Effect of changing water depth on muscle activity and motion kinematics during sit-to-stand motion.

BACKGROUND: Sit-to-stand (STS) movement is a fundamental activity in daily life. Studies have examined the effect of water depth during aquatic exercise; however, no investigation has examined the effect of water depth on STS movements. RESEARCH QUESTION: This study examined whether changing water depth affected muscle activity and motion kinematics during the STS movement. METHODS: Eleven participants performed the STS movement on the ground (land) and at different water depths (1.0-m [deep] and 0.6-m [shallow]) at a self-determined pace. Lower extremity and trunk muscle activity, lower extremity joint angle, and trunk segment inclination angle were measured. Mean muscle activity during STS movement, initial and final postures, and range of motion of each angle was evaluated. Correlations of a normalised time-series pattern of electromyography and motion kinematics measures between land and shallow (land-shallow) and between land and deep (land-deep) were investigated. RESULTS: The rectus femoris was more active in shallow than in deep water STS movement but less than that in land STS. Other muscles showed no significant differences between shallow and land STS movement. Correlation of the time series pattern in the tibialis anterior, rectus femoris, and erector spinae muscles was higher in the land-shallow than the land-deep STS. The trunk showed more forward inclination in the shallow STS than the land but less than the deep. Correlation of the time series pattern in the hip joint and trunk inclination angles was higher in the land-shallow STS than in the land-deep STS. SIGNIFICANCE: STS exercise in the shallow water depth reduced muscle load for the knee extensor but not for other muscles. The muscle activity pattern showed a higher correlation between the land STS and shallow water than deep. Sitting posture becomes upright when the water depth decreases, but a similar motion pattern could be attained regardless of water depth.

Comparison two-year effects of once-weekly and twice-weekly water exercise on health-related quality of life of community-dwelling frail elderly people at a day-service facility.

PURPOSE: The purpose of this study was to compare two-year effects of once-weekly and twice-weekly water exercise programmes at a day-service facility on the health-related quality of life (HRQL) of frail elderly people. METHOD: This single blind, prospective, longitudinal randomized pilot study separated 22 community-dwelling frail elderly people into once-weekly (once group: n = 10) and twice-weekly (twice group: n = 12) groups: the two-year exercise interventions were once- or twice-weekly 1-h sessions. Water exercise sessions comprised warming-up on land, activities of daily living (ADL) exercise, stretching, strength, and relaxation in water. The HRQL was evaluated using the Medical Outcomes Survey Short Form-36 questionnaire (SF-36); ADL dependence was assessed using the Functional Independence Measure (FIM). RESULT: Both groups showed significant increases over pre-intervention (pre) scores at 6 months and 12 months on Physical Component Summary and Mental Component Summary. In the once group, both were lower at 24 months than at 6 months and 12 months. The FIM scores were significantly different from pre at 6 months and 12 months in both once and twice groups, and between pre and 24 month in the twice group. CONCLUSION: Better than once-weekly exercise, twice-weekly water exercise controlled deterioration of HRQL, ADL, and knee extensor muscle strength (KEX) with ageing.

The features of muscle activity during chair standing and sitting motion in submerged condition.

This study aimed to measure muscle activity and motion kinematics during chair-based exercises under submerged and non-submerged conditions. Twelve healthy men performed chair-based standing and sitting movements. Surface electrodes were attached at the tibialis anterior, gastrocnemius, rectus femoris, biceps femoris, rectus abdominis, and erector spinae. The ankle, knee, and hip joint angles and forward inclination angle of the trunk segment in the sagittal plane were calculated. The mean muscle activities during both movements in the submerged condition for the entire motion were lower than those in the non-submerged condition except in the tibialis anterior and biceps femoris during the sitting movement (in the standing exercise, rectus femoris: 14.1% and 5.2%; and erector spinae: 18.3% and 13.6% in non-submerged and submerged conditions, respectively; and in the sitting exercise, rectus femoris: 12.1% and 4.5% and erector spinae: 12.9% and 9.9% in the non-submerged and submerged conditions, respectively). However, the integrated muscle activity in submerged conditions was similar or higher to that in non-submerged conditions during both movements, except for the rectus femoris. This was mainly due to the increased duration of motion (44.3% and 39.9% longer for standing and sitting exercises in submerged conditions, respectively, compared with non-submerged conditions). The hip joint flexion at the beginning and end of movement and forward inclination angles of the trunk segment at the beginning of the movement in the submerged condition were larger than those in the non-submerged condition during both movements (hip: 126.1° and 111.5° at the beginning, 182.3° and 178.4° at the end and trunk: 2.7° and 17.4° at the beginning in non-submerged and submerged conditions for the standing exercise, respectively; hip: 182.4° and 178.0° at the beginning, 125.9° and 111.1° at the end and trunk: 2.2° and 16.9° at the end in non-submerged and submerged conditions for the sitting exercise, respectively). Reduced or similar muscle activity but similar or higher muscular effort was observed in the submerged condition for all the muscles except the rectus femoris, with the upper body inclined forward. These findings could have beneficial implications for the prescription of exercise and rehabilitation regimens.

