Human thermoregulatory responses during prolonged walking in water at 25, 30 and 35 degrees C

The Use of Ratings of Perceived Exertion in Children and Adolescents: A Scoping Review

In adults, ratings of perceived exertion (RPE) can be used to predict maximal oxygen uptake, estimate time to exhaustion, assess internal training load and regulate exercise intensity. However, the utility of RPE in children is less researched and therefore, warrants investigation. The purpose of this scoping review is to map out the literature around the application of RPE specifically during aerobic exercise in paediatric populations. Seven bibliographic databases were systematically searched. Grey literature searching and pearling of references were also conducted. To be included for the review, studies were required to comply with the following: (1) participants aged ≤ 18 years asymptomatic of any injuries, disabilities or illnesses; (2) applied RPE in aerobic exercise, testing and/or training; (3) included at least one measure of exercise intensity; and (4) be available in English. The search identified 22 eligible studies that examined the application of RPE in children. These studies involved a total of 718 participants across ten different countries. Nine different types of RPE scales were employed. Overall, the application of RPE in paediatric populations can be classified into three distinct themes: prediction of cardiorespiratory fitness/performance, monitoring internal training loads, and regulation of exercise intensity. The utility of RPE in paediatric populations remains unclear due to the small body of available research and inconsistencies between studies. However, findings from the included studies in this scoping review may show promise. Further research focussing on child-specific RPE scales across various sports, subgroups, and in field-based settings is needed.

Effects of heated water-based versus land-based exercise training on vascular function in individuals with peripheral artery disease

Peripheral artery disease (PAD) is an atherosclerotic disease that is associated with poor vascular function, walking impairment, and reduced quality of life. Land-based exercise therapy (LBET) is frequently recommended to improve walking and reduce symptoms. Recently, evidence has suggested that heated-water exercise therapy (HWET) is an effective intervention for PAD. However, the efficacy of LBET versus HWET in PAD patients had not been elucidated. Therefore, we sought to compare effects of LBET with HWET on cardiovascular function, exercise tolerance, physical function, and body composition in PAD patients. PAD patients (n = 53) were recruited and randomly assigned to a LBET group (n = 25) or HWET group (n = 28). The LBET group performed treadmill walking, whereas the HWET group performed walking in heated water for 12 wk. Leg (legPWV) and brachial-to-ankle arterial stiffness (baPWV), blood pressure (BP), ankle-brachial index (ABI), 6-min walking distance (6MWD), claudication onset time (COT), physical function, and body composition were assessed before and after 12 wk. There were significant group-by-time interactions (P < 0.05) for legPWV, BP, 6MWD, COT, body composition, and resting metabolic rate (RMR). Both groups significantly reduced (P < 0.05) legPWV, BP, and body fat percentage, and HWET measures were significantly lower than LBET measures. Both groups significantly increased 6MWD, COT, and RMR, and HWET group measures were significantly greater than LBET measures. A time effect was noted for baPWV reduction in both groups (P < 0.05). These results suggest that both LBET and HWET improve cardiovascular function, exercise tolerance, and body composition, and HWET showed considerably greater improvements compared with LBET in patients with PAD.NEW & NOTEWORTHY The results of this study reveal for the first time that although land-based exercise therapy is effective for reducing arterial stiffness and blood pressure in patients with peripheral artery disease (PAD), heated-water exercise therapy demonstrates greater benefits on vascular function. The greater improvements in muscular strength, time to onset of claudication, and exercise tolerance after heated-water exercise therapy may have clinical implications for improving quality of life in patients with PAD. The heated-water exercise therapy intervention demonstrated relatively higher exercise training adherence (∼88%) compared with the land-based exercise intervention (∼81%).

