André Luiz Demantova Gurjão

Acute effect of static stretching on rate of force development and maximal voluntary contraction in older women.

Gurjão, ALD, Gonçalves, R, de Moura, RF, and Gobbi, S. Acute effect of static stretching on rate of force development and maximal voluntary contraction in older women. J Strength Cond Res 23(7): 2149-2154, 2009-The purpose of this study was to investigate, in older women, the acute effect of static stretching (SS) on both muscle activation and force output. Twenty-three older women (64.6 ± 7.1 yr) participated in the study. The maximal voluntary contraction (MVC), rate of force development (RFD) (50, 100, 150, and 200 ms relative to onset of muscular contraction), and peak RFD (PRFD) (the steepest slope of the curve during the first 200 ms) were tested under 2 randomly separate conditions: SS and control (C). Electromyographic (EMG) activity of the vastus medialis (VM), vastus lateralis (VL), and biceps femoris (BF) muscles also was assessed. The MVC was significantly lower (p < 0.05) in the 3 trials of SS when compared with the C condition (control: 925.0 ± 50.9 N; trial 1: 854.3 ± 55.3 N; trial 2: 863.1 ± 52.2 N; and trial 3: 877.5 ± 49.9 N). PRFD showed a significant decrease only for the first 2 trials of SS when compared with the C condition (control: 2672.3 ± 259.1 N/s; trial 1: 2296.6 ± 300.7 N/s; and trial 2: 2197.9 ± 246.3 N/s). However, no difference was found for RFD (50, 100, 150, and 200 ms relative to onset of muscular contraction). The EMG activity for VM, VL, and BF was not significantly different between the C and SS conditions. In conclusion, the older womens capacity to produce muscular force decreased after their performance of SS exercises. The mechanisms responsible for this effect do not appear to be related to muscle activation. Thus, if flexibility is to be trained, it is recommended that SS does not occur just before the performance of activities that require high levels of muscular force.

Efeito de 16 semanas de treinamento com pesos sobre a pressão arterial em mulheres normotensas e não-treinadas

The aim of this study was to analyze the impact of a 16-week weight training (WT) over blood pressure (BP) in normotensive women. The sample consisted of 21 young women (20.5 ± 2.1 years), non-trained, who were randomly grouped in training group (TG = 13) and control group (CG = 8). The WT protocol was progressively structured, in two phases, with duration of eight weeks each, being performed with weekly frequency of three sessions. BP measurements were conducted at rest through the auscultatory method, in the different moments of the study (baseline, after eight and 16 weeks). The Shapiro-Wilk test was used for analysis of the data normality. Two-way ANOVA for repeated measurements was used for the comparisons between groups during the time, followed by the Scheffe post-hoc test when P < 0.05. A group v. moment interaction was found in the systolic, diastolic and mean BP values, with significant decreases, during the 16 weeks of follow-up, in the order of 5, 8 and 6 mmHg, respectively, in the TG. The outcomes suggest that the 16 week-WT program may cause important reductions in BP in normotensive young women and previously non-trained.

Comparação entre o desempenho motor de homens e mulheres em séries múltiplas de exercícios com pesos

RESUMO A magnitude das respostas neuromusculares, metabolicas e morfologicas de homens e mulheres parece ser bastante diferenciada ate mesmo quando esses sujeitos sao submetidos a protocolos de exercicios com pesos semelhantes. Todavia, as diferencas no desempenho motor entre homens e mulheres tem sido relatadas predominantemente em protocolos baseados em contracoes isometricas e isocineticas. Assim, o objetivo deste estudo foi analisar o comportamento de homens e mulheres durante series multiplas de exercicios com pesos ate a exaustao e, posteriormente, verificar possiveis diferencas de desempenho fisico entre os sexos em exercicios com pesos com intensidades semelhantes. Para tanto, 83 individuos (50 homens e 33 mulheres), 48 horas apos serem submetidos a testes de 1-RM nos exercicios supino em banco horizontal, agachamento e rosca direta de biceps, executaram um protocolo composto por quatro series a 80% de 1RM ate a exaustao, em cada um dos tres exercicios, para avaliacao da capacidade de resistencia a fadiga nos diferentes grupos musculares. ANOVA e ANCOVA para medidas repetidas, seguidas pelo teste post hoc de Tukey, quando P < 0,05, foram utilizadas para o tratamento dos dados. Verificou-se uma queda significativa de desempenho, tanto nos homens quanto nas mulheres, da primeira a quarta serie em todos os exercicios investigados (P < 0,01). Embora a magnitude da fadiga tenha sido maior nos homens, nos tres exercicios, o efeito do sexo foi identificado somente no exercicio rosca direta de biceps (P < 0,01). Os resultados do presente estudo indicaram que homens e mulheres apresentam comportamentos relativamente diferentes em series multiplas de exercicios com pesos, com as mulheres apresentando um desempenho mais estavel e uma maior capacidade de resistencia a fadiga, sobretudo, no exercicio rosca direta de biceps.