Prediction of Physical Activity Intensity with Accelerometry in Young Children.

Background: An algorithm for the classification of ambulatory and non-ambulatory activities using the ratio of unfiltered to filtered synthetic acceleration measured with a triaxial accelerometer and predictive models for physical activity intensity (METs) in adults and in elementary school children has been developed. The purpose of the present study was to derive predictive equations for METs with a similar algorithm in young children. Methods: Thirty-seven healthy Japanese children (four- to six-years old) participated in this study. The five non-ambulatory activities including low-intensity activities, and five ambulatory activities were selected. The raw accelerations using a triaxial accelerometer and energy expenditure by indirect calorimetry using the Douglas bag method during each activity were collected. Results: For non-ambulatory activities, especially light-intensity non-ambulatory activities, linear regression equations with a predetermined intercept (0.9) or quadratic equations were a better fit than the linear regression. The equations were different from those for adults and elementary school children. On the other hand, the ratios of unfiltered to filtered synthetic acceleration in non-ambulatory activities were different from those in ambulatory activities, as in adults and elementary school children. Conclusions: Our calibration model for young children could accurately predict intensity of physical activity including low-intensity non-ambulatory activities.

Lower extremity muscle activity during deep-water running on self-determined pace.

Although deep-water running (DWR) is often used to obtain the benefits of aerobic fitness and to reduce vertical component stress, its attendant muscle stress remains unclear. The present study investigated lower extremity muscle activity and during DWR compared to that during land walking (LW) and water walking (WW). Surface electromyography was used to evaluate muscle activity in nine healthy adults during each exercise at self-determined slow, moderate, and fast paces. The duration of swing phase, ankle, knee and hip joint angle, and each joint range of motion (ROM) also investigated. Results show that the percentages of maximal voluntary contraction (%MVC) of the soleus and medial gastrocnemius were lower during DWR than during LW or WW in the backward swing phase. The %MVC of the rectus femoris was higher during WW and DWR than during LW; that of the vastus lateralis was lower during WW and DWR than during LW in the forward swing phase. In the biceps femoris, the %MVC was higher during DWR than during LW or WW in the forward and backward swing phase. Every pace showed a similar trend. These results suggest that DWR can stimulate the hip joint flexor or extensor muscles.

The development of an estimation model for energy expenditure during water walking by acceleration and walking speed.

OBJECTIVES: The aim of this study was to develop an estimation equation for energy expenditure during water walking based on the acceleration and walking speed. DESIGN: Cross-validation study. METHODS: Fifty participants, males (n=29, age: 27-73) and females (n=21, age: 33-70) volunteered for this study. Based on their physical condition water walking was conducted at three self-selected walking speeds from a range of: 20, 25, 30, 35 and 40 m/min. Energy expenditure during each trial was calculated. During water walking, an accelerometer was attached to the occipital region and recorded three-dimensional accelerations at 100 Hz. A stopwatch was used for timing the participant's walking speed. The estimation model for energy expenditure included three components; (i) resting metabolic rate, (ii) internal energy expenditure for moving participants' body, and (iii) external energy expenditure due to water drag force. RESULTS: When comparing the measured and estimated energy expenditure with the acceleration data being the third component of the estimation model, high correlation coefficients were found in both male (r=0.73) and female (r=0.77) groups. When walking speeds were applied to the third component of the model, higher correlation coefficients were found (r=0.82 in male and r=0.88 in female). Good agreements of the developed estimation model were found in both methods, regardless of gender. CONCLUSIONS: This study developed a valid estimation model for energy expenditure during water walking by using head acceleration and walking speed.

Comparison of once and twice weekly water exercise on various bodily functions in community-dwelling frail elderly requiring nursing care.

