Bruno Pena Couto

Pre Vertical Jump Performance to Regulate the Training Volume

The purpose of this study was to assess the effect of training load regulation, using the CMJ at the beginning of the session, on the total plyometric training load and the vertical jump performance. 44 males were divided into 4 groups: No Regulation Group (nRG), Regulation Group (RG), Yoked Group (YG) and Control Group (CG). The nRG received 6 weeks of plyometric training, with no adjustment in training load. The RG underwent the same training; however, the training load was adjusted according to the CMJ performance at the beginning of each session. The adjustment made in RG was replicated for the volunteers from the corresponding quartile in the YG, with no consideration given to the YG participants condition at the beginning of its session. At the end of the training, the CMJ and SJ performance of all of the participants was reassessed. The total training load was significantly lower (p=0.036; ES=0.82) in the RG and the YG (1905±37 jumps) compared to the nRG (1926±0 jumps). The enhancement in vertical jump performance was significant for the groups that underwent the training (p<0.001). Vertical jump performance, performed at the beginning of the session, as a tool to regulate the training load resulted in a decrease of the total training load, without decreasing the long-term effects on vertical jump performance.

Acute Effects of Resistance Training with Local Vibration

The aim of this study was to verify the acute effects of the application of local vibration on upper limbs during resistance training on the number of maximum repetitions, metabolic and hormonal responses. 32 volunteers performed a maximum voluntary contraction test during a lat pulldown exercise. After the test, all volunteers underwent one conventional resistance training session and one resistance training session with local vibration. In both interventions, volunteers performed 4 sets with the highest possible number of repetitions of the lat pulldown exercise at 55% of maximum voluntary contraction. During the vibratory resistance training intervention, vibration was locally applied (20-Hz and 12-mm). During the conventional resistance training, volunteers performed the same procedures without vibration. Blood samples were taken at each experimental session before and 5 min after the end of each intervention. No significant differences were observed in number of maximum repetitions between the series of vibratory and conventional training. Serum testosterone, cortisol and lactate were significantly increased after 2 interventions. Vibratory resistance training induced greater increases in testosterone and lactate concentrations. No significant changes were found in creatine kinase, creatinine or urea concentration. These data indicate that local vibration increases the metabolic and anabolic response to the resistance training, without changing the training volume.

Selected anthropometric variables and aerobic fitness as predictors of cardiovascular disease risk in children.

The aim of this study was to assess the suitability of body mass index, waist circumference, waist-to-height ratio and aerobic fitness as predictors of cardiovascular risk factor clustering in children. A cross-sectional study was conducted with 290 school boys and girls from 6 to 10 years old, randomly selected. Blood was collected after a 12-hour fasting period. Blood pressure, waist circumference (WC), height and weight were evaluated according to international standards. Aerobic fitness (AF) was assessed by the 20-metre shuttle-run test. Clustering was considered when three of these factors were present: high systolic or diastolic blood pressure, high low-density lipoprotein (LDL) cholesterol, high triglycerides, high plasma glucose, high insulin concentrations and low high-density lipoprotein (HDL) cholesterol. A ROC curve identified the cut-off points of body mass index (BMI), WC, waist-to-height ratio (WHtR) and AF as predictors of risk factor clustering. BMI, WC and WHR resulted in significant areas under the ROC curves, which was not observed for AF. The anthropometric variables were good predictors of cardiovascular risk factor clustering in both sexes, whereas aerobic fitness should not be used to identify cardiovascular risk factor clustering in these children.

