Paulo Henrique Marchetti

Acute effects of light emitting diodes therapy (LEDT) in muscle function during isometric exercise in patients with chronic obstructive pulmonary disease: preliminary results of a randomized controlled trial

Patients with chronic obstructive pulmonary disease (COPD) are susceptible to early muscle fatigue. Light-emitting diodes therapy (LEDT) has been used to minimize muscle fatigue in athletes and healthy subjects. The aim of this study is to investigate the acute effects of LEDT on muscle fatigue and perception of effort in patients with COPD during isometric endurance test of the quadriceps femoris (QF). Ten patients (VEF1 50u2009±u200913xa0% of predicted) underwent a single LEDT and sham application, 48xa0h apart, in a randomized crossover design. The LEDT and sham were applied in three localized areas of the QF (rectus femoris, vastus lateralis, and vastus medialis). Before and after exposure to LEDT and sham, the patients performed an isometric endurance test (60xa0% of the maximum voluntary isometric contraction), until the limit of tolerance concomitant to surface electromyography recording (median frequency as mean outcome). The slope obtained from linear regression analysis of the median frequency (MF) over endurance time was also used as an endurance index. Endurance time increased significantly after exposure to LEDT (from 26u2009±u20092 to 53u2009±u20095xa0s) as compared to sham (from 23u2009±u20093 to 30u2009±u20094xa0s) (Fu2009=u200964, Pu2009=u20090.0001). A greater decline in MF was observed during isometric endurance test after sham, compared to LEDT (Fu2009=u200914.6, Pu2009=u20090.004). The slope of the MF over time was lower post-LEDT compared to post-sham (−0.7u2009±u20090.3 vs. −1.5u2009±u20090.8; Pu2009=u20090.004). The dyspnea score corrected for endurance time was lower post-LEDT (Pu2009=u20090.008) but similar for fatigue both post-LEDT and post-sham. A single application of LEDT minimizes muscle fatigue and increases isometric endurance time.

Upper and Lower Limb Muscles in Patients With COPD: Similarities in Muscle Efficiency But Differences in Fatigue Resistance

BACKGROUND: Peripheral muscle dysfunction is a common finding in patients with COPD; however, the structural adaptation and functional impairment of the upper and lower limb muscles do not seem to be homogenous. We compared muscle fatigue and recovery time between 2 representative muscles: the middle deltoid and the quadriceps femoris. METHODS: Twenty-one subjects with COPD (FEV1 46.1 ± 10.3% of predicted) underwent maximal voluntary isometric contraction and an endurance test (60% of maximal voluntary isometric contraction, to the limit of tolerance). The maximal voluntary isometric contraction test was repeated after 10 min, 30 min, 60 min, and 24 hours for both the quadriceps femoris and middle deltoid. Surface electromyography was recorded throughout the endurance test. RESULTS: Maximal voluntary isometric contraction significantly decreased only for the middle deltoid between 10 and 60 min after the endurance test. A significant increase of the root mean square and a greater decline in median frequency throughout the endurance test occurred for the middle deltoid, compared with the quadriceps femoris. When dyspnea and fatigue scores were corrected by endurance time, higher values were observed for the middle deltoid (0.07 and 0.08, respectively) in relation to the quadriceps femoris (0.02 and 0.03, respectively). CONCLUSIONS: Subjects with COPD had a higher fatigability of a representative upper limb muscle (middle deltoid) than a lower limb muscle (quadriceps femoris).

Effects of light-emitting diodes on muscle fatigue and exercise tolerance in patients with COPD: study protocol for a randomized controlled trial

BackgroundLight-emitting diodes (LED) have been used to minimize muscle fatigue in athletes and healthy subjects. Patients with chronic obstructive pulmonary disease (COPD) are susceptible to early muscle fatigue.ObjectiveThe objective of this study is to investigate the acute effects of LED on muscle function, exercise capacity and cardiorespiratory responses during isometric and dynamic exercise in patients with COPD.MethodsThis study will assess 30 patients with moderate to severe obstruction (forced expiratory volume-one second,FEV1 ≤70% predicted). Isometric and dynamic protocols will be conducted in two visits each, for a total of four visits a week apart. First, venous blood will be taken from the patients. The isometric protocol will start with the determination of the maximum voluntary isometric contraction (MIVC) to determine the workload (60% of MIVC) for the isometric endurance test (IET). Patients will be randomized to receive either the placebo or LED application (each point will be irradiated for 30 s and the energy received at each point will be 41.7 J). Immediately after finishing this procedure, the patients will carry out the IET until the limit of tolerance or until a 20% fall of strength is observed. After the test, another blood draw will be taken. In another visit (one week later), the same order of procedures will be performed, except with the opposite (LED or placebo). For the dynamic endurance test (DET), the same procedures described above will be followed, except with 75% of the maximal workload obtained from the incremental cycle ergometer test used instead of the IET. The electromyography will be recorded during the isometric and dynamic protocols. Differences in muscle function, exercise capacity and cardiorespiratory responses between the LED and placebo applications will be analyzed. The therapeutic effects of LED could minimize muscle fatigue in patients with COPD by increasing exercise tolerance.Trial registrationTrial registration number:NCT01448564