Previous research suggests that water exercise (WE) improves bodily functions of the frail elderly, but there is as yet no research on the effect of once weekly WE. This study aims to compare the effects of once and twice weekly WE on bodily functions of frail elderly requiring nursing care in six months. The design is a prospective cohort study. Participants were assigned to two different exercise groups (once weekly group or twice weekly group; n=35). Once weekly group participate in a 60-min exercise session once a week, for six months while twice weekly group attended the session twice a week. Exercise sessions were divided into a 10-min warm-up on land and 50 min of exercise in water. The 50-min WE program consisted of 20 min walking, 10 min activities of daily living (ADL) exercise, 10 min stretching and strength exercises, and 10 min relaxation in water. Muscle strength, flexibility, balance, mobility and ADL disability were measured before the beginning of intervention and three months and six months after the program had started. Significant differences between the once and twice weekly groups were found in flexibility and balance at 3-months and 6-months and lower muscle strength and ADL disability only at 3-months. These results from present study suggested that the effects of WE frequency in the fail elderly who require nursing care were different for each bodily function.

Comparison of 2-year effects of once and twice weekly water exercise on activities of daily living ability of community dwelling frail elderly.

Previous research suggests that water exercise improves the activities of daily living (ADL) ability of the frail elderly, but the specific frequency and intensity of such programs is unclear. This study aims at comparing the effects of once- and twice-weekly water exercise on the ADL ability of frail elderly receiving nursing care for 2 years. The design is a prospective randomized longitudinal study. Participants were assigned to two different exercise groups (Group 1 and Group 2). Group 1 participated in a 60-min exercise session once a week, for 2 years, while Group 2 attended the session twice a week. Exercise sessions were divided into a 10-min warm-up on land and 50 min of exercise in water. The 50-min water exercise program consisted of 20 min walking, 10 min ADL exercise, 10 min stretching and strength exercises, and 10 min relaxation in water. ADL ability and lower muscle strength were measured before the beginning of exercise and 6 months, 1 year, and 2 years after the program had started. Significant group differences occurred for bathing transfer and stair climbing at the 2-year measurement. These results suggested that at least twice-weekly water exercise was necessary to maintain the ADL ability and KEX of the frail elderly during the 1-year water exercise period and for one additional year afterward.

EMG activity of hip and trunk muscles during deep-water running.

The present study used synchronized motion analysis to investigate the activity of hip and trunk muscles during deep-water running (DWR) relative to land walking (LW) and water walking (WW). Nine healthy men performed each exercise at self-determined slow, moderate, and fast paces, and surface electromyography was used to investigate activity of the adductor longus, gluteus maxima, gluteus medius, rectus abdominis, oblique externus abdominis, and erector spinae. The following kinematic parameters were calculated: the duration of one cycle, range of motion (ROM) of the hip joint, and absolute angles of the pelvis and trunk with respect to the vertical axis in the sagittal plane. The percentages of maximal voluntary contraction (%MVC) of each muscle were higher during DWR than during LW and WW. The %MVC of the erector spinae during WW increased concomitant with the pace increment. The hip joint ROMs were larger in DWR than in LW and WW. Forward inclinations of the trunk were apparent for DWR and fast-paced WW. The pelvis was inclined forward in DWR and WW. In conclusion, the higher-level activities during DWR are affected by greater hip joint motion and body inclinations with an unstable floating situation.

A comparison of the effects of different water exercise programs on balance ability in elderly people.

This study compared the effects of 2 types of water exercise programs on balance ability in the elderly. Thirty healthy elderly persons (60.7 +/- 4.1 yr) were randomly assigned to a deep-water-running exercise (DWRE, n = 15) group or a normal water exercise (NWE, n = 15) group. The participants completed a twice-weekly water exercise intervention for 12 wk. Exercise sessions comprised a 10-min warm-up on land, 20 min of water-walking exercise, 30 min of water exercise while separated into NWE and DWRE, a 10-min rest on land, and 10 min of recreation and relaxation in water. Postural-sway distance and tandem-walking time were decreased significantly in DWRE. Postural-sway area was decreased significantly in NWE. In both groups, simple reaction times were significantly decreased. The findings of this study show that a water exercise program including deep-water running is much better than normal water exercise for improving dynamic balance ability in the elderly.

Effect of non-uniform skin temperature on thermoregulatory response during water immersion.

