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Table 3 Mean (SD) muscle strength and co-activation variables across all diagnostic groups (* p ≤ 0.05; ** p ≤ 0.01 when compared to a matched control group)

From: Co-activation: its association with weakness and specific neurological pathology

Diagnostic groups

Mean (SD) (95% CI difference) predicted strength: quadriceps (%)

Mean (SD) (95% CI mean difference) predicted strength: hamstrings (%)

Mean (SD) (95% CI mean difference) isometric co-activation (%)

Mean (SD) (95% CI mean difference) co-activation during STS (%)

Muscle disease (n = 17)

50.6 (30.1) **

36.9 to 88.7

55.9 (42.7) **

32.7 to 85.4

17.4 (15.2)

-1.2 to 15.1 â—Š

22.3 (23.4)

-18.5 to 7.9 â—Š

LMN (sensory loss) (n = 18)

87.4 (27.5)

-45.3 to 0.6

61.4 (22.4) **

31.4 to 66.2

7.3 (5.1)

-6.9 to 0.6 â—Š

15.7 (11.0)

-14.2 to 1.5

LMN (sensory intact) (n = 12)

53.4 (38.0) **

21.5 to 78.3

55.6 (20.5) *

30.2 to 70.5

12.7 (10.9)

-5.3 to 9.2 â—Š

16.3 (10.6) Δ

-12.8 to 6.5

UMN (n = 12)

67.2 (30.7) **

12.1 to 65.4

55.9 (33.5) **

19.4 to 67.1

9.4 (9.3)

-7.7 to 2.9 â—Š

24.7 (16.5)

-7.5 to 13.6 â—Š

Extra-pyramidal lesion (n = 15)

81.3 (36.4)

-48.8 to 11.6

65.7 (30.6) *

13.9 to 57.0

6.7 (4.3) **

-11.2 to -3.9

14.7 (13.3) *

-17.9 to 0.9 â—Š

Control subjects (n = 32)

102.4 (37.0)

103.2 (30.1)

11.8 (6.2)

20.5 (12.9)

  1. â—Š non-parametric comparisons between groups were used hence, it is only possible to present approximate confidence intervals
  2. Δ based on the means of data from 8 subjects. 4 subjects in this group used hip and trunk flexion strategies to achieve STS thus preventing calculation of co-activation at the point of the maximum knee extension moment.