Abstract
[Purpose] The purpose of this study was to compare changes in balance ability of land exercise and underwater exercise on chronic stroke patients. [Subjects] A total of 60 patients received exercise for 40 minutes, three times a week, for 6 weeks. [Methods] Subjects from both groups performed general conventional treatment during the experimental period. In addition, all subjects engaged in extra treatment sessions. This extra treatment consisted of unstable surface exercise. The underwater exercise group used wonder boards in a pool (depth 1.1m, water temperature 33.5 °C, air temperature 27 °C) dedicated to underwater exercise, and the land exercise group used balance mats. [Result] The joint position sense, sway area, Berg Balance Scale showed significant improvements in both groups. However, the joint position sense test, sway area, and Berg Balance Scale showed there was more improvement in the underwater exercise group than in the land exercise group. [Conclusion] The results suggest that underwater exercise is more effective than land exercise at improving the joint position sense and balance of stroke patients.
Key words: Underwater exercise, Joint position sense, Balance
INTRODUCTION
Most stroke survivors suffer aftereffects of impairments in motor, sensory, cognitive, perceptive, psychological, social, and physical functions1). Additionally, 65% of stroke patients experience loss of tactile sense, the protection reaction, and proprioceptive sense2). The proprioceptive sense is closely correlated with balance ability3). Since declined balance ability reduces functional activities and increases the incidence rate of falls4), one of the physical functions that must be recovered first in stroke patients is balance ability5). However, the body sway applied during land balance training psychologically increases fear of falling and thus acts as a factor to limit balance training6). In this respect, Svedenhag et al. reported that the psychologically unstable state can be relieved, and mental stability can be induced through underwater techniques7). Exercise in underwater environments helps stroke patients to safely and comfortably improve their motor ability by providing low-risk exercise environments that support their bodies and reduce their fear of falling and the possibility of sudden damage8). Additionally, the slow-moving environment in water caused by viscosity and drag force can also help people reduce the velocity-dependent spastic response9).
Noh et al. reported that when 25 chronic stroke patients performed underwater exercise for eight weeks in a study intended to examine the effects of ai-chi and halliwick exercises on stroke patients' bodily balance and muscle force, the patients' balance ability and knee flexor muscle force improved10). Lee Dong-Jin et al. reported that when 34 chronic stroke patients divided into an underwater group and a land group received training for 12 weeks in a study intended to examine the effects of underwater and land task-oriented training on the patients' balance ability, the underwater group showed larger improvement in static and dynamic balance than the land group11). Park et al. reported that when 44 chronic stroke patients divided into an underwater exercise group and a land exercise group had performed exercise for six weeks in a study intended to examine the effects of underwater exercises using buoyant apparatuses on joint position senses and Performance-Oriented Mobility Assessment (POMA), the underwater group showed larger improvement in their joint position senses and POMA than the land exercise group12).
Recently, underwater exercise has gained more attention for stroke rehabilitation9). Therefore, underwater exercises are considered to be able to satisfy the social demands for more effective and safer therapeutic interventions. However, studies on underwater exercises are still insufficient, and previous studies did not apply the same exercise program to underwater and land exercises or implement underwater proprioceptive sense exercise programs.
In this respect, this study was intended to implement the same proprioceptive sense exercise program underwater and on the land in patients with hemiplegia resulting from stroke in order to examine the effects of the exercise program on the patients' balance ability.
SUBJECTS AND METHODS
Subjects
The subjects who participated in this study were 62 stroke patients hospitalized in D hospital located in Daejeon, Korea. To minimize the possibility of spontaneous recoveries, the subjects were selected from chronic stroke patients with onset at least six months previously, who had no internal medical disease such as diabetes, had no heart disease and no orthopedic problems, scored 24 or more on the Mini-Mental State Examination-Korea, had no visual problems, and could walk at least 15 m by themselves. These subjects had been given explanations until they sufficiently understood this experiment. Then the subjects or their guardians signed consent forms for participation in this experiment. General characteristics of the study subjects are as shown in Table 1.