Prediction of ground reaction forces while walking in water

Despite being a key concept in rehabilitation, controlling weight-bearing load while walking, following lower limb injury is very hard to achieve. Walking in water provides an opportunity to prescribe load for people who have pain, weakness or weight bearing restrictions related to stages of healing. The aim of this experimental study was to evaluate and validate regression models for predicting ground reaction forces while walking in water. One hundred and thirty seven individuals (24±5 years, 1.71±0.08 m and 68.7±12.5 kg) were randomly assigned to a regression group (n = 113) and a validation group (n = 24). Trials were performed at a randomly assigned water depth (0.75 to 1.35 m), and at a self-selected speed. Independent variables were: immersion ratio, velocity, body mass, and waist, thigh and leg circumferences. Stepwise regression was used for the prediction of ground reaction forces and validation included agreement and consistency statistical analyses. Data from a force plate were compared with predicted data from the created model in the validation group. Body mass, immersion ratio, and velocity independently predicted 95% of the vertical and resultant ground reaction force variability, while, together, velocity and thigh circumference explained 81% of antero-posterior ground reaction force variability. When tested against the data measured in validation samples, the models output resulted in statistically similar values, intraclass correlation coefficients ranging from 0.88 to 0.90 and standard errors of measurement, 11.8 to 42.3 N. The models introduced in this study showed good predictive performance in our evaluation procedures and may be considered valid in the prediction of vertical, antero-posterior and resultant ground reaction forces while walking in water. All predictive variables can be easily determined in clinical practice. Future studies should focus on the validation of these models in specific populations.

The effects of walking posture on affective and physiological states during stress

BACKGROUND AND OBJECTIVES

Embodiment theory proposes that motor processes are associated with emotions and cognitions. Previous research has shown that walking posture can influence affective memory bias. This study further investigated this theory by looking at the effects of an upright versus slumped walking posture on psychological and physiological states when faced with a psychological stressor.

METHODS

Seventy-three healthy adults completed baseline self-report measures of affect, power, and sleepiness, and physiological measures of blood pressure, galvanic skin response, and skin temperature. After walking in their usual posture, the same self-report and physiological measures were obtained. Participants were then randomly allocated into one of two groups where they were asked to walk in either an upright posture or a slumped posture. While walking, participants underwent a psychological stressor. After experimental walking, the same self-report and physiological measures were obtained.

RESULTS

The upright walking posture group showed significantly improved psychological states including less low arousal negative affect, less sleepiness, less pain and marginally greater feelings of power than the slumped walking posture group. Physiologically, the upright walking posture group showed significantly lower systolic blood pressure, galvanic skin response, and marginally lower skin temperature than the slumped walking posture group.

LIMITATIONS

This was a short-term laboratory-based experiment and results may not generalise to other situations.

CONCLUSIONS

Walking posture can affect both psychological and physiological states. Applications of these findings may have implications for improving mental and physiological health.

Effects of Aqua-Lymphatic Therapy on Lower Extremity Lymphedema: A Randomized Controlled Study

BACKGROUND

The purpose of this study is to investigate the effects of the aqua-lymphatic therapy (ALT) on unilateral lower extremity lymphedema in the maintenance phase.

MATERIALS AND METHODS

This is a randomized controlled trial with a blinded assessor. The study was completed with 30 ALT and 27 control group participants. Foot volume was assessed by a water displacement device, limb volume by circumference measurements, functional capacity by a 6-minute walk test, quality of life by Short Form-36, and social appearance by Social Appearance Anxiety Scale and hopeless by Beck Hopeless Scale. The ALT and the control group had group sessions twice in a week for 6 weeks directed by a physiotherapist.

RESULTS

The mean age of ALT patients was 44.50 ± 13.69 years, whereas that of the control patients was 47.66 ± 16.82 years. After the intervention, both groups' measurement of edema, functional level, quality of life, as well as social and future concerns improved significantly but this improvement was higher in the ALT group (p < 0.05, p ≤ 0.001).

CONCLUSIONS

ALT was found to be a safe effective method for unilateral lower extremity lymphedema patients during the maintenance phase of Complex Decongestive Physiotherapy.

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.

The effects of landed and aquatic treadmill walking at moderate intensity on heart rate, energy expenditure and catecholamine

PURPOSE

The present study was to examine whether or not the appropriate exercise intensity of water-walking could be accurately prescribed by land-based walking speed.

METHODS

Using a crossover design, nine healthy male college students completed bouts of walking for thirty minutes at 100m/min, 50m/min, respectively, on land and water treadmills. Heart rate (HR), ratings of perceived exertion (RPE), energy expenditure, blood lactic acid and catecholamine concentration were measured. Two-way repeated measured ANOVA was used with the SPSS program for data analysis.

