RELATIONSHIP BETWEEN HIP ROTATION RANGE OF MOTION AND SITTING HABITS OF YOUNG HEALTHY KOREANS

H. Han¹, S. Chon², M. Ishizaka¹, H. Maruyama³

Background: In countries such as Japan and Korea, sitting on the floor or on chairs is common everyday life at home. Some postures of sitting on the floor are related to the flexibility and laterality of the rotational range of motion (ROM) of the hip joint. It is important to understand the relationship between these postures and the habit of sitting on the floor as it causes excessive hip joint ROM in daily life. However, the relationship between sitting postures on the floor and hip rotation ROM is not clear.

Purpose: The purpose of this study was to clarify the relationship between hip rotation ROM and sitting habit on the floor in young healthy participants.

Methods: We analyzed 39 healthy young Korean university students (21 males, 18 females). The measurement order of the hip rotation ROM was randomized, and measurements were performed in Korea. The measurement was blinded so that the participants and the measurers did not share the information of measurement values until the end of the measurement. Furthermore, a single researcher in Japan analyzed the data; thus, the study was triple-blinded. The hip rotation ROM was measured for left and right internal and external rotation. The analyzed items were the difference between left and right internal rotation, the difference between the internal and external rotation, and the three floor sitting postures: straight sitting, W-sitting, and sitting sideways. Each of the sitting posture have using three questions: "rarely”, “often”, or “very often". The responses were classified into two items; habitual experienced, and having no habitual experienced. We also obtained feet direction data when sitting sideways. We analyzed the presence or absence of habitual experience and the characteristics of rotation ROM for each of the three postures. Statistical analysis was carried out using Fisher's exact test.

Results: In the three floor sitting postures, only one male had a sitting experience in the straight sitting item of the three. Among the females, 11 used straight sitting (61.1%), 2 used W-sitting (11.1%), and 5 used sideways sitting (27.8%). Of participants who had a larger total internal rotation than total external rotation, those who used the straight sitting posture had a wide distribution of total angles.
Those who used W-sitting had total internal rotation of more than 40.0° and sitting sideways of more than 26.7°. Fisher's exact test showed no significant difference between the feet direction of the sitting sideways posture and the difference in hip internal rotation ROM between sides.

Conclusion(s): Among the females, the most common sitting posture was straight sitting, followed by sideways sitting and W-sitting. The total internal rotation ROM was ≥26.7° in sideways sitting and ≥40° in W-sitting.

Implications: Regarding the floor sitting postures, there is a bias that a person who has a habit of W-sitting and sideways sitting exhibits a large internal rotation than external rotation. We believe that our findings provide a reference to clarify the relationship between hip rotation ROM and motor function in people in countries with sedentary habits on the floor, such as Japan and Korea.

Funding, acknowledgements: No funding was received.

Keywords: hip rotation, range of motion, sitting habits on floor

Topic: Musculoskeletal: lower limb

Did this work require ethics approval? Yes

Institution: International University of Health and Welfare

Committee: International University of Health and Welfare Ethics Review Board

Ethics number: ＃19-Io-235