Exercise intensity of head-out water-based activities (water fitness)

Magnitude of vertical ground reaction force during water-based exercises in women with obesity

Individuals with obesity are recommended to practice physical activity with reduced weight bearing, such as water-based exercises. However, the magnitude of the vertical ground reaction force (Fz) during these exercises is unknown in this population. This study aimed to verify the magnitude of peak Fz (Fzpeak) in women with obesity during different exercises performed in water and on land and at different intensities. Ten adult women with obesity class 1 (body mass index: 31.6 ± 0.57 kg·m-2) completed two randomised sessions, one performed on land and other in water, composed by three exercises (stationary running, frontal kick, butt kick) performed at cadences of 80 b·min-1, 100 b·min-1 and maximal. Fzpeak value was determined in each situation. Data were analysed using repeated-measures three-way ANOVA (α = 0.05). Significant lower Fzpeak values were observed in water (p < 0.001), with no significant differences between the exercises. A significant difference in the Fzpeak was verified between maximal cadence and 80 b·min-1 (p = 0.01). Water-based exercises performed by women with obesity revealed a Fzpeak reduction from land to water corresponding to 41-67%. Also, the three water-based exercises resulted in similar Fzpeak values, while an increase was observed 80 b·min-1 to the maximal cadence.

Energy Consumption of Water Running and Cycling at Four Exercise Intensities

Water exercise provides a workload in every direction of motion for training in a reduced impact environment. The selection of an appropriate physical activity and an individual exercise prescription are essential to obtain training effects. The aim of the present study was to determine individualised relative exercise intensities at four speeds of motion for water cycling and water running. Running was tested both in buoyancy and with the feet in contact with the bottom of the pool. To this purpose, gas exchanges, heart rate, and blood lactate were measured in each test session. Fourteen active, healthy females (23.2 ± 1.6 years) underwent a dry land maximal incremental protocol to exhaustion on a treadmill and hydrobike (HB); they engaged in water running with ground contact (RC) and water running suspended (RS) tests in a swimming pool at 30, 40, 50, and 60 cycles per minute (cpm), submerged at the individual xiphoid level. The four motion speeds of the three water exercise modalities ranged from 50% to 95% of the maximal heart rate and the maximal oxygen uptake, representing a moderate-to-vigorous training stimulus. RS elicited the lowest oxygen consumption, whereas HB demanded the significantly highest oxygen consumption and presented the highest blood lactate accumulation, with vigorous intensity being reached at 50 cpm and near maximal intensity at 60 cpm. It appears that water cycling could be more suitable for athletic training, whereas water running could be more appropriate for health and fitness purposes.

Effect of Aquatic Exercise Training on Aortic Hemodynamics in Middle-Aged and Elderly Adults

Aquatic exercise is an attractive form of exercise that utilizes the various properties of water to improve physical health, including arterial stiffness. However, it is unclear whether regular head-out aquatic exercise affects aortic hemodynamics, the emerging risk factors for future cardiovascular disease. The purpose of this study was to investigate whether head-out aquatic exercise training improves aortic hemodynamics in middle-aged and elderly people. In addition, to shed light on the underlying mechanisms, we determined the contribution of change in arterial stiffness to the hypothesized changes in aortic hemodynamics. Twenty-three middle-aged and elderly subjects (62 ± 9 years) underwent a weekly aquatic exercise course for 15 weeks. Aortic hemodynamics were evaluated by pulse wave analysis via the general transfer function method. Using a polar coordinate description, companion metrics of aortic pulse pressure (PPC = √{(systolic blood pressure)² + (diastolic blood pressure)²}) and augmentation index (AIxC = √{(augmentation pressure)² + (pulse pressure)²}) were calculated as measures of arterial load. Brachial-ankle (baPWV, reflecting stiffness of the abdominal aorta and leg artery) and heart-ankle (haPWV, reflecting stiffness of the whole aortic and leg artery) pulse wave velocities were also measured. The rate of participation in the aquatic training program was 83.5 ± 13.0%. Aortic systolic blood pressure, pulse pressure, PPC, AIxC, baPWV, and haPWV decreased after the training (P < 0.05 for all), whereas augmentation index remained unchanged. Changes in aortic SBP were correlated with changes in haPWV (r = 0.613, P = 0.002) but not baPWV (r = 0.296, P = 0.170). These findings suggest that head-out aquatic exercise training may improve aortic hemodynamics in middle-aged and elderly people, with the particular benefits for reducing aortic SBP which is associated with proximal aortic stiffness.

