2014 Volume 122 Issue 1 Pages 1-6
This study examined the use of the hip walking (HW) distance test as a physical performance parameter, and investigated the association between HW distance and strength, balance, and gait speed in the elderly. The study involved 106 community-dwelling elderly individuals (mean age 75.4 years). Participants performed the following physical performance tests: the HW distance test, the functional reach test (FRT), and tests for knee extensor strength, trunk extensor, and flexor strength, and 5 m maximum gait speed. For the HW distance test, participants were asked to move forward as fast as possible from the starting position with legs stretched out forwards and arms folded across the chest. Trunk rotation with lifting of the ischium was permitted during HW. The distances between right lateral malleoli was measured for HW distances of 10 seconds. To assess the test–retest reliability of HW, intra-class correlation coefficients (ICCs) were calculated from two trials. Pearson’s correlation analysis and linear regression analysis were used to examine the association between HW and physical performance using adjusted variables such as age, sex, and body mass index. ICC (1.1) for the test–retest reliability of HW was 0.95. HW was significantly associated with all physical performance tests according to Pearson’s correlation analysis (trunk flexor strength, r = 0.31; trunk extensor strength, r = 0.31; knee extensor strength, r = 0.29; FRT, r = 0.29; gait speed, r = 0.45). In linear regression analyses, HW distance scores were found to be significant determinants of each physical performance parameter. HW influenced physical performance by affecting muscle strength, balance, and gait ability. HW can be easily and safely performed on a floor or platform without the risk of falling. These results indicate that HW is a safe, simple, and reliable method for the assessment of physical performance in the elderly.
Muscle weakness can contribute to a decline in the activity of daily living (ADL) abilities of the elderly. In particular, lower extremity muscle weakness is related to decreased ADL ability in tasks such as standing, walking, and using the stairs (Foldvari et al., 2000; Bean et al., 2002). Age-related decrease in muscle mass is known as sarcopenia, in which the mass and function of the gluteal muscles as well as those of the trunk and lower limbs decline markedly (Israel, 1992; Abe et al., 2011). Moreover, cross-sectional (Bohannon, 1997; Schimpl et al., 2011) and longitudinal studies (Sugiura et al., 2003) have confirmed that walking speed decreases with advanced age. Suzuki et al. (2003) reported that a decrease in walking speed leads to a decline in ADL and in the instrumental activity of daily living (IADL). Therefore, accurate assessment of physical function is important to improve the quality of life as well as enhance ADL and IADL in the elderly.
Different types of scales have been proposed to assess various physical functions in the elderly living in a community setting. For example, measurement of grip strength and the use of a hand-held dynamometer (Martin et al., 2006; Bohannon et al., 2011) can be taken as an index of quantitative muscular strength, and chair stand (CS) tests (CS-5 (Lord et al., 2002) and CS-30 (Jones et al., 1999)) are established indices of muscle power. Furthermore, the measurement of gait speed is useful for assessing mobility in the timed up and go (TUG) test (Podsiadlo and Richardson, 1991), which is widely applied as an index of dynamic balance and mobility.
However, it is sometimes difficult for non-professionals to use these scales safely and accurately because the subjects are required to stand and walk, thus increasing the risk of falls, particularly in those with muscle weakness and impaired sensory capacity. Therefore, it is necessary to establish a safe and easy-to-use assessment system, which can be used by anyone to assess the elderly in a community setting.
Humans have developed erect bipedalism from quadrapedalism during evolution (Richmond and Strait, 2000). It is known that humans acquire the ability to roll over, sit, crawl, and walk as they grow (Kimura-Ohba et al., 2011). Acquired bipedalism plays a key role in movement; humans can choose various movement styles such as crawling, creeping, and shuffling depending on the situation.
Hip walking (HW) is an exercise designed to work the trunk muscles, which aid in the stabilization of the body during daily activities (Osawa and Oguma, 2011a, b). HW can be performed on the floor and, in light of the Japanese lifestyle, and be easily performed by the elderly in their homes. In brief, to perform HW, subjects move the trunk by lifting the ischium with legs stretched out forwards. However, there is currently no consensus regarding an established assessment index to determine HW performance. In addition, the benefits of HW therapy to physical function in the elderly remain unclear. Thus, it is necessary to clarify the mechanisms and usefulness of HW to accurately assess the benefits of HW therapy to the elderly in a community setting.
