A three-dimensional biomechanical analysis of sumo and conventional style deadlifts

Purpose: Strength athletes often employ the deadlift in their training or r ehabilitation regimens. The purpose of this study was to quantify kinematic and kinetic parameters by employing a three-dimensional analysis during su mo and conventional style deadlifts. Methods: Two 60-Hz video cameras recor ded 12 sumo and 12 conventional style lifters during a national powerliftin g 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 degrees more for the conventio nal group. The sumo group had 5-10 degrees greater vertical trunk and thigh positions, employed a wider stance (70 +/- 11 cm vs 32 +/- 8 cm), turned t heir feet out more (42 +/- 80 vs 14 +/- 6 degrees), and gripped the bar wit h their hands closer together (47 +/- 4 cm vs 55 +/- 10 cm). Vertical bar d istance, mechanical work. and predicted energy expenditure were approximate ly 25-40% greater in the conventional group. Hip extensor, knee extensor, a nd ankle dorsiflexor moments were generated for the sumo group. whereas hip extensor, knee extensor, knee flexor, and ankle plantar flexor moments wer e generated for the conventional group. Ankle and knee moments and moment a rms were significantly different between the sumo and conventional groups, whereas hip moments and moments arms did not show any significantly differe nces. Three-dimensional calculations were more accurate and significantly d ifferent than two-dimensional calculations, especially for the sumo deadlif t. Conclusions: Biomechanical differences between sumo and conventional dea dlifts result from technique variations between these exercises. Understand ing these differences will aid the strength coach or rehabilitation special ist in determining which deadlift style an athlete or patient should employ .