Table 2 Within-session and between-session reliability of stiffness measurements for lumbar tests

Mean (SD) of stiffness values (N/mm)

ICC_{3, 1} (95%CI)/Single measures

ICC_{3, 3} (95%CI)/Average measures

Mean (SD) of stiffness values (N/mm)

ICC_{3, 1} (95%CI)/Single measures

ICC_{3, 3} (95%CI)/Average measures

Within- session Reliability (session 1/ N = 17)

L5

2.6 (1.3)

0.99 (0.97_ 0.99)

1.00 (0.99_ 1.00)

9.0 (3.4)

0.99 (0.97_ 0.99)

1.00 (0.99_ 1.00)

L4

2.0 (1.5)

0.99 (0.97_ 1.00)

1.00 (0.99_ 1.00)

6.1 (3.0)

1.00 (0.99_ 1.00)

1.00 (0.99_ 1.00)

L3

2.0 (1.9)

0.92 (0.82_0.97)

0.97 (0.93_ 0.99)

6.2 (5.0)

0.95 (0.89_ 0.98)

0.98 (0.96_ 0.99)

L2

2.2 (1.7)

1.00 (0.99_ 1.00)

1.00 (0.99_ 1.00)

6.1 (4.4)

1.00 (0.99_ 1.00)

1.00 (0.99_ 1.00)

L1

2.7 (2.3)

0.98 (0.95_ 0.99)

0.99 (0.98_ 1.00)

7.4 (4.3)

0.99 (0.98_ 1.00)

1.00 (0.99_ 1.00)

Within- session Reliability (session 2/ N = 15)

L5

2.3 (0.8)

0.99 (0.97_ 0.99)

1.00 (0.99_ 1.00)

8.1 (2.3)

0.98 (0.96_ 0.99)

1.00 (0.99_ 1.00)

L4

1.6 (0.6)

0.99 (0.98_ 1.00)

1.00 (0.99_ 1.00)

5.2 (1.6)

0.99 (0.98_ 1.00)

1.00 (0.99_ 1.00)

L3

1.6 (0.6)

0.99 (0.98_ 1.00)

1.00 (0.99_ 1.00)

5.0 (1.6)

0.99 (0.98_ 1.00)

1.00 (0.99_ 1.00)

L2

2.4 (2.0)

0.96 (0.90_ 0.98)

0.99 (0.96_ 0.99)

5.9 (3.0)

0.99 (0.98_ 1.00)

1.00 (0.99_ 1.00)

L1

3.0 (2.4)

0.96 (0.90_ 0.99)

0.99 (0.96_ 1.00)

7.1 (3.4)

0.98 (0.94_ 0.99)

0.99 (0.98_ 1.00)

ICC_{3, 1} using the first trial

ICC_{3, 1} using the mean of the 3 trials

ICC_{3, 1} using the first trial

ICC_{3, 1} using the mean of the 3 trials

Between- session Reliability (N = 15)

L5

2.2 (0.7)

0.81 (0.54_ 0.93)

0.75 (0.41_ 0.91)

8.1 (2.3)

0.85 (0.60_ 0.95)

0.82 (0.55_ 0.94)

L4

1.5 (0.5)

0.85 (0.63_ 0.95)

0.84 (0.60_ 0.94)

5.2 (1.6)

0.87 (0.66_ 0.96)

0.93 (0.80_ 0.98)

L3

1.5 (0.6)

0.88 (0.67–0.96)

0.86 (0.65_ 0.95)

5.0 (1.8)

0.86 (0.62_ 0.95)

0.88 (0.67_ 0.96)

L2

2.3 (1.9)

0.94 (0.82_ 0.98)

0.96 (0.86_ 0.99)

5.5 (2.6)

0.83 (0.57_ 0.94)

0.86 (0.63_ 0.95)

L1

2.8(2.6)

0.88 (0.68_ 0.96)

0.75 (0.38_ 0.92)

6.9 (3.5)

0.92 (0.75_ 0.97)

0.89 (0.70_ 0.96)