Differences in Joint Kinematics and Electromyography Activity among the Conventional, Block, and Deficit Deadlifts

The conventional deadlift (CDL) is a commonly used lower-body exercise that utilizes the legs, hips, back, and trunk muscles. The block deadlift (BDL) and the deficit deadlift (DDL) are two variations that alter the starting position and height of a deadlift, however, there is a lack of literature that examines both. PURPOSE: To quantify and compare joint kinematics and peak muscle activation differences between a CDL, BDL, and DDL. METHODS: Twenty total resistance-trained male and female participants (25.1 ± 3.6 yrs old, 81.0 ± 15.2 kg) performed a one-repetition maximum (1RM) in the CDL on day one. At least 72 hours later, participants performed five repetitions for all three deadlift conditions (deadlift from the floor, 4” block, and 4” deficit) at 70% 1RM of their CDL. A one-way ANOVA was used to assess differences in initial sagittal joint angles and range of motion (ROM) of the ankle, knee, hip, and trunk during the concentric phase of the deadlifts. Muscle activity (peak electromyography) of the vastus lateralis (VL), gluteus maximus (GM), bicep femoris (BF), and the erector spinae (ES) muscles were also assessed. RESULTS: There were significant main effects in initial joint angles and ROM for the ankle, knee, hip, and trunk (p < 0.001 which were all significantly greater in the DDL compared to the CDL and BDL. The same variables were also significantly greater in the CDL than in the BDL. There were significant main effects for the BF (p = 0.010), GM (p < 0.001), and VL (p < 0.001) but not ES (p = 0.371) between the deadlift variations. Peak activation of the BF in the DDL was significantly greater than in the BDL (p = 0.049). Peak activation of the GM was significantly greater in the DDL than in the CDL (p = 0.046) and BDL (p = 0.002). However, there was no significant difference in GM activation between the CDL and BDL. Peak activation of the VL was significantly greater in the DDL compared to both the CDL and BDL (p < 0.001 for both). VL activation in the CDL was also significantly greater than the BDL (p < 0.001). CONCLUSION: Both the BDL and the DDL can be implemented in training programs by athletes and coaches. Each variation can be used to elicit different muscle activation responses of either the BF, GM, or VL.