Stiff-Legged Barbell Deadlift

The stiff-legged barbell deadlift (SLDL) is a barbell hinge-pattern exercise performed with the knees locked in full extension throughout the movement. This fully-extended knee position places the hamstrings under maximum passive tension during the eccentric descent and increases the horizontal moment arm of the bar relative to the lumbar spine compared to the Romanian deadlift.

Execution

1. Stand holding a barbell at hip height with a double-overhand grip, feet hip-width
2. Lock the knees in full extension and maintain this position throughout
3. Hinge at the hips with a neutral spine; allow the bar to drift slightly away from the legs as you descend
4. Lower until a maximum hamstring stretch is felt or the spine begins to flex
5. Drive the hips forward and extend to return to standing

What the EMG Data Shows

At 70% 1RM (Miranda 2013), the SLDL produces high activation across the posterior chain: gastrocnemius 108.3%, multifidus 106.0%, vastus lateralis 101.1%, and biceps femoris 98.6% (% of mean EMG peak). Values exceeding 100% indicate the muscle contracted harder at some point in the lift than its average dynamic peak — not a methodological error.

The high VL activation (101.1%) in an exercise with locked knees is notable: the quadriceps are not driving knee extension but instead contracting isometrically to prevent knee hyperextension against the forward pull of the hamstrings. This value is nonetheless significantly lower than the conventional deadlift VL (128.3%) in the same study, confirming reduced quadriceps drive in straight-legged variations.

Comparison with the Romanian Deadlift

The SLDL and RDL differ in two key ways: knee angle (0° vs 15–20°) and bar trajectory (drifts forward vs stays against the legs). These differences produce distinct neuromuscular profiles:

• Gluteus maximus: SLDL produces greater GM activation than the standard RDL (Effect Size 0.99, Coratella 2022). The fully-extended knee prevents the hamstrings from contributing to knee stabilization, shifting the hip extensor demand toward the gluteals.
• Semitendinosus: The RDL produces greater semitendinosus activation than the SLDL (ES 1.38). The slight knee flexion of the RDL keeps the medial hamstrings in a mechanically advantageous position for hip extension.
• Spinal load: Forward bar drift in the SLDL increases the horizontal moment arm to the lumbar spine, requiring greater static erector spinae force to maintain spine neutrality.

Variations

Variation	Key difference	Best for
Romanian deadlift	15–20° knee flexion; bar stays against legs	Hamstring-dominant development; lower spinal load
Step-SLDL	Standing on a raised platform	Maximum range of motion for advanced trainees

For system-specific training applications, see each system's lens entry.