Archivos de medicina del deporte: revista de la Federación Española de Medicina del Deporte y de la Confederación Iberoamericana de Medicina del Deporte, 2020
Revista Brasileira De Medicina Do Esporte, Feb 1, 2019
Introduction: Fatigue due to endurance exercise results from both peripheral and central changes,... more Introduction: Fatigue due to endurance exercise results from both peripheral and central changes, and may influence subsequent performance during a strength task. The increase in serotonin concentration is one of the central factors associated with endurance exercise-induced fatigue, particularly in hot environments. A nutritional strategy employed to reduce serotonergic activation is supplementation with branched-chain amino acids (BCAA). Objective: To investigate whether BCAA supplementation attenuates the reduction in isometric force caused by prior endurance exercise in a hot environment. Methods: Nine volunteers (aged 25.4 ± 1.2 years) performed a 2-min maximal voluntary isometric contraction (MVC ISO) of upper limb muscles before and after an endurance exercise on a cycle ergometer at 40% of the maximal aerobic power. The volunteers underwent three experimental trials: 1) endurance exercise in a temperate environment (23°C and 60% RH); exercise in a hot environment (35°C and 60% RH) with the ingestion of: 2) a placebo solution or 3) a solution containing BCAA 30 mg.kg-1. During the MVC ISO test, the isometric force of flexor muscles of the right elbow, core body temperature (T CORE) and heart rate (HR) were measured. Results: Isometric force decreased following endurance exercise in the hot environment, and BCAA administration did not attenuate this reduction. Greater T CORE and HR values were observed following endurance exercise in the heat, compared to pre-exercise values, and supplementation did not interfere with these physiological responses. Conclusion: The reduction in isometric force, caused by previous endurance exercise in a hot environment, was not diminished by supplementation with BCAA. Level of evidence I; Type of study: Therapeutic studies-Investigation of treatment outcomes.
O objetivo deste estudo foi comparar a concentração de lactato sanguíneo em protocolos de treinam... more O objetivo deste estudo foi comparar a concentração de lactato sanguíneo em protocolos de treinamento de força com diferentes durações das ações musculares no exercício supino. Dezessete voluntários executaram três protocolos com três séries de seis repetições a 60% de 1RM, pausa de três minutos entre as séries e diferentes durações das ações musculares (2-4: 2s concêntrica e 4s excêntrica; 3-3: 3s concêntrica e 3s excêntrica; 4-2: 4s concêntrica e 2s excêntrica). A análise da concentração de lactato sanguíneo considerou os valores médios por série em cada protocolo. Os resultados da ANOVA twoway mostraram que o efeito principal protocolo não apresentou diferença significante entre os três protocolos (F = 0,75; p = 0,48; poder = 0,48; η 2 = 0,17), assim como para a interação entre os fatores (F = 1,68; p = 0,13; poder = 0,09; η 2 = 0,62). Porém, houve diferença significante na concentração de lactato sanguíneo para o fator série (F = 320,23; p = 0,0001; poder = 1,00; η 2 = 0,95). Portanto, protocolos de treinamento de força equiparados com durações das ações musculares distintas não apresentaram diferenças na resposta do lactato sanguíneo e, independentemente do protocolo, a concentração deste substrato aumentou ao longo das três séries realizadas. Palavras-chave: Treinamento de força. Duração da repetição. Lactato sanguíneo.
The aging of populations is an international phenomena caused by the decline of birthrate and the... more The aging of populations is an international phenomena caused by the decline of birthrate and the progress of medical science. According to WHO individuals older than 65 years in developed countries and older than 60 years in developing countries are considered elderly. The aging process is characterized by the decrease of muscle mass, strength and power, one of the most important reasons for the decrease of functional abilities and the increase of falling risk (Zhong et al., 2007). Nevertheless, physical activity may retard this process. The principal changes in kinematic gait variables are the decrease of gait velocity, stride length and single support time with an increase of double support time (McGibbon,2003). These changes in gait pattern observed in the elderly population may arise from functional declines of aging and may be even more significant in the absence of appropriate regular physical exercises. Considering the higher proportion of women in the elderly population (WHO, 2002), it is important to understand the changes in gait patterns of elderly women related to physical activity. Therefore, the purpose of this study was to identify the effects of different intensities of physical activity on the cinematic gait variables in older women.