Study of Anthropometric and Body Composition Variables in the Overweight/Obese, Sedentary Elderly Men Using WATERinMOTION Aqua Training: A cross-Sectional Study

Background: The effect of aqua training on human body composition still causes inconsistency. Objectives: This study was set to identify the effects of WATERinMOTION (WiM) as a water-based exercise on anthropometric and body composition variables without dietetic supervision in overweight/obese, sedentary elderly men. Methods: Participants (n = 70; age: 70.5 ± 4.4 years) derived by purposive and accessible selection were randomly distributed to either a one-month WiM aqua training group (n = 35, two weekly sessions each included 55 minutes on WiM aqua training) or a control group (n = 35, at the same time in sitting state). Anthropometric measures (height, weight, and waist circumference [WC]) and body composition variables (body mass index [BMI], fat mass [FM], total body water [TBW], and free fat mass [FFM]) were evaluated pre/post-study. Results: Upon analysis, statistically significant changes (P ≤ 0.05) were set on weight, BMI, and FM by comparing pre/post study for the WiM group. Furthermore, comparing groups at post disclosed a significant change in anthropometric measures (weight and WC) and body composition variables (BMI, FM, TBW, and FFM). Conclusions: A short-run, non-diet-supervised WiM program suggests supporting a loss in weight, FM, and BMI in overweight/obese, sedentary elderly men.

Anaerobic Threshold in a Water-Based Exercise: Agreement Between Heart Rate Deflection Point and Lactate Threshold Methods

ABSTRACT

Alberton, CL, Andrade, LS, Pinheiro, RB, and Pinto, SS. Anaerobic threshold in a water-based exercise: agreement between heart rate deflection point and lactate threshold methods. J Strength Cond Res 35(9): 2472-2478, 2021-The purpose of this study was to compare and assess the agreement of the heart rate (HR) and rating of perceived exertion (RPE) corresponding to the anaerobic threshold (AT) between HR deflection point (HRDP) and lactate threshold (LT) methods during a water-based exercise in young men. Sixteen young men (24 ± 6 years) performed the experimental protocol, which comprised the performance of a maximal incremental test during the water-based stationary running exercise. The initial cadence corresponded to 90 b·min-1, with 10 b·min-1 increases every 3 minutes up to exhaustion. Heart rate was monitored every 30 seconds while blood lactate concentrations and RPE were measured at the end of each 3-minute bout. Anaerobic threshold was identified by HRDP and LT methods by experienced physiologists. Paired Student's t-test, Bland-Altman analysis, and Pearson correlation were used for data analysis (α = 0.05). As results, there was agreement between HRDP and LT methods for HR, while RPE presented significant higher values for the HRDP method, resulting in an absence of acceptable agreement between methods. In addition, strong relationships (p ≤ 0.001) were verified between methods of AT determination for HR (r = 0.786) and RPE (r = 0.916). Therefore, based on the agreement between HRDP and LT methods, the HR determined by HRDP may be a valid parameter used for the intensity prescription of water-based stationary running exercise in young men during water aerobics programs and may be considered more reliable than RPE.

