Metabolic costs and rating of perceived exertion during backward walking in water and on dry land.

The purpose of this study was to compare metabolic costs, rating of perceived exertion (RPE), and stride frequency during backward walking in water and on land. The walking speeds in water were set to be half of those on land. There was no significant difference in metabolic costs and RPE between backward walking in water with a current and on land, at slow and moderate speeds (P > 0.05). However, at the fast speed (i.e., 3.0 and 6.0 km · h(-1) for water and land, respectively), the metabolic costs and RPE during backward walking on land were significantly higher than when walking backward in water with a current (P < 0.05). With regard to backward walking at faster speeds, if the walking speed in water with a current is set at half the speed on land, then the speed will be inadequate for inducing metabolic costs and RPE that are similar to those produced on land.

Physiological responses, rating of perceived exertion, and stride characteristics during walking on dry land and walking in water, both with and without a water current.

CONTEXT: Walking in water has been included in rehabilitation programs. However, there is a dearth of information regarding the influence of a water current on physiological responses, rating of perceived exertion (RPE), and stride characteristics of subjects while they walk in water. OBJECTIVE: To compare physiological responses, RPE, and stride characteristics of subjects walking in water (with and without a current) with those of subjects walking on dry land. DESIGN: Repeated measures. SETTING: University laboratory. PARTICIPANTS: 7 male adults (mean age = 21.6 y). INTERVENTION: Subjects walked on a treadmill on dry land and on an underwater treadmill immersed to the level of the xiphoid process. The walking speeds in water were set to be half of that on dry land. MAIN OUTCOME MEASURES: Oxygen consumption (VO2), respiratory-exchange ratio (RER), heart rate (HR), minute ventilation (VE), RPE (for breathing and legs, RPE-Br and RPE-Legs, respectively), systolic (SBP) and diastolic (DBP) blood pressures, and stride frequency (SF) were measured. In addition, stride length (SL) was calculated. RESULTS: There was no significant difference in the VO2, RER, HR, VE, RPE-Br, and RPE-Legs while walking in water with a current compared with walking on dry land (P > .05). Furthermore, VO2, RER, HR, VE, RPE-Br, RPE-Legs, SF, and SBP while walking in water were significantly higher with a water current than without (P < .05). CONCLUSIONS: These observations suggest that half the speed should be required to work at the similar metabolic costs and RPE while walking in water with a current, compared with walking on dry land. Furthermore, it was suggested that the physiological responses and RPE would be higher while walking in water with a current than without.

Physiological and perceptual responses to backward and forward treadmill walking in water.

We compared physiological and perceptual responses, and stride characteristics while walking backward in water with those of walking forward in water. Eight males walked on an underwater treadmill, immersed to their xiphoid process level. Oxygen uptake ((.)V(O2)), respiratory exchange ratio (R), heart rate (HR), minute ventilation ((.)V(E)), blood lactate concentration (BLa), ratings of perceived exertion (RPE: for breathing and legs, RPE-Br and RPE-Legs, respectively), blood pressure (for systolic and diastolic pressures, SBP and DBP, respectively), and step frequency (SF) were measured. In addition, step length (SL) was calculated. (.)V(O2), R, HR, V (E), BLa, RPE-Br, RPE-Legs, and SBP were significantly higher while walking backward in water than when walking forward in water (P<0.05). Furthermore, SF was significantly higher (P<0.001) and SL was significantly lower (P<0.001) while walking backward in water, compared to walking forward in water. These results indicate that walking backward in water elicits higher physiological and perceptual responses than those produced when walking forward in water at the same speed.

Muscle activation, cardiorespiratory response, and rating of perceived exertion in older subjects while walking in water and on dry land.