Artículo original Resumen Objetivo: El objetivo del presente estudio fue comparar la amplitud de ... more Artículo original Resumen Objetivo: El objetivo del presente estudio fue comparar la amplitud de la señal electromiográfica (EMG) de las porciones de músculo cuádriceps vasto medial (VM), vasto lateral (VL) y recto femoral (RF) y la relación de activación (VM/VL, VM/RF y VL/ RF) en protocolos con diferentes duraciones de acciones musculares concéntricas y excéntricas. Material y método: Doce mujeres voluntarias realizaron el ejercicio extensor de rodilla con dos protocolos diferentes [1 s para la acción muscular concéntrica y 5 s para la acción muscular excéntrica (1: 5); 5s de acción muscular concéntrica y 1s de acción muscular excéntrica (5: 1)] y 3 series de 6 repeticiones, 180s de pausa entre cada serie y una intensidad del 50% de 1RM. La raíz media cuadrática de la amplitud de la señal electromiográfica normalizada se calculó para cada repetición en cada serie. Resultados: se observó un aumento en la EMG de las porciones de VM y VL en repeticiones equivalentes de cada serie y para la porción de VL, el protocolo 1: 5 proporcionó una mayor activación en comparación con el otro protocolo. No se encontraron diferencias para las relaciones de activación de los músculos VM/RF y VL/RF, siendo que para la relación VM/VL solo hubo cambios en una repetición. Conclusión: Los resultados sugieren que las partes del músculo del cuádriceps pueden presentar diferentes respuestas de EMG en protocolos similares, pero este hecho puede no interferir en el sinergismo entre ellos. Los grados reducidos de libertad del ejercicio de extensión de la rodilla y las características de los protocolos adoptados pueden ser los elementos que contribuyeron a las alteraciones limitadas que se produjeron en el presente estudio.
ABSTRACT Background: Previous studies on soccer small-sided games (SSGs) chose between with and w... more ABSTRACT Background: Previous studies on soccer small-sided games (SSGs) chose between with and without offside rule conditions without evidence-based criteria. The current study aimed to compare the positional dynamics of 3v3 SSGs with and without the offside rule. Methods: Twenty-four Brazilian U-17 national-level soccer players were recruited. They were split into eight teams and played SSGs with and without the offside rule . Positional data were gathered by a Global Positioning System, and teams’ length, width, the length per width ratio (LPWratio), stretch index and players’ spatial exploration index were calculated. Data were compared between the experimental conditions by a paired t-test. Results: Results showed that SSGs with the offside rule presented lower values of length (~16.63%, large effect), the LPWratio (~19.74%, large effect), and players’ spatial exploration (~4.13%, small-to-moderate effect). Conclusion: We conclude that the offside rule impacts players’ positional behavior in SSGs, inducing a less exploratory behavior mainly in the width axis. For this reason, we recommend caution when interpreting previous results on SSG when the offside rule was not applied since adopting this rule might elicit different responses to the players . Coaches can manipulate this rule aiming to achieve specific tactical goals for the training session.
Muscle volume (MV) and anatomical cross-sectional area (CSA) are used as measures of muscle-size,... more Muscle volume (MV) and anatomical cross-sectional area (CSA) are used as measures of muscle-size, but determining these from magnetic resonance imaging (MRI) is a very time-consuming process. Additionally, it is unclear if the use of different muscle size assessments (all vs. reduced number of slices images) would impact the muscle size-strength relationship. Thus, this study aimed to investigate if muscle size calculation by using a reduced or all slices images from pectoralis major (PM) would maintain a similar muscle size-strength relationship with bilateral maximal dynamic and isometric contractions on a bench press exercise. Twenty-four healthy males underwent an MRI examination to measure PM muscle size, and maximal isometric and dynamic contractions (by one repetition maximum, 1RM) were performed. Correlations between maximal isometric voluntary force (MVF) and dynamic strength (1RM) with muscle size variables [three images from the largest part of PM (CSA3MAX), three images accounting for the shape -first image, middle image, final image- of the PM (CSA3), and MV] were performed. The correlation between 1RM with MV, CSA3, and CSA3MAX were 0.84, 0.832, and 0.727 (p < 0.001), respectively. The correlation between MVF with MV, CSA3, and CSA3MAX were 0.738, 0.733, and 0.604 (p < 0.001), respectively. Overall, PM MV and CSA3 exhibit a stronger and similar muscle size-strength relationship during maximal dynamic and isometric tests than CSA3MAX. Therefore, a reduced number of slices (CSA3) could be used as an alternative to considerably reduce the time of analysis without compromise muscle size-strength relationship.
Revista Brasileira de Ciência e Movimento, May 6, 2009
Resumo O objetivo desse trabalho foi levantar e discutir as controvérsias na literatura, esclarec... more Resumo O objetivo desse trabalho foi levantar e discutir as controvérsias na literatura, esclarecendo o motivo de não se poder relacionar a flexibilidade como um fator de risco para lesões. Métodos: O estudo foi uma revisão bibliográfica, analisando estudos clínicos ...