Table 1. General characteristics of the subjects (M±SD).
| UG (n=31) | LG (n=31) | ||
| Age (years) | 56.1±7.3 | 56.6±10.0 | |
| Height (cm) | 158.2±9.6 | 161.3±6.4 | |
| Weight (kg) | 63.4±9.0 | 61.9±7.9 | |
| Onset (Month) | 15.2±5.1 | 16.1±5.4 | |
| K-MMSE | 26.3±3.7 | 27.0±3.4 | |
| Sex | Male | 15 | 13 |
| Female | 16 | 18 | |
| Affected side | Right | 14 | 15 |
| Left | 17 | 16 | |
K-MMSE, Mini-Mental State Examination-Korea. UG, Underwater group; LG, Land group
Methods
The proprioceptive sense exercise program in the present study was created referring to the proposal by Melzer13) and Hupperets et al.14) and implemented a total of 18 times, 3 times per week, for 6 weeks from January 2011. All the study subjects performed exercises for a total of 40 minutes each time consisting of 30 minutes of main exercises, 5 minutes of warming up exercises and warming down exercises underwater or on the land depending on their groups. The underwater exercise group used wonder boards in a pool (depth 1.1 m, water temperature 33.5 °C, air temperature 27 °C) dedicated to underwater exercise, and the land exercise group used balance mats in an exercise treatment room in the hospital building. The overall exercise programs for the underwater exercise group and the land exercise group were the same, and three sets consisting of 10 repetitions of motions at different levels were performed. The details of the exercise program are as follows.
(1) One-legged knee flexion: The subjects placed one foot toward the front and one toward the rear, with one on the land and the other on the wonder boards (balance mats), and then bent and straightened the knees while pushing the body forward. (2) Toe stand: The subjects stood on the wonder boards (balance mats) with the feet comfortably apart laterally and repeated motions to raise and lower the heels. (3) One-legged stance: The subjects stood on the wonder boards (balance mats) on one foot (for 30 seconds). (4) Knee flexion of both legs: The subjects stood with their feet comfortably apart laterally with one foot in the water and the other foot on the wonder boards (balance mats) and bent and straightened the knees. (5) Weight shift: The subjects stood with their feet comfortably apart laterally with one foot in the water and the other foot on the wonder boards (balance mats) and moved the pelvis laterally.
The joint position sense test is a method of assessing the position of individual body segments without a visual aid, and it can also be applied to the proprioceptive sense in hemiplegic patients15). In this study, we employed the Biometrics (Biometrics Ltd. UK) motion analysis system that helped us compose a base unit that digitizes the analog joint angles and an electrogoniometer that measures the joint motion angle. The joint position sense test was performed as an active setting-active reproduction test. For the active setting-active reproduction test, the subjects were asked to actively move their joints within the full motion range, maintain an arbitrary angle in the middle for 3 seconds, and remember the joint angle as the reference angle. After 10 seconds of rest, the subjects were asked to press a button while actively reproducing the reference angle within one second. The zero point of the motion analysis system operating software was adjusted when the subjects were sitting. After covering the eyes of the subjects with an eye patch and checking the maximum joint motion range of the knee joint, a reference angle was set in the middle of the joint motion range. Measurement was started after allowing the patients to practice sufficiently with the decided reference angle. The duration for one measurement was seven seconds: two seconds each at the beginning and the end were discarded, and the three seconds in the middle were recorded as the measurement value. The measurement was repeated three times, and the mean value was calculated.
In this study, balance was measured using a Good Balance system (Metitur, Jyväskylä, Finland). This equipment has been commercialized as equipment for measuring the static and dynamic balance of the elderly, stroke patients, etc., and is widely used11). The measuring methods used included measuring for each 30 seconds while the patient kept his or her eyes open and closed for 30 seconds in each state.
The Berg balance test was performed by applying daily living motions and is largely divided into three areas: the ability to maintain postures, the ability to voluntarily control movements, and reflexes to external factors comprised of a total of 14 evaluation items. The performance of each item is scored between 0 points at the minimum and 4 points at the maximum, and thus the full score of the test is 56 points16).
