Abstract
Background Because the number of elderly people is rapidly increasing, reference values for the physical abilities necessary to independently conduct daily activities are crucial for promoting good health. Although a few studies have reported reference values for functional tests relating to these abilities, all of those values were derived from populations in developed countries, which have baseline demographic and anthropometric characteristics different from those of Thai people.
Objective The purpose of this study was to describe reference values for 5 physical performance tests for Thai elderly people who were functioning well and dwelling in the community.
Design A cross-sectional design was used in this study.
Methods A total of 1,030 Thai elderly people who were functioning well were cross-sectionally assessed for their physical abilities with 5 functional tests: 10-Meter Walk Test, Berg Balance Scale, Timed “Up & Go” Test, Five Times Sit-to-Stand Test, and Six-Minute Walk Test. The data were reported with descriptive statistics according to decade of age and sex. Differences among the age decades and between the sexes were analyzed with a 1-way analysis of variance and an independent-sample t test, respectively. Multiple linear regression analyses were used to determine baseline characteristics important in functional abilities.
Results Most of the values found for the performance-based measures were lower than those previously reported, with a significant trend toward age- and sex-related functional decline. Weight and height were important contributors to level of functional ability.
Limitations Only a few elderly individuals older than 90 years of age participated in this study. Therefore, their findings were combined with those of participants aged 80 to 89 years.
Conclusions The findings described here may be useful as reference values for 5 physical performance tests for Thai elderly people. Health practitioners can use this information to identify functional impairments early and to promote independence in Thai and other elderly populations with similar anthropometric characteristics, such as those in the Association of South East Asian Nations.
The life expectancy of people has dramatically increased in recent years.1 This increased life expectancy has rapidly changed the structure of elderly populations worldwide, including those in developing countries such as Thailand.2 The United Nations reported that the number of Thai elderly people would increase from 8% in the year 2000 to 16% in the year 2020. In other words, the number of elderly people in Thailand will double in only 20 years, whereas population doubling takes 70 to 100 years in some developed countries.3 Increasing age is likely to be accompanied by changes in function that affect the ability to conduct daily activities independently and by increases in the number of people who are dependent in Thailand.4–6 Therefore, reference values for the physical abilities necessary in daily living would provide important guidelines for the promotion of good health.
Several studies have reported important contributors to the ability to be independent, including safe and efficient ambulatory status, good static and dynamic balance, adequate lower extremity muscle strength, and good functional endurance.4,7,8 These abilities can be quantified with the 10-Meter Walk Test (10MWT), Berg Balance Scale (BBS), Timed “Up & Go” Test (TUG), Five Times Sit-to-Stand Test (FTSST), and Six-Minute Walk Test (6MWT).4,9 The validity, reliability, feasibility, and responsiveness of these tests for assessing the abilities of elderly people in both clinical and community settings have been verified.4,9–11 Therefore, objective data obtained with these performance-based measures would be useful for rehabilitation practitioners in monitoring and promoting independence in the elderly population.4
Although some studies have reported reference values for physical performance in elderly people,4,9 the findings have faced some criticisms. Steffen et al9 investigated physical performance in elderly people (60–89 years old) using 4 functional tests (10MWT, BBS, TUG, and 6MWT). However, the findings were derived from a small sample (N=96), with only 8 to 22 participants in each age decade. Lusardi et al4 reported reference values for 6 functional tests (10MWT, BBS, TUG, 6MWT, FTSST, and Physical Performance Test) in 76 elderly people, including 17 who were 90 years old or older. However, the findings were obtained from elderly people who walked with or without a walking device; thus, the data may not be suitable for use as reference values for the promotion of good health. In addition, in several other studies12–20 the physical performance of elderly people was investigated with 1 or 2 variables. However, the findings were mostly derived from populations in Western countries, which have anthropometric characteristics different from those of Thai people.
The distinctive diet, habitat, nature of work, and geographical location of general Thai populations have significant impacts on anthropometric data. Although the height and weight of the current Thai populations appear to be greater than those of Thai populations in the 1980s and 1990s, they are still smaller than those of Western populations.21 Therefore, reference values for physical performance specifically for Thai populations are crucial to the effectiveness of Thailand's system for the promotion of good health. In this study, we explored the relationship of physical performance to levels of independence in Thai elderly people who were functioning well and dwelling in the community. The findings of this study may also be applied appropriately to elderly people in the Association of South East Asian Nations or others with similar sociodemographic characteristics.
