THE RELATIONSHIPS BETWEEN PHYSICAL ACTIVITY AND STATIC BALANCE IN ELDERLY PEOPLE

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1 Original Article THE RELATIONSHIPS BETWEEN PHYSICAL ACTIVITY AND STATIC BALANCE IN ELDERLY PEOPLE Yung-Hui Tien, Kuei-Fu Lin National Hsinchu University of Education, Hsinchu, TAIWAN The aim of this study was to investigate the relationships between physical activity levels, types and static balance in elderly people. The Physical Activity Scale for the Elderly (PASE) was used to assess physical activity levels and types. Static balance indicating the path length and the body sway area of the center of pressure was measured by five static balance tests using the static force platform. The tests included standing on one leg with eyes opened, standing on two legs with feet apart and together, and being in the two-leg stance positions with eyes opened and closed. Thirty-seven subjects completed all measurements. In the total sample, most (55.32%) PASE points were accounted for by household-related activity, and the PASE scores were between and But there was no significant difference between static balance and physical activity levels, and between static balance and various physical activity types. However, static balance with eyes opened was significantly better than with eyes closed. Physical activity levels were low amongst elderly people and the primary physical activity types were sedentary-orientated and walking. Hence, the physical activity of elderly people might be too light to affect static balance. However, the results inferred the importance of vision in the static balance of elderly people. Use of vision as a factor to measure static balance in elderly people could increase the discriminability. Further investigations on the factors that influence the capability of elderly to balance are required to improve and to serve as references in the prescription of exercise for elderly people. Keywords: elderly people, physical activity level, physical activity type, static balance Introduction From the 2004 general health statistics of the Department of Health, Executive Yuan, Taiwan (2005), the second most common cause of death in elderly people aged 65 years or older is accidental falls. The incidence of falls increases with age, with a 35 40% increase in falls in people over 60 years of age (Daley & Spinks 2000). The survey reported by the Bureau of Health Promotion, Department of Health, Taiwan, and the National Health Research Institutes showed that the percentage of people over 65 years of age who experienced a fall in the past year in Taiwan increased from 18.7% in 1999 to 20.5% in 2005, i.e. one among five elderly people experienced Corresponding Author Kuei-Fu Lin, P.O. Box , Hsinchu 300, TAIWAN. Tel: (886) ext Fax: (886) steve@mail.nhcue.edu.tw a fall (Gao 2007 pp. A6). Among elderly people, falls accounted for 87% of all fractures (Fife & Barancik 1985). Approximately 20% of females who experience a hip fracture do not survive the first year post fracture, and another 20% do not regain the ability to walk without assistance, which often leads to institutionalization (Schultz 1992). Falls in elderly people greatly affect their quality of life. Risk factors associated with falls include musculoskeletal weakness, balance deficit, history of falls, visual deficit, gait abnormalities, cognitive impairment, arthritis, impaired activities of daily living, cardiovascular disease, depression, medication, use of assistive device, or age (> 80 years) (Spirduso et al. 2005; Spirduso 1995). However, muscle weakness, impaired gait and diminished balance are the most significant risk factors for falling (Daley & Spinks 2000). Physical activities are based on balance ability; when the perturbation increases and leads to an unstable balance state of the trunk, a fall is more likely. Balance is the ability to maintain the body s position over its base of support, J Exerc Sci Fit Vol 6 No