Archivos de medicina del deporte: revista de la Federación Española de Medicina del Deporte y de la Confederación Iberoamericana de Medicina del Deporte, 2020
Revista Brasileira De Medicina Do Esporte, Feb 1, 2019
Introduction: Fatigue due to endurance exercise results from both peripheral and central changes,... more Introduction: Fatigue due to endurance exercise results from both peripheral and central changes, and may influence subsequent performance during a strength task. The increase in serotonin concentration is one of the central factors associated with endurance exercise-induced fatigue, particularly in hot environments. A nutritional strategy employed to reduce serotonergic activation is supplementation with branched-chain amino acids (BCAA). Objective: To investigate whether BCAA supplementation attenuates the reduction in isometric force caused by prior endurance exercise in a hot environment. Methods: Nine volunteers (aged 25.4 ± 1.2 years) performed a 2-min maximal voluntary isometric contraction (MVC ISO) of upper limb muscles before and after an endurance exercise on a cycle ergometer at 40% of the maximal aerobic power. The volunteers underwent three experimental trials: 1) endurance exercise in a temperate environment (23°C and 60% RH); exercise in a hot environment (35°C and 60% RH) with the ingestion of: 2) a placebo solution or 3) a solution containing BCAA 30 mg.kg-1. During the MVC ISO test, the isometric force of flexor muscles of the right elbow, core body temperature (T CORE) and heart rate (HR) were measured. Results: Isometric force decreased following endurance exercise in the hot environment, and BCAA administration did not attenuate this reduction. Greater T CORE and HR values were observed following endurance exercise in the heat, compared to pre-exercise values, and supplementation did not interfere with these physiological responses. Conclusion: The reduction in isometric force, caused by previous endurance exercise in a hot environment, was not diminished by supplementation with BCAA. Level of evidence I; Type of study: Therapeutic studies-Investigation of treatment outcomes.
O objetivo deste estudo foi comparar a concentração de lactato sanguíneo em protocolos de treinam... more O objetivo deste estudo foi comparar a concentração de lactato sanguíneo em protocolos de treinamento de força com diferentes durações das ações musculares no exercício supino. Dezessete voluntários executaram três protocolos com três séries de seis repetições a 60% de 1RM, pausa de três minutos entre as séries e diferentes durações das ações musculares (2-4: 2s concêntrica e 4s excêntrica; 3-3: 3s concêntrica e 3s excêntrica; 4-2: 4s concêntrica e 2s excêntrica). A análise da concentração de lactato sanguíneo considerou os valores médios por série em cada protocolo. Os resultados da ANOVA twoway mostraram que o efeito principal protocolo não apresentou diferença significante entre os três protocolos (F = 0,75; p = 0,48; poder = 0,48; η 2 = 0,17), assim como para a interação entre os fatores (F = 1,68; p = 0,13; poder = 0,09; η 2 = 0,62). Porém, houve diferença significante na concentração de lactato sanguíneo para o fator série (F = 320,23; p = 0,0001; poder = 1,00; η 2 = 0,95). Portanto, protocolos de treinamento de força equiparados com durações das ações musculares distintas não apresentaram diferenças na resposta do lactato sanguíneo e, independentemente do protocolo, a concentração deste substrato aumentou ao longo das três séries realizadas. Palavras-chave: Treinamento de força. Duração da repetição. Lactato sanguíneo.
The aging of populations is an international phenomena caused by the decline of birthrate and the... more The aging of populations is an international phenomena caused by the decline of birthrate and the progress of medical science. According to WHO individuals older than 65 years in developed countries and older than 60 years in developing countries are considered elderly. The aging process is characterized by the decrease of muscle mass, strength and power, one of the most important reasons for the decrease of functional abilities and the increase of falling risk (Zhong et al., 2007). Nevertheless, physical activity may retard this process. The principal changes in kinematic gait variables are the decrease of gait velocity, stride length and single support time with an increase of double support time (McGibbon,2003). These changes in gait pattern observed in the elderly population may arise from functional declines of aging and may be even more significant in the absence of appropriate regular physical exercises. Considering the higher proportion of women in the elderly population (WHO, 2002), it is important to understand the changes in gait patterns of elderly women related to physical activity. Therefore, the purpose of this study was to identify the effects of different intensities of physical activity on the cinematic gait variables in older women.
