ABSTRACT
Intermittent fasting (IF) is commonly used by combat sports athletes for weight loss. However, IF can decrease performance. This study aimed to investigate the effect of IF on total body mass (TBM) and Taekwondo performance. Nine athletes (seven male, two female; 18.4 ± 3.3 years) underwent 4 weeks of 12 h IF. TBM, countermovement jump (CMJ), mean kicks (MK), and total number of kicks (TNK) were compared weekly. Performance was measured in the fed state (FED) and fast state (FAST). Results showed decreased TBM in week 1 (62.20 ± 6.56 kg; p = 0.001) and week 2 (62.38 ± 6.83 kg; p = 0.022) compared to pre-intervention (63.58 ± 6.57 kg), stabilizing in week 3 (62.42 ± 6.12 kg), and no significant change in week 4 (63.36 ± 6.20 kg). CMJ performance in week 1 was lower in FED (35.26 ± 7.15 cm) than FAST (37.36 ± 6.77 cm; p = 0.003), but in week 3, FED (38.24 ± 6.45 cm) was higher than FAST (35.96 ± 5.05 cm; p = 0.047). No significant differences were found in MK and TNK in FSKTmult. RPE, KDI, and HR were similar between FED and FAST (p < 0.05). [LAC] was higher post-test compared to pre-test (p = 0.001), with higher concentrations in FED than FAST (p = 0.020). BG was higher in FED than FAST (p < 0.05) before physical tests. Therefore, IF promotes decreased TBM without decreasing performance.
Subject(s)
Athletic Performance , Martial Arts , Humans , Male , Female , Intermittent Fasting , Weight Loss , AthletesABSTRACT
Abstract The use of devices that produce stochastic whole-body vibration as a resource for rehabilitation and training programs has been founded on the theory of stochastic resonance. However, the prescription of rehabilitation and training programs must be preceded by the verification of imposed-vibration magnitude and of how it can be affected by the presence of an individual on the devices. The aim of this research was to characterize and analyze the effect of an individual's mass on the vibratory stimulus provided by stochastic whole-body vibration (SWBV) devices. The sample consisted of 30 repetitions for each one of the 6 vibration levels of the SWBV device (level 02, 04, 06, 08, 10 and 12), performed in two experimental situations (Without Load; Load [70Kg]; ≈ 35 kg on the right and left surfaces of the platform). For the antero-posterior, latero-lateral, and vertical directions, all variables showed significant differences between treatments, levels and interaction between experimental factors (p<.05), except for the Disp variable between treatments (p=.075). To measure vibration magnitude, a triaxial accelerometer was attached at the center of the board of one of the platform surfaces. Load interferes with parameters of vibration imposed by SWBV platforms, increasing ARMS and APEAK in the latero-lateral and antero-posterior directions, reducing these same parameters in the vertical direction.
Resumo O uso de dispositivos que produzem vibração estocástica de corpo inteiro como recurso para programas de reabilitação e treinamento foi fundamentado na teoria da ressonância estocástica. Entretanto, a prescrição de programas de reabilitação e treinamento deve ser precedida da verificação da magnitude da vibração imposta e de como ela pode ser afetada pela presença de um indivíduo nos dispositivos. O objetivo deste estudo foi caracterizar e analisar o efeito da massa do indivíduo sobre o estímulo vibratório proporcionado por dispositivos de vibração estocástica de corpo inteiro. A amostra consistiu em 30 repetições para cada um dos 6 níveis de vibração de um dispositivo de vibração estocástica de corpo inteiro (nível 02, 04, 06, 08, 10 e 12), realizados em duas situações experimentais (Sem carga e Carga [70Kg], 35 kg nas superfícies direita e esquerda da plataforma). Para medir a magnitude da vibração, um acelerômetro triaxial foi fixado ao centro do assoalho de uma das superfícies da plataforma. Para os eixos ântero-posterior, látero-lateral e vertical, todas as variáveis mostraram diferenças entre tratamentos, níveis e interação entre fatores experimentais (p<.05), exceto para a variável de deslocamento pico - a - pico (Disp) entre tratamentos (p=.075). A carga interfere com parâmetros de vibração impostos sobre as plataformas de vibração estocástica de corpo inteiro, aumentando a aceleração média (ARMS) e de pico (APEAK) nas direções látero-lateral e ântero-posterior, reduzindo estes mesmos parâmetros na direção vertical.