RESULTS

HR (P < 0.001), RPE (P < 0.001), energy expenditure (P < 0.001), blood lactic acid (P < 0.001) and epinephrine concentration (P < 0.05) were significantly increased during walking both in water and on land. The change of HR was significantly lower at 50min/m in water than 100min/m on land (P < 0.01). There were no significant interaction effects for RPE, energy expenditure, blood lactic acid and catecholamine concentration, but these variables were slightly lower in water than on land. These results indicated that the use of land walking speed-based prescriptive norms would underestimate the physiological cost in water walking at the moderate intensity.

CONCLUSION

Therefore, approximately two-half of the speed would be needed to walk in water in order to obtain the same level of physiological load as during treadmill walking at the moderate intensity.

Efeito da temperatura da água nas respostas cardiovasculares durante a caminhada aquática

O objetivo deste estudo foi verificar o efeito da temperatura da água nas respostas cardiovasculares: frequência cardíaca (FC), pressão arterial sistólica (PAS) e pressão arterial diastólica (PAD), durante a caminhada aquática em três temperaturas (29°C, 33°C e 37°C). Participaram do estudo 10 homens, com média de idade de 23,2 ± 2,25 anos, massa corporal de 78,4 ± 4,01kg e estatura de 1,774 ± 0,017m. Os participantes realizaram caminhadas aquáticas durante 30 min, a uma cadência controlada de 55 passos/minuto, na altura do processo xifoide, em dias diferentes para cada temperatura, sendo as respostas cardiovasculares monitoradas nos minutos 5, 10, 20 e 30. Apesar do efeito principal de 75,4% (p < 0,001) da temperatura da água sobre a variação da FC, também foi identificado um efeito do tempo de exercício de 91,8% (p = 0,001). A FC aumentou gradativamente no decorrer da caminhada, especialmente na temperatura de 37°C (71,3 ± 8,4 para 114,6 ± 4,4); ao final da caminhada foi maior que os 29°C (p < 0,01) e 33°C (p < 0,05); estas últimas não apresentaram diferença entre si. A temperatura parece ter tido pouco efeito sobre a PAS, visto que apenas nos minutos 20 e 30 foi maior aos 33°C comparada com a de 29°C (p < 0,05). A PAD sofreu efeito da temperatura, diminuindo gradativamente no decorrer da caminhada, especialmente na temperatura de 37°C (70,0 ± 5,0 para 40,0 ± 2,5); apresentou diferença significativa em relação às temperaturas de 29°C e 33°C (p < 0,05), as quais não mostraram diferença entre si. Considerando o efeito da temperatura da água sobre a FC e a PAD durante a caminhada aquática, sugere-se que, quando piscinas terapêuticas forem utilizadas para realização de caminhada na água, a escolha da temperatura da água seja considerada, recomendando-se valores entre 29°C e 33°C para menor estresse cardiovascular.

Caminhada em ambiente aquático e terrestre: revisão de literatura sobre a comparação das respostas neuromusculares e cardiorrespiratórias

O objetivo deste estudo foi realizar uma revisão de literatura sobre a comparação das respostas neuromusculares e cardiorrespiratórias durante a caminhada em meio aquático e em meio terrestre. As respostas foram apresentadas para a caminhada em piscina rasa e para a caminhada em piscina funda. Em relação à caminhada em piscina rasa, as respostas neuromusculares (sinal EMG) e cardiorrespiratórias (FC e VO2) são muito dependentes da velocidade do exercício. As respostas neuromusculares podem ser menores no meio aquático quando a velocidade da caminhada é menor nesse ambiente. Por outro lado, quando o exercício é realizado com velocidades similares, a atividade dos músculos propulsores pode ser superior durante a caminhada aquática. Da mesma forma, respostas cardiorrespiratórias maiores são registradas no exercício aquático quando velocidades similares de caminhada são utilizadas. Contudo, com velocidades menores, essas respostas são semelhantes ou menores que as encontradas em meio terrestre. No que diz respeito à caminhada em piscina funda, as respostas neuromusculares diferem daquelas encontradas durante a caminhada em meio terrestre devido à ausência das forças de reação com o solo. Essa característica possivelmente modifica os músculos envolvidos na produção de força propulsiva nesse exercício. Além do mais, durante a caminhada em piscina funda, as respostas cardiorrespiratórias parecem sempre mais baixas devido à grande redução no peso hidrostático e à menor atividade dos músculos posturais e pela utilização do cinturão flutuador nessa modalidade.

