. Therefore, contractions imposed by electrostimulation (ES) can be an alternative. There is little background comparing the locations of IZ obtained by two different types of contractions. OBJECTIVE: Evaluate the concordance between using voluntary and imposed contractions from electrostimulation in order to determine the location of the innervation zone of the tibialis anterior muscle in healthy volunteers. METHODS: The tibialis anterior (TA) muscle of sixteen volunteers (men: 8; women: 8; age: 22.1±1.4years, weight: 61.6±7.5kg, height: 167.1±7.5cm) were evaluated using a linear electrode array. The IZ of the TA muscle was located using two types of muscle contractions, voluntary (10% MVC) and imposed contractions by ES. The concordance between both conditions was evaluated using the Bland-Altman method and the concordance correlation coefficient (CCC). The analyses were applied to the absolute and relative positions to the length of an anatomical landmark frame. RESULTS: CCC for absolute position was 0.98 (p<0.0001, 95% CI [0.98-1.00], and CCC for relative positions also was 0.98 (p<0.0001, 95% CI [0.97-1.00]). The Bland-Altman analysis for absolute data showed an average difference of -0.63mm (SD: 4.1). Whereas, for adjusted data, the average difference was -0.20% (SD: 1.2). The power of the results, based on absolute data, was 98%, whereas for relative data, 82%. CONCLUSION: In healthy volunteers, there was a substantially concordance between the location of the IZ of the TA muscle derived from using contractions imposed by ES and the location derived from using VC.

Electromyographic adjustments during continuous and intermittent incremental fatiguing cycling.

We studied the sensitivity of electromyographic (EMG) variables to load and muscle fatigue during continuous and intermittent incremental cycling. Fifteen men attended three laboratory sessions. Visit 1: lactate threshold, peak power output, and VO2max . Visits 2 and 3: Continuous (more fatiguing) and intermittent (less fatiguing) incremental cycling protocols [20%, 40%, 60%, 80% and 100% of peak power output (PPO)]. During both protocols, multichannel EMG signals were recorded from vastus lateralis: muscle fiber conduction velocity (MFCV), instantaneous mean frequency (iMNF), and absolute and normalized root mean square (RMS) were analyzed. MFCV differed between protocols (P < 0.001), and only increased consistently with power output during intermittent cycling. RMS parameters were similar between protocols, and increased linearly with power output. However, only normalized RMS was higher during the more fatiguing 100% PPO stage of the continuous protocol [continuous-intermittent mean difference (95% CI): 45.1 (8.5% to 81.7%)]. On the contrary, iMNF was insensitive to load changes and muscle fatigue (P = 0.14). Despite similar power outputs, continuous and intermittent cycling influenced MFCV and normalized RMS differently. Only normalized RMS was sensitive to both increases in power output (in both protocols) and muscle fatigue, and thus is the most suitable EMG parameter to monitor changes in muscle activation during cycling.