2 whether that base is stationary or moving. Controlling postural sway during stable conditions is called static balance (Spirduso 1995). The incidence of falls is known to increase with age (Lin & Hu 1995). Studies have shown that in elderly people, exercise training can help to maintain and promote their balance ability significantly (Anderson & Behm 2005; Lin 2005; Daley & Spinks 2000; Mazzeo et al. 1998). However, the relationships between physical activities and balance ability in elderly people remain unclear. Therefore, the purpose of this study was to investigate the relationships between physical activity levels, physical activity types and static balance of elderly people, to anticipate maintaining and improving the balance ability of elderly people. Methods Subjects Thirty-seven elderly Taiwanese, aged above 65 years, served as subjects in this study. The male to female ratio was 1:2. The subjects did not have neurological and/or psychiatric disorders, did not show signs of any serious cognitive dysfunction, did not use a cane or walker for daily living, and could shuttle walk over 6 m (about 10 steps) by themselves. Materials and measurements The modified Physical Activity Scale for the Elderly (PASE), translated from American English into traditional Chinese by Wu (2002), was used to evaluate the subjects physical activity levels and types. According to the PASE, the levels of physical activities were the total PASE score computed by multiplying the level of time spent in each activity (hours/week), or participation (yes/no) in an activity, by empirically derived item weights and summing over all activities. The types of physical activities were categorized into leisure time activity, household activity, and work-related activity (Washburn et al. 1993). Both levels and types comprised the physical activity (PA) in this study. The original questionnaire was designed specifically to assess physical activities in an epidemiologic study of people aged 65 years and older, and included information on leisure, household and occupational activities in the preceding 7 days. The modified PASE scores were significantly associated with the 6-minute walk test (r = 0.38; p < 0.01) and test retest (r = 0.89; p < 0.001). The types of leisure time and household activities listed in Table 1 were classified according to the intensity of physical activities, which were defined by the energy expenditure (Ainsworth et al. 2000) coordinate of the metabolism equivalent, heart rate reserve, rating perceived exertion, and physical responses (breathing rate, body temperature, etc.) (American College of Sports Medicine 2006; Warburton et al. 2006). Work-related activity described any paid or unpaid work that required some physical activity (i.e., not sitting), which was recorded in total hours/week. Static balance was measured using a firmly secured force platform (AccuSway System, Advanced Mechanical Technology Inc., Watertown, MA, USA) consisting of one aluminum plate placed on four force transducers, recording the vertical ground reaction forces. Signals were processed by BIOPAC MP100, six DC amplifiers (BIOPAC Systems Inc., Santa Barbara, CA, USA), and then stored in a microprocessor (AcqKnowledge software) after AD conversion at a sampling rate of 200 Hz. The coordinates of the center of pressure (COP) were passed through a digital low-pass 5-Hz filter (Melzer et al. 2003), and the smoothed fluctuations of the COP Table 1. Classifications of physical activities in the PASE Type Component Intensity Leisure time Sitting MET 2 Light MET < 3, HRR = 20 39%, RPE = Level of exertion light, unapparent sweat, start to feel warm, breathing rate slightly increased Moderate MET = 3 6, HRR = 40 59%, RPE = Level of exertion somewhat harder, a little bit of sweat, warm, breathing rate more greatly increased Strenuous MET > 6, HRR = 60 84%, RPE = Level of exertion hard (heavy) or very hard, obvious sweat, quite warm, breathing rate is out of breath Household Light MET 3 Heavy MET > 3 MET = metabolism equivalent; HRR = heart rate reserve; RPE = rating perceived exertion. 22 J Exerc Sci Fit Vol 6 No

3 Y.H. Tien, K.F. Lin were further processed by a first-order differentiation of the displacements. The static balance indicated the length of the COP path (PL) and the body sway area of the COP (SA). While undertaking the tests, subjects stood still with feet comfortably spaced, arms at sides, and looking at a target placed 1 meter in front of them at eye level in the eyes-opened situation (Lord & Menz 2000). Five static conditions were measured by standing upright. Four were tested with eyes opened and closed: two conditions were applied with wide base of support (feet apart, FAO and FAC) (Karlsson & Frykberg 2000), two conditions were applied with a narrow base of support (feet together, FTO and FTC) (Melzer et al. 2003), and the last condition was applied with one-leg standing with eyes opened (OLS) (Bohannon et al. 1984). Each condition was tested three times, with the subject given a 1-minute resting period between tests. Data were retrieved for 5 seconds each still standing test (Cho et al. 2004), and were analyzed with the means. Statistical analysis An independent t test and mixed-design two-way ANOVA were employed to determine if statistically significant differences existed in static balance between the dissimilar levels of the physical activity groups. Associations between the types of physical activities and static balance were evaluated using Pearson s product-moment correlation. The level of significance was α=0.05 for all statistical analyses. Results There were 37 subjects who completed all measurements. Mean age was ± 5.40 years, mean height was ± 6.90 cm, mean weight was ± 7.40 kg, and mean PASE score was ± Based on the classifications of physical activities in the PASE, the analyses were separated into PA levels, PA types, and static balance to investigate the relationships among them. Physical activities of elderly people In the total sample, ± 24.72% of PASE points were due to leisure-time exercise activity, and ± 25.53% were due to household-related activity, whereas only 1.65 ± 4.93% of the total PASE scores were accounted for by work-related PA. In this study, the frequencies of sitting and walking were high: 6.14 ± 1.49 days/week (3.34 ± 1.14 hours/day) and 5.53 ± 2.04 days/week (2.39 ± 1.16 hours/day), respectively. The frequency of light activities was 2.56 ± 2.60 days/week (1.87 ± 0.98 hours/day), Frequencies (day/week) Sitting Walking Light Moderate Physical activity type Strenuous Muscular fitness Fig. Leisure-time physical activities of elderly people for 1 week. Table 2. ANOVA of PA levels and static balance: one leg standing Static balance df t PL SA df = degrees of freedom; PL = length of the center of pressure path; SA = body sway area of the center of pressure. and that of moderate activities was 1.90 ± 2.62 days/ week (0.51 ± 0.78 hours/day). However, the time spent on muscular fitness and strenuous activities was less than 1 day (Figure). The results showed that the PA types in which elderly people participated were brisk/vigorous walking, physical jerks and swinging of the arms. Physical activity levels and static balance The mean PASE score was ± 58.11; the maximum and the minimum were and 20.04, respectively. To increase discriminability from the PA levels and static balance, the groups greater than 27% and those lower than 73% were separated from the percentile points. Tables 2 4 show that there were no significant differences between static balance and different levels of PA (p > 0.05). Nevertheless, static balance performed with eyes opened was significantly better than with eyes closed (p < 0.05). It also meant that there were no apparent effects on static balance among the different levels of PA in elderly people, but static balance was different between dissimilar visions. Further, there was no interaction between the two factors (p > 0.05), there were no effects on static balance with eyes opened or closed, in the dissimilar groups. J Exerc Sci Fit Vol 6 No