ABSTRACT
This study determined the time-course of recovery after resistance training (RT) sessions and the association between changes in performance with changes in biomechanical, physiological and perceptual parameters. After a 4-week familiarization period, 14 resistance-trained males performed 3 experimental conditions, each one including 2 sessions with a recovery interval of 24, 48â h or 72â h, in a randomized order. RT sessions consisted of 5 sets of 8-10RM on squat and leg press exercises. The resistance was equal for the 2 sessions of each condition and repetitions were performed until concentric failure. Volume load (VL) and first set volume load (FSVL) were compared between sessions. Tests before each session included countermovement jump (CMJ), maximal voluntary isometric contraction (MVIC), creatine kinase (CK) and delayed onset muscle soreness (DOMS). (2 × 3) ANOVA with effect sizes (ES) assessed the time-course of recovery and Kendall test the correlation between variables (α = 0.05). Significant interaction was observed for all variables, except for CK, where a condition main effect occurred. Comparisons between post and pre-intervals showed VL (p = 0.011;ES = -0.90) decreased for 24â h condition, while FSVL remained decreased for 48â h (p = 0.031;ES = -0.63) and DOMS increased (p = 0.001;ES = 3.52). CMJ (p = 0.025;ES = 0.25) and MVIC (p = 0.031;ES = 0.14) performance increased at 72â h. FSVL (r = 0.424), CMJ (r = 0.439), MVIC (r = 0.389) and DOMS (r = -0.327) were significantly correlated with VL (p < 0.05). Time-course of VL showed the necessity of at least 48â h for the reestablishment of performance, though better perceptual responses were evident at 72h. Thus, both recovery intervals may be beneficial after lower-limbs RT until concentric failure, though chronic effects still need to be investigated.
Subject(s)
Athletic Performance/physiology , Resistance Training , Adult , Biomechanical Phenomena , Creatine Kinase/blood , Exercise Test/methods , Humans , Isometric Contraction , Male , Muscle Fatigue/physiology , Myalgia/enzymology , Perception/physiology , Physical Exertion/physiology , Time Factors , Young AdultABSTRACT
ABSTRACT This study aimed to compare the vertical rebound jump performance of basketball players by using Hurdle Jump and Drop Jump tests based on different performance parameters, in addition to investigating whether the height of the hurdles used (barrier and box) are equivalent when the optimal and maximum heights for the tests mentioned are determined. Thirteen players of a male basketball team were included in this study (age 18.77 ±1.78 years old, height 182 ±7.97 m, body mass 76.4 ±9.55 kg, practice time 6.0 ±1.8 years). Data normality and homogeneity were tested by applying Shapiro-Wilk and Levene tests, respectively. The paired t-test was used to compare the means of the results obtained in the tests; the significance level was p ≤ 0.05. The results regarding the comparison of the performance parameters means were the following: the maximum vertical rebound jump and reactive strength index did not show significant differences (p = 0.256 and p = 0.243, respectively); on the other hand, differences were seen for the corresponding obstacle heights. These differences can be attributed to both, individual characteristics of each subject and the specificities of the tests.
RESUMO O objetivo do presente estudo foi comparar o desempenho do ressalto vertical de jogadores de basquetebol por meio dos testes Hurdle Jump e Drop Jump a partir de diferentes parâmetros de desempenho e verificar se a altura dos obstáculos utilizados (barreira e caixote) se equivalem quando forem determinadas a altura ótima e a máxima para os testes mencionados. Participaram do estudo 13 jogadores de uma equipe de basquetebol masculina (idade 18,77 ±1,78 anos, estatura 182 ±7,97 centímetros, massa corporal 76,4 ±9,55 quilogramas, tempo de prática 6,0 ±1,8 anos). A normalidade e a homogeneidade dos dados foram testadas por meio dos testes Shapiro-Wilk e Levene, respectivamente. O Test T pareado foi utilizado na comparação das médias dos resultados obtidos nos testes e o nível de significância foi p≤0,05. Os resultados das comparações das médias dos parâmetros de desempenho: ressalto vertical máximo e índice de força reativa, não apresentaram diferenças significativas (p=0,256 e p=0,243, respectivamente), em contrapartida, foram identificadas diferenças nas alturas dos obstáculos correspondentes. Essas diferenças podem ser atribuídas às características da individualidade de cada sujeito e às especificidades dos testes.