Method
Participants
This study was conducted in a cross-sectional manner with elderly people who were functioning well (or who were independent in performing basic daily activities without any difficulty or life-threatening illnesses)22 in several communities in Thailand from April 2010 to April 2012. A sample size calculation for a descriptive quantitative research study23 indicated that the study needed 1,002 participants.
Participants were recruited through direct contact with community leaders. Eligible participants were able to execute daily activities independently without a walking device and did not have a history of falls during the 6 months preceding participation in the study. In addition, participants needed to have a body mass index between 18.5 and 29.9 kg/m2 and the ability to understand simple commands to complete the tests.24 Elderly people with signs and symptoms that might affect participation in the study were excluded; examples of such signs and symptoms were inflammation in the joints of the lower extremities with a pain level of more than 5 of 10 on a visual analog scale, sequelae of neuromuscular diseases (eg, Parkinson disease, stroke) that affected balance and walking abilities, dizziness, acute illness or injury, unstable heart disease (eg, angina), and uncontrolled hypertension. Eligible participants provided written informed consent and were given an honorarium for their participation.
Study Protocols
A questionnaire was used to assess the health status of the potential participants. This questionnaire was developed on the basis of data from previous studies.4,9,25 The content validity of the questionnaire was verified by 4 rehabilitation professionals (3 physical therapists and 1 nurse) who had clinical experience with elderly populations. After the content validity was verified, the questionnaire was preliminarily tested with 15 elderly people. Subsequently, some items were modified, rearranged, or deleted to improve the conciseness, clarity, and completeness of the questionnaire.
The participants were involved in the study on 2 days. On the first day, the potential participants were interviewed and assessed for baseline demographics and health status with the questionnaire. This screening process took approximately 30 minutes per participant. On the second day, the physical performance of the eligible participants was assessed with 5 functional tests in a random order to minimize carryover effects, such as learning and fatigue, that might occur because of the sequence of the tests. Details of the tests follow.
10MWT.
The 10MWT was used to quantify ambulatory status in terms of both comfortable gait speed (CGS) and fast gait speed (FGS). The participants walked along a 10-m walkway, and the time was recorded during the middle 3 m.25 For the CGS, participants were instructed to “walk at a usual, comfortable pace,” and for the FGS, participants were instructed to “walk at their fastest and safe speed.” The participants performed 2 trials at each speed, and the average time was converted to gait speed in meters per second.
BBS.
The BBS is a standard clinical assessment that was designed to measure balance ability in elderly people dwelling in the community through the use of 14 static and dynamic sitting and standing activities.9,10 A 5-point ordinal scale ranging from 0 to 4 was used to rate the ability to perform each task in terms of the time required to execute the activity. The total score ranged from 0 to 56.26
TUG.
The TUG is a simple and valid method for assessing function. The time taken to complete the test is strongly correlated with the level of functional mobility.12,27,28 The participants were instructed to stand up from a standard armrest chair (with a seat height of 43 cm)17 without using their hands, walk around a traffic cone that was placed 3 m from the front edge of the chair, and return to sit down on the chair. The time from the command “Go” until the participant's back touched the backrest of the chair was recorded in seconds, and the average time from 2 trials was calculated.4,28
FTSST.
The ability of elderly people to rise from a chair or bed independently is a crucial fundamental movement for normal activities.29 The FTSST can be used to predict independent living because a longer time to complete the test indicates the likelihood of disability.30,31 The participants sat on a standard armless chair (with a seat height of 43 cm)17 with their arms at their sides, their back upright, and their feet flat on the floor 10 cm behind their knees. The participants were instructed to stand up with their hips and knees in full extension and then to sit down 5 times as quickly and safely as they could without using their arms. The time from the command “Go” until the participant's back touched the backrest of the chair on the fifth repetition was recorded in seconds, and the average time from 2 trials was used for data analyses.11,32
6MWT.
The 6MWT is widely used to measure functional exercise capacity in elderly people dwelling in the community.4,14,33 It is a submaximal test of aerobic capacity; hence, the test appears to be a better measure of exercise endurance than maximal exercise capacity.9 The participants were instructed to walk as far as possible in 6 minutes around a rectangular walkway measuring 6 m by 4 m and marked at 1-m intervals with an orange traffic cone at each corner. During the test, an assessor walked alongside the participants to ensure their safety and inform them every minute of the time left. The participants were able to rest as needed, but the timing was not stopped. In addition, they received the following encouragements at 1, 3, and 5 minutes during the test: “You have done a good job” (minute 1); “You are halfway done” (minute 3); and “You have 1 minute to go” (minute 5).9 The distance covered in 6 minutes was recorded to the nearest meter.
