Electromyographic signal and force comparisons during maximal voluntary isometric contraction in water and on dry land.

This study was designed to compare surface electromyographic (sEMG) signal and force production during maximal voluntary isometric contractions (MVCs) in water and on dry land. The reproducibility of sEMG and isometric force measurements between water and dry land environments was also assessed. Nine women performed MVC for elbow flexion and extension, hip flexion, and extension against identical fixed resistance in both environments. The sEMG signal from biceps brachii, triceps brachii, rectus femoris, and biceps femoris was recorded with waterproof adhesives placed over each electrode. The sEMG and force production showed no significant difference between water and dry land, except for HEX (p = 0.035). In addition, intraclass correlation coefficient values were significant and ranged from moderate to high (0.66-0.96) for sEMG and force production between environments. These results showed that the environment did not influence the sEMG and force in MVC.

Effects of Nordic walking training on quality of life, balance and functional mobility in elderly: A randomized clinical trial.

PURPOSE: There is physiological and biomechanical evidence suggesting a possible advantage of using poles in walking training programs. The purpose of this proof-of-concept study was to test the hypothesis that untrained elderly training Nordic walking for eight weeks will show higher improvements on the functional mobility, quality of life and postural balance than that training without poles; more likely to occur in self-selected walking speed (primary outcome), and the locomotor rehabilitation index than the quality of life, the static balance and the dynamic stability. It was a two-arm randomized sample- and load-controlled study. METHODS: Thirty-three untrained older people were randomly assigned into Nordic walking (n = 16, age: 64.6±4.1 years old) and free walking (n = 17, age: 68.6±3.9 years old) training groups. RESULTS: Improvements in the self-selected walking speed (primary outcome, p = 0.011, ES = 0.42 95%CI -0.31 to 1.16), locomotor rehabilitation index (p = 0.013, ES = 0.36; (95%CI -0.39 to 1.10), quality of life (p<0.05), static balance (p<0.05) and dynamic variability (p<0.05) were found in both groups. CONCLUSIONS: The hypothesis was not supported, our findings indicated that after 8 weeks, the Nordic walking training did not result in greater improvements than free walking training for the primary outcome (self-selected walking speed) and most of the secondary outcomes (including locomotor rehabilitation index, static balance, dynamic stability, and psychological and social participation domains of quality of life). TRIAL REGISTRATION: ClinicalTrials.gov NCT03096964.

Rating of Perceived Exertion and Physiological Responses in Water-Based Exercise.

The aim of the present study was to relate the overall rating of perceived exertion (RPE-overall) with cardiorespiratory and neuromuscular variables during stationary running with the elbow flexion/extension performed with water-floating equipment. The sample consisted of eleven women that performed the water-based exercise at submaximal cadences. The heart rate, oxygen uptake, ventilation, and electromyographic signal (EMG) from biceps brachii (%EMG BB), triceps brachii (%EMG TB), biceps femoris (%EMG BF) and rectus femoris (%EMG RF) muscles were measured during the exercise, and the overall RPE was measured immediately following its completion. The Pearson product-moment linear correlation was used to investigate associations between the variables analyzed in the present study. Significant relationships were observed between the RPE-overall and all the cardiorespiratory variables, with the r values ranging from 0.60 to 0.70 (p<0.05). In addition, the RPE-overall showed a significant (p<0.05) relationship with %EMG BB (r=0.55) and %EMG BF (r=0.50). These results suggest an association between the RPE-overall with all cardiorespiratory and two neuromuscular variables during the execution of a water-based aerobic exercise using water-floating equipment.

Effects of two deep water training programs on cardiorespiratory and muscular strength responses in older adults.

This study aimed to investigate the effects of two deep water training programs on cardiorespiratory and muscular strength responses in older adults. Thirty-four older adults men were placed into two groups: deep water endurance training (ET; n = 16; 66 ± 4 years) and deep water strength prior to endurance training (concurrent training: CT; n = 18; 64 ± 4 years). The training period lasted 12 weeks, with three sessions a week. The resting heart rate and the oxygen uptake at peak (VO2peak) and at the second ventilatory threshold (VO2VT2) were evaluated during a maximal incremental test on a cycle ergometer before and after training. In addition, maximal dynamic strength (one repetition maximum test--1RM) and local muscular resistance (maximum repetitions at 60% 1RM) of the knee extensors and flexors were evaluated. After the training period, the heart rate at rest decreased significantly, while the VO2peak and VO2VT2 showed significant increases in both groups (p<0.05). Only the VO2VT2 resulted in significantly greater values for the ET compared to the CT group after the training (p<0.05). In addition, after training, there was a significant increase in the maximal dynamic strength of the knee extensors and the local muscular endurance of the knee extensors and flexors, with no difference between the groups (p > 0.05). In summary, the two training programs were effective at producing significant improvements in cardiorespiratory and muscular strength responses in older adult men. However, deep water endurance training at high intensities provides increased cardiorespiratory responses compared to CT and results in similar muscular strength responses.

