Transfer of strength training to running mechanics, energetics, and efficiency.

To examine the effects of increased strength on mechanical work, the metabolic cost of transport (Cost), and mechanical efficiency (ME) during running. Fourteen physically active men (22.0 ± 2.0 years, 79.3 ± 11.1 kg) were randomized to a strength-training group (SG, n = 7), who participated in a maximal strength training protocol lasting 8 weeks, and a control group (CG, n = 7), which did not perform any training intervention. Metabolic and kinematic data were collected simultaneously while running at a constant speed (2.78 m·s-1). The ME was defined as the ratio between mechanical power (Pmec) and metabolic power (Pmet). The repeated measures two-way ANOVA did not show any significant interaction between groups, despite some large effect sizes (d): internal work (Wint, p = 0.265, d = -1.37), external work (Wext, p = 0.888, d = 0.21), total work (Wtot, p = 0.931, d = -0.17), Pmec (p = 0.917, d = -0.17), step length (SL, p = 0.941, d = 0.24), step frequency (SF, p = 0.814, d = -0.18), contact time (CT, p = 0.120, d = -0.79), aerial time (AT, p = 0.266, d = 1.12), Pmet (p = 0.088, d = 0.85), and ME (p = 0.329, d = 0.54). The exception was a significant decrease in Cost (p = 0.047, d = 0.84) in SG. The paired t-test and Wilcoxon test only detected intragroup differences (pre- vs. post-training) for SG, showing a higher CT (p = 0.041), and a lower Cost (p = 0.003) and Pmet (p = 0.004). The results indicate that improved neuromuscular factors related to strength training may be responsible for the higher metabolic economy of running after 8 weeks of intervention. However, this process was unable to alter running mechanics in order to indicate a significant improvement in ME.

Rating of perceived exertion in maximal incremental tests during head-out water-based aerobic exercises.

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.

Vertical ground reaction force responses to different head-out aquatic exercises performed in water and on dry land.

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.

Maximal and ventilatory thresholds cardiorespiratory responses to three water aerobic exercises compared with treadmill on land.

The purpose of this study was to compare the cardiorespiratory responses of young women to exercise at the first ventilatory threshold (VT1), the second ventilatory threshold (VT2), and at maximum effort (MAX) between maximal incremental tests performed using water aerobic exercises and a treadmill on land (TL). Twenty women (24.0 ± 2.5 years; 163.3 ± 6.7 cm; 60.0 ± 6.7 kg) underwent 4 maximal tests in randomized order, with a 48-hour interval between tests. Three tests involved performing water aerobic exercises (stationary running, frontal kick, and cross-country skiing) and 1 TL. Oxygen uptake (VO2), ventilation (VE), and heart rate were measured throughout the tests, and their values at the VT1, VT2, and MAX intensities were determined by 3 independent, experienced physiologists. Repeated measures analysis of variance with Bonferroni post hoc tests were used for comparisons between tests (α = 0.05). Heart rate was significantly higher in the TL condition compared with the water aerobic exercises at the VT1 (p = 0.001), VT2 (p < 0.001), and MAX (p < 0.001) intensities. VO2 and VE had similar values across the 4 protocols at the VT1 intensity, but significantly higher values were observed with TL (VO2: p < 0.001; VE: p < 0.001) at the VT2 intensity. At the MAX intensity, VO2 was significantly higher with TL compared with the 3 water aerobic exercises (p < 0.001), whereas no significant differences in VE between the 4 protocols were found. These results suggest that the prescription of water aerobics classes should be based on specific maximal tests for water aerobic exercises. Training intensities could be overestimated if they were based on maximal tests on dry land.

Correction: Pilates training improves 5-km run performance by changing metabolic cost and muscle activity in trained runners.

[This corrects the article DOI: 10.1371/journal.pone.0194057.].

Pilates training improves 5-km run performance by changing metabolic cost and muscle activity in trained runners.

PURPOSE: Strength training improves distance running economy and performance. This finding is based predominantly on maximal and explosive strength programmes applied to locomotor muscles, particularly on the lower limbs. It is not certain whether a minimization of metabolic cost (Cmet) and an improvement in running performance is feasible with strength training of the postural and trunk muscles. METHODS: Using kinematic, neuromuscular and metabolic measurements of running at two different speeds before and after a 12-week Pilates training programme, we tested the hypothesis that core training might improve the running Cmet and performance of trained runners. Thirty-two individuals were randomly assigned to the control group (CG, n = 16) or the Pilates group (PG, n = 16). RESULTS: Confirming our hypothesis, a significant improvement (p<0.05) was observed for running performance in the PG (pre: 25.65±0.4 min; post: 23.23±0.4 min) compared to the CG (pre: 25.33±0.58 min; post: 24.61±0.52 min). Similarly, the PG (4.33±0.07 J.kg-1.m-1) had better responses than the CG (4.71±0.11 J.kg-1.m-1) during post-training for Cmet. These findings were accompanied by decreased electromyographic activity of the postural muscles at submaximal running intensities in the PG. CONCLUSIONS: Overall, these results provide a rationale for selecting strength training strategies that target adaptations on specific postural and locomotor muscles for trained distance runners.