Weight-Loss Parameters and Quality of Life in Obese Aged Women Using WATERinMOTION

Background: There are controversial studies on weight loss, cardiometabolic markers, and quality of life (QOL) in obese aged women participating in water sports. Objectives: This study aimed to determine the effects of the WATERinMOTION exercise program accompanied with no diet on the inactive obese aged women’s weight, cardiometabolic markers, and QOL. Methods: Sixty-four inactive obese aged women were recruited to participate in this cross-sectional study at the Ukrainian Sports Center, Kyiv, 2019. They were randomly assigned into two Case (n = 32, with the WATERinMOTION aquatics exercise program) and control (n = 32, held in a sitting position simultaneously) groups using the convenient sampling method. The two programs were run twice a week (55 minutes each time) and lasted for one month. Moreover, anthropometric indices (weight, height, waist circumference), cardiometabolic markers (blood lipid markers and glycaemia), QOL (SF-36 questionnaire), and dietary monitoring were assessed before and after the intervention. Results: The groups did not differ significantly regarding each of the analyzed variables prior to the intervention. Comparing pre-and post-intervention results revealed significant weight loss (-1.3, P = 0.004) and average BMI (-0.4, P = 0.002) in the case group. Moreover, a significant variation was revealed only in terms of weight after the intervention (P = 0.001). Regarding QOL, improvements in health status, vitality, and social aspects were significant in the case group after the intervention. Conclusions: The present study suggests that the WATERinMOTION program accompanied with no diet has a positive effect on weight loss, waist circumference, and metabolic profiles in obese aged women. However, the improvement in the QOL should not be neglected.

The Effect of Head-Out Aquatic Exercise on Arterial Stiffness in Middle-Aged and Elderly People

Aquatic exercise is ideal for older adults because it mitigates weight-bearing stress. However, the effect of head-out aquatic exercise on arterial stiffness, a strong future cardiovascular disease (CVD) risk, remains unclear. We determined whether head-out aquatic exercise would mitigate arterial stiffness in middle-aged and elderly people. In 25 middle-aged and older people (9 men, mean age 64 ± 8 years), blood pressure (BP) and brachial-ankle pulse wave velocity (baPWV) were measured before and after a supervised aquatic exercise training program (60 min, 1 session/week, 14 sessions) which mainly consisted of walking, stretching, and muscle strengthening in water. In the pooled subjects, systolic BP tended to decrease (p = 0.07) after the training intervention, whereas no significant changes were observed, including baPWV (from 1,537 ± 301 to 1,496 ± 308 cm/s). In the sub-analysis, by dividing subjects into a healthy group (n = 13) and a CVD risk group (n = 12), no significant interaction between time and group was seen in BP. On the other hand, baPWV decreased significantly in the healthy group (from 1,476 ± 299 to 1,365 ± 215 cm/s) but not in the CVD risk group (from 1,603 ± 301 to 1,637 ± 339 cm/s). The current study demonstrates that regular head-out aquatic exercise, even at a low frequency, could mitigate CVD risk in apparently healthy middle-aged and older people.

Energy expenditure and EPOC between water-based high-intensity interval training and moderate-intensity continuous training sessions in healthy women

The present study compared the energy expenditure (EE) during and after two water aerobics protocols, high-intensity interval training (HIIT) and moderate continuous training (CONT). A crossover randomized design was employed comprising 11 healthy young women. HIIT consisted of eight 20s bouts at 130% of the cadence associated with the maximal oxygen consumption (measured in the aquatic environment) with 10s passive rest. CONT corresponded to 30 min at a heart rate equivalent to 90-95% of the second ventilatory threshold. EE was measured during and 30 min before and after the protocols and excess post-exercise oxygen consumption (EPOC) was calculated. Total EE during session was higher in CONT (227.62 ± 31.69 kcal) compared to HIIT (39.91 ± 4.24 kcal), while EE per minute was greater in HIIT (9.98 ± 1.06 kcal) than in CONT (7.58 ± 1.07 kcal). Post-exercise EE (64.48 ± 3.50 vs. 63.65 ± 10.39 kcal) and EPOC (22.53 ± 4.98 vs.22.10 ± 8.00 kcal) were not different between HIIT and CONT, respectively. Additionally, oxygen uptake had already returned to baseline fifteen minutes post-exercise. These suggest that a water aerobics CONT session results in post-exercise EE and EPOC comparable to HIIT despite the latter supramaximal nature. Still, CONT results in higher total EE.