Hence, the purpose of the present study was to investigate the relationship between HW performance and changes in physical functions, such as muscle strength, balance, and gait speed, in the elderly living in a community setting. The influence of HW distances on physical performance was also assessed using multiple regression analysis. Here we assessed the suitability and reliability of the HW performance by measuring the distance traveled in 10 seconds.
We enrolled 106 elderly Japanese subjects (mean age 75.4 ± 4.8 years; 43 males, 63 females) living in Sapporo, north Japan. All the included subjects were ambulatory with or without a supporting device, whereas the excluded subjects were those with dementia, those receiving long-term care, those who had had a medical emergency within the last six months, and those experiencing pain that limited their movement. Informed consent was obtained from all subjects, and this study was approved by the ethics committee of Sapporo Medical University (Sapporo, Japan).
Methods HW testIn the HW test, participants were asked to move forward as fast as possible from the starting with legs stretched out forwards and arms folded across the chest. Trunk rotation by lifting the ischium was permitted during HW. The distances between right lateral malleoli was measured for HW distances of 10 seconds (Figure 1). The position of the right distal malleolus was marked with a tag, and the subject was instructed to begin the movement by the verbal command “go.” After 10 seconds, the distance traveled by the right lateral malleolus was recorded as the HW distance. The angle of the knee was not considered in the measurement, and the subjects were given a demonstration of the HW movement and allowed to practice the movement in advance. All subjects performed the trial twice, and the best result was used for analysis. The time was measured using a stopwatch, and the floor surface was covered with polyethylene mats coated with an aluminum film (EverNew Inc., Tokyo, Japan). The subjects wore socks to reduce friction.
The HW method: subjects assume a sitting position with their arms folded across their chest while rotating the trunk, lifting the ischium, and moving the lower limbs forward as fast as possible.
Physical performance was assessed by measurements of trunk flexor strength, trunk extensor strength, knee extensor strength, the functional reach test (FRT), and 5 m maximum gait speed. The trunk flexor and extensor strength was assessed using an isokinetic testing and rehabilitation system (Biodex System 3, Biodex Medical Systems, Inc., Shirley, NY, USA). In particular, the Biodex Dual Position Back Ex/Flex Attachment was connected to the dynamometer, and the subjects sat on the adjustable seat with velcro straps fastened over the torso, waist, and thighs. The fixed axis of the machine was aligned with the subject’s anterior superior iliac spine (ASIS), and the spinal range of motion (ROM) was set from −30° (extension) to +30° (flexion). The angular velocity was set at 120° per second. After five warm-up repetitions, the subjects were instructed to perform the trunk motion at the preset ROM for five repetitions. Trunk muscle strength was estimated as the value of peak torque divided by body weight (N·m/kg) (Grabiner et al., 1990; Ripamonti et al., 2008).
To measure knee extensor strength, a maximal voluntary contraction of the knee extensor muscle group using the dominant leg was measured using a hand-held dynamometer (μTas F-1, Anima Corp., Tokyo, Japan) under isometric conditions in a seated position with the ankle, knee, and hip joints at 90° of flexion (Shimada et al., 2010). The test was performed once. Isometric knee extension torque was normalized against arm moment and body mass (N·m/kg) in the data analysis. For the FRT, each subject was positioned next to a wall, with one arm raised at 90° with the fingers extended, and was then instructed to reach forward from an initial upright posture to the maximum anterior posture, while not moving or lifting the feet (Duncan et al., 1990). Horizontal length was measured in centimeters. To measure gait speed, an 11 m walkway was constructed, and the time to walk 5 m was measured (Shinkai et al., 2000). The subjects were instructed to walk as fast as possible without running. The test was performed twice and the best result was used for analysis of the physical performance tests.