Horizontal ground reaction forces to stationary running performed in the water and on dry land at different physiological intensities.

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.

Active Female Maximal and Anaerobic Threshold Cardiorespiratory Responses to Six Different Water Aerobics Exercises.

PURPOSE: Maximal tests conducted on land are not suitable for the prescription of aquatic exercises, which makes it difficult to optimize the intensity of water aerobics classes. The aim of the present study was to evaluate the maximal and anaerobic threshold cardiorespiratory responses to 6 water aerobics exercises. Volunteers performed 3 of the exercises in the sagittal plane and 3 in the frontal plane. METHOD: Twelve active female volunteers (aged 24 ± 2 years) performed 6 maximal progressive test sessions. Throughout the exercise tests, we measured heart rate (HR) and oxygen consumption (VO2). We randomized all sessions with a minimum interval of 48 hr between each session. For statistical analysis, we used repeated-measures 1-way analysis of variance. RESULTS: Regarding the maximal responses, for the peak VO2, abductor hop and jumping jacks (JJ) showed significantly lower values than frontal kick and cross-country skiing (CCS; p < .001; partial η(2) = .509), while for the peak HR, JJ showed statistically significantly lower responses compared with stationary running and CCS (p < .001; partial η(2) = .401). At anaerobic threshold intensity expressed as the percentage of the maximum values, no statistically significant differences were found among exercises. CONCLUSION: Cardiorespiratory responses are directly associated with the muscle mass involved in the exercise. Thus, it is worth emphasizing the importance of performing a maximal test that is specific to the analyzed exercise so the prescription of the intensity can be safer and valid.

Correlação entre índice de esforço percebido e respostas cardiopulmonares em exercício de hidroginástica com equipamento / Correlation between rate of perceived exertion and cardiorespiratory responses in water exercise performed with equipment

O objetivo deste estudo foi analisar a correlação entre o índice de esforço percebido e as variáveis cardiopulmonares durante a execução de um exercício de hidroginástica nas situações de uso de equipamento resistido Aquafins® nos membros superiores, equipamento resistido nos membros inferiores e equipamento resistido nos membros superiores e inferiores simultaneamente. Onze mulheres participaram de três sessões: uma sessão para caracterização da amostra e teste de esforço máximo, uma de familiarização e outra correspondente ao protocolo experimental. O protocolo experimental consistiu da execução do exercício deslize frontal combinado com a flexão e extensão horizontal de ombros, durante quatro minutos na cadência de 60 batidas por minuto, nas três situações de uso de equipamento resistido. Para correlacionar o índice de esforço percebido (IEP) com a frequência cardíaca, percentual da frequência cardíaca máxima, consumo de oxigênio, percentual do consumo de oxigênio máximo e ventilação, utilizou-se a correlação de Spearman, com ?=5%. Observou-se correlações significativas (rho=0,60-0,88; p<0,05) entre o IEP e as variáveis cardiopulmonares na situação de uso de equipamento nos membros inferiores. Todavia, nas demais situações (com equipamento resistido nos membros inferiores e em ambos os membros) não houve correlações significativas entre esses parâmetros, com exceção do IEP e a ventilação na situação de uso de equipamento em ambos os membros (rho=0,71; p=0,015). Em suma, o IEP está associado com a com a frequência cardíaca, o consumo de oxigênio e a ventilação e reflete a intensidade do exercício de hidroginástica quando realizado com equipamento resistido nos membros inferiores.

The aim of the present study was to correlate the rating of perceived exertion with cardiopulmonary variables during the performance of a water-based exercise in situations with the use of Aquafins® aquatic drag equipment in upper limbs, in lower limbs and in both upper and lower limbs. Eleven women took part in three data collection sessions: sample characterization, maximal test, familiarization and experimental protocol. The experimental protocol was performed with the execution of cross country skiing combined with horizontal shoulder flexion and extension exercise during four minutes at 60 bpm in the three situations with the use of aquatic drag equipment. Spearman correlation was used, in order to correlate the rating of perceived exertion (RPE) with heart rate, percentage of the maximal heart rate, oxygen uptake, percentage of the maximal oxygen uptake and ventilation, with ?=5%. The results showed significant correlations between RPE and cardiopulmonary variables in the situation with the use of equipment in lower limbs (rho=0.60-0.88; p<0.05). However, in the others situations (with aquatic drag equipment in lower limbs and in both upper and lower limbs) there was no relationship between these parameters, except the correlation between RPE and ventilation in the situation with the use of equipment in both upper and lower limbs (rho=0.71; p=0.015). In conclusion, the RPE is associated with the heart rate, oxygen uptake and ventilation and corresponds to the intensity of the water-based exercise performed with aquatic drag equipment in lower limbs.

Comparação das respostas cardiorrespiratórias de repouso entre os meios terrestre e aquático / Comparison of cardiorespiratory responses at rest between land and water environments

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.