The influence of Aqua Power aerobics on body mass reduction in middle-aged, overweight women

Objectives

This study aims to evaluate the effects of Aqua Power exercises on the body composition and cardiovascular response in middle- aged, overweight women after a six-month intervention.

Patients and methods

Between November 2013 and May 2014, a total of 37 middle-aged, overweight women (mean age 42.6 years, range 36 to 57 years) participated in the Aqua Power aerobic sessions twice per week for six months. The body composition was evaluated using the near-infrared method. The heart rate was self-controlled by the participant during the exercise.

Results

The majority of the body composition elements decreased after six months of the Aqua Power aerobic training. The heart rate values decreased in the females after the intervention period.

Conclusion

Aqua Power aerobics can be recommended for middle-aged females for the treatment of overweight and in the process of cardiopulmonary fitness improvement.

The aging influence on cardiorespiratory, metabolic, and energy expenditure adaptations in head-out aquatic exercises: Differences between young and elderly women

The purpose of this study was to: (1) establish the relationship between acute physiological responses and musical cadence; and (2) compare physiologic responses between young and older women. Eighteen older (mean = 65.06 ± 5.77 years) and 19 young (mean = 22.16 ± 2.63 years) women underwent an intermittent and progressive protocol performing the head-out aquatic exercise the "rocking horse." Results showed that older women demonstrated lower mean heart rate, blood lactate concentration (bLa), and oxygen uptake (VO₂) at rest. Hierarchical linear modeling showed that variations in the rating of perceived effort and individual metabolic equivalent of task did not differ significantly by age group. However, during exercise, physiological responses of younger women were significantly different than for older women: in mean values, for each increased musical beat per minute, mean bLa was 0.003 mmol/l, VO₂ was 0.024 ml/kg/min, and energy expenditure was 0.0001 kcal/kg/min higher for younger women. This study shows that increases in musical cadence increased the cardiorespiratory, metabolic, and energy expenditure responses. However, these responses during increasing intensity seemed to differ between young and older women, with lower values for the elderly group, when performing head-out aquatic exercises.

Human Physiology in an Aquatic Environment

Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head-out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and elevation of plasma volume by autotransfusion of fluid from cells to the vascular compartment lead to increased cardiac stroke volume and output and there is a hyperperfusion of some tissues. Pulmonary artery and capillary hydrostatic pressures increase causing a decline in vital capacity with the potential for pulmonary edema. Atrial stretch and increased arterial pressure cause reflex autonomic responses which result in endocrine changes that return plasma volume and arterial pressure to preimmersion levels. Plasma volume is regulated via a reflex diuresis and natriuresis. Hydrostatic pressure also leads to elastic loading of the chest, increasing work of breathing, energy cost, and thus blood flow to respiratory muscles. Decreases in water temperature in HOWI do not affect the cardiac output compared to TN; however, they influence heart rate and the distribution of muscle and fat blood flow. The reduced muscle blood flow results in a reduced maximal oxygen consumption. The properties of water determine the mechanical load and the physiological responses during exercise in water (e.g. swimming and water based activities). Increased hydrostatic pressure caused by submersion does not affect stroke volume; however, progressive bradycardia decreases cardiac output. During submersion, compressed gas must be breathed which introduces the potential for oxygen toxicity, narcosis due to nitrogen, and tissue and vascular gas bubbles during decompression and after may cause pain in joints and the nervous system.

Metabolic and cardiovascular responses during aquatic exercise in water at different temperatures in older adults

PURPOSE

The aim of this study was to investigate the physiological responses during upper-body aquatic exercises in older adults with different pool temperatures.

METHOD

Eleven older men (aged 65 years and older) underwent 2 identical aquatic exercise sessions that consisted of 3 upper-body exercises using progressive intensities (30, 35, and 40 metronome beat · min(- 1)) on separate visits. Water temperatures for the visits were 28°C (cold water [CW]) and 36°C (hot water [HW]), and water depth ranged from 1.2 m to 1.4 m. Measurements for heart rate (HR), blood pressure (BP), oxygen consumption (VO2), and rate of perceived exertion (RPE) were compared between the CW and HW conditions.