The tests were administered by 5 physical therapists who were familiar with the tests. Before participation in the study, the testers were trained to use the same and standard methods, and their interrater reliability for the 5 tests was excellent (intraclass correlation coefficients= .90–.99). During administration of the tests, a tester was always beside a participant without interruption to ensure the participant's safety and the accuracy of the tests. Furthermore, the participants had to wear properly sized sports sandals, which were prepared by the researchers to minimize risk of injury and reduce the effects of different shoes on the outcomes. The participants were able to rest between the trials and the tests as needed.
Data Analysis
SPSS for Windows was used for data analyses (SPSS Statistic 17.0, IBM Corp, Armonk, New York). The findings of the study were reported with descriptive statistics (mean, standard deviation, range, and 95% confidence intervals) according to sex and decade of age (60–69, 70–79, 80–89, and 90–99 years old). To facilitate data interpretation, the findings between the sexes and among the age decades were compared by use of the independent-sample t test and the 1-way analysis of variance, respectively. Post hoc analysis (Scheffé test) was used to identify the difference in every pairwise condition. Moreover, multiple linear regression analyses were used to determine the contribution of baseline demographics to the findings from the functional tests. Statistical significance was set at a P value of less than .05.
Role of the Funding Source
This study was supported by funding from the Improvement of Physical Performance and Quality of Life (IPQ) Research Group, the Faculty of Associated Medical Sciences, and the Graduate School, Khon Kaen University, Khon Kaen, Thailand.
Results
Participant Demographics
The study participants were 1,030 Thai elderly people (320 men and 710 women) who were functioning well and dwelling in the community (eFigure). Of these, 138 participants reported a controlled underlying disease, including diabetes (n=116), hypertension (n=101), hyperlipidemia (n=68), heart disease (n=19), and renal disease (n=12) and ranging from 1 to 4 diseases per participant. These participants needed medications; 120 participants (87%) used 1 or 2 medications, and 18 participants (13%) took 3 or more medications daily. Other baseline data are shown in Table 1. Because only 7 participants were at least 90 years old, the findings for these participants were combined with those for participants who were 80 to 89 years old.
Participant Characteristics According to Decade of Age and Sexa
Data From Functional Tests
Tables 2, 3, 4, 5, and 6 show data from the functional tests reported with descriptive statistics (mean, standard deviation, range, and 95% confidence intervals) according to decade of age and sex. The findings demonstrated that the physical abilities of male participants were significantly better than those of female participants in every age decade (P<.05) (Tabs. 2–6), except in the FTSST for those who were 60 to 69 years old (P>.05) (Tab. 5). The findings indicated significant age-related functional decline for both male (P<.05) and female (P<.001) participants in every test, except in the FTSST for male participants (P>.05). In all tests, age, sex, weight, and height were significant predictors of the functional data. However, these variables accounted for only 13% to 23% of the variance in the functional abilities of the participants.
Data From the 10-Meter Walk Test (Comfortable and Fast Gait Speeds) According to Decade of Age and Sexa
Data From the Berg Balance Scale (Scores) According to Decade of Age and Sexa
Data From the Timed “Up & Go” Test (Seconds) According to Decade of Age and Sexa
Data From the Five Times Sit-to-Stand Test (Seconds) According to Decade of Age and Sexa
Data From the Six-Minute Walk Test (Meters) According to Decade of Age and Sexa
Discussion
In the present study, we investigated the physical performance of elderly people who were functioning well, who were able to conduct daily activities independently without a walking device, and who did not have a history of falls during the 6 months before study participation. We used these criteria rather than recruiting elderly people who did not have any pathology or underlying disease because it might be difficult to find elderly people without any (known or unknown) underlying disease. The criteria that we used seemed to offer more realistic data for comparison with data from elderly people in clinics and communities.9
Physical performance was measured in terms of gait speed (10MWT), static and dynamic balance (BBS and TUG), lower extremity muscle strength (FTSST), and functional endurance (6MWT) because these abilities have been suggested to be important contributors to independence in elderly people.4,7,8 The findings suggested that the levels of physical abilities of the participants in the present study were lower than those previously reported4,9,12–20 but still supported a significant trend toward age- and sex-related functional decline (P<.05) (Tabs. 2, 3, 4, 5, and 6).
