Electromyographic Examination Of Hex Bar Deadlift Variations Differentiated By Starting Knee And Torso Angles.

Multiple variations of the deadlift/hip hinge exercise can be executed using the hexagonal (hex) bar with each variation differentiated, for instance, by starting knee and torso angles while maintaining a constant hip angle. These variations would plausibly accompany alterations to the overall electromyography (EMG) profile; however, no data exists to objectively substantiate these effects. PURPOSE: To examine and compare the muscle activation patterns of the biceps femoris, rectus femoris, and erector spinae during three deadlift/hip and knee extension exercise variations using the hex bar. METHODS: Twenty resistance trained male and female subjects performed deadlift variations using a hex bar in three different starting knee flexion positions: 128.4 ± 8.5 degrees (similar to an elevated Romanian Deadlift), 111.9 ± 8.7 degrees (similar to a conventional elevated deadlift), and 98.3 ± 6.5 degrees (conventional hexagonal bar deadlift). Subjects performed three repetitions at 75% of their three-repetition maximum at a 1-2 second tempo (concentric-eccentric). Electromyography sensors were placed on the dominant biceps femoris, rectus femoris, and lumbar erector spinae of each subject. A one-way repeated measures ANOVA was used to detect significant differences in mean and peak EMG values normalized to maximum voluntary isometric contraction (MVIC) (p<0.05). RESULTS: As knee flexion increased at the starting position, mean activation of the rectus femoris increased (24.7±21.5 to 35.5±25.4 to 62.1±31.3% MVIC, p<0.001), while the biceps femoris (40.6±17.9 to 34.0±16.4 to 28.1±14.5% MVIC, p=0.003) and erector spinae (73.0±27.6 to 65.9±34.4 to 54.9±32.5% MVIC, p=0.009) activation decreased. Peak activations of the rectus femoris also increased (46.9±33.0 to 60.9±38.7 to 99.3±41.6% MVIC, p<0.001) while decreasing in the erector spinae (118.6±47.1 to 105.9±49.4 to 89.1±40.1% MVIC, p=0.008). The rectus femoris experienced the greatest mean differences of the three muscles. CONCLUSIONS: Coaches and practitioners should consider the muscular goals when adjusting the starting position of a hexagonal bar deadlift as posterior chain recruitment diminished as knee flexion increased. Rectus femoris activation increased with increased knee flexion. [ABSTRACT FROM AUTHOR]