PHYSICAL ACTIVITY LEVEL DOES NOT INFLUENCE THE NEUROMUSCULAR FATIGUE IN ADULTS

Introduccion: La fatiga durante las contracciones musculares voluntarias es un fenomeno complejo y multifactorial, asociado a los cambios centrales y adaptaciones del sistema neuromuscular. Objetivo: Evaluar la fatiga inducida por las extensiones sucesivas intermitentes de la rodilla entre los estudiantes universitarios activos e inactivos. Metodos: Veinte hombres sanos (≥ 18 anos) participaron voluntariamente en este estudio. Para determinar la contraccion isometrica voluntaria maxima (CIVM) del grupo de los musculos extensores de la rodilla, se realizaron tres contracciones isometricas de extension de la rodilla, durante cinco segundos, con cinco minutos de descanso entre las series. El CIVM se determino por la media de los tres intentos. El protocolo de la fatiga consistio en 10 series de 10 contracciones concentricas maximas del extensor de la rodilla derecha, realizadas en el 75% de CIVM con un intervalo de 45. Resultados: Se observaron reducciones significativas (p < 0,01), tanto en la fuerza isometrica (-34 ± 4%) y la dinamica (-40 ± 3%). Ademas, la recta de la relacion fuerza x repeticion presento inclinacion de -0,79 ± 0,07 Nm/repeticiones y la magnitud del efecto alcanzo -8,9. Conclusion: El protocolo fue util para inducir fatiga periferica, aunque la fuerza muscular es mayor en el grupo activo. En accion isometrica y dinamica, la fatiga muscular no difirio entre los grupos.

Effects of a full season on stabilometric Parameters of team handball elite athletes

Nao e claro na literatura cientifica se atletas mudam seu controle postural ao longo de uma temporada esportiva, ou mesmo se tornam mais assimetricos em relacao ao seu desempenho neuromuscular durante o mesmo periodo. O objetivo deste estudo foi investigar os efeitos de uma temporada esportiva completa no controle postural de atletas de elite do handebol. Dez jogadores de elite de handebol, saudaveis, realizaram a tarefa de postura ereta quieta bipodal (BP) e unipodal direito e esquerdo durante 30 segundos. Foi utilizada a RMS e a velocidade do centro de pressao para descrever a oscilacao postural. Para a tarefa de BP, a oscilacao foi menor apos a temporada esportiva (p < 0,005). Para as tarefas unipodais, a oscilacao foi menor apos temporada esportiva apenas para o membro nao dominante (p < 0,001). Apenas apos a temporada, foram observadas diferencas entre os membros (p < 0,03). Em conclusao, uma temporada esportiva para o handebol nao levou a deterioracao do controle postural dos atletas, entretanto no final da temporada, os atletas apresentaram-se mais assimetricos.

Acute neuromuscular and metabolic responses to upper body strength, power, and hypertrophy protocols in resistance trained men

Aim: The purpose of this study was to compare the acute neuromuscular and metabolic responses between strength (S), hypertrophy (H), and power (P) resistance training protocols in the elbow flexors. Methods: Fourteen resistance trained men (age: 25 ± 4 years, body mass: 79.5 ± 9 kg, height: 177 ± 4cm) volunteered to participate. They attended four sessions separated by at least one week. On the first session, they performed a one repetition maximum (1RM) test for the standing barbell curl exercise. On the following three sessions, the training protocols were randomized to either a S (11 sets of 3 repetitions, 90% 1RM, 5-minute rest), H (4 sets of 10 repetitions, 75% 1RM, 90-second rest), or P (8 sets of 6 repetitions, 30% 1RM, 3-minute rest). Peak force (PF) and biceps brachii muscle activity (EMG) were quantified before and after each session via maximal voluntary isometric contraction of the elbow flexors. Blood samples were taken before and at 0, 3, 5, 10, 15 and 30 minutes after each session to measure the concentration of blood lactate (BL). Results: Higher total volume load (VL) in the S protocol compared to H (577.5±142.2 vs 568.5±133.3, P=0.03, respectively), and S compared to P (577.5±142.2 vs 294.8±67.5, P=0.001, respectively). Additionally, H showed higher VL compared to P (P=0.001). Conclusion: This study showed that the equated load between muscular strength and hypertrophy protocols compromised the neuromuscular and metabolic performance after single-joint exercise for upper limbs.