Neuromuscular responses of elite skaters during different roller figure skating jumps.

This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions.

Strength training prior to endurance exercise: impact on the neuromuscular system, endurance performance and cardiorespiratory responses.

This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise.

Treinamento de força no meio aquático: uma revisão sobre os aspectos históricos, fi siológicos e metodológicos / Aquatic resistance training: a review about historical, physiological and metodological aspects

Exercitar-se na água é uma prática constatada há vários séculos, embora seja recente sua realização de forma sistemática e planejada. A literatura científi ca é ampla no estudo dos efeitos do treinamento aeróbico aquático, tendo investigado diferentes modalidades. Nas últimas décadas têm ganhado elevância os estudos que avaliam treinamentos aquáticos de caráter de força e sua melhora no sistema neuromuscular. Contudo estes trabalhos apresentam métodos de prescrição muito diferentes,dificultando sua comparação. Assim, o objetivo desta revisão é elucidar aspectos metodológicos para prescrição de exercícios de força no meio aquático. Este artigo tem caráter narrativo e para a localização e aquisição dos estudos foram consultadas as bases de dados eletrônicas SCOPUS, SCIELO e MEDLINE, realizando-se buscas de artigos publicados entre os anos 1980 e 2016, com os seguintes descritores: hidroginástica, treinamento de força aquático e corrida em piscina funda. Os resultados demonstraram que os primeiros estudos publicados mundialmente relacionados a este tema datam do início dos anos 2000. Estes seguiam métodos de treinamento que buscavam reproduzir o modelo aplicado no meio terrestre, ou seja, utilizando número de repetições e número de séries. Por outro lado, os estudos mais recentes têm proposto a utilização da velocidade máxima e o tempo de execução para enfatizar vias metabólicas específi cas (anaeróbica alática e anaeróbica lática) e promover níveis adequados de tensão mecânica (velocidade máxima) e estresse metabólico (tempo de execução). Assim, os trabalhos demonstram que o treinamento de força no meio aquático têm proporcionado resultados satisfatórios em variáveis neuromusculares e morfológicas. Ainda, a prescrição de um treinamento de força neste meio, visando a ênfase sobre vias metabólicas específi cas, utilizando o tempo de execução e a máxima velocidade, parece ser uma forma adequada de se alcançar objetivos relacionados ao treinamento de força....(AU)

Exercising in the water environment is a practice that has been observed for several centuries, although its realization in a systematic and planned manner is recent. The scientifi c literature is broad in the study of the eff ects of water-based aerobic training, having investigated diff erent modalities. In the last decades, studies that evaluate water-based resistance training and its improvement in the neuromuscular system have gained relevance. However, these studies present very diff erent prescription methods, making diffi cult to compare them. Thus, the purpose of this review is to elucidate methodological aspects for prescription of water-based resistance exercises. This manuscript is a narrative review and for location and acquisition of the studies the electronic databases SCOPUS, SCIELO and MEDLINE were searched, searching articles published between 1980 and 2016, with the following descriptors: water gymnastics, water--based resistance training and deep water running. The results showed that the fi rst published studies related to this topic date back to the early 2000s. These studies followed training methods that sought to reproduce the model applied in the land environment, that is, using number of repetitions and number of series. On the other hand, more recent studies have proposed the use of maximum velocity and time to execution to emphasize specifi c metabolic pathways (lactic and alactic anaerobic) and to promote adequate levels of mechanical stress (maximal velocity) and metabolic stress (time to execution). Thus, the studies demonstrate that water-based resistance training has provided satisfactory results in neuromuscular and morphological variables. Furthermore, prescribing strength training in this environment, aiming at emphasizing specificmetabolic pathways, using time to execution and maximum velocity, seems to be an appropriate way of achieving goals related to strength training....(AU)