The differences between the findings in the present study and those previously reported may relate mainly to the baseline demographics of the participants and to the characteristics and methods of administration of the tests. Existing reference values for elderly people are from developed countries, in which demographic data indicate that people are taller than Thai people.9,19 Young34 reported that populations in developing countries have generally poorer health status than those in developed countries. The distinctive diet, lifestyle, nature of work, and geographical location of general Thai populations also contribute significantly to the anthropometric data that are significantly different from those of Western populations.21 Moreover, Wang et al35 reported that Asian populations have smaller muscle size than Western populations. These findings may explain why the values for participants in the present study were lower than those previously reported.4,9,12–20 In addition, these findings support the necessity for reference values for physical abilities specific to Thai people.
The findings of the present study suggested that age, sex, weight, and height were significant contributors to the functional abilities of the participants (P<.001). Similarly, Bautmans et al36 found that health status, age, and sex were independent factors for determining levels of physical ability in elderly people. Therefore, the application of reference values for functional abilities should be specific for these baseline data. However, the low predictive capability of these demographic variables for physical performance, particularly the FTSST, and the wide range of values in the present study (Tabs. 2, 3, 4, 5, and 6) may suggest the influence of other, uncontrolled factors, such as various daily lifestyles and levels of exercise of the participants. Furthermore, the low impact of weight and height on the functional data may be associated with the inclusion criterion for body mass indexes of 18.5 to 29.9 kg/m2.
Moreover, the differences between the values in the present study and the previously published values may relate to the characteristics of the tests. The 10MWT, TUG, FTSST, and 6MWT are time-based assessments, whereas the BBS provides an aggregate score for 14 activities, with each activity being graded on a 5-point ordinal scale. Whitney et al37 indicated that the outcomes of time-based instruments were more sensitive than those of an ordinal scale. Consequently, the scores on the BBS in the present study (50.1–54.7 [Tab. 3]) were similar to those previously reported (50–55),9 whereas the results of the other tests were obviously different from those in the existing literature.4,9,19
Furthermore, the differences between the values in the present study and the previously published values may be associated with the methods of administration of the tests. For the 10MWT, the different values (0.88–1.48 m/s [Tab. 2] versus 0.88–1.96 m/s4 and 1.15–2.05 m/s9) may relate to the settings of the tests. Bohannon and Williams Andrews15 reported that gait speed was measured over a distance of 3 to 30 m of the total distance of a 6- to 30-m walkway. However, Finch et al38 suggested that acceleration and deceleration periods of walking take up to 3 m. Therefore, to measure walking speed during a rhythmic phase, we allowed 3.5 m before and after timing and recorded the time over 3 m in the middle of the 10-m walkway.25 We measured both CGS and FGS and the differences between FGS and CGS because evidence suggested that CGS may only partially reflect the potential to participate in a community.39 The ability to voluntarily increase gait speed may better reflect the residual capacity for a community challenge.40 Furthermore, differences in walking speed help to clearly indicate and quantify how well people can adapt their gait patterns to various demands during daily activities.39 The findings demonstrated that participants in higher age decades had fewer differences between FGS and CGS (Tab. 2).
For the TUG and the FTSST, the differences between the findings of the present study and those in previous reports4,9 (9.2–13.4 seconds [Tab. 4] versus 7.3–14.7 seconds4 and 8–11 seconds9 for the TUG and 12.9–17.1 seconds [Tab. 5] versus 8.4–18.0 seconds4 for the FTSST) may relate to contributions of the arms and seat height of the chair during the tests. Using the arms may increase the level of mobility, but the resulting findings may not reflect actual abilities for balance control and lower limb function.41 Therefore, we did not allow participants in the present study to use their arms while performing the tests. In addition, these tests can be performed with an armrest (for the TUG) or an armless (for the FTSST) chair with a seat height ranging from 40 to 46 cm.29 Previous studies suggested that the minimum seat height for successful rising for elderly people appears to be 120% of the lower leg length with approximately 100 degrees of knee flexion.42,43 Therefore, we used a chair with a 43-cm seat height and foot placement 10 cm behind the knees to allow an appropriate starting position.17 Janssen et al41 indicated that an inappropriate seat height may affect a person's ability to complete the sit-to-stand task. However, the seat height was shown to predict only 2% of the variance in FTSST performance in elderly people who were healthy.29
For the 6MWT, the differences in the findings (256.3–389.6 m [Tab. 6] versus 324.4–497.7 m,4 392–572 m,9 and 383–820 m19) may relate to the methods of instruction and the characteristics of the walkway. In previous studies, the participants were instructed to walk at a comfortable or fastest pace along an oval walking track (from end to end) or a large rectangular walkway.4,9,19 The different walking speeds indicated in the instructions may have had a significant influence on the distance covered in 6 minutes. Moreover, the number of turns, particularly total turns, considerably affects walking speed and the outcomes of the 6MWT.44 Therefore, in the present study, we assessed the 6MWT along a rectangular walkway and instructed the participants to walk for as long as possible in 6 minutes to allow them to select a speed at which they could cover the greatest distance for the test. However, the study was conducted in many communities, where it was difficult to find large areas of equal sizes to perform the test. Therefore, after a community survey, we found that a rectangular walkway measuring 6 m by 4 m was best for performing the test in different areas. However, this walking area was smaller and, thus, the walking path contained more turns than the walking area used in a previous study (30 m × 2.3 m)9; these factors may have reduced the distance covered in 6 minutes.
