2015 ISAKOS Biennial Congress ePoster #818

3D Hip Joint Kinematics During the Sumo Squat: A Unique Exercise to Strengthen and Stretch the Lower Extremity Muscles

Yasushi Sera, MD, Tokyo JAPAN
Hideo Matsumoto, MD, PhD, Tokyo JAPAN
Asako Sera, MD, Tokyo JAPAN
Koichiro Azuma, MD, Tokyo JAPAN
Takuma Shinjo, MD, Tokyo JAPAN
Toshiro Otani, MD, PhD, Ichikawa, Chiba JAPAN
Takeo Nagura, MD, Tokyo JAPAN

Institute for Integrated Sports Medicine, Keio University, Tokyo, JAPAN

FDA Status Cleared

Summary: The sumo squat, an original training exercise of sumo wrestlers for strengthening and stretching mainly the hip joint, involves significant flexion, abduction, and external rotation of the hip joint compared to the standard squat, suggesting this exercise may yield training benefits not acquired by other training methods.

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Abstract:

Introduction

The sumo squat, a basic sumo training exercise, is a motion of lifting the leg and stamping it down. The effects of this training movement are expected as follows: strengthening the muscles around the legs and lower back, stretching the muscles of the hip region, improving the body’s sense of balance, strengthening and stabilizing the core. However, no study has revealed details of this unique exercise which includes a complex 3D motion of the hip joint.

Materials And Methods

Eight professional sumo wrestlers participated in this study. Seventeen reflective markers were attached to the skin of the spine, hip, knee, ankle joints, and feet. The subjects were asked to do four cycles of the sumo squat on each leg. In order to attain a better understanding, we analyzed and compared this kinematic data with those of ten healthy males doing the standard 90 degrees squat exercise. In the starting position of the sumo squat, the hip joint is in flexion, abduction, and external rotation with both feet on the ground. As one leg is lifted, the hip joint of the rising leg extends and adducts, then flexes and abducts just before touchdown. When the foot lands on the ground, the hip joint flexes, and abducts, returning to the starting positon. In the transverse plane, the hip joint of the rising leg is constantly in the externally rotated position. The hip joint of the loaded leg is in extension and adduction as the other leg rises. Then it abducts and externally rotates as the other leg comes down. When the foot of the rising leg touches down, the hip joint of the loaded leg flexes, abducts, and internally rotates, coming back to the starting position.

Results

During the sumo squat, significant hip motion was observed in all three planes and the range of hip flexion, abduction, and external rotation were 101 to 144 degrees, 17 to 57 degrees, and 40 to 89 degrees, respectively. Most of the movement during the 90 degrees squat was seen in the sagittal and transverse planes, both within 60 degrees.

Discussion

The starting position of the sumo squat with the hip joint in flexion, abduction, and external rotation is a very characteristic pose. It has been used by various athletes as

Method

of stretching the extensor and adductor muscles of the hip joint. The sumo squat itself is a multiple-joint lower extremity activity, and like the squat exercise, requires synchronized coordination of the hip, knee, and ankle joint muscles. However, fundamental differences in the kinematic patterns of these two exercises observed in this study are likely to invoke differences in kinetics as well. During the leg lifting phase, the hip joint of the loaded leg adducts then abducts, thus training the abductor muscles as the other leg rises. Studies have shown that training of hip abductor muscles, rather than the quadriceps, is recommended for controlling body balance. The sumo squat is expected as an innovative method of stretching, muscle training, injury prevention, and rehabilitation.