Age-related differences in muscle activity, stride frequency and heart rate response during walking in water

This study aimed to examine whether walking in water produces age-related differences in muscle activity, stride frequency (SF), and heart rate (HR) response. Surface electromyography (EMG) was used to evaluate muscle activities in six older and six young subjects while they walked in water immersed to the level of the xiphoid process. The trials in water utilized the Flowmill which consists of a treadmill at the base of a water flume. The measurement of maximal voluntary contraction (MVC) of each muscle was made prior to the gait analysis. The %MVCs, which refer to the surface EMG measures, from the gastrocnemius of the older subjects were significantly lower than those of the young subjects, in every experimental condition (P<0.05). In contrast, the %MVCs from the rectus femoris (P<0.05) and the biceps femoris (P<0.001) of older subjects were significantly greater than those of young subjects in every experimental condition. Moreover, the SFs of older subjects were also significantly greater than those of young subjects (P<0.05), while the HR responses of older and young subjects were similar. In conclusion, the older subjects had increased hip musculature activity and decreased ankle plantar flexor activity while walking in water, compared with the young subjects.

Freqüência cardíaca e percepção subjetiva do esforço no meio aquático: diferenças em relação ao meio terrestre e aplicações na prescrição do exercício - uma revisão

A intensidade na qual o esforço é realizado constitui um aspecto fundamental na elaboração e no controle de qualquer programa de exercícios. Atividades conduzidas nos meios terrestre e aquático apresentam especificidades distintas; aspectos como volume do corpo imerso, posição corporal e temperatura da água levam o organismo a condições diferenciadas daquelas observadas no meio terrestre, assim influenciando os indicadores de intensidade do esforço. Considerando que freqüência cardíaca e percepção subjetiva do esforço são os indicadores mais utilizados no controle da intensidade do esforço em exercícios aquáticos, a presente revisão objetiva analisar as principais alterações que ocorrem nessas variáveis em condição de imersão, comparando com o meio terrestre, bem como as implicações dessas alterações na prescrição do exercício. Para tanto, são apresentadas as principais alterações decorrentes de situações de repouso e exercício, na corrida e no ciclismo aquáticos, na hidroginástica e na natação. Por fim, são tecidas algumas considerações acerca das implicações dessas alterações na prescrição do exercício, bem como algumas estratégias para utilização dessas variáveis em sessões de exercícios no meio aquático. Em relação à freqüência cardíaca, pode-se concluir que ocorre redução nos batimentos cardíacos durante a imersão, influenciada pela temperatura da água, pela profundidade de imersão, pela ausência ou presença de esforço, pelo tipo e intensidade do exercício. Tal redução deve ser considerada ao utilizar esse indicador de intensidade do esforço no meio aquático. Quanto à percepção subjetiva do esforço, a escala de Borg parece ser uma opção adequada para o controle da intensidade de exercícios aquáticos, considerando-se as recomendações inerentes a sua aplicação.

Muscle activity and heart rate response during backward walking in water and on dry land

The primary purpose of this study was to examine whether walking backward in water and walking backward on dry land elicit different electromyographic (EMG) activities in lower-extremity and trunk muscles. Surface EMG was used to evaluate muscle activities while six healthy subjects walked backward in water (with and without a water current, Water + Cur and Water - Cur, respectively) immersed to the level of the xiphoid process, and while they walked backward on dry land (DL). The trials in water utilized the Flowmill which consists of a treadmill at the base of a water flume. Integrated EMG analysis allowed the quantification of muscle activities. The measurement of maximal voluntary contraction (MVC) of each muscle was made prior to the gait analysis, and all data were expressed as the mean (SD). The %MVCs from the muscles tested while walking backward in water (both with and without a current) were all significantly lower than those obtained while walking backward on dry land (P < 0.05), with the exception of the paraspinal muscles. In the case of the paraspinal muscles, the %MVC while walking backward with a water current was significantly greater than when walking backward on dry land [Water + Cur 19.4 (6.8)%MVC vs. DL 13.1 (1.4)%MVC; P < 0.05], or walking backward without a water current [vs. Water - Cur 13.3 (1.8)%MVC; P < 0.05]. Furthermore, when walking backward in water, the %MVCs from the muscles investigated were significantly greater in the presence of a water current than without (P < 0.05). In conclusion, walking backward in water with a current elicits the greatest muscle activation of the paraspinal muscles. These data may help in the development of water-based exercise programs.