Subject(s)
Humans , Adolescent , Young Adult , Basketball/statistics & numerical data , Athletic Performance , Mentoring/statistics & numerical data , Play and Playthings , Efficiency , Muscle Strength , Test Taking Skills/methods , Plyometric Exercise , Team SportsABSTRACT
RESUMO O objetivo desse estudo foi verificar o efeito agudo da aplicação de vibração de corpo inteiro (VCI) sobre o impulso e sobre a força máxima de membros superiores. Vinte voluntários do sexo masculino, treinados, com idade: 23,8 ± 3,3 anos, foram submetidos a 3 sessões (uma sessão de familiarização e duas sessões de intervenção). Em cada uma das sessões de intervenção os voluntários realizaram uma contração voluntária máxima (CVM) de flexores do cotovelo sem aplicação de vibração e duas CVM com adição de vibração. Foram utilizadas 4 frequências de VCI (10, 20, 30 e 40Hz) distribuídas de maneira aleatória nas 4 CVM realizadas com vibração nas duas sessões de coleta. Os resultados encontrados mostraram que a força máxima e o impulso gerados na contração sem vibração foram significativamente maiores do que a força máxima e o impulso gerados durante a contração realizada com aplicação de VCI. Para o treinamento de força, a aplicação de VCI, nas frequências testadas na presente investigação, representou um menor estímulo de treinamento para os membros superiores, uma vez que gerou uma redução na força máxima e no impulso dos músculos flexores do cotovelo.
ABSTRACT The aim of this study was to investigate, from a protocol of maximal isometric contractions of the elbow flexors, the effect of WBV in the maximal force and of impulse in strength-trained individuals. Twenty male volunteers, age: 23.8 ± 3.3 years, performed 3 sessions (one familiarization session and two intervention session). The sessions were composed by 3 MVC of the elbows flexor muscles with 5 minute of rest between them. The first CVM was performed without vibration and the others, applying aleatory WBV with 10, 20, 30, 40Hz, and amplitude of 6mm. The results showed that the maximal force and of impulse obtained during the MVC without vibration was significantly higher than the maximal force and of impulse recorded during the application of WBV. For strength training, the application of WBV, in the adopted frequencies, was not able to generate sufficient stimulus to induce acute adaptations in muscle strength of upper limbs.
Subject(s)
Humans , Male , Adult , Muscle Strength , Isometric Contraction , VibrationABSTRACT
Abstract Physical activity measurement with accuracy and precision is extremely important in establishing the dose-response relationship between levels of physical activity and the different outcome possibilities. Subjective methods of measurement, such as proxy-reports have been used as a possibility to check physical activity in children. The aim of this study was to test the Netherlands Physical Activity Questionnaire (NPAQ), valid for Brazilian schoolchildren using physical aerobic fitness as a criterion. The study included 290 children aged 6-10 years from public schools of Itaúna/MG. NPAQ was applied to parents or guardians and children were tested using the Luc Léger test. NPAQ had mean score of 25 for children (25 for boys and 24 for girls) and VO2max was 50.8 ml/kg/min for children (52.6 and 50.2 ml/kg/min for boys and girls, respectively). The Spearmam correlation test showed significant correlation (rsho = 0.146; p = 0.013) between NPAQ and VO2max, but the correlation is weak (Kappa -0.14). The results showed that NPAQ presented poor construct validity for physical activity measurement in a Brazilian schoolchildren sample, based on aerobic physical fitness criteria.
Resumo A mensuração da atividade física com acurácia e precisão é de extrema importância no estabelecimento da relação de dose-resposta entre os níveis de atividade física e as diversas possibilidades de desfecho, sendo um desafio de extrema complexidade. A utilização de métodos subjetivos de mensuração, como os instrumentos proxy-reports, é uma possibilidade de verificação de atividade física em crianças. O objetivo deste estudo foi testar a validade do Netherland Physical Activity Questionnaire (NPAQ) em escolares brasileiros tendo como medida critério a aptidão física aeróbica. Participaram deste estudo 290 crianças de seis a 10 anos de idade, matriculados em escolas públicas do município de Itaúna/MG. Foi aplicado aos responsáveis o NPAQ e as crianças realizaram o teste de Luc Léger. O NPAQ apresentou um escore mediano de 25 para as crianças (25 meninos e 24 meninas) e o VO2máx foi de 50,8 ml/kg/min para as crianças (52,6 e 50,2 ml/kg/min para meninos e meninas, respectivamente). O NPAQ e o VO2máx apresentaram no teste de correlação simples de Spearmam rsho = 0,146 (p = 0,013) correlação significativa, porém fraca (Kappa -0.14). Os resultados permitem concluir que o NPAQ apresentou fraca validade de constructo para mensuração de atividade física em uma amostra de escolares brasileiros, tendo como medida critério a aptidão física aeróbica.