Efeitos da temporada completa em parâmetros estabilométricos em atletas de handebol de elite

Nao e claro na literatura cientifica se atletas mudam seu controle postural ao longo de uma temporada esportiva, ou mesmo se tornam mais assimetricos em relacao ao seu desempenho neuromuscular durante o mesmo periodo. O objetivo deste estudo foi investigar os efeitos de uma temporada esportiva completa no controle postural de atletas de elite do handebol. Dez jogadores de elite de handebol, saudaveis, realizaram a tarefa de postura ereta quieta bipodal (BP) e unipodal direito e esquerdo durante 30 segundos. Foi utilizada a RMS e a velocidade do centro de pressao para descrever a oscilacao postural. Para a tarefa de BP, a oscilacao foi menor apos a temporada esportiva (p < 0,005). Para as tarefas unipodais, a oscilacao foi menor apos temporada esportiva apenas para o membro nao dominante (p < 0,001). Apenas apos a temporada, foram observadas diferencas entre os membros (p < 0,03). Em conclusao, uma temporada esportiva para o handebol nao levou a deterioracao do controle postural dos atletas, entretanto no final da temporada, os atletas apresentaram-se mais assimetricos.

Efectos de la temporada completa en parámetros estabilométricos en atletas de balonmano de élite

Nao e claro na literatura cientifica se atletas mudam seu controle postural ao longo de uma temporada esportiva, ou mesmo se tornam mais assimetricos em relacao ao seu desempenho neuromuscular durante o mesmo periodo. O objetivo deste estudo foi investigar os efeitos de uma temporada esportiva completa no controle postural de atletas de elite do handebol. Dez jogadores de elite de handebol, saudaveis, realizaram a tarefa de postura ereta quieta bipodal (BP) e unipodal direito e esquerdo durante 30 segundos. Foi utilizada a RMS e a velocidade do centro de pressao para descrever a oscilacao postural. Para a tarefa de BP, a oscilacao foi menor apos a temporada esportiva (p < 0,005). Para as tarefas unipodais, a oscilacao foi menor apos temporada esportiva apenas para o membro nao dominante (p < 0,001). Apenas apos a temporada, foram observadas diferencas entre os membros (p < 0,03). Em conclusao, uma temporada esportiva para o handebol nao levou a deterioracao do controle postural dos atletas, entretanto no final da temporada, os atletas apresentaram-se mais assimetricos.

Maximum number of repetitions performed by resistance-trained men: Effect of maximum load intensity and exercise selection

El objetivo de este estudio fue comparar el numero de repeticiones maximas (RMS) realizado con una intensidad de 80% de una repeticion maxima (1RM) y el 80% de una repeticion maxima excentrica (1RMecc) para el ejercicio supino horizontal (SH) y rosca scott (RS). Quince hombres con experiencia en el entrenamiento de fuerza participaron en este estudio cruzado aleatorio. No hubo diferencia significativa en el numero de los RMs realizado a 80% 1RM (RS: 7,0±1,2 RMs e SH: 5,8±1,2 RMs) y 80%-1RMecc (RS: 6,0±1,1 RMs e SH: 5,4±1,1 RMs) para ambos ejercicios. No se detecto diferencia significativa en el numero de los RMs entre el ejercicio RS (80%- 1RM: 7,0±1,2 RMs and 80%-1RMecc: 6,0±1,1 RMs) y SH (80%-1RM: 5,8 ±1,2 RMs and 80%-1RMecc: 5,4±1,1 RMs) para ambas intensidades. En conclusion, el numero de RMs realizados por hombres entrenados en la fuerza no afecto la intensidad maxima de la carga basada en la accion muscular y la seleccion de los ejercicios.O objetivo deste estudo foi comparar o numero de repeticoes maximas (RMs) realizadas com intensidade de 80% dos testes de uma repeticao maxima (1RM) e 80% de uma repeticao maxima excentrica (1RMecc) para os exercicios supino-horizontal (SH) e rosca-scott (RS). Quinze homens com experiencia em treinamento de forca participaram desse estudo randomizado cruzado. Nao houve diferenca significativa no numero de RMs realizadas a 80%-1RM (RS: 7,0±1,2 RMs e SH: 5,8±1,2 RMs) e 80%-1RMecc (RS: 6,0±1,1 RMs e SH: 5,4±1,1 RMs) para ambos os exercicios. Nao foi detectada diferenca significativa no numero de RMs entre o exercicio RS (80%-1RM: 7,0±1,2 RMs and 80%-1RMecc: 6,0±1,1 RMs) e SH (80%-1RM: 5,8 ±1,2 RMs and 80%-1RMecc: 5,4±1,1 RMs) para ambas intensidades. Em conclusao, o numero de RMs realizados por homens treinados em forca nao foi afetado pela intensidade maxima da carga baseada na acao muscular e pela selecao de exercicios.