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.