Because increasing age likely is associated with greater impairments of many body systems,45 participants in higher age decades—particularly female participants—showed lower levels of physical performance (Tabs. 2, 3, 4, 5, and 6). Nicklett46 found that women had more functional limitations in all age decades for both activities of daily living and instrumental activities of daily living, and the differences between the sexes increased with age. Other investigators also found higher rates of mortality among men and higher rates of disability among women.47,48 Therefore, the men included in a higher age band would represent the male participants who were the healthiest, whereas the women would have a blend of health statuses. This factor may be another reason why male participants showed higher levels of functional ability than female participants or why the decrease in physical ability with increasing age in male participants was smaller than that in female participants. The effects of age- and sex-related functional decline may also explain the nonsignificant difference in the findings for the FTSST, which represents a fundamental daily activity,29 in participants with a lower level of functional deterioration, that is, participants who were 60 to 69 years old (Tab. 5) and male participants.
Because the number of elderly people is rapidly increasing, reference values for standardized testing procedures are required to promote good health in elderly people. The findings of the present study suggested that the application of reference values should be specific to a particular age range and sex (for which a small range of 95% confidence intervals may confirm the utility of the findings), in particular, elderly people with anthropometric characteristics similar to those in the present study (eg, people in countries in the Association of South East Asian Nations).
Nonetheless, data covering a wide range of values (minimum–maximum values), particularly for elderly participants in higher age decades (Tabs. 2, 3, 4, 5, and 6), may suggest the influence of uncontrolled factors, such as daily lifestyle, level of exercise, and the number of underlying diseases. In addition, the participants were a convenience sample with a large number of women in lower age decades (60–69 and 70–79 years old), and only 7 participants were 90 to 99 years old (2 men and 5 women). Therefore, the data for the latter participants were combined with those for participants who were 80 to 89 years old. Furthermore, the seat height of the chair was not individually adjusted for each participant. Standing from an inappropriate seat height may affect the outcomes of the TUG and FTSST.41 However, we attempted to minimize this effect by defining the starting position (back upright with ankle placement 10 cm behind the knees). Further study with systematic sampling, larger numbers of elderly people in higher age decades, and delicately controlled demographic variables would strengthen the findings.
Footnotes
Dr Thaweewannakij, Dr Saengsuwan, Dr Siritaratiwat, and Dr Amatachaya provided concept/idea/research design and data analysis. Dr Thaweewannakij and Dr Amatachaya provided writing and data collection. Dr Thaweewannakij, Ms Wilaichit, Ms Chuchot, and Ms Yuenyong provided study participants. Ms Wilaichit, Ms Chuchot, Ms Yuenyong, and Dr Amatachaya provided facilities/equipment. Dr Amatachaya provided project management, fund procurement, institutional liaisons, clerical support, and consultation (including review of manuscript before submission). The authors thank Mr Ian Thomas for his contribution in preparing the article.
The study protocols were approved by the office of the Khon Kaen University Ethics Committee in Human Research.
This study was supported by funding from the Improvement of Physical Performance and Quality of Life (IPQ) Research Group, the Faculty of Associated Medical Sciences, and the Graduate School, Khon Kaen University, Khon Kaen, Thailand.
- Received October 4, 2012.
- Accepted April 16, 2013.
- © 2013 American Physical Therapy Association
References
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