Statistical analysisData were analyzed using the SPSS statistical software (version 19.0, IBM Japan Ltd., Tokyo, Japan). To assess the test–retest reliability of the HW, intraclass correlation coefficients (ICCs) were calculated from two trials. Relationships between HW distance and other physical performance parameters were examined using Pearson’s correlation analysis. To examine the influence of HW distances on physical performance, linear regression analyses were performed using each physical performance parameter as the dependent variable and age, sex, body mass index (BMI), and HW distances as the independent variables. Adjusted r2 values and standardized β values were calculated. All reported P values are two-tailed and P < 0.05 was considered statistically significant.
Table 1 summarizes the subjects’ characteristics. The ICC (1.1) of the test–retest reliability was 0.95 (P < 0.01) in measurements of two trials. Simple correlations were examined between the HW distance and physical performance (Table 2). Trunk flexor and extensor strength, knee extensor strength, FRT, and gait speed scores were significantly associated with the HW distance (trunk flexor strength, r = 0.31, P < 0.01; trunk extensor strength, r = 0.31, P < 0.01; knee extensor strength, r = 0.29, P < 0.01; FRT, r = 0.29, P < 0.01; gait speed, r = 0.45, P < 0.01). Figure 2 shows the relationship between HW distances and the physical performance parameters. In linear regression analyses, HW distance scores were found to be significant determinants of each physical performance parameter (trunk flexor strength, adjusted r2 = 0.43, P < 0.01, β = 0.18, P < 0.05; trunk extensor strength, adjusted r2 = 0.22, P < 0.01, β = 0.31, P < 0.01; knee extensor strength, adjusted r2 = 0.30, P < 0.01, β = 0.33, P < 0.01; FRT, adjusted r2 = 0.18, P < 0.01, β = 0.26, P < 0.01; gait speed, adjusted r2 = 0.29, P < 0.01, β = 0.44, P < 0.01) (Table 3).
| (n = 106) | ||
|---|---|---|
| Sex | (female, %) | 63 (59.4) |
| Age | (years) | 75.4 ± 4.8 |
| (≥75, %) | 59 (55.7) | |
| Height | (cm) | 156.1 ± 8.4 |
| Weight | (kg) | 56.3 ± 10.3 |
| BMI | (kg/m2) | 23.0 ± 3.0 |
| Trunk flexor strength | (N·m/kg) | 1.9 ± 0.7 |
| Trunk extensor strength | (N·m/kg) | 2.7 ± 0.9 |
| Knee extensor strength | (N·m/kg) | 1.3 ± 0.4 |
| FRT | (cm) | 32.0 ± 6.1 |
| HW distance | (cm) | 82.9 ± 33.8 |
| Gait speed | (m/sec) | 2.2 ± 0.4 |
Data are expressed as means ± SD and numbers (%).
BMI, body mass index; FRT, functional reach test; HW, hip walking.
| Dependent variable | Simple correlation (r) |
|---|---|
| Trunk flexor strength | 0.31** |
| Trunk extensor strength | 0.31** |
| Knee extensor strength | 0.29** |
| FRT | 0.29** |
| Gait Speed | 0.45** |
Pearson’s r values represent the simple correlation between hip walking distance and physical performance.
BMI, body mass index; FRT, functional reach test.
Relationship between HW distance and physical performance. Increased HW distances were associated with increased physical performance.
| (n = 98) | |||
|---|---|---|---|
| Dependent variables | Adjusted r2 | B | Standardized β |
| Trunk flexor strength | 0.43** | ||
| Age | −2.22 | −0.15 | |
| Sex | −39.37 | −0.28** | |
| BMI | −13.91 | −0.62** | |
| HW distance | 0.36 | 0.18* | |
| Trunk extensor strength | 0.22** | ||
| Age | −0.59 | −0.03 | |
| Sex | −64.24 | −0.36** | |
| BMI | −7.94 | −0.28** | |
| HW distance | 0.78 | 0.31** | |
| Knee extensor strength | 0.30** | ||
| Age | −0.01 | −0.11 | |
| Sex | −0.44 | −0.51** | |
| BMI | −0.02 | −0.18 | |
| HW distance | 0.004 | 0.33** | |
| FRT | 0.18** | ||
| Age | −0.28 | −0.22** | |
| Sex | −3.66 | −0.29** | |
| BMI | −0.29 | −0.14 | |
| HW distance | 0.05 | 0.26** | |
| Gait speed | 0.29** | ||
| Age | −0.02 | −0.20** | |
| Sex | −0.21 | −0.28** | |
| BMI | −0.01 | −0.12 | |
| HW distance | 0.005 | 0.44** |
Independent variables were age, sex, BMI, and HW distance.