For the data processing in this study, the paired sample t-test was performed to test the difference before and after the exercise in each group, and the independent sample t-test was performed to test the difference between the groups. The SPSS 18.0 software for Windows was used for the analysis, and a significance level, α, of 0.05 was chosen.
RESULTS
The underwater exercise group and land exercise group showed a significant decrease in joint position sense errors (p<0.05), and the change was greater in the underwater exercise group than the land group (p<0.05) (Table 2).
Table 2. A comparison of pre- and post-intervention JPS, sway area, and BBS in the underwater exercise and land exercise groups (M±SD).
| Pre | Post | diff | |||
| JPS (˚) | UG (n=31) | 4.84±1.04 | 3.07±1.34* | 1.78±1.11† | |
| LG (n=31) | 4.66±1.55 | 3.58±1.52* | 1.08±1.13 | ||
| SA (mm2/s) | EO | UG (n=31) | 53.22±26.52 | 39.89±21.21* | 13.33±11.46† |
| LG (n=31) | 60.02±16.53 | 54.36±15.50* | 5.66±7.97 | ||
| EC | UG (n=31) | 61.79±21.26 | 35.56±12.72* | 26.23±13.21† | |
| LG (n=31) | 66.65±14.85 | 52.85±19.31* | 13.80±16.07 | ||
| BBS | UG (n=31) | 39.35±8.32 | 44.16±7.84* | −4.81±1.89† | |
| LG (n=31) | 40.90±4.10 | 42.39±6.87* | −1.48±1.36 | ||
*Paired sample t-test p<0.05; †Independent sample t-test p<0.05. Diff, pre-post; UG, underwater group; LG, land group; JPS, joint position sense; SA, sway area; EO, eyes open; EC, eyes closed; BBS, Berg Balance Scale
The underwater exercise group and land exercise group showed a significant decrease in sway area (eyes open and closed) (p<0.05), and the change was greater in the underwater exercise group than in the land group (p<0.05) (Table 2).
The underwater exercise group and land exercise group showed a significant increase in Berg Balance Scale (BBS) (p<0.05), and the change was greater in the underwater exercise group than the land group (p<0.05) (Table 2).
DISCUSSION
The purpose of this study was to compare changes in balance ability with land exercise and underwater exercise in chronic stroke patients. In the results of the present study, joint position sense errors significantly decreased in the underwater exercise group that implemented the proprioceptive exercise program, and the decreases in the underwater exercise groups were more significant compared with the land exercise group. Through these results, it could be seen that the proprioceptive exercise programs in the present study were effective in improving proprioceptive senses, and in particular, the underwater exercise program was more effective. Nashner and Peters stated that after proprioceptive sense improving exercises, posture swaying when the eyes were closed showed larger improvement than those when the eyes were open17). In the present study, based on the results of functional standing balance tests, the decreases in swaying areas before and after exercises were performed were larger when the exercises were performed with the eyes closed than when the exercises were performed with the eyes open. This is considered to be associated with the fact that when implementing the exercise programs, the land exercise group performed exercises only within the limit of stability due to fear of falling, while the underwater exercise group challenged the limit of stability without any fear of falling. In general, hemiplegia patients tend to support their weight less with the lower extremity on their paretic side in standing postures and show asymmetrical characteristics of postures, which reduce the patients' functional abilities18) and act as a major cause of the patients' falling19). Therefore, equal weight bearing by the lower extremity on the paretic side should be induced20). However, it is considered that during training using unstable surfaces on the land, patients will support more weight with the lower extremity on their unaffected side. On the other hand, during underwater balance exercises, the patients can support their weight with the lower extremities on both the paretic and unaffected sides in order to maintain balance on the buoyant apparatus, since the buoyant apparatus will be lost and float away easily if the patients support their weight only with the lower extremity on their unaffected side. Therefore, underwater exercises are considered more advantageous for equal weight bearing by both lower extremities.
Consequently, through the present study, it could be seen that underwater proprioceptive sense exercise programs implemented by stroke patients were effective in improving the patients' proprioceptive sense and balance ability.
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