Effects of 12 weeks of dynamic strength training with local vibration

Abstract The purpose of this study was to investigate the chronic effects of dynamic strength training (ST) with local vibration on the maximum strength of elbow flexor muscles. Twenty healthy male untrained volunteers were divided randomly into the following two groups: the conventional training group (CTG) or the vibration training group (VTG). Both groups performed ST for 12 weeks, three times a week. The ST protocol included four sets of 8–10 repetition maximums (RMs) of unilateral elbow flexion exercise. The VTG performed this training protocol with local vibration at a frequency of 30 Hz and amplitude of 6 mm. The mean values of the one repetition maximum (1RM) tests for both groups increased significantly from the pretest week to the fourth week and from the fourth week to the eighth week (CTG: mean 19.02, s = 7.88%, p = 0.01; mean 10.50, s = 6.86%, p = 0.019, respectively; VTG: mean 16.02, s = 8.30%, p = 0.017; mean 12.55, s = 8.76%, p = 0.019, respectively). The increases in the maximal voluntary contraction (MVC) tests were also statistically significant from the pretest week to the fourth week and from the fourth week to the eighth week (CTG: mean 12.32, s = 8.33%, p = 0.004; mean 9.95, s = 5.32%, p = 0.006, respectively; VTG: mean 10.16, s = 11.71%, p = 0.003; mean 10.36, s = 2.96%, p = 0.01, respectively). There was no significant difference between the 1RM and MVC test results in the eighth and twelfth weeks in either group. No significant differences were observed between the groups (p < 0.05). In conclusion, the application of local vibration does not change the chronic effects of dynamic ST in untrained individuals.

Content Validation of a Catalog of Exercises for Judo.

This study aimed to assess the content validity of a catalog of 76 judo exercises. Two groups of raters comprising 16 judo experts evaluated the following content validity indicators: Clarity of Language, Practical Pertinence, Theoretical Relevance, and the Dimension of each exercise. The results confirmed the content validity of the judo training catalog with indicators showing scores greater than 0.80. These findings suggest that all 76 judo exercises are pertinent, representative of judo training and understandable for judo coaches. Thus, this catalog of judo exercises may help judo coaches in the selection and recording of exercises.

Associação de índice de massa corporal e aptidão física aeróbica com fatores de risco cardiovascular em crianças

Resumo Objetivo Identificar a associacao do indice de massa corporal e aptidao fisica aerobica com fatores de risco de doencas cardiovasculares em criancas. Metodos Estudo transversal realizado na cidade de Itauna-MG no ano de 2010 com 290 escolares de 6 a 10 anos de ambos os sexos, aleatoriamente selecionados. Criancas de escolas da zona rural e aquelas com limitacoes medicas para pratica de atividade fisica nao foram incluidas. Coletou-se o sangue apos jejum de 12 horas. A pressao arterial, a estatura e o peso foram avaliados segundo padroes internacionais. Foram considerados fatores de risco cardiovascular: hipertensao arterial, colesterol total, LDL, triacilglicerois e insulinemia elevados e HDL baixo. A analise estatistica incluiu a Correlacao de Spearman e a Regressao Logistica, com os fatores de risco cardiovascular como variaveis dependentes. Resultados Correlacoes significativas foram encontradas, nos dois sexos, entre indice de massa corporal e aptidao fisica aerobica com a maioria dos fatores de risco cardiovascular. Criancas dos dois sexos com indice de massa corporal acima do percentil 75 apresentaram chances aumentadas para insulinemia alterada e agrupamento de fatores de risco cardiovascular. Meninas com aptidao fisica aerobica no primeiro quartil apresentaram chances aumentadas para insulinemia alterada e agrupamento de fatores de risco cardiovascular. Conclusao As associacoes significativas e as chances aumentadas para presenca de fatores de risco cardiovascular em criancas com menor aptidao fisica aerobica e maior indice de massa corporal justificam o uso dessas variaveis no monitoramento da saude em pediatria.Objective: To identify the association between both, body mass index and aerobic fitness, with cardiovascular disease risk factors in children. Methods: Cross-sectional study, carried out in Itaúna-MG, in 2010, with 290 school children ranging from 6 to 10 years-old of both sexes, randomly selected. Children from schools located in the countryside and those with medical restrctions for physical activity were not included. Blood sample was collected after a 12-hour fasting period. Blood pressure, stature and weight were evaluated in accordance with international standards. The following were considered as cardiovascular risk factors: high blood pressure, high total cholesterol, LDL, triglycerides and insulin levels, and low HDL. The statistical analysis included the Spearmans coefficient and the logistic regression, with cardiovascular risk factors as dependent variables. Results: Significant correlations were found, in both sexes, among body mass index and aerobic fitness with most of the cardiovascular risk factors. Children of both sexes with body mass index in the fourth quartile demonstrated increased chances of having high blood insulin and clustering cardiovascular risk factors. Moreover, girls with aerobic fitness in the first quartile also demonstrated increased chances of having high blood insulin and clustering cardiovascular risk factors. Conclusion: The significant associations and the increased chances of having cardiovascular risk factors in children with less aerobic fitness and higher levels of body mass index justify the use of these variables for health monitoring in Pediatrics.