4 Table 3. ANOVA of PA levels and static balance: feet apart standing Static balance SV SS df MS F PL SV b (level) SV w (vision) * Interaction SA SV b (level) SV w (vision) * Interaction *p < SV = source of variations; SS = sum of square of deviations from the mean; df = degrees of freedom; MS = mean square; b = between subjects; w = within subjects. Table 4. ANOVA of PA levels and static balance: feet together standing Static balance SV SS df MS F PL SV b (level) SV w (vision) * Interaction SA SV b (level) SV w (vision) * Interaction *p < SV = source of variations; SS = sum of square of deviations from the mean; df = degrees of freedom; MS = mean square; b = between subjects; w = within subjects. Table 5. Correlations between physical activity types and static balance (r) PL SA Item Eyes opened Eyes closed Eyes opened Eyes closed OLS FA FT FA FT OLS FA FT FA FT Leisure Household Work-related PL = length of the center of pressure path; SA = body sway area of the center of pressure; OLS = one leg standing with eyes opened; FA = feet apart standing; FT = feet together standing. Physical activity types and static balance The PA types according to the PASE were included in leisure time activity, household activity and work-related activity. However, there were no significant correlations between PA types and static balance (p > 0.05; Table 5). Discussion PASE scores were significantly (p < 0.05) associated with static balance (r = 0.33) (Washburn et al. 1993). Regular exercise or moderate physical activities have been shown to significantly improve and maintain balance in older people (Lin 2005; Melzer et al. 2003; Daley & Spinks 2000; Mazzeo et al. 1998). But there was no significant difference between static balance and PA levels. PA levels were low amongst older people and the primary PA types were sedentary-orientated and walking. These findings are similar to the results of the Directorate- General of Budget, Accounting and Statistics of the Executive Yuan, Taiwan (2000a, 2000b). This study demonstrated that the duration of over and above moderate physical activities participated in by elderly people was short of 2 days a week (1.79 ± 2.45 day/week) and the duration spent on muscular fitness was even less (0.57 ± 1.61 day/week). Washburn et al. (1993) developed the PASE for Dutch elderly people, and recorded PASE mean scores of ± 78.0 and ± 66.3 in 56 and 134 elderly Dutch men and women, respectively. But with 45 older men and 55 older women in Taiwan, the PASE score was 60.1 ± (Wu 2002); the result in this study was ± 58.11, and the mode was centered on the closed interval between 101 and 150. The PASE scores of Taiwanese were not consistent with those in 24 J Exerc Sci Fit Vol 6 No

5 Y.H. Tien, K.F. Lin Dutch, and the total PASE scores were up to 360. Therefore, the results indicate that PA in Taiwanese elderly may be lower than in Dutch, or the PASE developed for the Dutch is just not suitable for Taiwanese. There are significant differences between elderly and youth for standing on an unstable surface, with eyes closed, or with OLS. Standing balance may be affected by sensory feedback with age (Shimada et al. 2003; Hu & Lin 1994). Rogers and Mille (2003) showed that OLS might be predictive of falls. However, there was no significantly different OLS performance between different PA level groups. In this study, static balance performed with eyes opened was significantly better than with eyes closed. The ability of sensory integration to maintain balance is decreased in elderly adults. Proprioception might not be immediately influenced by aging, but aging could indirectly reduce message input, such as that from the sense of vision (Wade & Jones 1997). The study findings infer the importance of vision in the static balance of elderly people. Results of this study were not the same as the hypothesis and relational studies. The errors for this study could have been caused by the fact that: (1) the PA of elderly people might be too light to affect static balance; (2) the classifications of physical activities in the PASE might not differentiate the varieties of static balance; (3) the effect on PA types might not be obvious with regard to static balance in elderly people; (4) there were only 37 subjects, which might not be an accurate representation of the target population. The effect of vision on the static balance of elderly people was obvious. Use of vision as a factor to measure static balance in elderly people could increase the discriminability. For the survey of physical activities, direct measurements (like pedometers) might result in fewer errors than using questionnaires. There are many risk factors associated with balance in elderly people, including coordination deficit, musculoskeletal weakness, gait abnormalities, neuromuscular system impairment, and sensitivity for spatial orientation deficit. These factors could limit balance ability. Further investigation of the factors that influence balance in elderly people is required to improve the balance of the elderly and to serve as references in the prescription of exercise for them. References Ainsworth BE, Haskell WL, Whitt MC, Irwin ML, Swartz AM, Strath SJ, O Brien WL, Bassett DR, Schmitz KH, Emplaincourt PO, Jacobs DR, Leon AS (2000). Compendium of physical activities: an update of activity codes and MET intensities. Med Sci Sports Exerc 32(9 Suppl): S American College of Sports Medicine (2006). ACSM s Guidelines for Exercise Testing and Prescription (7 th ed). Lippincott Williams & Wilkins, Champaign, IL, pp. 3 5, Anderson K, Behm DG (2005). 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