RESULTS

The comparison between temperatures showed a higher HR response during exercise in HW, particularly when participants exercised at the highest intensities. During a 30-min postexercise period in resting conditions, HR was statistically significantly higher for the HW condition compared with the CW condition, with a large effect size (15.9%, d = 1.23). Systolic and diastolic BPs were found to be lower for the HW condition ( - 7.2%, d = - 0.60; - 10.1%, d = - 0.65), while VO2 and RPE showed no differences. The effect size between double products (HR · systolic BP) for the 2 conditions was small (CW = 8,649 ± 1,287, HW = 9,340 ± 1,672; d = 0.36), suggesting similar myocardial oxygen requirements.

CONCLUSION

This study showed that HR response was higher in an HW condition for older men. Warmer environments may add additional stressors to the body, which may impact training strategies and should be considered when estimating the effort of performing aquatic exercise.

Maximal and ventilatory thresholds of oxygen uptake and rating of perceived exertion responses to water aerobic exercises

This study aimed to compare the V[Combining Dot Above]O2max and first and second ventilatory threshold (1stVT and 2ndVT) V[Combining Dot Above]O2 values and rating of perceived exertion (RPE) responses of treadmill running (TR) with those of 3 water aerobic exercises: stationary running (SR), jumping jack (JJ), and forward kick (FK). Nine women (22.89 ± 1.81 years, 1.66 ± 0.07 m, 58.46 ± 4.19 kg) performed 1 maximal test session for each of the 4 exercise protocols in a randomized order to determine the V[Combining Dot Above]O2max and V[Combining Dot Above]O2 values and RPE responses corresponding with the 1stVT and 2ndVT. V[Combining Dot Above]O2 values were also expressed as a percentage of V[Combining Dot Above]O2max (%V[Combining Dot Above]O2max). A repeated measures analysis of variance and Bonferroni's post hoc test were used, with α = 0.05 denoting statistical significance. The analyses showed that the V[Combining Dot Above]O2 responses were significantly higher for TR than for the other exercises at all effort intensities (V[Combining Dot Above]O2max: p < 0.001; 1stVT and 2ndVT V[Combining Dot Above]O2: p < 0.001), followed by intermediate responses for SR and FK and lower responses for JJ. However, no significant differences between exercises for values of %V[Combining Dot Above]O2max (1stVT: p = 0.099; 2ndVT: p = 0.131) and RPE (1stVT: p = 0.275; 2ndVT: p = 0.477) were found at submaximal intensities, indicating that it is possible to achieve and maintain the same training intensity with these exercises during a typical water fitness lesson. Moreover, the RPE values obtained for the 1stVT and 2ndVT can make the prescription of intensity for these water exercises for young women more simple and practical.

The cadence and water temperature effect on physiological responses during water cycling

The aim of the study was to compare the maximal physiological responses during three protocols: maximal test on land cycle ergometer, maximal test on water cycling in an indoor pool at 27 °C (WC27) and at 31 °C (WC31). Moreover, the submaximal physiological responses were compared according cycling cadences and water temperatures during the water protocols. Ten young men were included and performed the protocols in separate days. Blood lactate (BL) concentration, heart rate (HR), oxygen uptake (VO2), ventilation (VE) and thermal comfort (TC) were collected during the exercise. The maximal HR and VO2 showed no significant differences between the protocols: HRmax: 189 ± 7 (Land), 188 ± 14 (WC27), 185 ± 9 bpm (WC31) and VO2max: 4.2 ± 0.4 (Land), 4.1 ± 0.5 (WC27) and 4.3 ± 0.5 l min(-1) (WC31). However, the maximal BL demonstrated significant lower values during the water protocols compared to the land protocol (p=0.018). All the submaximal physiological responses showed significant differences between the cadences (60, 70, 80 and 90 rpm). The effect of water temperature was significant for TC response (p=0.001) showing higher values at 31 °C than 27 °C (TCW27: 7 ± 1 and TCW31:9 ± 1). In conclusion, higher physiological responses were showed by increasing the cadence by 10 rpm and the subjects were more comfortable when cycling in the lower water temperature.