The present study investigated the effect of non-uniform skin temperature distribution on thermoregulatory responses and subjective thermal sensation during water immersion. Ten healthy male subjects carried out 60 min water immersion twice, once with uniform (UST) and once with non-uniform (NUST) skin temperature. In UST condition, subjects immersed at 29 degrees C in naked condition, while in NUST condition, subjects immersed at 26 degrees C with partial coverage wetsuit (PCWS). The PCWS covers trunk region, upper arms, and thighs. The non-uniform skin temperature distribution, higher at trunk and lower at distal extremities, was observed in NUST condition. Shivering thermogenesis was not influenced by the skin temperature distribution at the experimental condition of this study. On the other hand, the tissue insulation (I (tissue)) was significantly higher in NUST condition compared to the UST condition. The increment of I (tissue) might have been caused by the peripheral vasoconstriction induced by the cold input from the distal extremities in NUST condition. The higher I (tissue) in NUST condition might lead to the significantly higher esophageal temperature compared to UST condition. No difference was observed in thermal sensation between the two conditions. Subjects felt slightly more comfortable in NUST condition than in UST condition. In conclusion, the non-uniform skin temperature distribution, higher at trunk and lower at distal extremities, might affect the peripheral vasoconstriction to increase the I (tissue). On the other hand, shivering thermogenesis and subjective thermal sensation were not affected by the non-uniform skin temperature distribution at the present experimental condition.

The water exercise improves health-related quality of life of frail elderly people at day service facility.

OBJECTIVE: The purpose of this study was to investigate the effects of water exercise at a day service facility and the effects of water exercise frequency on health-related quality of life (HRQL). METHODS: Participants (n = 30) were randomly separated into three groups: two indicating exercise frequency, at once-weekly or twice-weekly, and a control group. One-hour exercise intervention sessions were carried out once or twice a week, accordingly, for 24 weeks. The water exercise session comprised a warm-up on land, activities of daily living (ADL) exercises, stretching, strength training, and relaxation in water. HRQL was evaluated using the Medical Outcomes Survey Short-Form 36 (SF-36) questionnaire, and ADL disability was assessed using the Functional Independence Measure. RESULTS: Significant differences were found between pre- and 6 months in both the once- and twice-weekly groups in HRQL (p < 0.05). No significant difference was found among pre-, 3 months, and 6 months. The effect size between the once and twice groups was moderate in both the physical component summary (0.72) and mental component summary (0.75) at 3 months. ADL disability shows significant correlation with HRQL. CONCLUSION: Water exercise intervention at a day service facility improved participants' HRQL for 6 months by improving exercise habits and ADL disability. Furthermore, the HRQL change differed according to exercise frequency: twice-weekly exercise showed more rapid improvement than once-weekly.

Insulation and body temperature of prepubescent children wearing a thermal swimsuit during moderate-intensity water exercise.

This study investigated thermal swimsuits (TSS) effects on body temperature and thermal insulation of prepubescent children during moderate-intensity water exercise. Nine prepubescent children (11.0+/-0.7 yrs) were immersed in water (23 degrees C) and pedalled on an underwater cycle-ergometer for 30 min with TSS or normal swimsuits (NSS). The rectal temperature (Tre) was maintained slightly higher with TSS than with NSS. The total insulation (Itotal) was significantly higher with TSS. The DeltaTre, Deltamean body temperature (Tb), and tissue insulation (Itissue) in the NSS condition were correlated with % body fat, which indicated that the insulation layer of subjects with low body fat was thinner than that of obese subjects, and tended to decrease body temperature. Wearing TSS increased Itotal, thereby reducing heat loss from subjects' skin to the water. Consequently, subjects with TSS were able to maintain higher body temperatures. In addition, TSS is especially advantageous for subjects with low body fat to compensate for the smaller Itissue.

Lower extremity muscle activity during different types and speeds of underwater movement.

To compare the activity of lower extremity muscles during land walking (LW), water walking (WW), and deep-water running (DWR), 9 healthy young subjects were tested at self-selected low, moderate, and high intensities for 8 sec with two repetitions. Surface EMG electrodes were placed on the tibialis anterior (TA), soleus (SOL), medial gastrocnemius (GAS), rectus femoris (RF), and biceps femoris (BF). During DWR, the SOL and GAS activities were lower than LW and WW. The BF activities were higher during DWR than LW and WW. It was considered that the lower activity of SOL and GAS depended on water depth, and higher activity of BF occurred by greater flexion of the knee joint or extension of the hip joint during exercise.