Oxygen uptake in water polo, comparison and agreement in cycle ergometer and eggbeater kick: A pilot study

The aim of this study was to compare and verify the agreement of maximal oxygen uptake (VO2 max) values obtained from tests on land and in water. Twelve recreational water polo players (30.5 ± 7.7 years; 79.2 ± 7.2 kg body mass; 179.1 ± 5.9 cm height) were assessed in two phases: (1) in laboratory with maximal test on a cycle ergometer and (2) in a swimming pool with maximal test in eggbeater kick. Maximum values obtained in the two tests (respectively, cycle ergometer, and eggbeater kick: VO2 max = 40.2 ± 2.7 ml.kg-1.min-1 and 38.4 ± 5.7 ml.kg-1.min-1; RER = 1.17 ± 0.08 and 1.19 ± 0.12; HR max = 181.4 ± 11.7 bpm and 179 ± 11.7 bpm; IEP = 20 and 20) did not show significant differences. According to the Bland-Altman analyses, there were acceptable limits of agreement between the two tests (land and water). Therefore, it can be concluded that the eggbeater kick test is a specific and valid protocol to asses VO2 max in water polo players

Maximal and anaerobic threshold cardiorespiratory responses during deep-water running / Respostas cardiorrespiratórias máximas e no limiar anaeróbio da corrida em piscina funda

Aquatic exercises provide numerous benefits to the health of their practitioners. To secure these benefits, it is essential to have proper prescriptions to the needs of each individual and, therefore, it is important to study the cardiorespiratory responses of different activities in this environment. Thus, the aim of this study was to compare the cardiorespiratory responses at the anaerobic threshold (AT) between maximal deep-water running (DWR) and maximal treadmill running (TMR). In addition, two methods of determining the AT (the heart rate deflection point [HRDP] and ventilatory method [VM]) are compared in the two evaluated protocols. Twelve young women performed the two maximal protocols. Two-factor ANOVA for repeated measures with a post-hoc Bonferroni test was used (α < 0.05). Significantly higher values of maximal heart rate (TMR: 33.7 ± 3.9; DWR: 22.5 ± 4.1 ml.kg−1.min−1) and maximal oxygen uptake (TMR: 33.7 ± 3.9; DWR: 22.5 ± 4.1 ml.kg−1.min−1) in TMR compared to the DWR were found. Furthermore, no significant differences were found between the methods for determining the AT (TMR: VM: 28.1 ± 5.3, HRDP: 26.6 ± 5.5 ml.kg−1.min−1; DWR: VM: 18.7 ± 4.8, HRDP: 17.8 ± 4.8 ml.kg−1.min−1). The results indicate that a specific maximal test for the trained modality should be conducted and the HRDP can be used as a simple and practical method of determining the AT, based on which the training intensity can be determined.

Os exercícios aquáticos proporcionam inúmeros benefícios à saúde de seus praticantes. Para assegurar esses benefícios, é indispensável uma prescrição adequada às necessidades de cada indivíduo e, para isso, faz-se importante estudar as diferentes respostas cardiorrespiratórias das atividades desenvolvidas nesse meio. Deste modo, o objetivo do estudo foi comparar as respostas cardiorrespiratórias no limiar anaeróbio (LAn) entre o teste máximo de corrida em piscina funda (CPF) e da corrida em esteira terrestre (CET). Além disso, comparar dois métodos de determinação do LAn (ponto de deflexão da frequência cardíaca [PDFC] e método ventilatório [MV]) entre os protocolos máximos. Doze mulheres jovens participaram do estudo. Foi utilizada ANOVA de dois fatores para medidas repetidas com post-hoc de Bonferroni (α<0,05). Foram encontrados valores significativamente maiores de frequência cardíaca máxima (CET: 190±5; CPF: 174±9 bpm) e de consumo de oxigênio máximo (CET: 33,7±3,9; CPF: 22.5±4.1 ml.kg-1.min-1) na CET em comparação à CPF. Além disso, não foram encontradas diferenças significativas entre os métodos de determinação do LAn (CET: MT: 28.1±5.3; PDFC: 26.6±5.5 ml.kg-1.min-1; CPF: MV: 18.7±4.8, PDFC: 17.8±4.8 ml.kg-1.min-1). Os resultados indicam a importância da realização de um teste máximo especifico da modalidade treinada e o PDFC parece ser uma alternativa simples e prática para a determinação do LAn.