Effect of strength training on rate of force development in older women.

We analyzed the effect of an 8-week strength training (ST) program on the rate of force development (RFD) and electromyographic activity (EMG) in older women. Seventeen women (M age = 63.4 years, SD = 4.9) without previous ST experience were randomly assigned to either a control (n = 7) or training (n = 10) group. A leg-press isometric test was used for assessment. ST (three sessions/ week, three sets of 10–12 repetition maximum, five different exercises) induced significant increases (p < .05) on peak RFD (48.4%) and on RFD and EMG of vastus medialis at time intervals of 0–50, 0–100, 0–150, and 0–200 ms (41.1–69.2% and 43.8– 64.3%, respectively). Therefore, ST resulted in favorable changes in neuromuscular responses in older women.

Estimativa da composição corporal e análise de concordância entre analisadores de impedância bioelétrica bipolar e tetrapolar

The aim of this study was to analyze the body composition estimation and agreement of the measurements produced from two bioelectrical impedance analysers in young adult men. Twenty-two apparently healthy subjects (23.6 ± 2.9 yrs; 73.0 ± 6.8 kg; 177.6 ± 6.0 cm; 23.1 ± 1.9 kg/m2), were submitted to bioelectrical impedance measurements by tetra-polar whole body (TWB, Biodynamic Body Composition Analyser, model 310) and bipolar for upper body (BUB, OMRONTM, model HBF-306BL) after 12 h fast. Relative body fat (%BF), lean body mass (LBM) and fat mass (FM) estimation were established from information supplied by two analysers. No significant difference was verified for %BF (10.9 ±4.3 vs. 10.0 ±4.2%; P = 0.09), FM (8.1 ±3.5 vs. 7.4 ±3.5 kg; P = 0.10) or LBM (64.9 ±5.2 vs. 65.5 ±4.9 kg; P = 0.09) between TWB and BUB, respectively. Positive significant correlations (P < 0.001) were found between both analysers for LBM (r = 0.948), FM (r = 0.891) and %BF (r = 0.859). The agreement thresholds were -0.6 ± 3.2 kg for LBM (r = 0.135; P = 0.551), 0.8 ± 4.5% for %BF (r = 0.050; P = 0.824), and 0.6 ± 3.2 kg for FM (r = 0.032; P = 0.886). The results suggest that the body composition estimation by bioelectrical impedance does not seem to be affected by use of different analysers (BUB vs. TWB) or the total body adiposity.

O Efeito de diferentes intervalos de recuperação entre as séries de treinamento com pesos, na força muscular em mulheres idosas treinadas

O objetivo do presente estudo foi verificar a influencia de dois diferentes intervalos de recuperacao (IR) entre series de repeticoes de treinamento com pesos (TP), no desempenho da forca muscular em mulheres idosas treinadas. Dez mulheres idosas (66,6 ± 5,8 anos), com experiencia previa em TP, realizaram o seguinte protocolo: a) o teste de repeticoes maximas (10-12RM) no exercicio Rosca Scott para biceps; b) com a carga encontrada no teste de 10-12RM, outras duas sessoes de teste (separadas por 48 horas), agora com tres series, foram realizadas ate a fadiga muscular em cada serie. Dois diferentes IR foram utilizados para diferenciar essas duas sessoes, isto e, numa sessao o IR era de 90 segundos (IR 90) entre as series e na outra, de 180 segundos (IR 180). O teste t de Student para amostras dependentes mostrou que o volume total da sessao de teste com IR 180 foi estatisticamente superior (19%; P < 0,05) ao da sessao com IR 90 (27,5 ± 3,4 e 23,1 ± 3,3 repeticoes, respectivamente). A ANOVA two-way (2x3), tendo como fatores IR e numero de repeticoes de cada uma das tres series, para medidas repetidas no ultimo fator, apresentou interacao significativa (F(1,18) = 4,62; P = 0,02), demonstrando que a sustentabilidade das repeticoes e dependente da duracao do IR. Conclui-se que o emprego de diferentes IR tem importante influencia sobre o volume total de uma sessao de TP e no numero de repeticoes em multiplas series subsequentes. Tais achados podem apresentar relevante implicacao para a intervencao profissional com TP para mulheres idosas treinadas.

Effect of eight weeks of strength training on fatigue resistance in men and women

The purpose of the present study was to compare the effects of eight weeks of strength training on fatigue resistance in men and women. Thirty-three men and twenty-three women performed eight weeks of strength training in three weekly sessions. Subjects performed four sets using 80% of 1-RM tests on bench press, squat and arm curl. Fatigue index (FI) was used for analysis of decline in motor performance along the sets. The sum of the number of repetitions accomplished in the four sets in each exercise was used to indicate the fatigue resistance. Anova or Ancova two-way (time x gender) was employed for statistical analysis ( P< 0.05). Eight weeks of strength training increased significantly 1-RM strength, fatigue resistance and total number of repetitions in both genders. FI decreased significantly in both genders after training (men = 50% vs. women = Time x gender interaction was observed in the total number of repetitions in squat (P = 0.04) and arm curl exercises, regarding gains to women (P = 0.01). In conclusion, eight weeks of ST improved strength, FR, FI and total number of repetitions performed. However, women obtained greater adaptations than men.

