Electromyographic Examination of Hip and Knee Extension Hex Bar Exercises Varied by Starting Knee and Torso Angles

Variations of the deadlift can be executed using the hexagonal (hex) bar by altering, for instance, the knee and torso angles while maintaining a constant hip angle at the start position.

To examine muscle activation patterns of the biceps femoris, rectus femoris, and erector spinae during three deadlift variations using the hex bar.

Twenty resistance-trained male and female subjects performed hex bar deadlift variations in three different starting knee flexion positions: 128.4 ± 8.5°, 111.9 ± 8.7°, and 98.3 ± 6.5°. Subjects performed three repetitions at 75% of their three-repetition maximum. Electromyography sensors were placed on the dominant biceps femoris, rectus femoris, and lumbar erector spinae. A one-way repeated measures ANOVA was used to detect differences in mean and peak EMG values normalized to maximum voluntary isometric contraction (MVIC) (p < 0.05).

As knee flexion increased at the starting position, mean activation of the rectus femoris increased (24.7 ± 21.5 → 35.5 ± 25.4 → 62.1 ± 31.3% MVIC, p < 0.001), while biceps femoris (40.6 ± 17.9 → 34.0 ± 16.4 → 28.1 ± 14.5% MVIC, p = 0.003) and erector spinae (73.0 ± 27.6 → 65.9 ± 34.4 → 54.9 ± 32.5% MVIC, p = 0.009) activation decreased. Peak activation of the rectus femoris increased (46.9 ± 33.0 → 60.9 ± 38.7 → 99.3 ± 41.6% MVIC, p < 0.001) while decreasing in the erector spinae (118.6 ± 47.1 → 105.9 ± 49.4 → 89.1 ± 40.1% MVIC, p = 0.008). The rectus femoris experienced the greatest mean differences of the three muscles.

Practitioners should consider the muscular goals when adjusting the starting position of a hex bar deadlift as posterior chain recruitment diminished and quadriceps activation increased as knee flexion increased.