Table 3 Mean ± SD absolute and normalized root mean square values (absRMS (mV) and normRMS (% of the highest RMS values of the three maximum voluntary contractions)) of the left and right erector spinae surface electromyograms during standardized box lifting at day 1 and day 2, intraclass correlation coefficient (ICC3.K) values and between-day normRMS difference for left and right erector spinae

41.2 ± 10.0

41.1 ± 12.1

0.79

−0.1 ± 9.2

14.1 ± 4.5

14.3 ± 5.0

0.92

0.2 ± 2.8

43.7 ± 17.6

45.3 ± 15.6

0.64

1.6 ± 17.1

15.3 ± 6.0

16.3 ± 9.1

0.77

1.0 ± 6.7

52.0 ± 14.9

50.3 ± 16.1

0.90

−1.7 ± 9.1

17.4 ± 5.5

17.5 ± 6.8

0.91

0.1 ± 3.5

52.0 ± 20.4

52.0 ± 16.1

0.82

−0.0 ± 14.5

18.0 ± 6.1

17.8 ± 5.6

0.77

−0.2 ± 5.1

57.4 ± 22.0

57.0 ± 18.2

0.88

−0.4 ± 13.4

18.8 ± 6.4

19.4 ± 5.9

0.86

0.6 ± 4.3

37.2 ± 19.9

31.7 ± 9.6

0.71

−5.5 ± 14.8

12.6 ± 5.6

10.8 ± 3.0

0.80

−1.8 ± 3.7

78.5 ± 25.7

72.9 ± 20.3

0.80

−5.6 ± 19.0

26.3 ± 9.3

25.0 ± 7.4

0.82

−1.3 ± 6.5

77.3 ± 30.1

77.8 ± 19.9

0.88

0.5 ± 17.0

26.9 ± 9.3

26.8 ± 8.3

0.88

−0.1 ± 5.7

104.6 ± 34.4

96.7 ± 29.1

0.92

−7.9 ± 17.8

34.5 ± 11.5

32.6 ± 9.2

0.85

−1.9 ± 7.6

105.1 ± 42.8

99.4 ± 27.9

0.83

−5.7 ± 27.6

35.8 ± 10.5

33.8 ± 9.7

0.88

−2.0 ± 6.6

94.3 ± 33.8

97.5 ± 35.1

0.86

3.2 ± 24.2

30.9 ± 10.0

33.0 ± 10.0

0.86

2.1 ± 6.9

71.2 ± 50.1

66.9 ± 19.7

0.51

−4.3 ± 43.6

23.7 ± 11.9

23.2 ± 9.4

0.63

−0.5 ± 11.1

123.5 ± 40.9

112.4 ± 33.6

0.88

−11.1 ± 24.7

41.3 ± 15.2

38.0 ± 10.4

0.79

−3.3 ± 10.9

124.2 ± 55.2

117.2 ± 35.4

0.88

−7.0 ± 30.0

42.5 ± 14.2

40.1 ± 13.4

0.90

−2.4 ± 8.5

125.5 ± 57.4

117.9 ± 44.8

0.91

−7.6 ± 29.4

38.8 ± 7.1

38.8 ± 9.8

0.76

0.0 ± 7.5

135.1 ± 62.2

117.2 ± 42.0

0.88

−17.9 ± 34.3

45.0 ± 12.2

39.0 ± 9.6

0.75

−6.0 ± 9.8

135.2 ± 60.9

117.9 ± 37.2

0.83

−17.3 ± 38.9

42.0 ± 8.9

39.3 ± 10.0

0.34

−2.7 ± 11.9

131.5 ± 57.3

120.2 ± 38.1

0.72

−11.3 ± 45.7

44.0 ± 11.4

40.3 ± 9.7

0.38

−3.7 ± 13.1

122.8 ± 54.5

116.0 ± 35.6

0.89

−6.8 ± 28.6

38.2 ± 8.3

38.5 ± 8.1

0.65

0.3 ± 8.4

122.3 ± 54.1

120.6 ± 31.7

0.67

−1.7 ± 44.2

41.1 ± 10.8

41.2 ± 11.3

0.50

0.1 ± 12.8

176.4 ± 69.9

172.4 ± 60.5

0.93

−4.0 ± 34.2

55.4 ± 10.8

57.1 ± 14.5

0.59

1.7 ± 13.8

181.2 ± 73.3

173.6 ± 58.8

0.88

−7.6 ± 44.3

60.3 ± 11.5

57.8 ± 13.5

0.48

−2.5 ± 14.6

195.0 ± 77.4

183.1 ± 56.3

0.87

−11.9 ± 45.2

61.4 ± 13.1

61.1 ± 15.9

0.21

−0.3 ± 19.3

197.1 ± 84.8

187.2 ± 66.6

0.85

−9.9 ± 55.5

65.5 ± 14.3

62.2 ± 15.4

0.33

−3.3 ± 18.8

172.0 ± 55.8

165.3 ± 46.1

0.91

−6.7 ± 28.9

55.1 ± 10.1

55.3 ± 11.6

0.51

0.2 ± 12.4

179.3 ± 70.7

169.8 ± 45.9

0.88

−9.5 ± 39.6

59.8 ± 12.4

57.5 ± 13.3

0.59

−2.3 ± 13.8

228.2 ± 84.7

209.3 ± 69.1

0.86

−18.9 ± 53.4

72.1 ± 13.8

70.5 ± 21.2

0.30

−1.6 ± 22.9

235.1 ± 95.0

214.1 ± 74.1

0.85

−21.0 ± 62.3

77.7 ± 13.9

71.2 ± 17.4

0.46

−6.5 ± 18.6