This study compared the muscle activities, cardiorespiratory responses, and ratings of perceived exertion (RPE) of nine older individuals while walking in water with those obtained while walking on dry land. Electromyography, stride frequency (SF), stride length (SL), oxygen uptake (V O(2)), heart rate (HR), RPE (for breathing and legs, RPE-Br and RPE-Legs, respectively), and blood lactate concentration (BLa) were measured. There were no significant differences in the V O(2), HR, RPE-Br, RPE-Legs or BLa while walking in water and on dry land (moderate and fast speeds). Both in water and on dry land, the V O(2)-HR, V O(2)-walking speed, and HR-walking speed relationships were significantly correlated. The SF and SL while walking in water were significantly lower than on dry land. The %MVCs while walking in water were all significantly lower than on dry land within each speed condition. Conversely, the V O(2), HR, RPE-Br and RPE-Legs, BLa, SL, and %MVC (the rectus femoris, vastus medialis, biceps femoris, and gastrocnemius) while walking in water were significantly higher than on dry land at the same speeds. In conclusion, walking in water elicits higher muscle activities, higher cardiorespiratory responses, and increased perceived exertion levels in older adults than walking on dry land at the same speed.

Gait patterns and muscle activity in the lower extremities of elderly women during underwater treadmill walking against water flow.

This study sought to determine the characteristics of gait patterns and muscle activity in the lower extremities of elderly women during underwater treadmill walking against water flow. Eight female subjects (61.4+/-3.9 y) performed underwater and land treadmill walking at varying exercise intensities and velocities. During underwater walking (water level at the xiphoid process) using the Flowmill, which has a treadmill at the base of a water flume, the simultaneous belt and water flow velocities were set to 20, 30 and 4 m.min(-1). Land walking velocities were set to 40, 60 and 80 m.min(-1). Oxygen uptake and heart rate were measured during both walking exercises. Maximum and minimum knee joint angles, and mean angular velocities of knee extension and knee flexion in the swing phase were calculated using two-dimensional motion analysis. Electromyograms were recorded using bipolar surface electrodes for five muscles: the tibialis anterior (TA), medial gastrocnemius (MG), vastus medialis (VM), rectus femoris (RF) and biceps femoris (BF). At the same exercise intensity level, cadence was almost half that on land. Step length did not differ significantly because velocity was halved. Compared to land walking, the maximum and minimum knee joint angles were significantly smaller and the mean angular velocity of knee extension was significantly lower. Knee extension in the swing phase was limited by water resistance. While the muscle activity levels of TA, VM and BF were almost the same as during land walking, those of MG and RF were lower. At the same velocity, exercise intensity was significantly higher than during land walking, cadence was significantly lower, and step length significantly larger. The knee joint showed significantly smaller maximum and minimum angles, and the mean angular velocity of knee flexion was significantly larger. The muscle activity levels of TA, VM, and BF increased significantly in comparison with land walking, although those of MG and RF did not significantly differ. Given our findings, it appears that buoyancy, lower cadence, and a moving floor influenced the muscle activity level of MG and RF at the same exercise intensity level and at the same velocity. These results show promise of becoming the basic data of choice for underwater walking exercise prescription.

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.

A comparison of muscle activity and heart rate response during backward and forward walking on an underwater treadmill.

This investigation compared muscle activities and heart rate (HR) responses while subjects walked backward or forward in water, with and without a water current. Ten healthy males (23.5+/-1.4 years) volunteered for the study. Surface electromyography (EMG) was used to evaluate muscle activities while the subjects walked in water, immersed to the level of the xiphoid process. HR responses were monitored continuously by a telemetry method. A "Flowmill" was used for this study, which involves a treadmill at the base of a water flume. Measurement of maximal voluntary contraction (MVC) of each tested muscle was undertaken prior to gait analysis. The %MVCs obtained from the paraspinal muscles, vastus medialis and tibialis anterior were all significantly greater when walking backward than when walking forward, for every experimental condition (P<0.05). HR responses tended to be greater while walking backward than when walking forward, with a statistical significance at fast speed (P<0.05). In conclusion, walking backward in water resulted in significantly greater muscle activation of the paraspinal muscles, vastus medialis and tibialis anterior compared with walking forward in water. These findings may be helpful in developing water-based exercise programs.

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.