Table 3 Test–retest reliability of the Health app.

From: Validity and reliability of the Apple Health app on iPhone for measuring gait parameters in children, adults, and seniors

Parameter

Test

Retest

Bias (95% CI)

95% LOA

ICC2,1 (95% CI)

SEM (SEM%)

MDC95 (MDC95%)

Gait speed (m/s)

 Children (n = 12)

1.34 ± 0.15

1.38 ± 0.17

− 0.04 (− 0.14 to 0.06)

− 0.34 to 0.26

0.61 (0.10–0.87)

0.11 (8.1)

0.30 (22.4)

 Adults (n = 20)

1.37 ± 0.17

1.41 ± 0.16

− 0.04 (− 0.10 to 0.01)

− 0.27 to 0.18

0.75 (0.47–0.89)

0.08 (5.8)

0.22 (16.0)

 Seniors (n = 24)

1.27 ± 0.20

1.31 ± 0.23

− 0.04 (− 0.08 to 0.01)

− 0.23 to 0.16

0.88 (0.74–0.95)

0.07 (5.5)

0.20 (15.2)

Step length (cm)

 Children (n = 12)

68.2 ± 4.5

67.3 ± 7.9

0.9 (− 3.7 to 5.5)

− 13.2 to 15.0

0.39 (0.25–0.78)

5.1 (7.5)

14.1 (20.8)

 Adults (n = 20)

71.7 ± 7.7

72.2 ± 7.6

− 0.6 (− 2.8 to 1.7)

− 9.9 to 8.8

0.80 (0.57–0.92)

3.4 (4.7)

9.4 (13.0)

 Seniors (n = 24)

66.2 ± 7.7

65.9 ± 8.1

0.3 (− 1.2 to 2.0)

− 5.8 to 6.4

0.93 (0.84–0.97)

2.2 (3.3)

6.1 (9.2)

Double support time (%)

 Children (n = 7)

25.0 ± 2.9

24.6 ± 2.1

0.4 (− 1.2 to 2.0)

− 3.0 to 3.8

0.79 (0.20–0.96)

1.2 (4.9)

3.4 (13.5)

 Adults (n = 10)

27.4 ± 2.0

27.0 ± 1.4

0.4 (− 0.4 to 1.2)

− 1.8 to 2.6

0.78 (0.37–0.94)

0.8 (2.9)

2.2 (8.1)

 Seniors (n = 21)

27.8 ± 2.1

27.6 ± 2.2

0.2 (− 0.2 to 0.6)

− 1.6 to 2.0

0.91 (0.80–0.96)

0.7 (2.4)

1.8 (6.5)

  1. Descriptive data given as mean ± standard deviation.
  2. CI confidence interval, LOA limits of agreement, ICC intraclass correlation coefficient, SEM standard error of measurement, MDC minimal detectable change.
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