FRT, functional reach test.
The current study investigated the reliability of the HW distance and the validity of external criteria. In particular, we measured HW distances for 10 seconds in the elderly residing in a community setting to examine the relationship between HW performance and the physical attributes of muscle strength, balance, and gait speed.
Although there are various indices to assess physical performance in a community setting, a safe and easy-to-use assessment method for the elderly has not yet been established. Current performance tests with the subjects on the floor consist of the sit and reach test (Singh et al., 2006) and a test to measure the time required to rise from the floor (Saito et al., 2011). However, the former test is an index of flexibility and is not particularly designed to assess muscular strength and mobility, whereas the latter is considered to be an index of physical capacity, which requires significant postural changes. While standing and sitting positions are associated with a risk of falling, a performance test on the floor may be safer; however, the relationship between the HW distance and physical performance remains unclear.
The results of the present study showed that the intra-rater reliability [ICC (1,1)] of the HW distances was 0.95, indicating a reliable assessment. Simple correlations and the linear regression model adjusted for age, sex, and BMI showed that the HW distance was associated with trunk flexor strength, trunk extensor strength, knee extensor strength, FRT, and gait speed.
Our results also confirmed that the HW performance associate with various factors, such as muscle strength, balance, gait, and coordination because the subjects were required to maintain the trunk in an upright position and a sitting position while moving the lower limbs forward and lifting one side of the ischium. Thus, there exists a relationship between HW performance and physical performance parameters involving muscle strength, balance, and gait ability. HW can be easily and safely performed on a floor or platform without the risk of falling. All subjects who participated in this study were able to perform the movement and experienced no lower back pain or fatigue. These results imply that HW is a safe, simple, and reliable method to assess physical performance in the elderly. Therefore, the HW exercise might be useful as an in-home exercise therapy for the elderly.
While HW exercise can be used to train the muscles of the trunk (Osawa and Oguma, 2011b), we measured only trunk flexor and extensor strength. The relationship between HW and various trunk movements, such as trunk rotation and side bending, remains unclear. It is necessary to clarify movement mechanisms through analysis of trunk muscle activity by electromyography and to compare the trunk muscle activity involved in HW with that used in walking in future studies. Furthermore, it would be insightful to examine the association between HW performance and health-related indices such as IADL, fall experience, and exercise habit to apply the HW performance as an indicator to assess physical performance in the elderly. In addition, future researches are needed to clarify physical functioning contents assessed by HW performance using additional analyses such as covariance structure analyses.
A limitation to this study was its cross-sectional nature; thus, it was difficult to identify a cause-and-effect relationship between HW and physical performance. To clarify this relationship, a longitudinal study is necessary. The subjects of the current study were a comparatively healthy older group in comparison with the study that was performed as a complete survey of community-dwelling older people (Ishizaki et al., 2011). Moreover, in order to generalize our results it is important to assess not only healthy but also frail elderly people.
In conclusion, HW can be easily and safely performed on a floor or platform without the risk of falling. The present findings show that HW distances are associated with physical performance parameters, such as muscle strength, balance, and gait ability. Results from this study imply that HW is a safe, simple, and reliable method to assess physical performance in the elderly. Future research should be aimed at clarifying the HW movement mechanism and showing clearly the relation between covariance structure analyses and the physical performance of HW.
We are exceptionally grateful for the support of Mika Kimura, the International Life Sciences Institute Japan, who has helped us to collect data. We also would like to acknowledge and appreciate Yoko Miyabe for helping with the manuscript.