Physiological and biomechanical responses to walking underwater on a non-motorised treadmill: effects of different exercise intensities and depths in middle-aged healthy women

Non-motorised underwater treadmills are commonly used in fitness activities. However, no studies have examined physiological and biomechanical responses of walking on non-motorised treadmills at different intensities and depths. Fifteen middle-aged healthy women underwent two underwater walking tests at two different depths, immersed either up to the xiphoid process (deep water) or the iliac crest (shallow water), at 100, 110, 120, 130 step-per-minute (spm). Oxygen consumption (VO2), heart rate (HR), blood lactate concentration, perceived exertion and step length were determined. Compared to deep water, walking in shallow water exhibited, at all intensities, significantly higher VO2 (+13.5%, on average) and HR (+8.1%, on average) responses. Water depth did not influence lactate concentration, whereas perceived exertion was higher in shallow compared to deep water, solely at 120 (+40%) and 130 (+39.4%) spm. Average step length was reduced as the intensity increased (from 100 to 130 spm), irrespective of water depth. Expressed as a percentage of maximum, average VO2 and HR were: 64-76% of peak VO2 and 71-90% of maximum HR, respectively at both water depths. Accordingly, this form of exercise can be included in the "vigorous" range of exercise intensity, at any of the step frequencies used in this study.

Energy expenditure, cardiorespiratory, and perceptual responses to shallow-water aquatic exercise in young adult women

INTRODUCTION

Aquatic exercise (AE) is a popular form of physical activity, yet few studies have assessed the individual's energy expenditure (EE) associated with a continuous bout of AE. Studies using indirect calorimetry to measure EE have reported limitations associated with test methodology and the ability to control individual's exercise intensity or tempo.

PURPOSE

To evaluate EE and cardiorespiratory (CR) responses during a 40-minute shallow-water AE session in young adult women.

METHODS

Twenty-one healthy women (aged 21.7 ± 3.4 years) completed an orientation practice session and a 40-minute shallow-water AE session using a traditional exercise class format and the SWEAT video-based instructional cuing program. The high-intensity interval format included the following segments: 1) warm-up (3 minutes); 2) CR segment ( 22 minutes); 3) muscular endurance segment (ME; 10 minutes); and 4) cool-down (5 minutes). Subject oxygen consumption (VO2; mL/kg/min), heart rate (HR) and OMNI overall ratings of perceived exertion (RPE-O) were assessed each minute. Average kcal/min1, metabolic equivalents (METs; 1 MET = 3.5 mL/kg/min), and total kcals per segment and for the overall session were calculated.

RESULTS

The total subject EE throughout the 40-minute trial (including warm-up and cool-down segments) was 264 kcals, with an overall average of 6.3 kcals/min (5.6 METs).The average kcals/min expended throughout CR segments 2 through 6 was 8.05 (7.1 METs), with the Hoverjog segment producing the greatest average kcals/min at 8.3 (7.3 METs). The CR portion (22 min) contributed 65% of the total EE (171 kcals) of the 40-minute AE trial. For the overall AE trial, the highest and average subject VO2 achieved were 33.3 and 19.7 mL/kg/min, respectively. The average highest subject heart rate achieved was 177 beats per minute (bpm), equivalent to 90% of the participant's age-predicted HRmax.

CONCLUSION

Energy expenditure during a 40-minute AE session met national recommendations for a daily moderate-to-vigorous bout of physical activity offering a viable alternative to land-based exercise. Because AE serves as a partial-weight bearing modality, future studies are needed to clarify the EE of shallow-water AE in apparently healthy and clinical populations.