Subject(s)
Humans , Child , Physical Fitness/physiology , Surveys and Questionnaires , Oxygen Consumption/physiology , Exercise TestABSTRACT
INTRODUÇÃO: Doenças cardiovasculares representam a principal causa de morte no Brasil, sendo uma destas a hipertensão arterial. A prática regular de exercício físico permite um melhor controle da pressão arterial e indivíduos com maiores níveis de aptidão física apresentam um menor risco para desenvolver hipertensão. Além disso, pessoas com frequências cardíacas de repouso mais baixas apresentam uma menor probabilidade de desenvolverem cardiopatias. OBJETIVO: Comparar o efeito do treinamento aeróbico, de força e combinado nas pressões arteriais sistólica, diastólica e média e na frequência cardíaca de repouso em homens normotensos. MÉTODOS: Ensaio clínico aleatorizado com três grupos experimentais e um grupo controle. Cada grupo experimental realizou uma destas três modalidades de treinamento, três vezes por semana, durante doze semanas. Participaram homens de 30 a 57 anos, sedentários e normotensos. A pressão arterial e a frequência cardíaca pré e pós intervenção foi aferida utilizando um aparelho automático validado e seguindo recomendações da Sociedade Brasileira de Cardiologia. Os dados foram comparados pelo teste t de Student e pela ANOVA one-way. RESULTADOS: 39 voluntários completaram o estudo. Não houve variação significante da pressão arterial sistólica, diastólica e média e frequência cardíaca nos três grupos de treinamento entre pré e pós-intervenção. Apenas a frequência cardíaca nestes grupos apresentou diferenças significativas quando comparada ao grupo controle. CONCLUSÃO: Resultados sugerem que o treinamento físico, realizado três vezes por semana, durante doze semanas, não é suficiente para reduzir a pressão arterial de modo significativo em homens normotensos, seja este treinamento aeróbico, de força ou combinado.
INTRODUCTION: Cardiovascular diseases are the most common cause of death in Brazil and one of these diseases is hypertension. Regular practice of physical exercise may contribute to a better control of blood pressure and individuals with higher levels of physical fitness have lower risk for developing hypertension. In addition, people with lower heart rate have lesser likelihood for developing cardiovascular diseases. OBJECTIVE: Compare the effect of aerobic, strength and combined training on systolic, diastolic and mean blood pressure and at the resting heart rate in normotensive men. METHODS: A randomized trial with three experimental groups and one control group was conducted. Each experimental group practiced a determined type of training, three times per week during, twelve weeks. Men aged 30 to 57 years, sedentary and normotensive participated in this study. Blood pressure and heart rate values were checked at pre and post-intervention in all four groups by using a validated automatic device as recommend the Brazilian Cardiologic Society. The data were compared by Student's t test and by ANOVA one-way. RESULTS: 39 participants completed the study. There was no significant variation of systolic, diastolic and mean blood pressure and at the resting heart rate in the three experimental groups between pre and post-intervention. However, only heart rate in three training groups showed differences when compared to the control group. CONCLUSION: The results suggest aerobic, strength or combined training when performed as in this study did not change blood pressure significantly in normotensive men.
Subject(s)
Humans , Male , Adult , Middle Aged , Exercise , Exercise/physiology , Resistance Training , Arterial Pressure , Heart Rate , Men , Resistance Training/methodsABSTRACT
RESUMO A avaliação do desempenho físico de atletas é um dos complexos processos que envolvem o treinamento esportivo. O objetivo deste estudo foi verificar o efeito de três diferentes pausas (15, 30 e 60 segundos) entre as tentativas do teste de salto com contramovimento (SCM) de atletas nacionais do Centro de Treinamento esportivo da UFMG. A amostra foi composta por 12 atletas que participaram de cinco sessões: 2 familiarizações e 3 de protocolo experimental. O protocolo experimental consistiu de três sessões de teste de 15 SCM aleatorizado entre as diferentes pausas entre tentativas (15, 30 e 60 segundos). Não houve diferença significativa para a altura do salto entre os três protocolos de pausa adotados e entre as 15 tentativas de salto no mesmo protocolo. Estes resultados sugerem que, durações de pausas menores, como a de 15 segundos, são suficientes para a manutenção do desempenho em testes de SCM com uma série única de até 15 tentativas.
ABSTRACT 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.
