Introduction and objective:
Low back pain (LBP) is a problem which causes human suffering and entails costs for treatment. Chronic LBP is considered a civilization diseases in developed countries and one of the major public health problem worldwide. Squatting is a part of such daily activities as sitting down, standing up or lifting objects. In this study, hip, knee, and ankle joint motions during squatting are analyzed in the sagittal plane. The aim of the study was to find a relationship between the function of the lower limb during squatting and LBP incidence.

Material and methods:
Eleven healthy subjects and eight subjects suffering from low back pain were enrolled in tes study. Participants performed squat while maintaining heel contact with the ground throughout the movement. The participants attempted to make a squat as deep as possible. Kinematic data were captured using a Vicon optical motion capture system.

The low back pain group had a greater range of motion of the hip and knee with reference to the ankle joint motion, compared to the control group. There was no statistically significant difference in ankle dorsiflexion between groups. Control group reached maximal ankle dorsiflexion at higher point of descent than LBP group.

The findings support the hypothesis that the strategy of movement is different in subjects with and without back pain. They may suggest that subjects with low back pain in maximal squat use the hip joint and knee joint to a greater extent than subjects without back pain, with comparable ankle dorsiflexion. Clinicians should take into consideration the influence of ankle motion and timing on exercise biomechanics in persons suffering from low back pain.

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