RESUMO

The aim of the present study was to compare the peak anterior-posterior (Fy) and medio-lateral (Fx) ground reaction forces (GRFs) of women performing stationary running at different intensities in aquatic and dry land environments. Fourteen young women performed the stationary running exercise at three cadences (first ventilatory threshold, second ventilatory threshold and maximum effort, as determined during exercise in water) in aquatic and dry land environments. Two-way repeated measures ANOVA was used to analyse the data (α = .05). As a result, significantly lower peak Fy anterior, Fy posterior, Fx medial and Fx lateral values were observed for the aquatic environment, except for the Fy posterior at the first ventilatory threshold. Significant differences were observed between cadences in the peak Fy anterior, Fy posterior, Fx medial and Fx lateral values, with higher values for the cadence corresponding to maximum effort compared to the first ventilatory threshold, except for the Fy posterior and Fx medial in the aquatic environment. The results indicate that the horizontal GRFs are reduced in the aquatic environment and depend on the intensity of stationary running exercise performance.

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The present study aimed to assess the relationship between rating of perceived exertion (RPE) and percentage of peak oxygen uptake ([Formula: see text]) during three head-out water-based aerobic exercises. In addition, the RPE at the second ventilatory threshold (VT2) was also compared among them. Twenty young women performed head-out water-based maximal tests for the exercises stationary running (SR), frontal kick (FK) and cross-country skiing (CCS). RPE was monitored during the tests and the values corresponding to VT2 and training zones corresponding to 50-59%, 60-69%, 70-79%, 80-89% and [Formula: see text] were determined. Regression analysis, descriptive statistics and ANOVA with repeated measures were used. Significant relationships were observed between the RPE and [Formula: see text] (r = 0.858-0.893; P < 0.001) for all head-out water-based aerobic exercises. Average RPE ranged from 12.1-12.7 in the training zone corresponding to 50-59%, from 13.7-14.8 to 60-69%, from 15.8-16.4 to 70-79%, from 17.3-18.1 to 80-89% and from 18.5-18.9 to [Formula: see text]. No significant differences were found among the three head-out water-based aerobic exercises at VT2 (P > 0.05; SR: 16.1 ± 0.9, FK: 16.7 ± 1.5, CCS: 15.9 ± 1.3). The results support the use of RPE to control the relative intensity of training during head-out water-based aerobic exercises and indicate values near to 16-17 when targeting VT2 intensity for young women.

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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.

RESUMO

The purpose was to analyse the vertical ground reaction forces (Fz) of head-out aquatic exercises [stationary running (SR), frontal kick (FK), cross-country skiing (CCS), jumping jacks (JJ), adductor hop (ADH) and abductor hop (ABH)] at two cadences in both aquatic and dry land environments. Twelve young women completed two sessions in each environment, each consisting of three exercises performed at two cadences (first and second ventilatory thresholds - C1 and C2, respectively). Two-way and three-way repeated measures analysis of variance were used to the statistical analysis. The results showed that the peak Fz and impulse were significantly lower in the aquatic environment, resulting in values from 28.2% to 58.5% and 60.4% to 72.8% from those obtained on dry land, respectively. In the aquatic environment, the peak Fz was lower and the impulse was higher at the C1 than at the C2. Furthermore, it was observed that SR and FK (0.9-1.1 BW) elicited a significantly higher peak Fz values compared to the ADH and JJ exercises (0.5-0.8 BW). It can be concluded that the aquatic environment reduces the Fz during head-out aquatic exercises. It should be noted that its magnitude is also dependent on the intensity and the identity of the exercise performed.

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Os menores valores de frequência cardíaca (FC) no meio aquático são bem consolidados na literatura. No entanto, as respostas de consumo de oxigênio (VO2) e pulso de oxigênio (PulsoO2) em imersão em repouso são menos investigadas e os estudos que realizaram tal análise apresentam diferentes resultados, permanecendo uma lacuna acerca dessa comparação na literatura. Dessa forma, o objetivo do presente estudo foi analisar os valores de FC, VO2 e PulsoO2 em repouso nos meios terrestre e aquático. Sessenta mulheres (24,0 ± 2,5 anos) participaram do presente estudo. Inicialmente, as participantes permaneceram 30 minutos em repouso em decúbito dorsal fora da água. A seguir, os valores de FC, VO2 e PulsoO2 foram avaliados na posição ortostática nos meios terrestre (MT) e aquático (MA). Utilizou-se Teste T pareado para comparar as variáveis entre os meios, adotando-se um alfa de 5%. Como resultados, a FC apresentou redução significativa do MT para o MA. Por outro lado, observou-se aumento significativo nas variáveis VO2 e PulsoO2 da situação de repouso em MT para MA. Portanto, as respostas cardiorrespiratórias diferem entre os meios aquático e terrestre, sendo que as respostas de FC são reduzidas enquanto as de VO2 e PulsoO2 são incrementadas com a imersão em repouso.

The lower values of heart rate (HR) in the aquatic environment are well-established in the literature. However, the oxygen consumption (VO2) and oxygen pulse (PulseO2) responses in immersion at rest are poorly investigated, and the studies that performed such analysis show different results, remaining a gap in the literature about this comparison. Thus, the purpose of the present study was to analyze the HR, VO2 and PulseO2 values at rest on dry land and in the aquatic environments. Sixty young women (24.0 ± 2.5 years) participated of the present study. Initially, the participants remained 30 minutes at rest in the supine position out of water. Then, the HR, VO2 and PulseO2 were assessed in the orthostatic position on dry land (DL) and in the aquatic environments (AE). Paired T test was used to compare the variables between the environments, adopting an alpha level of 5%. As results, the HR presented a significant reduction from DL to the AE. On the other hand, it was observed a significant increase in the VO2 and PulseO2 at rest from the DL to AE. Therefore, the results demonstrated that the environment exerts influence on the cardiorespiratory response, because the HR responses are reduced, while the VO2 and PulseO2 are increased with the immersion at rest.

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The purpose of the present study was to correlate the rating of perceived exertion (RPE) with cardiorespiratory and neuromuscular variables during the execution of stationary running in water at different cadences. The sample consisted of 12 apparently healthy women (age: 22.33 ± 0.57 years). During the assessment session, the subjects performed the stationary running exercise in water at 3 different cadences: 60, 80, and 100 bpm. The heart rate (HR), oxygen uptake (V(O2)), ventilation (Ve), and electromyographic (EMG) signal of the vastus lateralis (VL), biceps femoris (BF), rectus femoris (RF), and semitendinosus (ST) muscles were measured during the exercise, and the overall body RPE was measured immediately following the end. Pearson's linear correlation and multiple linear regression were used, with p < 0.05. The analyses demonstrate a high and significant relationship between RPE and HR (r = 0.65; p < 0.001), RPE and %HR maximal (r = 0.65; p < 0.001), RPE and V(O2) (r = 0.60; p = 0.001), RPE and %V(O2) maximal (r = 0.71; p < 0.001), and RPE and Ve (r = 0.77; p < 0.001). However, there was no relationship between the RPE and the EMGs of the VL, BF, RF, and ST muscles. With regard to the regression, the model was significant (p < 0.001) with an r2 = 0.79, whereas the variables that explained better the RPE were %V(O2) maximal and Ve. Hence, these results suggest an association between the perception of exertion and cardiorespiratory variables, which was not the case with the neuromuscular variables evaluated in this study. Therefore, the Borg scale of RPE can be used when prescribing stationary running exercise in water for young women.

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