Subject(s)
Humans , Male , Adolescent , Physical Education and Training , Reference Values , Athletic Performance , AltitudeABSTRACT
The aim of this study was to evaluate acute neuromuscular responses to local vibrations (LV) exposure through monitoring of imposed acceleration. Nineteen healthy males (age = 22.43 ± 2.76 years; body mass = 76.4 ± 12.94 kg; height = 175 ± 6.76 cm) performed an elbow flexion isometric exercise (Scott bench) in two experimental conditions: simple isometric exercise (Control - CON) and vibrating isometric exercise (Local Vibration - LV; Frequency = 20.01 ± 0.13, displacement = 2 - 5 mm). Protocols consisted of 5 maximal voluntary contractions of 12 seconds each and five minutes of recovery between series with (LV) or without vibration (CON). During the exercise, individuals were seated on the bench with the dominant arm resting on the bench support at an approximate angle of 45º between shoulder flexion and the torso. Strength parameters (Rate of Force Development - RFD, p = .030; Peak Force - PF, p = .027; and Fatigue Index - FI, p = .001) significantly increased in LV compared to CON. For EMG parameters, significant changes were only observed for highest value of increase rate of the EMG signal - RER (p = .041), median frequency of EMG signal between peak force and force at the end of the isometric action - MFFbic (p = .045) (agonist) and root mean square of EMG signal of peak force at the end of the isometric action - RMSFtric (p <.001) (antagonist). The addition of local vibrations in resistance training induced an increase in maximal strength, explosive strength and reduced the capacity to sustain strength generation.
O objetivo deste estudo foi avaliar as respostas neuromusculares durante o exercício com a variação dos parâmetros de vibração local. Foram recrutados 19 indivíduos saudáveis do gênero masculino (idade = 22,43 ± 2,76 anos; massa corporal = 76,4 ± 12,94 kg; altura = 175 ± 6,76 cm) que executaram o exercício isométrico em duas situações experimentais: somente o exercício isométrico (Controle); exercício com a adição de vibrações locais (LV; Frequência = 20 ± 3Hz, Deslocamento = 2 - 5 mm). Os parâmetros de força foram significativamente aumentados no tratamento LV comparados ao tratamento controle (RFD, p = ,030; PF, p = ,027; and FI, p = ,001). Para os parâmetros de atividade eletromiográfica, foram observadas alterações significativas para a RER (p = ,041), MFFbic (p = ,045) no músculo bíceps braquial (agonista) e RMSFtric (p <.001) no músculo tríceps braquial (antagonista). A adição de vibrações locais no treinamento contra resistência, induziu um aumento da força máxima, força explosiva e uma redução da capacidade de sustentar a produção de força.
Subject(s)
Vibration , Biomechanical Phenomena , Electromyography , MusclesABSTRACT
Vários estudos apontam que o treinamento com vibrações pode contribuir no desenvolvimento da força muscular e do desempenho esportivo. O objetivo deste estudo foi verificar o efeito da vibração mecânica aplicada na direção da resultante das forças musculares sobre a impulsão vertical. A amostra foi composta por 18 voluntários que realizaram o teste de salto vertical antes e após 20 segundos de vibração mecânica, 20 Hz de frequência e 6 mm de amplitude, aplicada na direção da resultante das forças musculares. Os mesmos voluntários foram utilizados como controle e, para isto, realizaram pré e pós-teste sem treinamento com vibração. Houve um aumento significativo de 8,5% na altura de salto vertical após o treinamento com vibração. O procedimento controle não gerou alterações significativas. Estes resultados sugerem que a aplicação de vibração mecânica na direção da resultante das forças musculares de membros inferiores foi capaz de gerar aumentos agudos na 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.
Subject(s)
Humans , Male , Adult , Athletic Performance , Muscle Strength/physiology , Sports , VibrationABSTRACT
The aim of this study was to verify if there are differences in the amplitude of signals from surface electromyography (EMG) during maximal and submaximal voluntary isometric contraction (MVC and 50% MVC, respectively) under different conditions, in our case, water and air, with and without extra protection (water-resistant tape) on the electrode. The isometric force and muscle activation of the MVC and 50% MVC of the biceps brachial muscle of nine healthy trained men were measured simultaneously, performed in water and on air, with and without protection of the EMG electrode. The multivariate analysis of variance with a post hoc Tukey test was applied to detect significant differences between the levels of muscular force. For the amplitude values of the EMG signal, the Wilcoxon signed rank test was applied to compare all experimental conditions in order to detect a significance of p<0.05. The values of isometric force were not significantly different among conditions (MVC and 50% MVC). The results showed a significant difference among conditions in the water without extra protection compared to the conditions on air with and without extra protection and in water with extra protection. Reduced EMG amplitude was seen in water without extra protection from 37.04% to 55.81% regarding the other conditions. However, no significant difference was seen among conditions in water with extra protection in relation the conditions on air (with and without extra protection). This study suggest that it is necessary to use a water-resistant tape as an extra protection on the electrode when using EMG underwater, to avoid having a significant decrease in the EMG amplitude underwater and not to suffer interference from the water. There was no significant difference among the recordings of EMG with and without the use of protection on air; therefore, the protection does not influence the recording of EMG amplitude and isometric force on air.