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°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.

Eight healthy and physically well-trained male students exercised on a treadmill for 60 min while being immersed in water to the middle of the chest in a laboratory flowmill. The water velocity was adjusted so that the intensity of exercise correspond to 50% maximal oxygen uptake of each subject, and experiments were performed once at each of three water temperatures: 25, 30, 35 degrees C, following a 30-min control period in air at 25 degrees C, and on a treadmill in air at an ambient temperature of 25 degrees C. Thermal states during rest and exercise were determined by measuring rectal and skin temperatures at various points, and mean skin temperatures were calculated. The intensity of exercise was monitored by measuring oxygen consumption, and heart rate was monitored as an indicator for cardiovascular function. At each water temperature, identical oxygen consumption levels were attained during exercise, indicating that no extra heat was produced by shivering at the lowest water temperature. The slight rise in rectal temperature during exercise was not influenced by the water temperature. The temperatures of skin exposed to air rose slightly during exercise at 25 degrees C and 30 degrees C water temperature and markedly at 35 degrees C. The loss of body mass increased with water temperature indicating that both skin blood flow and sweating during exercise increased with the rise in water temperature. The rise in body temperature provided the thermoregulatory drive for the loss of the heat generated during exercise. Heart rate increased most during exercise in water at 35 degrees C, most likely due to enhanced requirements for skin blood flow. Although such requirements were certainly smallest at 25 degrees C water temperature, heart rate at this temperature was slightly higher than at 30 degrees C suggesting reflex activation of sympathetic control by cold signals from the skin. There was a significantly greater increase in mean skin and rectal temperatures in subjects exercising on the treadmill in air, compared to those exercising in water at 25 degrees C.

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°C and 35°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°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°C water were significantly higher (PϽ0.01) than in 31°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.

The purpose of the present study was to examine the effect of water temperature on the human body during low-intensity prolonged swimming. Six male college swimmers participated in this study. The experiments consisted of breast stroke swimming for 120 minutes in 23°C, 28°C and 33°C water at a constant speed of 0.4 m · sec -1 in a swimming flume. The same subjects walked on a treadmill at a rate of approximately 50% of maximal oxygen uptake (V • O 2 max) at the same relative int ensit y as the t hree swimming trials. Re ctal temperature (Tre) in 33°C water was unchanged during swimming for 120 minutes. Tre during treadmill walking increased significantly compared to the three different swimming trials. Tre, mean skin temperature (T --sk) and mean body temperature (T --b) in 23°C and 28°C water decreased significantly more than in both the 33°C water and walking on land. V• O 2 during swimming in 23°C water increased more than during swimming in the 28°C and 33°C trials; however, there were no significant differences in V• O 2 between the 23°C swimming trial and treadmill walking. Heart rate (HR) during treadmill walking on land increased significantly compared with HR during the three swimming trials. Plasma adrenaline concentration at the end of the treadmill walking was higher than that at the end of each of the three swimming trials. Noradrenaline concentrations at the end of swimming in the 23°C water and treadmill walking were higher than those during the other two swimming trials. Blood lactate concentration during swimming in 23°C water was higher than that during the other two swimming trials and walking on land. These results suggest that the balance of heat loss and heat production is maintained in the warm water temperature. Therefore, a relatively warm water temperature may be desirable when prolonged swimming or other water exercise is performed at low intensity.

Abstract. The ergometer can be a versatile means of measurement if attachments are developed for special purposes or if attachment is developed for multi-uses. In this study, an ergometer attachment for the measurement of power was designed and the measurement of power and the maximum anaerobic power in swimming was tested. A rotation drum was attached to one pedal of an ergometer. The rotation of this drum was synchronized with the rotation of the pedal. One end of a wire for a traction by a swimmer was connected to the drum. The other end of the wire was attached to a belt around the waist of a swimmer. The swimmer swam at full strength, thus causing the drum to rotate. The rotational velocity of the drum was detected as voltage by a magnetic permanent motor and transformed to wire tractional velocity; this velocity was equal to swimming velocity. The wire tension (=load) was controlled by a load adjusting lever of the ergometer. This wire tension was equal to the load which was added to the swimmer. The power calculation was based on a curved regression equation approximated from the load and the velocity. This equation was shown as follows; (P + a) (v + b) = (P0 + a)b or its development (P + a)v = b(P0 P) and provided that P: force or load, v: swimming velocity, P0: maximum tractional force, a and b: constants. This ergometer attachment made it possible to measure and evaluate the power and the maximum anaerobic power in swimming with ease and at low cost. Measurement and evaluation are easily performed using the system, which is just one example of the possible applications of the ergometer.