Electromyographic Analysis of Walking in Water in Healthy Humans

This study was designed to describe and clarify muscle activities which occur while walking in water. Surface electromyography (EMG) was used to evaluate muscle activities in six healthy subjects (mean age, 23.3 +/- 1.4 years) while they walked on a treadmill in water (with or without a water current) immersed to the level of the xiphoid process, and while they walked on a treadmill on dry land. The trials in water utilized the Flowmill which has a treadmill at the base of a water flume. Integrated EMG analysis was conducted for the quantification of muscle activities. In order to calculate the %MVC, the measurement of maximal voluntary contraction (MVC) of each muscle was made before the gait analysis, thus facilitating a comparison of muscle activities while walking in water with those on dry land. The %MVCs obtained from each of the tested muscles while walking in water, both with and without a water current, were all found to be lower than those obtained while walking on dry land at a level of heart rate response similar to that used when walking on dry land. Furthermore, the %MVCs while walking in water with a water current tended to be greater when compared to those while walking in water without a water current. In conclusion, the present study demonstrated that muscle activities while walking in water were significantly decreased when compared to muscle activities while walking on dry land, that muscle activities while walking in water tended to be greater with a water current than without, and that the magnitude of the muscle activity in water was relatively small in healthy humans. This information is important to design water-based exercise programs that can be safely applied for rehabilitative and recreational purposes.

Body temperature, oxygen uptake and heart rate during walking in water and on land at an exercise intensity based on RPE in elderly men

The purpose of this study was to clarify the characteristics of the physiological response that occurs while walking in water and on land at an exercise intensity based on the rating of perceived exertion (RPE) in elderly men. Nine elderly men ranging from 66-70 years of age participated in this study as subjects. The actual trials consisted of walking for 20 minutes in 31 degrees C and 35 degrees C water on an underwater treadmill. The water depth of the treadmill corresponded to the level of the xiphoid process in the subject. The same subjects performed on-land walking using a moving belt treadmill for 20 minutes at a room temperature of 27 degrees C. The exercise intensity during walking in the two water trials and the on-land trial was the same "somewhat hard" measured on the basis of the subject's RPE rating of 13. There was no significant difference between the subjects' rectal temperatures among the three trials. The mean skin temperature and mean body temperature while walking for 20 minutes in 35 degrees C water were significantly higher (P<0.01) than in 31 degrees C water and on land. There were no significant differences in oxygen uptake and heart rate among the two trials in water and the on-land trial. The above results suggest that the exercise intensity based on a subject's RPE may be an effective index for the prescription of thermoneutral water walking in the same way that it is for land walking in the elderly.

Cardiorespiratory response to low-intensity walking in water and on land in elderly women

The purpose of the present study was to determine whether or not the exercise intensity of water-walking for elderly women could be accurately prescribed by heart rate data obtained during treadmill exercise on land. Six healthy female volunteers, with a mean age of 62.2 +/- 4.2 years, took part in this study. Walking on land was performed on a treadmill. Each subject completed three consecutive 4-minute walks at a progressively increasing velocity (40, 60 and 80 m.min-1), with a 1-minute rest after both the first and second walks. The room temperature and relative humidity were 24.5 +/- 0.2 degrees C and 54.8 +/- 4.0%, respectively. Walking in water was performed in a Flowmill, which is a treadmill positioned at the base of a water flume. Each subject completed three consecutive 4-minute walks at a progressively increasing belt and water-flow velocity (20, 30 and 40 m.min-1), with a 1-minute rest after both the first and second walks. The water depth was at the level of the xiphoid process of each subject. The water temperature was 30.7 +/- 0.1 degrees C. The exercise intensity at the highest workrate was equivalent to 44.2 +/- 10.3% of the heart rate reserve (HRR) during water-walking and 38.4 +/- 4.7% of the HRR during land-walking. There was a highly significant linear relationship between heart rate (HR) and oxygen uptake (VO2) during both water-walking and land-walking. The relationship between HR and VO2 in both exercise modes was similar. Thus, the relationship of HR to VO2 derived from a treadmill-graded walking test on land may be used to prescribe exercise intensity for water-walking in thermoneutral water.

