Functional Tests for Walking Ability

For functional tests, we adopted the Two-Step test and Stand-Up test. The Two-Step test, shown in Fig. 1a, which was previously examined by Muranaga et al. [9 ] has been developed as a screening tool for walking ability. The subject starts from the standing posture and moves two steps forward with maximum stride with the caution not to lose balance. If the subject succeeds in holding the final standing position longer than 3 s without any additional steps, the trial is judged as completed. The distance is then standardized by dividing it by the subject’s height. The test is performed twice, and the best result is recorded. Muranaga et al. [9 ]. reported that the value of the Two-Step test has a strong correlation with maximum walking speed. The Stand-Up test, shown in Fig. 1b, was also developed by Muranaga et al. [10 ] and is performed with stools of 10, 20, 30, and 40 cm in height. Subjects are requested to stand from each stool with one leg or two legs. If the subject succeeds in holding the final standing position longer than 3 s without any additional steps, the trial is judged as completed. A 0–8 score is allocated to the performance as shown in Table 1. Muranaga et al. [10 ] reported a significant correlation between the Stand-Up test score and the weight bearing index which is calculated as knee extension torque divided by body weight. To evaluate the reliability of these functional tests, we examined test–retest reproducibility. For that purpose, another 88 subjects were recruited and performed the Two-Step test and Stand-Up test two times each with 5–9 day intervals.Fig. 1

The schematic procedure of the Two-Step test (a), and Stand-Up test (b)

Table 1

Scoring system of Stand-Up test

	Two-leg stand					One-leg stand
Height	Fail at40 cm	40 cm	30 cm	20 cm	10 cm	40 cm	30 cm	20 cm	10 cm
Score	0	1	2	3	4	5	6	7	8

One-leg stand requires subjects to succeed at indicated height in both right and left leg