On the Cause of Experienced C are W orkers ’ Lower B ack Pain : Considering Posture and the Strength of Back M uscle. Ryuichi ITO [email protected] Production Engineering of Advanced Engineering Course Niihama National College of Technology
In Japan, 70 ％ of people in the care workers have complained of lower back pain.
Examinee（18 pairs in total）
make 9 pairs within each group.
After the experiment, the patient evaluates
the care level of comfort in five point scales.
Model of marker
There are four patterns.
model of waist angle
Moment of F＞
Moment of WP＋ Moment of WC
F＞ WP+0.3・W c total
F・ＬS・ ＞WP・ＬS・+ WC・Ｌg・
LS / LS
F ＞ WP・+ WC・Lg/LS
H=height LS＝0.28・H Lg＝0.14・H WC=0.6・W c total
F＞ WP+0.6・W c total・（0.14H）/（0.28H）
Care worker : weight is 60 (kg)
Patient : weight is 50 (kg)
F : Strength of back muscle
F > 50 + 0.3 ・ 60 = 68 (kg)
If strength of back muscle of him is
value less than 70 (kg),
he has higher risk of lower back pain.
Model of roundness of the back
Strength of Back Muscle [kgf]
1. When expert care workers’ strength of
back muscle is less than “Wp+0.3*Wc”,
even if he has not had lower back pain.
2. When care workers have the posture of
large roundness of the back.