Table 2 Adverse ergonomic factors of LBP among OMPWF with univariate analysis

Awkward posture

Working with the hand(s) above the head, or the elbows above the shoulders, more than 4 h total per day

 No

6

4

1

 Yes

145

130

4.33

(0.73–25.68)

Repeatedly raising the hand(s) above the head, or the elbow(s) above the shouder(s) more than once per minute, more than 4 h total per day

 No

12

10

1

 Yes

139

124

1.65

(0.33–8.27)

Working with the neck bent more than 45° (without support or the ability to vary posture), more than 4 h total per day

 No

14

11

1

 Yes

137

123

2.40

(0.60–9.63)

Working with the back bent forward more than 30° (without support or the ability to vary posture), more than 4 h total per day

 No

10

8

1

 Yes

141

126

2.10

(0.41–10.82)

Working with the back bent forward more than 45° (without support or the ability to vary posture), more than 2 h total per day

21

17

1

 No

130

117

2.12

(0.620–7.25)

 Yes

Squatting more than 4 h total per day

 No

4

2

1

 Yes

147

132

8.80

(1.15–67.10)^*

Kneeling more than 4 h total per day

 No

32

27

1

 Yes

119

107

1.65

(0.54–5.09)

High hand force

Pinching an unsupported object(s) weighing 2 lbs or more per hand, or pinching with a force of 4 lbs or more per hand, meanwhile highly repetitive motion more than 3 h total per day

 No

22

10

1

 Yes

129

114

0.76

(0.16–3.58)

Pinching an unsupported object(s) weighing 2 lbs or more per hand, or pinching with a force of 4 lbs or more per hand, meanwhile hand/wrist in awkward posture more than 3 h total per day

 No

28

23

1

 Yes

123

111

2.01

(0.65–6.26)

Pinching an unsupported object(s) weighing 2 lbs or more per hand, or pinching with a force of 4 lbs or more per hand, meanwhile no other risk factors more than 4 h total per day

 No

22

18

1

 Yes

129

116

1.98

(0.58–6.76)

Gripping an unsupported object(s) weighing 10lbs or more per hand, or gripping with a force of 10 lbs or more per hand, meanwhile highly repetitive motion more than 3 h total per day

 No

15

12

1

 Yes

136

122

2.179

(0.55–8.67)

Gripping an unsupported object(s) weighing 10lbs or more per hand, or gripping with a force of 10 lbs or more per hand, meanwhile hand/wrist in awkward posture more than 3 h total per day

 No

27

23

1

 Yes

124

111

1.49

(0.44–4.97)

Gripping an unsupported object(s) weighing 10lbs or more per hand, or gripping with a force of 10 lbs or more per hand, meanwhile no other risk factors more than 4 h total per day

 No

10

10

1

 Yes

141

124

1.14

(1.07–1.21)^*

Highly repetitive motion

Using the same motion with little or no variation every few seconds, and high, forceful exertions with the hand(s) more than 2 h total per day

 No

28

25

1

 Yes

123

109

0.93

(0.25–3.50)

Using the same motion with little or no variation every few seconds, meanwhile no other risk factors more than 6 h total per day

 No

32

29

1

 Yes

119

105

0.78

(0.21–2.88)

Intensive keying and hand / wrist in awkward posture more than 4 h total per day

 No

26

24

1

 Yes

125

110

0.61

(0.13–2.85)

Intensive keying and no other risk factors more than 7 h total per day

 No

31

29

1

 Yes

120

105

0.44

(0.10–2.23)

Repeated impact

Using the hand (heel/base of palm) as a hammer more than once per minute, more than 2 h total per day

 No

41

34

1

 Yes

110

100

2.06

(0.73–5.83)

Using the knee as a hammer more than once per minute, or more than 2 h total per day

 No

55

45

1

 Yes

96

89

2.83

(1.01–7.92)^*

Heavy, Frequent or Awkward Lifting

Lifting object weighing more than 75 lb and more than 10 times per day

 No

115

104

1

 Yes

36

30

0.53

(0.18–1.55)

Lifting object weighing more than 55 lb and more than 10 times per day

 No

13

11

1

 Yes

138

123

1.49

(0.30–7.38)

Lifting objects weighing more than 10 lb if done more than twice per minute, or more than 2 h total per day

 No

28

21

1

 Yes

123

113

3.77

(1.29–11.01)^*

Lifting objects weighing more than 25 lb above the shoulders, below the knees or at arms length more than 25 times per day

 No

27

23

1

 Yes

124

111

1.49

(0.44–4.97)

Moderate to high hand-arm vibration

Using impact wrenches, carpet strippers, chain saws, percussive tools (jack hammers, scalers, riveting or chipping hammers) or other tools that typically have high vibration levels, more than 30 min total per day

 No

52

44

1

 Yes

99

90

1.82

(0.66–5.03)

Using grinders, sanders, jigsaws or other hand tools that typically have moderate vibration levels more than 2 h total per day

 No

46

41

1

 Yes

105

93

0.95

(0.31–2.86)