Respostas pressóricas pós-exercícios com pesos executados em diferentes sobrecargas por mulheres normotensas

Resistance training (RT) has been widely recommended for improvement of some health-related physical fitness components. Recently, the impact of RT in individuals with chronic-degenerative dysfunctions such as hypertension has been discussed. Thus, the aim of this study was to compare the effects of one program of resistance training performed at different intensities on post-exercise blood pressure response. Therefore, sixteen apparently healthy young women (20.5 ± 1.5 year-old) were randomly separated in two groups after having been submitted to an eight-week RT for equalization of muscular fitness levels. Each group then performed 12 weeks of RT prescribed by one of two different-intensity protocols (GI = 3 x 6-8 RM; GII = 3 x 10-12 RM; three alternated days per week). Systolic (SBP) and diastolic (DBP) blood pressures were assessed at rest and at minutes 1, 5, 10 and 30 after training, through auscultatory technique. Two-way ANOVA for repeated measures was used for comparison between groups at the different moments, and Scheffe post-hoc test (a = 5%) was applied to point out where the differences occur. No significant statistical difference (P > 0.05) was found for SBP or DBP between groups at any moment. However, the RT hypotensive effect was observed only for GI, with the SBP showing a significant reduction when compared to rest values at minutes 10 and 30 of recovery (P < 0.05). In conclusion, only higher intensity resistance training can exert a slightly acute hypotensive effect on young females.

The acute effects of static stretching on peak force, peak rate of force development and muscle activity during single- and multiple-joint actions in older women

Abstract The present study investigated the acute effects of static stretching on peak force, peak rate of force development and integrated electromyography (iEMG) in 27 older women (65 ± 4 years; 69 ± 9 kg; 157 ± 1 cm; 28 ± 4 kg · m−2). The participants were tested during two exercises (leg press and knee extension) after two conditions: stretching and control. The data were collected on four days (counterbalanced with a 24-hour rest period). In the stretching condition, the quadriceps muscle was stretched (knee flexion) for three sets of 30 s with 30 s rest intervals. No significant difference was detected for peak force and peak rate of force development during the single- and multiple-joint exercises, regardless of the following interactions: condition (stretching and control) vs. time (pre x post x 10 x 20 x 30 minutes post; P > 0.05) and exercise vs. time (P > 0.05). Additionally, no significant interaction was found for the iEMG activity (condition vs. time; P > 0.05) in the single- and multiple-joint exercises. In conclusion, a small amount of stretching of an agonist muscle (quadriceps) did not affect the peak force, peak rate of force development and EMG activity in older women during single- and multiple-joint exercises.

A comparison of motor performance between men and women in multiple series of weight exercises

RESUMO A magnitude das respostas neuromusculares, metabolicas e morfologicas de homens e mulheres parece ser bastante diferenciada ate mesmo quando esses sujeitos sao submetidos a protocolos de exercicios com pesos semelhantes. Todavia, as diferencas no desempenho motor entre homens e mulheres tem sido relatadas predominantemente em protocolos baseados em contracoes isometricas e isocineticas. Assim, o objetivo deste estudo foi analisar o comportamento de homens e mulheres durante series multiplas de exercicios com pesos ate a exaustao e, posteriormente, verificar possiveis diferencas de desempenho fisico entre os sexos em exercicios com pesos com intensidades semelhantes. Para tanto, 83 individuos (50 homens e 33 mulheres), 48 horas apos serem submetidos a testes de 1-RM nos exercicios supino em banco horizontal, agachamento e rosca direta de biceps, executaram um protocolo composto por quatro series a 80% de 1RM ate a exaustao, em cada um dos tres exercicios, para avaliacao da capacidade de resistencia a fadiga nos diferentes grupos musculares. ANOVA e ANCOVA para medidas repetidas, seguidas pelo teste post hoc de Tukey, quando P < 0,05, foram utilizadas para o tratamento dos dados. Verificou-se uma queda significativa de desempenho, tanto nos homens quanto nas mulheres, da primeira a quarta serie em todos os exercicios investigados (P < 0,01). Embora a magnitude da fadiga tenha sido maior nos homens, nos tres exercicios, o efeito do sexo foi identificado somente no exercicio rosca direta de biceps (P < 0,01). Os resultados do presente estudo indicaram que homens e mulheres apresentam comportamentos relativamente diferentes em series multiplas de exercicios com pesos, com as mulheres apresentando um desempenho mais estavel e uma maior capacidade de resistencia a fadiga, sobretudo, no exercicio rosca direta de biceps.