ESCAMILLA, R. F., A. C. FRANCISCO, G. S. FLEISIG, S. W. BARRENTINE, C. M. WELCH, A. V. KAYES, K. P. SPEER, and J. R. ANDREWS. A three-dimensional biomechanical analysis of sumo and conventional style deadlifts. Med. Sci. Sports Exerc., Vol. 32, No. 7, pp. 1265–1275, 2000.
Purpose: Strength athletes often employ the deadlift in their training or rehabilitation regimens. The purpose of this study was to quantify kinematic and kinetic parameters by employing a three-dimensional analysis during sumo and conventional style deadlifts.
Methods: Two 60-Hz video cameras recorded 12 sumo and 12 conventional style lifters during a national powerlifting championship. Parameters were quantified at barbell liftoff (LO), at the instant the barbell passed the knees (KP), and at lift completion. Unpaired t-tests (P < 0.05) were used to compare all parameters.
Results: At LO and KP, thigh position was 11–16° more horizontal for the sumo group, whereas the knees and hips extended approximately 12° more for the conventional group. The sumo group had 5–10° greater vertical trunk and thigh positions, employed a wider stance (70 ± 11 cm vs 32 ± 8 cm), turned their feet out more (42 ± 8° vs 14 ± 6°), and gripped the bar with their hands closer together (47 ± 4 cm vs 55 ± 10 cm). Vertical bar distance, mechanical work, and predicted energy expenditure were approximately 25–40% greater in the conventional group. Hip extensor, knee extensor, and ankle dorsiflexor moments were generated for the sumo group, whereas hip extensor, knee extensor, knee flexor, and ankle plantar flexor moments were generated for the conventional group. Ankle and knee moments and moment arms were significantly different between the sumo and conventional groups, whereas hip moments and moments arms did not show any significantly differences. Three-dimensional calculations were more accurate and significantly different than two-dimensional calculations, especially for the sumo deadlift.
Conclusions: Biomechanical differences between sumo and conventional deadlifts result from technique variations between these exercises. Understanding these differences will aid the strength coach or rehabilitation specialist in determining which deadlift style an athlete or patient should employ.
The deadlift, which measures overall body strength, is the last of three lifts in powerlifting competition. The starting position for the deadlift is with the lifter in a squat position, arms straight and pointing down, and an alternating hand grip used to hold a bar positioned in front of the lifter’s feet. According to the American Drug Free Powerlifting Association (ADFPA) rules at the time of this study, the barbell is lifted upward in a continuous motion until the lifter is standing erect with knees locked and the shoulders thrust back. Causes for disqualification included failure to wait for the referee’s “down” signal at the completion of the lift, any stopping or downward movement of the bar once the bar leaves the lifting platform, failure to stand erect with locked knees and shoulders thrust back, and any “hitching,” bouncing, or resting of the bar against the thighs during the lift. All deadlift trials analyzed in the current study were in accordance with these rules.
Strength athletes, such as American football players, often employ the barbell deadlift in their training or rehabilitation regimens. These athletes use the deadlift to enhance hip, thigh, and back strength. The deadlift is performed using either a conventional or sumo style. The primary differences between these two styles are that the feet are positioned further apart and turned out in the sumo style, and the arms are positioned inside the knees for the sumo style and outside the knees for the conventional style. Stance width, foot angle, and hand width differences between these two styles have not yet been quantified. Although both deadlift styles are used in training, the efficacy of one style over another is unclear.
Because the deadlift is considered a closed kinetic chain exercise (23), it can also be employed in knee rehabilitation programs, such as after anterior cruciate ligament (ACL) reconstruction. Numerous studies have already shown that the squat is an effective exercise during ACL rehabilitation (11,15,20,22,25,26,29). Because the deadlift is performed in a similar manner as the squat, it is hypothesized that the deadlift may provide similar benefits during ACL rehabilitation. The moderate to high hamstring activity that has been reported during the deadlift (28) may help protect the ACL during knee rehabilitation. However, which deadlift style would be most effective in knee rehabilitation has not yet been established.
There are seven known studies that have examined biomechanical variables during the barbell deadlift (2,4,5,8–10,17). Three studies examined lumbar spinal loads (4,5,8), two studies investigated the effects of intra-abdominal and intra-thoracic pressures (9,10), one study quantified joint and segmental angles (17), and the remaining study calculated joint angles and joint moments (2). However, only two studies have compared kinematic or kinetic parameters between sumo and conventional deadlifts (5,17). McGuigan and Wilson (17) performed a kinematic analysis using male lifers from two regional powerlifting championships. The only significant differences they observed were that the sumo group had a more upright trunk and less hip flexion at liftoff, and the shank range of motion was greatest in the sumo group. Cholewicki et al. (5) quantified lumbar loads and hip and knee moments between the sumo and conventional deadlifts during a national powerlifting championship. They found significantly greater L4–L5 shear forces and moments in the conventional group, whereas hip and knee moments were not significantly different between the two deadlift styles. One limitation to all previous deadlift studies was that two-dimensional (2-D) analyses (i.e., one camera employed to record a sagittal view of the lifter) were conducted in quantifying kinematic and kinetic parameters. Although trunk movements through spinal and hip flexion and extension occur primarily in the sagittal plane, flexion and extension movements at the ankle and knee occur in the sagittal plane only if the feet are positioned in that plane (i.e., pointing straight ahead). This is because the ankles and knees primarily function as hinge joints and thus move in the direction the feet point. Therefore, the lower extremities will move out of a sagittal plane as the feet turn outward. These will cause erroneous measurements of lower extremity joint and segment angles, ankle and knee moments, and moment arms. These errors may be minimal during the conventional deadlift, because the feet point either straight ahead or are slightly turned out, but considerable errors can occur during the sumo deadlift, because the feet turn out to a greater degree. Therefore, it was the purpose of this study to compare joint and segment angles and ankle, knee, and hip moments and moment arms using three-dimensional (3-D) analyses during sumo and conventional deadlifts. Mechanical work and predicted energy expenditure was also quantified. A secondary purpose was to compare kinematic and kinetic calculations between 2-D and 3-D analyses for both sumo and conventional deadlifts.
Michael W. Krzyzewski Human Performance Laboratory, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710; American Sports Medicine Institute, Birmingham, AL 35205; and Human Performance Technologies, Inc., Jupiter, FL 33477
Submitted for publication April 1999.
Accepted for publication October 1999.
Address for correspondence: Rafael Escamilla, Ph.D., C.S.C.S., Duke University Medical Center, P.O. Box 3435, Durham, NC 27710; E-mail: email@example.com.