Reliability of a new rapid step test for older women and its relationship with fall risk and leg muscle function

Shunsuke Yamaji, Shinichi Demura, Sohee Shin, Masanobu Uchiyama

Akita Prefectural University, Akita, Japan.
Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan.
School of Medicine, Gifu University, Gifu, Japan.

DOI: 10.4236/health.2012.429110                

Abstract

This study aimed to examine trial-to-trial reliability of a new clinical test, rapid reaction step cued on a screen test, and its relationship with fall risk score, independence in activity of daily living score, and various leg muscle function tests. One-hundred fifty seven older women participated in this study. Nine square plates (32 × 32 cm) were lined up with three plates. Participants stood on a center plate and were instructed to step, using one leg, to one of the other eight plates, as quickly as possible, when that plate changed in color from white to red. The mean total time and the mean total error time of rapid reaction step cued on a screen and, fall risk score, activity of daily living score, lower muscle function (isometric muscle strength: toe flexion, plantar flexion, knee extension, hip flexion; balance: one leg standing time with eye open, functional reach test; gait: 10 m walk time with maximal speed). Results: trial-to-trial reliabilities of step parameters were high (intraclass correlation coefficient [ICC] = 0.75 - 0.85). The step parameters correlated significantly with the other parameters except for toe flexion and hip flexion strengths. In conclusion, the present step test was found to evaluate physical function related to prevention of falls in older people.

Keywords

Fall Risk; Older Person; Balance; Mobility

1. INTRODUCTION

In most countries with an aging society, the primaryprevention of bedridden and other elderly persons unable to care for themselves was critical issue. To achieve successful aging, emphasis should be placed on improving independence in daily living rather than seeking perfect health. Falls in older people produce physical and psychological trauma, loss of independence, or even death, and is a serious problem in terms of decreasing quality of life [1].

Falls occur due to a complex combination of factors such as physiological function level, visual acuity and hearing, disease and disorder, cognitive function, medication, home environment, and age [2,3]. On the other hand, fall prevention intervention for the older living in self-reliant attach importance to improve physical fitness related fall prevention.

Physical function is a modifiable risk factor in every older individual and contributes greatly to falls. Particularly, it was reported that a decrease in leg muscle strength, gait and balance ability all have a higher relative risk ratio (RR = 4.4, 2.9, and 2.9, respectively) [2]. In addition, many tests that evaluate these physical function levels have been proposed. Mobility was evaluated by the 10 m walk test [4], Tandem gait test [5] which walks in the toes of the back foot touch the heel of the front foot at each step, figure eight track walk test [6], Timed up & Go test [7,8], Obstacle walk test [9], and Maximal stepping test [10-12]. Balance ability was evaluated by functional reach [13], and one-leg standing with open eye [14]. Leg muscle strength was evaluated by isometric strength and the sit-to-stand test [15,16]. These test performances are not only useful for evaluating the independence in daily-living activities of older persons, but can also be used as a training tool for improving physical function.

However, falls occur when a stable body posture cannot be maintained due to accidental disturbance [1]. It is very difficult to simulate fall-inducing accidental disturbances in these tests because they are voluntarily performed as a single task based on prospective movement [12,17]. An effective strategy to avoid falls is a stepping strategy, which extends a base of support when body sway cannot be controlled by ankle and hip strategies [18]. Maki et al. [18] examined stepping ability by physical disturbance using floor tilt, floor vibration, and traction apparatus, but they had problems with respect to practicability and safety using these techniques as a general exercise or an evaluation test.

The stepping strategy of avoiding a fall requires rapid postural control and quick step. From this view point, previous studies proposed several voluntary stepping tests, such as repeated stepping on the spot with maximal effort [10-12] and stepping to forward, backward, left and right directions (Four square stepping) [19,20]. However, they are also insufficient for assessing the stepping strategy since they are limited to a single task. Melzer et al. [21] proposed a voluntary step execution test under dual task, performing a modified—Stroop test. Shin and Demura [22] and Demura et al. [23] proposed new step tests with a relatively safe task in which older people step with slower fixed tempos than a usual walking tempo. A step adjusted to a fixed tempo, with extension of one leg during the support phase, demands maintaining body balance and correct tempo step. The use of dual or secondary tasks (Stroop test or keeping pace with the tempo) in addition to the main movement (stepping), as used in the above tests, have been used to evaluate the attention required in balance control. The premise is that the individuals performing two tasks simultaneously require more than the total information processing capacity, and performances of either or both tasks generally decrease.

However, the tempo step test is not enough of a disturbance stimulus for assessing stepping strategy, because the step patterns are determined in advance. In addition, avoiding a fall depends not only on a person’s sensory motor function and balance ability, but also on a perception of dangerous signs of falling and the proper responses to keep body posture [24]. The perception required for body control does not demand complex cognitive processes as in a Stroop test. Rather, the dual task test to assess fall avoidance is thought to involve a simple selective reaction.

Based the above, we developed a new step test which requires participants to rapid step in random directions along with a fixed tempo (rapid reaction step cueing by a screen), as a balance task combined with a visuospatial secondary task would properly evaluate the ability to avoid falls.

It is hypothesized that the reliability of the step test are good, and can evaluate both the fall risk scores and independence in activity of daily living scores, rather than various other leg muscle functions. Thus, the step test may be useful to evaluate the ability of fall avoidance in a clinical setting.

This study aimed to examine the trial-to-trial reliability of this test and its relationship with the fall risk score, independence in activity of daily living score, and various leg muscle function tests in older women.

2. METHODS

2.1. Participants

One-hundred fifty seven older women aged 65 - 87 years (Age: 72.0 ± 6.7 years, Height: 148.3 ± 6.3 cm, Body mass: 51.9 ± 6.3 kg) living independently in a community dwelling participated in this study. The participants were selected based on the following criteria: ambulatory without walking aid and no visual problem in visible colors. The participants have taken part in a weekly light exercise program (stretch exercise for 15 minutes) for over a year. Informed consent was obtained from each participant after a full explanation of the experimental project and its procedure. This study received approval from the Kanazawa University ethical committee.

2.2. Rapid Reaction Step Cued on a Screen Test

Figure 1 shows the rapid reaction step cued on a screen test (step test). The device consisted of nine square plates (32 × 32 cm), with three plates placed in every direction at 5 cm intervals. Participants were instructed to step onto a plate as quickly as possible when the corresponding squares on the screen changed from white to red according to a step pattern at 40 bpm tempo. The device measured the reaction time using a sampling frequency of 100 Hz of the subject stepping a correct plate in response to cueing by the screen, and time required to step (time from leaving the plate to contacting on another plate). A seventeen-inch screen was set at 2 m distance in front of participants with cells directly representing the plates making contact on the ground.

Conflicts of Interest

The authors declare no conflicts of interest.

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