Effect of stride frequency on metabolic costs and rating of perceived exertion during walking in water

We investigated the effect of stride frequency (SF) on metabolic costs and rating of perceived exertion (RPE) during walking in water and on dry land. Eleven male subjects walked on a treadmill on dry land and on an underwater treadmill at their preferred SF (PSF) and walked at an SF which was lower and higher than the PSF (i.e., PSF ± 5, 10, and 15 strides min(-1)). Walking speed was kept constant at each subject's preferred walking speed in water and on dry land. Oxygen uptake, heart rate, RPE, PSF and preferred walking speeds were measured. Metabolic costs and RPE were significantly higher when walking at low and high SF conditions than when walking at the PSF condition both in water and on dry land (P<0.05). Additionally, the high SF condition produced significantly higher metabolic costs and RPE than the equivalent low SF condition during walking in water (P<0.01). Furthermore, metabolic costs, RPE, PSF, and the preferred walking speed were significantly lower in water than on dry land when walking at the PSF (P<0.05). These observations indicate that a change in SF influences metabolic costs and RPE during walking in water.

Consumo de oxigênio e índice de esforço percebido em diferentes ritmos de execução na hidroginástica

O objetivo do estudo foi correlacionar o consumo de oxigênio (VO2) e o percentual do VO2 máximo (%VO2máx) com o índice de esforço percebido (IEP) e comparar essas variáveis entre exercícios de hidroginástica executados no meio aquático em diferentes ritmos de execução. Seis mulheres realizaram quatro sessões de testes, uma no meio terrestre (teste de esforço máximo) e três no meio aquático, cada uma com a execução de um exercício de hidroginástica: corrida estacionária, deslize lateral e chute frontal até 45°. Cada exercício aquático foi realizado em três ritmos de execução, 80, 100 e 120bpm, durante 6 min (intervalo de 30 min). Para todas as variáveis, não foram observadas diferenças significativas entre os três exercícios, todavia, as mesmas apresentaram diferenças significativas entre os ritmos, indicando que com o aumento do ritmo, o esforço para executar os exercícios foi intensificado. Correlações significativas foram observadas entre VO2 e IEP e entre %VO2máx e IEP. Logo, baseado nessas associações, sugere-se que a prescrição da intensidade dos exercícios analisados possa ser feita através do IEP durante aulas de hidroginástica.

The metabolic response to treadmill graded exercise: traditional vs. underwater

The purpose of this study was to determine the metabolic effect(s) of four graded exercise tests (GXT) performed on the underwater treadmill (UWT), and compare them to the results from performing the standard Bruce protocol on a traditional land treadmill (LT). Twelve male Division I college athletes performed the stand Bruce protocol on a LT and 4 different GXT protocols on the UWT. Each test was performed to volitional max. oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (RER) and blood lactate (BL), which were measured at regular intervals throughout each of the GXTs. A two-way ANOVA with repeated measures was used to determine any main effect among the variables within the protocols and within the stages. Established effects were identified further using Tukey's post-hoc analysis. VO2and HR were positively correlated in all the GXTs, (r=0.992−0.999). When comparing the UWT GXTs to the Bruce, significant (P≤0.001) differences were found within certain stages for each of the dependent variables. While the Bruce resulted in attainment of VO2max, (mean = 55.72±5.92 ml/kg/min), only one of the UWT GXTs resulted in the same level of metabolic stress. At maximum speed and water velocity, the UWT produced a mean VO2of 53.9±3.68 ml/kg/min. HR and RER both increased by stage in all the GXTs as did BL. The onset of blood lactate accumulation (OBLA) was identified in all of the GXTs with the exception of one of the UWTs. Mean BL at OBLA ranged from, 3.12+1.31 to 5.98+4.24 mmol/dl. Our results suggest that an UWT GXT protocol can be developed that would produce metabolic results similar to the Bruce through stage 5. Buoyancy and variation in biomechanics need to be studied further for their effects on energy metabolism while performing work on the UWT. However, this study provides a better understanding of the metabolic demands at different treadmill speeds and water jet settings with the UWT.