Artículo original Resumen Objetivo: El objetivo del presente estudio fue comparar la amplitud de ... more Artículo original Resumen Objetivo: El objetivo del presente estudio fue comparar la amplitud de la señal electromiográfica (EMG) de las porciones de músculo cuádriceps vasto medial (VM), vasto lateral (VL) y recto femoral (RF) y la relación de activación (VM/VL, VM/RF y VL/ RF) en protocolos con diferentes duraciones de acciones musculares concéntricas y excéntricas. Material y método: Doce mujeres voluntarias realizaron el ejercicio extensor de rodilla con dos protocolos diferentes [1 s para la acción muscular concéntrica y 5 s para la acción muscular excéntrica (1: 5); 5s de acción muscular concéntrica y 1s de acción muscular excéntrica (5: 1)] y 3 series de 6 repeticiones, 180s de pausa entre cada serie y una intensidad del 50% de 1RM. La raíz media cuadrática de la amplitud de la señal electromiográfica normalizada se calculó para cada repetición en cada serie. Resultados: se observó un aumento en la EMG de las porciones de VM y VL en repeticiones equivalentes de cada serie y para la porción de VL, el protocolo 1: 5 proporcionó una mayor activación en comparación con el otro protocolo. No se encontraron diferencias para las relaciones de activación de los músculos VM/RF y VL/RF, siendo que para la relación VM/VL solo hubo cambios en una repetición. Conclusión: Los resultados sugieren que las partes del músculo del cuádriceps pueden presentar diferentes respuestas de EMG en protocolos similares, pero este hecho puede no interferir en el sinergismo entre ellos. Los grados reducidos de libertad del ejercicio de extensión de la rodilla y las características de los protocolos adoptados pueden ser los elementos que contribuyeron a las alteraciones limitadas que se produjeron en el presente estudio.
ABSTRACT Background: Previous studies on soccer small-sided games (SSGs) chose between with and w... more ABSTRACT Background: Previous studies on soccer small-sided games (SSGs) chose between with and without offside rule conditions without evidence-based criteria. The current study aimed to compare the positional dynamics of 3v3 SSGs with and without the offside rule. Methods: Twenty-four Brazilian U-17 national-level soccer players were recruited. They were split into eight teams and played SSGs with and without the offside rule . Positional data were gathered by a Global Positioning System, and teams’ length, width, the length per width ratio (LPWratio), stretch index and players’ spatial exploration index were calculated. Data were compared between the experimental conditions by a paired t-test. Results: Results showed that SSGs with the offside rule presented lower values of length (~16.63%, large effect), the LPWratio (~19.74%, large effect), and players’ spatial exploration (~4.13%, small-to-moderate effect). Conclusion: We conclude that the offside rule impacts players’ positional behavior in SSGs, inducing a less exploratory behavior mainly in the width axis. For this reason, we recommend caution when interpreting previous results on SSG when the offside rule was not applied since adopting this rule might elicit different responses to the players . Coaches can manipulate this rule aiming to achieve specific tactical goals for the training session.
Muscle volume (MV) and anatomical cross-sectional area (CSA) are used as measures of muscle-size,... more Muscle volume (MV) and anatomical cross-sectional area (CSA) are used as measures of muscle-size, but determining these from magnetic resonance imaging (MRI) is a very time-consuming process. Additionally, it is unclear if the use of different muscle size assessments (all vs. reduced number of slices images) would impact the muscle size-strength relationship. Thus, this study aimed to investigate if muscle size calculation by using a reduced or all slices images from pectoralis major (PM) would maintain a similar muscle size-strength relationship with bilateral maximal dynamic and isometric contractions on a bench press exercise. Twenty-four healthy males underwent an MRI examination to measure PM muscle size, and maximal isometric and dynamic contractions (by one repetition maximum, 1RM) were performed. Correlations between maximal isometric voluntary force (MVF) and dynamic strength (1RM) with muscle size variables [three images from the largest part of PM (CSA3MAX), three images accounting for the shape -first image, middle image, final image- of the PM (CSA3), and MV] were performed. The correlation between 1RM with MV, CSA3, and CSA3MAX were 0.84, 0.832, and 0.727 (p < 0.001), respectively. The correlation between MVF with MV, CSA3, and CSA3MAX were 0.738, 0.733, and 0.604 (p < 0.001), respectively. Overall, PM MV and CSA3 exhibit a stronger and similar muscle size-strength relationship during maximal dynamic and isometric tests than CSA3MAX. Therefore, a reduced number of slices (CSA3) could be used as an alternative to considerably reduce the time of analysis without compromise muscle size-strength relationship.
Revista Brasileira de Ciência e Movimento, May 6, 2009
Resumo O objetivo desse trabalho foi levantar e discutir as controvérsias na literatura, esclarec... more Resumo O objetivo desse trabalho foi levantar e discutir as controvérsias na literatura, esclarecendo o motivo de não se poder relacionar a flexibilidade como um fator de risco para lesões. Métodos: O estudo foi uma revisão bibliográfica, analisando estudos clínicos ...
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