Physiological responses to water-walking in middle aged women

The purpose of the present study was to examine the physiological responses to water-walking using the Flowmill, which has a treadmill at the base of a water-flume, in two groups of women. In the first group, the women were known to regularly swim and exercise in water (group A), while in the second, they did not routinely participate in water-exercise (group B). In both groups, twelve healthy female volunteers in their fifties participated in the study. All of the subjects walked in water using the Flowmill for the first time. Subjects completed four consecutive bouts of 4-minute duration at progressively increasing speeds (20, 30, 40, and 50 m.min-1), with 1-minute rests between each bout. In addition, water-velocity was adjusted to the walking speed of each bout. The water-depth of the Flowmill was the level of the xiphoid process. The water and room temperatures were 30.3 +/- 0.1 degrees C and 24.9 +/- 0.4 degrees C, respectively. In both groups, the relationship between walking speed and oxygen uptake (VO2) as well as that between walking speed and heart rate (HR) changed exponentially as the walking speed increased, and the relationship between HR and VO2 was linear. The relationship between HR and VO2 was similar in both groups, and there was no significant difference between the predicted maximal oxygen uptake (VO2max) of the two groups. VO2 and HR of group B during water-walking, however, were significantly higher than those of group A at all walking speeds. The results of this study clearly showed that experience in moving through the water strongly affects physiological responses to water-exercise, even when fitness levels are equivalent.

Physiological responses and RPE during underwater treadmill walking in women of middle and advanced age

The purpose of this study was to examine the physiological responses and RPE during water walking using the Flowmill, which has a treadmill at the base of a water flume, in order to obtain basic data for prescribing water walking for people of middle and advanced age. Twenty healthy female volunteers with an age of 59.1 +/- 5.2 years took part in this study. They belonged to the same swimming club and regularly swam and exercised in water. Walking in water took place in the Flowmill. Subjects completed four consecutive bouts of 4 min duration at progressively increasing speeds (20, 30, 40 and 50 m/min) with 1 min rest between each bout. In addition, water velocity was adjusted to the walking speed of each bout. Subjects were instructed to swing both arms in order to maintain their balance during walking in water. The water depth was to the level of the xiphoid process and the water temperature was 30.31 +/- 0.08 degrees C. Both heart rate (HR) and oxygen uptake (VO2) increased exponentially as walking speed increased. HR was 125 +/- 15 bpm, and VO2 was 18.10 +/- 2.72 ml/kg.min-1 during walking in water at 50 m/min, which was the highest speed. The exercise intensity at this speed was equivalent to 5.2 +/- 0.8 Mets. The relationship between HR and VO2 during walking in water showed a highly significant linear relationship in each subject. There was also a highly significant linear relationship in the mean HR and VO2 of all subjects. Blood lactate concentration (LA) measured at rest and immediately after each bout was 1.1 +/- 0.4 mmol/l at rest, 1.0 +/- 0.2 mmol/l at 20 m/min, 1.0 +/- 0.3 mmol/l at 30 m/min, 1.1 +/- 0.2 mmol/l at 40 m/min, and 2.4 +/- 0.7 mmol/l at 50 m/min. LA at 50 m/min was significantly higher than at rest and at the other speeds. The relationship between HR and RPE during walking in water showed a highly significant linear relationship. The relationship between walking speed and energy expenditure calculated from VO2 and the respiratory exchange ratio (R) showed a high significant exponential relationship. These results suggested that HR and RPE can be effective indices for exercise prescription during Flowmill walking as with land walking.