Efeito da aplicação de vibração mecânica sobre a impulsão vertical

Several studies have indicated that vibratory training can contribute to the development of muscle strength and sports performance. The aim of this study was to investigate the effect of mechanical vibration application in the direction of the result of muscle forces vector addition on vertical jump. Eighteen volunteers performed vertical jump test 20 s before and after the application of mechanical vibration of 20 Hz and 6 mm amplitude in the direction of the result of muscle forces vector addition. The same volunteers were used as control group by performing the vertical jump test without pre- and post-test vibration application. The vibratory training caused an significantly increase of 8,5% at vertical jump height while jump height did not vary significantly in the control experiment. These data suggest that the application of mechanical vibration in the direction of muscle forces vector addition can increase the performance in vertical jumps.

Electromyographic activity during maximal isometric contraction combined with local sinusoidal vibration

Electromyographic activity during maximal isometric contraction combined with local sinusoidal vibration Study aim: To compare the electromyographic activity during maximal isometric contraction alone or combined with local sinusoidal vibration. Material and methods: A group of 6 men aged 23 - 29 years performed 3 maximal voluntary contractions of the dominant elbow flexors lasting 10 s each and separated by 5-min intermissions. One repetition was without vibration, one was associated with 15-Hz and the other one with 20-Hz vibrations of 5-mm amplitude, the sequence of repetitions being random. A new system to generate local vibration was applied, the parameters of the vibratory stimulus being measured using an accelerometer. Force and EMG activity were also measured. The subjects performed the task in sitting position in a Scott Bench-type device. Results: Mean acceleration RMS significantly (p<0.01) differed between vibration frequencies for the X, Y, Z-axes. No significant differences were found, however, for EMG RMS. Vibration frequencies coincided with the machine-predicted ones; acceleration frequencies around 5 Hz were present in all situations, even without vibration, most likely brought about by tremor. Conclusion: The local vibration applied was not enough to generate different responses in EMG activity. The features of vibratory stimulus confirmed the expected frequency range and revealed frequencies around 5 Hz, that could be attributed to muscle tremor.

EFFECT OF DIFFERENT REST INTERVAL LENGTHS ON THE COUNTERMOVEMENT JUMP

The evaluation of athlete’s physical performance is one of the complex processes that involve sports training. The purpose of this study was to measure the effects of varied rest interval lengths on countermovement jump (CMJ) performance test. The subjects were 12 national athletes from UFMG Sport Training Center, who performed five sessions, two familiarization sessions and three CMJ experimental sessions. The experimental sessions consisted of three sessions with 15 CMJ attempts, each session with a different rest interval duration. The three rest intervals between CMJ attempts were 15, 30, and 60 seconds and were counterbalanced for each subject. No significant difference was founded in the jump height between the 3 pause protocols adopted and between the 15 attempts in the same protocol. Therefore, this study demonstrated a 15 seconds rest interval was sufficient for recovery during the performance of 15 CMJ attempts.

Effect of strength training on regional hypertrophy of the elbow flexor muscles

Introduction: Muscle hypertrophy is the main structural adaptation to strength training. We investigated the chronic effects of strength training on muscle hypertrophy in different regions of the elbow flexor muscles. Methods: Eleven untrained men (21.8 ± 1.62 years) underwent magnetic resonance imaging to determine the proximal, medial, distal, and mean cross‐sectional areas (CSA) of the elbow flexors. The volunteers completed 12 weeks of strength training. The training protocol consisted of 4 sets of 8–10 maximum repetitions of unilateral elbow flexion. The interval between sets was 120 s. The training frequency was 3 sessions per week. Results: The magnetic resonance images verified the presence of significant and similar hypertrophy in the distal, medial, and proximal portions of the elbow flexor muscles. Conclusions: Muscle hypertrophy may be assessed using only the medial CSA. We should not expect different degrees of hypertrophy among the regions of the elbow flexor muscles. Muscle Nerve 54: 750–755, 2016